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Cancer Patent Abstract
A method of screening for breast cancer, comprising: testing a plurality
of asymptomatic women by measuring at least one electrical impedance
characteristic on at least one breast, said asymptomatic woman being
classified as belonging to a first group having a first risk factor
for breast cancer; and re-classifying some of the women as belonging
to a second group having a second risk factor greater than the first
risk factor, based on the at least one impedance characteristic,
wherein the second group has a risk factor of at least twice that
of the first group, but less than 15 times that of the first group;
and wherein fewer than 60% of those in the first group that have
breast cancer are reclassified into the second group.
Cancer Patent Claims
What is claimed is:
1. A method of screening for breast cancer, comprising: testing
a plurality of asymptomatic women by measuring at least one electrical
impedance characteristic on at least one breast, said asymptomatic
woman being classified as belonging to a first group having a first
risk factor for breast cancer; and re-classifying some of the women
as belonging to a second group having a second risk factor greater
than the first risk factor, based on the at least one impedance
characteristic, wherein the second group has a risk factor of at
least twice that of the first group, but less than 15 times that
of the first group; and wherein fewer than 50% of those in the first
group that have breast cancer are reclassified into the second group.
2. A method according to claim 1, wherein the second group has
a risk factor at least 5 times as high as that of the first group.
3. A method according to claim 1, wherein the second group has
a risk factor at least 10 times as high as that of the first group.
4. A method according to claim 1 wherein the first group consists
of a general population of women between 15 and 40 years old.
5. A method according to claim 4 wherein the first group consists
of a general population of women between 20 and 35 years old.
6. A method according to claim 1 wherein more than 20% percent
of women having cancer in the first group are re-classified in said
second group.
7. A method according to claim 6 wherein more than 25% percent
of women having cancer in the first group are re-classified in said
second group.
8. A method according to claim 6 wherein more than 30% percent
of women having cancer in the first group are re-classified in said
second group.
9. A method according to claim 6, wherein fewer than 40% of women
having cancer in the first group are re-classified in said second
group.
10. A method according to claim 7, wherein fewer than 40% of women
having cancer in the first group are re-classified in said second
group.
11. A method according to claim 8, wherein fewer than 40% of women
having cancer in the first group are re-classified in said second
group.
12. A method according to claim 1, wherein up to 10% of the women
in the first group not having cancer are placed in the second group.
13. A method according to claim 1 wherein between 5% and 10% of
the woman in the first group, not having cancer are placed in the
second group.
14. Apparatus for breast cancer screening, comprising: a probe
for acquiring electrical signals from a breast of a patient, belonging
to a low risk group for breast cancer, having a first risk factor
for having breast cancer; and a processor adapted to determine at
least one dielectric parameter value responsive to signals acquired
by the probe and to classify the patient as to whether she belongs
to a high risk group, having a second risk factor of having breast
cancer greater than the first risk factor, based on the at least
one dielectric parameter, wherein the processor is calibrated to
classify less than 50% of women having cancer detectable by mammography
in the low risk group as belonging to the high risk group and wherein
the high risk group has a risk factor of at least twice that of
the low risk group, but less than 15 times that of the low risk
group.
15. Apparatus according to claim 14, wherein the processor is calibrated
to classify less than 45% of women having cancer detectable by mammography
in the low risk group as belonging to the high risk group.
16. Apparatus according to claim 14, wherein the processor is calibrated
to classify less than 40% of women having cancer detectable by mammography
in the low risk group as belonging to the high risk group.
17. Apparatus according to claim 14, wherein the processor is calibrated
to classify less than 35% of women having cancer detectable by mammography
in the low risk group as belonging to the high risk group.
18. Apparatus according to claim 14, wherein the processor is calibrated
to classify less than 10% of the women in the low risk group as
belonging to the high risk group.
19. A method of screening for breast cancer, comprising: testing
a plurality of asymptomatic women by measuring at least one electrical
impedance characteristic on at least one breast, said asymptomatic
woman being classified as belonging to a first group having a first
risk factor for breast cancer; and re-classifying some of the women
as belonging to a second group having a second risk factor greater
than the first risk factor, based on the at least one impedance
characteristic, wherein fewer than 10% of the women in the first
group are reclassified into the second group.
20. A method according to claim 19, wherein fewer than 50% of the
women in the first group that have cancer are reclassified into
the second group.
Cancer Patent Description
RELATED APPLICATION
The present application is a U.S. national application of PCT Application
No. PCT/IL03/00281, filed on Apr. 3, 2003.
FIELD OF THE INVENTION
The present invention relates to systems for tissue characterization
and particularly for detecting breast cancer.
BACKGROUND OF THE INVENTION
Breast cancer is a major cause of mortality in women. One of the
factors that influence the chances of curing a patient having breast
cancer is early detection of the disease. The major methods for
detecting breast cancer currently in use are X-ray mammography imaging
and ultrasound imaging. In detecting breast cancer, an image of
the breast is generated, using one of these imaging modalities,
and a physician inspects the image to determine whether the image
is indicative of breast cancer. Such inspection of images requires
image analysis specialization from the physician, which adds to
the cost of the cancer detecting procedure and/or limits the availability
of the procedure to relatively large medical centers. Therefore,
in general, only women in high risk groups of breast cancer undergo
tests for early detection of breast cancer. These risk groups include,
for example, women above the age of about 45 and women having a
family history of breast cancer. Generally, different countries
set different ages in which X-ray mammography screening is recommended.
The chances that a woman in a risk group has cancer is usually much
less than 10% and therefore even many women in the risk groups do
not go for regular breast cancer detection procedures as recommended.
For women not in a high risk group, for example in the age group
of 25 45, there are very low chances, in accordance with current
practice, that their cancer will be detected at an early stage.
These women, however, have a chance of about 3 to 1000 of having
breast cancer, which may not be detected until the cancer is in
advanced stages. Women's physicians and aware women perform palpation
tests in search for cancer and woman who have suspected lumps detected
in their breasts by palpitation are sent for further screening by
ultrasound and/or mammography and/or biopsy. However, due to the
low risk within the general population, mammography and/or ultrasound
are not indicated as screening tools for the general asymptomatic
population.
U.S. Pat. No. 5,800,350, to Coppleson et al., the disclosure of
which is incorporated herein by reference, describes a probe adapted
to apply a plurality of stimuli to a suspected tissue. According
to detected responses to the stimuli, the probe provides an indication
of the surface tissue type (e.g., normal, pre-cancerous/cancerous,
unknown) of the suspected tissue. The probe of U.S. Pat. No. 5,800,350
is not suitable for use with the breast, as cancerous cells in the
breast are not generally on the surface of the breast.
An article titled "Breast Electrical Impedance and Estrogen
Use in Postmenopausal Women", G. Piperno, S. Lenington, Mauturitas
41 (2002), the disclosure of which is incorporated herein by reference,
describes a clinical test which suggests a correlation between electrical
measurements on the nipple and estrogen activity in breast tissue.
U.S. Pat. No. 6,122,544 to Organ, the disclosure of which is incorporated
herein by reference, describes a method of identifying cancer by
comparing maps of electrical impedance measurements of the breasts.
The impedance maps (in the form of matrices) of both breasts of
the patient are compared and if a substantial difference is found,
cancer is diagnosed in the breast with the higher impedance. U.S.
patent publication 2002/0123694 to Organ et al., the disclosure
of which is incorporated herein by reference, uses a greater number
of electrodes and attempts to localize the lesion, according to
a region of the map having a different impedance.
U.S. Pat. No. 5,415,164 to Faupel, the disclosure of which is incorporated
herein by reference, describes a self-test method for a breast screening
system based on measurement of passive DC signals from the breast.
As DC signals require long settling times (due to polarization)
before measurements may be acquired, the method includes determining
whether the measured signals are stable before measurement of the
DC signals for breast screening is allowed, so that it is not required
to wait long periods of time when it is not necessary. Such stabilizing
waiting periods are characteristic of DC measurements, especially
in polarizable materials.
U.S. Pat. No. 6,167,300 to Cherepenin, the disclosure of which
is incorporated herein by reference, describes an electric mammography
system for obtaining three dimensional images of the breast. The
system uses a large surface probe, which may include elements that
do not contact the examined breast. These elements are detected
according to the values they sense and are excluded from the reconstruction
of the three dimensional image.
U.S. Pat. No. 6,026,323 to Skaldnev, the disclosure of which is
incorporated herein by reference, describes a probe for characterizing
tissue type, for example for breast cancer examination. The probe
checks for poor contact due to reasons such as the probe being in
an angle to the cervix.
The use of impedance measurements in screening has been mooted
by several authors. However, no such screening method has ever been
shown to be feasible. In particular, screening requires both high
specificity and high sensitivity. In general, it was believed that
in the absence of both high sensitivity and specificity, if screening
was performed on a general population in which the probability of
cancer of the breast is low, either large numbers of women would
be subjected to unnecessary additional tests or many woman with
cancer would be diagnosed as being free of cancer. It should be
noted that mammography, which is used for testing high risk groups
has a high sensitivity but a low specificity as do other modalities
used to "screen" suspect patients.
SUMMARY OF THE INVENTION
In the past, attempts have been made to provide a definitive or
semi-definitive diagnosis for breast cancer based on impedance measurement.
In general, these attempts have failed since they require that the
results have both a high specificity and a high sensitivity. Unfortunately,
impedance imaging methods to date have not been able to provide
such a combination. Impedance imaging has provided a useful adjunct
to conventional diagnostic methods such as mammography and ultrasound
imaging, in which case it can be effective when configured in a
high sensitivity, low specificity mode.
Attempts have been made to utilize impedance imaging as a scanning
tool. To be effective, again, high sensitivity and specificity are
necessary, since false positives result in unnecessary and sometimes
dangerous situations and false negatives can be deadly.
In an aspect of some embodiments of the invention, impedance imaging
is used in a relatively high specificity, relatively low sensitivity
mode. Generally such screening is not considered effective, since
it means that large numbers of false negative indications are provided.
However, for some classes of examinees, such methods can be effective.
In an embodiment of the invention, low risk groups, such as pre-menopausal
women between the ages of 20 and 45, or 25 40, for whom standard
screening is not considered justified, are tested using impedance
techniques. In this group, the occurrence of breast cancer is less
than about 3 4 in 1000. This group is thus not a candidate for normal
mammographic screening, except when there are significant risk factors,
such as having close relatives with breast cancer. Having two first
degree relatives with cancer, which warrants early mammography breast
cancer screening, raises the probability to have cancer by a factor
of 2.9 to about 8.7 in 1000. Diagnosis of atypical hyperplasia raises
the probability by a factor of having cancer to about 12 in 1000
and women identified as carrying a BRCA gene are considered to have
a cancer risk of about 17 in 1000.
However, utilizing a method of the present invention (or some prior
art methods with suitable thresholds), a smaller group can be chosen
from the general population with a higher risk, estimated to be
as high as 11 20 in 1000.
Unlike other screening procedures, which attempt to find patients
who have the disease with relatively high certainty, the present
methodology is used to choose a higher risk group out of a lower
risk group, which will then be screened using more definitive screening.
An aspect of some embodiments of the present invention relates
to a method of identifying groups of women with high risk for breast
cancer. The method includes comparing values of one or more dielectric
parameters determined from signals measured from tested women to
values of those parameters from a learning group of women with and
without cancer. According to the comparison, an indication is made
as to whether the tested women belong to a high risk group for breast
cancer, the women in the high risk group having no more than a 2
5% chance for having cancer. Stated otherwise, women in the high
risk group have a cancer probability 4 10 times greater than asymptomatic
women (i.e., a risk factor of 4 10). The identification of women
as belonging to a high risk group, rather than as either having
or not having cancer symptoms, allows applying tests to selected
portions of the general low risk population who otherwise would
not be examined at all, thus finding a larger percentage of cancerous
women.
In some embodiments of the invention, impedance tests of the present
invention are applied to women in low risk groups who generally
are not instructed to perform screening using other modalities.
Optionally, the impedance tests are performed on asymptomatic women
who have no symptoms requiring additional testing for breast cancer.
Optionally, the impedance tests are performed on pre-menopausal
women and/or women who do not use hormones, as it has been found
that on these groups of women a higher specificity was achieved.
Alternatively or additionally, the impedance tests are performed
on young women (e.g., up to age 40 45), for example in the age group
of 25 40, as the specificity and sensitivity of impedance tests
decrease with age, but the probability of cancer increases with
age. In an exemplary embodiment of the invention, tests are performed
on a smaller age group, for example between 35 45. In some embodiments
of the invention, the impedance tests do not search for a lesion,
but rather search for general impedance characteristics of a malignant
breast.
An aspect of some embodiments of the invention relates to methods
and apparatus for breast screening. In the past, methods utilizing
impedance attempted to determine the location of a lesion or at
least based their determination on methods that depended on the
location of the lesion. This is the basis for most of the breast
imaging methodologies described above.
The present aspect is radically different in that it does not attempt
to determine the site of a cancer, but rather gives a risk score,
which is indicative of whether a cancer is present in a particular
breast tested or in an (optionally) unstated one of a pair of breasts.
Thus, in some embodiments, the score is a global score that does
not even indicate which breast is involved.
This aspect of the invention is made possible by the discovery
of methods that indicate the presence of breast cancer, using impedance
measurements, without utilizing image analysis or array manipulation
of data representing the volume of the breast in the determination.
An aspect of some embodiments of the present invention relates
to providing an indication of the chances of a patient having breast
cancer, at least partially based on a dielectric parameter of a
nipple region of the breast. The term nipple refers herein to the
area including both the nipple tip and the areola.
One theory as to why a measurement in the nipple region has been
found to serve as a relatively good cancer predictor is that breast
cancer often develops in early stages in the ducts of the nipple.
By determining whether a breast includes abnormal impedance values
in the area of the nipple (and in some embodiments, limited to the
areola surrounding the tip of the nipple), a useful indication of
whether the breast includes cancerous or pre-cancerous tissue can
be made available. In addition, the low impedance of the areola
allows for a good "window" into the breast. Therefore,
signals sensed at the nipple can provide an indication for the entire
breast.
An aspect of some embodiments of the present invention relates
to providing an indication of the chances of an asymptomatic patient
having breast cancer, based on one or more local impedance measurements
from one or more breasts of the patient. The local impedance measurements
are used to determine a dielectric parameter representative of the
entire breast or of the patient, under the understanding that many
breast cancer cases affect the impedance of the entire breast and
not only of a local region in which a tumor develops.
In some embodiments of the invention, in order to allow fast screening,
the local impedance measurements are acquired in a limited number
of positions of a probe on the breast, optionally in only a single
positioning. In an exemplary embodiment of the invention, a small
probe, covering less than 20%, or even less than 15% of the breast
is used in the screening and probe is placed in a limited number
of positions, for example in no more than 2 3 positions. Alternatively
or additionally, in order to reduce noise due to irregularities
in the measurement procedure, e.g., gel spreading, probe contact
with the breast, etc., the probe is placed on a plurality of locations
of the breast and in each location a dielectric parameter of the
patient as a whole is determined. The dielectric parameter values
of the different regions are then summed or averaged to reduce the
noise. The weights used in averaging may be equal for all the measurements
or may differ according to the quality of the measurements, for
example as a function of a contact quality measure determined for
the positioning of the probe. Alternatively to averaging the dielectric
parameter values, the raw data collected in some or all of the positions
may be averaged to reduce the noise. Optionally, the positions of
the probe used for collecting the local impedance data are those
which are known to have less noise affects. Such positions are optionally
included in the upper surface of the breast and/or in the surface
of the breast distanced from the other breast, where placing the
probe is relatively simple and therefore involves less measurement
noise.
In those embodiments in which local impedance measurements are
accumulated from a plurality of positions, a value of the same dielectric
parameter (or parameters) is optionally determined for all the probe
positions. Alternatively, different parameters are determined for
different positions.
In some embodiments of the invention, one or more regions of the
breast, such as the nipple and/or areola areas, are identified as
good predictors of breast cancer for the entire breast or even for
both breasts of the patient. The impedance parameters of these regions
are optionally different from the parameters used for other breast
positions.
In some embodiments of the invention, the breast positions include
areas from both breasts of the patient. A score generated based
on the measurements optionally provides an indication on the probability
of the patient having breast cancer without relating to which breast
may have the cancer. One use of the present invention is in screening
and referral to other modalities for further testing and localization
of the lesion, if any. As such, the indication of the breast in
which the lesion is present is less important for screening than
the indication that additional tests are required.
It is noted that it is known in the art that finding LCIS (labula
carcinoma in sito) in a breast can serve as a marker for possible
or future cancers not only in the breast for which it was found.
Without being bound by any explanation, it may be that the sensitivity
of measurements as described herein made in one breast can act as
a indicator for the other breast as well.
In some embodiments of the invention, the score is determined as
an additive function of the values of the dielectric parameters.
Optionally, the additive function comprises an averaging function,
giving the same weight to each of the positions of the probe. Alternatively
or additionally, the averaging function gives different weight to
different positions of the probe, for example according to the proximity
of the positions to the nipple and/or the contact quality at the
position.
An aspect of some embodiments of the present invention relates
to a method of providing a breast cancer risk score to a patient,
based on dielectric measurements. The method includes determining
values for at least first and second dielectric parameters, which
are not directly related to a suspected lesion. In determining the
score, the determined value of the first dielectric parameter is
compared to a threshold, which is selected responsive to the measured
value of the second dielectric parameter.
In some embodiments of the invention, the first and second dielectric
parameters are not related to an impedance map or matrix of the
breast. Alternatively or additionally, they are related to an image
map, but are not related to any suspected or actual position of
a lesion. Optionally, the first parameter comprises a characteristic
frequency, for example a frequency at which the imaginary admittance
has a maximum or one of a predetermined group of frequencies at
which the imaginary admittance has a maximum.
In some embodiments of the invention, the first parameter is a
function of the shape of a high admittance area in the vicinity
of the nipple. This dependence may be additionally to or instead
of the non-imaging methodology described above. In this case the
first parameter would be based on an image, but would not be based
on determination of a suspected cancer site.
In some embodiments of the invention, the second parameter comprises
a phase of the impedance at one or more frequencies, optionally
at the frequency of the second parameter.
In some embodiments of the invention, the patient is classified
as belonging to one of a plurality of groups, each group having
a separate threshold. Optionally, the threshold of each group is
adjusted according to clinical data on other women belonging to
the group. In some embodiments of the invention, the threshold of
each group is adjusted so as to meet a desired specificity and/or
sensitivity of the group. Optionally, the threshold of each group
is a function of the size of the group and the distribution of cancer
cases in the group (according to the value of the first parameter).
The thresholds of the groups are optionally set together so that
the overall specificity and/or sensitivity, for both groups together,
reaches a desired level. Alternatively, the thresholds of all the
groups are set to achieve a same sensitivity.
Various aspects of some embodiments of the invention are related
to methods and apparatus for simplifying the procedures related
to acquiring data for impedance based screening, imaging or diagnosis.
An aspect of some embodiments of the present invention relates
to an apparatus for breast cancer examination, based on AC electrical
signals, which determines an indication on the quality of the contact
between a breast and a probe used to measure electrical signals
from the breast. Although a probe for collecting electrical signals
from the breast is easily placed by an operator as there is generally
easy access of the probe to the breast, a determination of the quality
of the contact is proposed herein to enhance the measurement results.
In some embodiments of the invention, the apparatus includes a
display (or other output unit) that provides an indication on the
quality of the contact of the probe with an examined breast. Optionally,
the apparatus additionally includes a second output unit that provides
an indication on the cancer risk of patients.
In some embodiments of the invention, the display provides a multi-level
(i.e., including at least three different possible values) indication.
Optionally, the multi-level display provides an indication on a
single scale, e.g., ranging from very bad to very good. A physician
operating the apparatus optionally adjusts the placement of the
probe until a sufficient level of contact quality is achieved and
optionally the contact has a stable quality level.
Alternatively or additionally, the multi-level display comprises
an impedance image of the breast under the probe, which image is
determined and/or displayed for analysis of the contact quality
of the probe. In some embodiments of the invention, each pixel in
the image is indicative (single or multi-level) of the contact quality
of one of the elements of a multi-element probe used to acquire
the impedance signals.
In some embodiments of the invention, the apparatus automatically
controls collection and/or analysis of data for cancer risk determination
of the patient, based on the determined contact quality indication.
Optionally, the apparatus automatically determines when the impedance
results are sufficiently stable to allow cancer score determination.
Such stability is especially required when the measurements are
used to provide a score, as opposed to when the measurements are
used for image display, in which case the operator can easily determine
the stability from the displayed image.
An aspect of some embodiments of the present invention relates
to a method of acquiring impedance measurements from a patient,
using a measurement probe. The method includes applying one or more
first electrical signals having a first characteristic, for determining
the quality of the contact between the probe and the patient, and
applying one or more second signals, having a second characteristic
different from the first, for determining at least one dielectric
parameter used to determine a medical state of the patient, and
not for determining the contact quality of the probe. Optionally,
the signals having the first characteristic are not used for determining
the medical state of the patient.
In some embodiments of the invention, the first and second characteristics
comprise different frequencies. Optionally, the first electrical
signals for determining the contact quality include signals at a
plurality of frequencies. The second signals used for determining
the at least one dielectric parameter optionally include fewer frequencies
than the first electrical signals, optionally only two or one frequencies.
Alternatively or additionally, the different frequencies of the
first electrical signal are applied together in a broadband signal,
while the frequencies of the second signals are applied separately
in single band signals.
Alternatively or additionally, the first and second signals differ
in their amplitude. For example, in determining the contact quality,
signals of lower amplitude may be used, as the accuracy may be less
important.
Another method of determining contact quality, in accordance with
an embodiment of the invention utilizes the signal to noise ratio
of electrical signals acquired as an indicator of contact quality.
The method includes acquiring electrical signals from the patient
and determining a signal to noise ratio (SNR) of the acquired signals.
In some embodiments of the invention, a contact quality indication
is determined and displayed, responsive to the SNR. The contact
quality indication may depend solely on the SNR or may depend on
one or more other quality dielectric parameters, such as stability
or the range of the measured values. Optionally, the values of the
one or more dielectric parameters are determined and/or considered
valid only if the SNR has a sufficient value.
An aspect of some embodiments of the present invention relates
to a method of determining a contact quality between a patient and
a probe, used for collecting electrical signals from the patient.
The method includes determining the pressure of the contact between
the probe and the patient and determining the contact quality responsive
to the determined pressure.
An aspect of some embodiments of the invention is related to a
probe having a structure adapted for sensing signals from a nipple
region. In an embodiment of the invention, electrodes having a hole
or depression formed therein with a diameter suitable for insertion
of the tip of the nipple are used. Some of these embodiments utilize
multi-element probes and others utilize a single electrode probe
having a diameter small enough to encompass only areola or a portion
thereof. In an exemplary embodiment of the invention, a probe comprises
two rings of different diameters. A first ring has a small diameter
enough to encompass only the areola or a portion thereof. A second
ring has a larger diameter, such that it does not encompass any
part of the areola, so that the signals it senses represent non-nipple
areas. The signals from the inner ring are used for testing with
the signals from the outer ring used for normalization or other
comparison.
In some embodiments of the invention, the probe includes an additional
ring whose position and size is such that the inner and outer portions
of the areola are measured separately. These measurements may be
compared and/or combined in the risk determination.
In some embodiments of the invention, each ring includes a single
contiguous electrode. Optionally, the width of the rings are adjusted
such that both the rings have substantially the same surface area.
Alternatively or additionally, portions of the larger ring are covered
by an insulator so that the conducting contact area of the rings
with the breast is substantially the same. Further alternatively
or additionally, the rings have different contact areas with the
breast and the collected signal values are adjusted accordingly.
Alternatively to including a single contiguous electrode, one or
both of the rings may include a plurality of sensing elements mounted
on the ring. Using a plurality of elements allows determination
of the contact quality of each element separately, so that elements
without proper contact may be compensated for and/or the contact
may be corrected by an operator.
In some embodiments of the invention, the electrode is a circular,
square, rectangular or other shaped electrode having an area small
enough so that it is only covers a portion of the areola and not
the surrounding tissue or the tip of the nipple.
An aspect of some embodiments of the present invention relates
to determining a breast cancer risk score for a patient. Values
of a dielectric parameter are determined for a plurality of frequencies,
and the score is determined as a function of the values of the different
frequencies. In some embodiments of the invention, the score is
a function of the maximal or average value of the parameter. Performing
the measurements over a plurality of frequencies provides robustness
to the dielectric parameter, in case of a measurement problem for
one or more of the frequencies.
An aspect of some embodiments of the present invention relates
to a method of determining a portion of a breast from which signals
are to be used for determining the state of the breast. The method
includes placing a multi-element probe on the patient, and acquiring
signals at one or more first frequencies. The signals of the one
or more first frequencies are used in selecting a sub-group of the
elements of the multi-element probe, such as the element touching
the areola or those that have poor contact. A value of a dielectric
parameter is determined based on measurements from the selected
elements, at one or more second frequencies, and the dielectric
parameter is used in determining the state of the breast. The second
and first frequencies are generally not the same. Optionally, the
first frequency is a lower frequency.
In some embodiments of the invention, the selected elements are
included in a contiguous region, for example they represent the
areola, which is well differentiated at low frequencies, which have
high contrast between nipple and non-nipple areas. Alternatively,
the selected elements are not necessarily adjacent each other, for
example when the selection is based at least partially on the quality
of the contact.
As used herein, when reference is made to a measurement based on
the nipple or the areola, such measurements may include normalization
and/or comparison to areas out of the nipple.
There is therefore provided in accordance with an embodiment of
the invention, a method of breast examination of a patient, comprising
providing electrical signals to a portion of the patient, sensing
electrical signals from a nipple of a breast of the patient, determining
a value of a characteristic dielectric parameter for the breast,
responsive to electrical signals sensed from the nipple, determining
a cancer risk score responsive to the value of the dielectric parameter,
wherein the dielectric parameter based on nipple signals is treated
differently from any dielectric parameters based on signals sensed
from outside the nipple and providing an indication related to the
cancer risk score to an operator.
Optionally, the dielectric parameter is determined only utilizing
signals sensed at the nipple or areola. Optionally, the cancer risk
is determined only utilizing signals sensed at the nipple and in
an area within 1 cm from the edge of the areola. Optionally, the
cancer risk is determined only utilizing signals sensed at the areola
and in an area within 1 cm from the edge of the areola. Optionally,
the dielectric parameter is determined utilizing signals sensed
at the nipple and at other portions of the breast. Optionally, signals
sensed at different portions of the breast outside the nipple and
the areola are added or averaged in determining the dielectric parameter
of the breast. Optionally, local dielectric parameters are computed
for each portion outside the areola and wherein the characteristic
dielectric parameter is responsive to the sum or average of the
local characteristic values. Optionally, the cancer risk is determined
only utilizing signals sensed by a single placement of a probe on
the breast. Optionally, sensing the electrical signals comprises
sensing through a surface multi-element probe.
There is further provided in accordance with an embodiment of the
invention, a method of breast examination of a patient, comprising
providing electrical signals to a portion of the patient, sensing
electrical signals from an area of the breast, including at least
a portion of the areola, differentiating between signals received
from the areola and regions external to the outer edge of the areola,
determining a value of a first characteristic dielectric parameter
for the breast, responsive to only electrical signals from the nipple,
determining a cancer risk score responsive to the value of the first
dielectric parameter and providing an indication related to the
cancer risk score to an operator.
Optionally, the method includes determining a value of a second
characteristic dielectric parameter for the breast, responsive to
electrical signals sensed at the external regions, the cancer risk
score is responsive to the value of the first and second dielectric
parameter. Optionally, differentiating comprises differentiating
on the basis of at least some of the sensed signals. Optionally,
differentiating comprises determining an outer periphery of the
areola. Optionally, determining the outer periphery comprises finding
an edge on a map of signal values or impedance related values. Optionally,
differentiating comprises differentiating based on low frequency
signals. Optionally, sensing the electrical signals is performed
through a multi-element surface probe and wherein differentiating
comprises selecting pixels having values of a dielectric parameter
above an average value of the pixels by at least a predetermined
margin.
There is further provided in accordance with an embodiment of the
invention, a method of differentiating between portions of the breast,
comprising acquiring electrical signals from a plurality of areas
on the breast, determining impedance values of the plurality of
areas; and differentiating between the nipple and areas outside
the nipple based on the impedance values.
Optionally, differentiating comprises determining an outer periphery
of the areola. Optionally, determining the outer periphery comprises
finding an edge on a map of signal values or impedance related values.
Optionally, differentiating comprises differentiating based on low
frequency signals. Optionally, sensing the electrical signals is
performed through a multi-element surface probe and wherein differentiating
comprises selecting pixels having values of a dielectric parameter
above an average value of the pixels by at least a predetermined
margin.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast cancer screening, comprising a source
electrode adapted to provide electrical signals to the patient,
a multi-element surface probe for sensing electrical signals from
a breast of the patient, a processor operative to determine which
signals were sensed by the probe from an areola area of the breast
of the patient and to calculate a cancer risk score responsive to
the signals sensed from the areola area and an output unit operative
to provide an indication related to the cancer risk score. Optionally,
the processor also determines signals not sensed from an areola
area and provides the score responsive to the signals sensed from
the non-areola area.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast examination of a patient, comprising
a source electrode adapted to provide electrical signals to the
patient, a sensing unit including a surface probe capable of sensing
electrical signals from a nipple area of a breast of the patient,
a processor operative to determine a value of a nipple dielectric
parameter, responsive to electrical signals sensed by the sensing
unit from a nipple area of at least one breast of the patient, and
to calculate a cancer risk score responsive to the value of the
nipple dielectric parameter and an output unit operative to provide
an indication related to the cancer risk score.
Optionally, the processor is adapted to determine which signals
sensed by the sensing unit were acquired from the nipple. Optionally,
the sensing unit is adapted for proper placement on the nipple.
Optionally, the sensing unit includes an indent or hole for receiving
the tip of the nipple, to improve contact of the sensing unit with
the areola. Optionally, the sensing unit comprises an annular probe
of a diameter such that it fits on the areola of patients. Optionally,
the at least one electrode includes at least one ring electrode
centered at the hole or indent. Optionally, the at least one ring
comprises a ring having an outer diameter small enough so that it
sits completely on the areola. Optionally, the at least one ring
comprises a second ring having an inner diameter large enough so
that it does not sit on the areola.
There is further provided in accordance with an embodiment of the
invention, a sensing unit for measurement of the breast impedance,
comprising a base, at least one electrode situated on the base and
an indent or hole for receiving the tip of the nipple, to improve
contact of the sensing unit with the areola.
Optionally, the at least one electrode includes at least one ring
electrode having a centered at the hole or indent. Optionally, the
at least one ring comprises a ring having an outer diameter small
enough so that it sits completely on the areola. Optionally, the
at least one ring comprises a second ring having an inner diameter
large enough so that it does not sit on the areola.
There is further provided in accordance with an embodiment of the
invention, a method of screening for breast cancer, comprising testing
a plurality of asymptomatic women by measuring at least one electrical
impedance characteristic on at least one breast, the asymptomatic
woman being classified as belonging to a first group having a first
risk factor for breast cancer and re-classifying some of the women
as belonging to a second group having a second risk factor greater
than the first risk factor, based on the at least one impedance
characteristic, the second group has a risk factor of at least twice
that of the first group, but less than 15 times that of the first
group and fewer than 60% of those in the first group that have breast
cancer are reclassified into the second group.
Optionally, the second group has a risk factor at least 5 times
or even ten times as high as that of the first group. Optionally,
the first group consists of a general population of women between
15 and 40 years old optionally between 20 and 35 years old. Optionally,
more than 20% percent of women having cancer in the first group
are re-classified in the second group. Optionally, more than 25%
percent of women having cancer in the first group are re-classified
in the second group. Optionally, more than 30% percent of women
having cancer in the first group are re-classified in the second
group. Optionally, fewer than 50% of women having cancer in the
first group are re-classified in the second group. Optionally, fewer
than 40% of women having cancer in the first group are re-classified
in the second group. Optionally, up to 10% of the women in the first
group not having cancer are placed in the second group. Optionally,
between 5% and 10% of the woman in the first group, not having cancer
are placed in the second group.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast cancer screening, comprising a probe
for acquiring electrical signals from a breast of a patient, belonging
to a low risk group for breast cancer, having a first risk factor
for having breast cancer and a processor adapted to determine at
least one dielectric parameter value responsive to signals acquired
by the probe and to classify the patient as to whether she belongs
to a high risk group, having a second risk factor of having breast
cancer greater than the first risk factor, based on the at least
one dielectric parameter, the processor is calibrated to classify
less than 50% of women having cancer detectable by mammography in
the low risk group as belonging to the high risk group and wherein
the high risk group has a risk factor of at least twice that of
the low risk group, but less than 15 times that of the low risk
group.
Optionally, the processor is calibrated to classify less than 45%,
40% or even 35% of women having cancer detectable by mammography
in the low risk group as belonging to the high risk group. Optionally,
the processor is calibrated to classify less than 10% of the women
in the low risk group as belonging to the high risk group.
There is further provided in accordance with an embodiment of the
invention, a method of screening for breast cancer, comprising testing
a plurality of asymptomatic women by measuring at least one electrical
impedance characteristic on at least one breast, the asymptomatic
woman being classified as belonging to a first group having a first
risk factor for breast cancer and re-classifying some of the women
as belonging to a second group having a second risk factor greater
than the first risk factor, based on the at least one impedance
characteristic, fewer than 10% of the women in the first group are
reclassified into the second group. Optionally, fewer than 50% of
the women in the first group that have cancer are reclassified into
the second group.
There is further provided in accordance with an embodiment of the
invention, a method of screening for breast cancer, comprising determining
at least one electrical impedance related characteristic for a breast
of a patient, the at least one impedance characteristic being determined
by impedance measurements at at least one portion of the breast,
without reference to an impedance related map of the breast, except,
optionally, to determine an external feature of the breast to be
used in defining the portion and classifying the patient as requiring
additional testing, responsive to the value of the characteristic.
Optionally, the method includes determining at least one second
electrical impedance related characteristic for a second breast
of the patient, the impedance characteristic being determined by
impedance measurements of a portion of the second breast, without
reference to an impedance related map of the second breast, except,
optionally, to determine an external feature of the breast to be
used in defining the position and classifying the patient as requiring
additional testing, responsive to the value of the first and second
characteristic, wherein classifying is not based on a difference
between the first and second characteristics.
There is further provided in accordance with an embodiment of the
invention, a method of screening for breast cancer, including determining
at least one first electrical impedance related characteristic for
a first breast of a patient, determining at least one second electrical
impedance related characteristic for a second breast of a patient,
and classifying the patient as requiring additional testing, responsive
to the value of the first and second characteristics, wherein classifying
is not based on a difference between the first and second characteristics.
Optionally, classifying is performed for each breast separately
and wherein the patient is classified as requiring further testing
if either breast indicates such further testing. Optionally, the
characteristics for the two breasts are averaged and the classification
is based on the averaged value. Optionally, the at least one portion
of the breast includes one or both of the nipple and areola of the
respective breast. Optionally, the at least one portion is limited
to the nipple and of the respective breast. Optionally, the at least
one portion includes one or more additional portions of the breast
not including the nipple. Optionally, the additional portions are
limited to areas within 1 cm of the areola. Optionally, determining
includes averaging the values of the characteristic measured at
the additional portions. Optionally, the additional portion excludes
the nipple tip. Optionally, the nipple portion is determined by
using an electrode shaped to include only desired regions. Optionally,
a determination of the area of the is made based on an impedance
map. Alternatively or additionally, a determination of the area
of the nipple is made based on an impedance map. Optionally, classifying
the patient comprises providing a binary rating on whether the patient
belongs to a high risk group. Optionally, classifying the patient
comprises providing a multi-level rating.
Optionally, the patient is originally classified as being in a
first risk group having a first risk factor and wherein classifying
comprises re-classifying the patient as a member of a second risk
group, for which a diagnosis is not made, but for which the risk
justifies the additional testing, the second risk group having a
second risk factor greater than the first risk factor. Optionally,
the second group has a risk of greater than 2 but less than 15,
the first risk factor.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast cancer screening, comprising an
electrode for applying electrical signals to a patient, a probe
for acquiring impedance signals from a breast of the patient, responsive
to signals applied from the electrode, a processor adapted to determine
at least one electrical impedance related characteristic for the
breast of the patient, responsive to signals acquired by the probe,
without reference to an impedance related map of the signals acquired
by the probe, except, optionally, to classify signals acquired by
the probe as to an external feature of the location from which the
signals were collected, and to determine a score as to whether the
patient belongs to a high risk group responsive to the determined
at least one characteristic; and an output unit adapted to provide
an indication as to whether the patient belongs to a high risk group.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast cancer screening, including a probe
for acquiring electrical signals from the breasts of a patient and
a processor adapted to determine for each breast of the patient
a respective dielectric parameter value of the breast, responsive
to signals acquired by the probe and to classify the patient as
to whether additional testing is required, responsive to the values
of the determined parameter values, wherein the classifying is not
based on a difference between the parameter values.
Optionally, the processor determines values of the same dielectric
parameter for both breasts. Optionally, the processor is adapted
to classify the patient as to whether additional testing is required,
without relation to an impedance map of the breasts. Optionally,
the processor is adapted to classify the patient based on an additive
function of the parameter values of the breast. Optionally, the
processor is adapted to classify each breast separately and the
patient is classified as requiring further testing if either breast
is classified as requiring further testing. Optionally, the processor
is adapted to classify each breast separately and the patient is
classified as requiring further testing based on an average of the
classifications of the two breasts.
There is further provided in accordance with an embodiment of the
invention, a method of providing a breast cancer risk score for
an asymptomatic patient, comprising applying electrical signals
to the asymptomatic patient, acquiring electrical signals from the
breast, responsive to the applied signals, determining a value of
a first dielectric parameter based on the acquired signals, determining
a value of a second dielectric parameter, responsive to the acquired
signals, selecting a threshold to which the second dielectric parameter
is to be compared, responsive to the value of the first parameter;
and determining a breast cancer risk score, by comparing the dielectric
parameter to the selected threshold.
Optionally, determining the first dielectric parameter comprises
determining a frequency characteristic of the dielectric parameter.
Optionally, determining the first dielectric parameter comprises
determining a peak frequency of an imaginary portion of an admittance
determined from the acquired signals. Optionally, determining the
second frequency comprises determining at the phase of the admittance
at the determined peak frequency. Optionally, determining the first
dielectric parameter comprises determining a parameter without relating
to an impedance map of the breast, other than to determine an external
feature of a portion of the breast at which the signals are acquired.
Optionally, acquiring the signals comprises acquiring through a
surface multi-element probe and wherein determining the first dielectric
parameter comprises determining a parameter without comparing values
determined from different elements of the probe, other than to determine
an external feature of a portion of the breast at which the signals
are acquired. Optionally, determining the second dielectric parameter
comprises determining a phase parameter.
Optionally, selecting the threshold comprises determining a group
to which the patient belongs based on the first parameter and selecting
the threshold responsive to the determined group. Optionally, the
threshold responsive to the determined group is generated based
on clinical data of the determined group. Optionally, the threshold
is selected so that the score has a high specificity.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast cancer screening, including a probe
for acquiring electrical signals from a breast of a patient and
a processor adapted to determine first and second dielectric parameter
values responsive to signals acquired through the probe, without
relation to an impedance map of the breast, to select a threshold
based on the first parameter value and to provide a breast cancer
risk score responsive to a comparison of the value of the second
parameter value to the threshold.
There is further provided in accordance with an embodiment of the
invention, apparatus for providing a clinical indication on a breast
of a patient, comprising a source of electrical signals adapted
to apply AC electrical signals to the patient, a probe adapted to
acquire AC electrical signals from the patient, responsive to the
applied signals, a processor adapted to determine a contact quality
level of the contact between the probe and the patient, responsive
to signals acquired by the probe, a first output element adapted
to provide an indication of the determined contact quality level.
Optionally, the first output element is connected to a signal acquiring
unit, such that the processor automatically acquires information
suitable for providing a clinical indication of the health of the
patient when the determined contact is above a predetermined contact
quality level. Optionally, the first output element comprises a
human interface. Optionally, the first output unit is adapted to
provide an indication on a multi-scale level of at least three possible
values.
Optionally, the probe comprises a multi-element probe and wherein
the first output unit is adapted to provide an image of contact
quality indication, including a pixel corresponding to the contact
quality of substantially each element of the probe. Optionally,
the contact quality level is responsive to a predetermined plurality
of consecutive similar measurements which are made and which show
a stable acquired signal level. Optionally, the probe is a multi-electrode
probe and wherein the contact quality level for the probe is responsive
to the number of the electrodes that make quality contact. Optionally,
the contact quality level is responsive to a measured pressure of
the probe against the breast. Optionally, the contact quality level
is responsive to a signal to noise level of the signals. Optionally,
the apparatus includes a second output element adapted to provide
an indication on the medical state of the breast.
There is further provided in accordance with an embodiment of the
invention, a method of acquiring electrical signals from a patient,
comprising placing a probe on a surface of the patient, applying
first source electrical signals having a first characteristic to
the patient, acquiring first acquired electrical signals by the
probe responsive to the applied first source electrical signals,
applying second electrical signals having a second characteristic,
different from the first characteristic, to the patient, acquiring
second acquired electrical signals by the probe responsive to the
applied second source electrical signals, determining a contact
quality of the probe responsive to the first acquired signals, but
not responsive to the second acquired electrical signals and providing
an indication on a medical state of the patient, responsive to the
second acquired electrical signals.
Optionally, the indication on the medical state of the patient
is determined without relation to the acquired first acquired electrical
signals. Optionally, applying the applied electrical signals of
the first characteristic comprises applying an electrical signal
including a plurality of frequencies concurrently. Optionally, applying
the applied electrical signals of the second characteristic comprises
applying signals including one or more frequencies, each frequency
signal being applied separately. Optionally, the signals having
the first and second characteristics differ in amplitude. Optionally,
the signals having the first characteristic include at least one
frequency not included in the signals of the second characteristic.
Optionally, the signals having the second characteristic include
at least one frequency not included in the signals of the first
characteristic. Optionally, the contact quality level is responsive
to a predetermined plurality of consecutive similar measurements
which are made and which show a stable acquired signal level. Optionally,
the probe is a multi-electrode probe and wherein the contact quality
level for the probe is responsive to the number of the electrodes
that make quality contact.
Optionally, the contact quality level is responsive to a measured
pressure of the probe against the breast. Optionally, the contact
quality level is responsive to a signal to noise level of the acquired
signals. Optionally, the contact quality level is responsive to
the acquired signals having values within a predetermined range.
There is further provided in accordance with an embodiment of the
invention, a method of determining a quality of contact of a probe
to a patient, comprising placing a probe on a surface of the patient,
applying electrical signals to the patient acquiring electrical
signals by the probe responsive to the applied electrical signals,
determining a signal to noise ratio of the acquired signals and
determining a contact quality of the probe responsive to the signal
to noise ratio. Optionally, the probe comprises a multi-element
probe and wherein the signal to noise ratio is determined as the
minimal ratio determined for a plurality of the elements.
There is further provided in accordance with an embodiment of the
invention, a method of determining a quality of contact of a probe
to a patient, comprising placing a probe adapted to acquire electrical
signals for medical diagnosis on a surface of the patient, determining
a parameter of the pressure of the probe on the surface of the patient
and determining a contact quality of the probe responsive to the
determined pressure parameter.
Optionally, the method includes acquiring electrical signals from
the patient through the probe, responsive to the contact quality
having a sufficient level. Optionally, acquiring the electrical
signals comprises acquiring automatically responsive to the contact
quality having a sufficient level.
There is further provided in accordance with an embodiment of the
invention, apparatus for acquiring electrical signals from a patient,
comprising a probe including a plurality of sensing elements adapted
to sense electrical signals, at least one pressure sensor adapted
to determine the pressure of the probe on a patient surface and
an output element adapted to provide an indication of the contact
quality level of the probe responsive to readings of the at least
one pressure sensor.
Optionally, the at least one pressure sensor is mounted on the
probe. Optionally, at least one of the sensing elements is mounted
on a base of the probe through a pressure sensor.
There is further provided in accordance with an embodiment of the
invention, a method of determining a contact quality of a probe
to a patient, comprising placing a probe on a surface of the patient,
applying electrical AC signals to the patient, repeatedly acquiring
AC signals through the probe, responsive to the applied signals
and determining a contact quality of the probe on the surface, responsive
to the stability of the values of the repeatedly acquired AC signals.
Optionally, determining the contact quality comprises determining
that the contact quality is sufficient responsive to receiving similar
values in at least 10 repeated acquired signals.
There is further provided in accordance with an embodiment of the
invention, apparatus for acquiring electrical signals from a patient,
comprising a probe suitable for placement on a surface of the patient,
a source electrode that is suitable for applying electrical applied
signals to a patient, the applied signals being suitable for impedance
measurements, a controller that in a first mode is operative to
apply first applied electrical signals having a first characteristic
to the patient, acquire first acquired electrical signals by the
probe responsive to the first applied electrical signals; and determine
a contact quality of the probe responsive to the first acquired
signals; and in a second mode is operative to apply second applied
electrical signals having a second characteristic, different from
the first characteristic, to the patient, acquire second acquired
electrical signals by the probe responsive to the applied second
electrical signals and provide an indication on a medical state
of the patient, responsive to the acquired second electrical signals,
the determination of contact quality is not responsive to the second
electrical signals.
Optionally, the controller determines the indication on the medical
state of the patient without relation to the first acquired electrical
signals. Optionally, the electrical signals of the first characteristic
comprise an electrical signal including a plurality of frequencies
applied concurrently. Optionally, electrical signals of the second
characteristic comprise signals including one or more frequencies,
each frequency signal being applied separately. Optionally, the
signals of the first and second characteristics differ in amplitude.
Optionally, the signals of the first characteristic include at least
one frequency not included in the signals of the second characteristic.
Optionally, the signals of the second characteristic include at
least one frequency not included in the signals of the first characteristic.
Optionally, the controller determines the contact quality level
responsive to a predetermined plurality of consecutive similar measurements
which are made and which show a stable acquired signal level. Optionally,
the probe is a multi-electrode probe and wherein the controller
determines the contact quality level for the probe responsive to
the number of the electrodes that make quality contact.
Optionally, the apparatus includes a pressure sensor and wherein
the controller determines the contact quality level responsive to
a measured pressure of the probe against the breast. Optionally,
the controller determines the contact quality level responsive to
a signal to noise level of the signals. Optionally, the controller
determines the contact quality level responsive to the signals having
values within a predetermined range. Optionally, the controller
acquires the electrical signals automatically responsive to the
contact quality having a sufficient level.
There is further provided in accordance with an embodiment of the
invention, apparatus for determining quality of contact of a probe
with a patient, comprising a probe suitable for placement on a surface
of the patient, a source electrode that is suitable for applying
electrical applied signals to a patient, the applied signals being
suitable for impedance measurements, a controller that is operative
to apply electrical signals to the patient via the source electrode,
acquire electrical signals via the probe responsive to the applied
electrical signals and determine a contact quality of the probe
responsive to a signal to noise level of the acquired signals.
Optionally, the probe comprises a multi-element probe and wherein
the signal to noise ratio is determined as the minimal ratio determined
for a plurality of the elements. Optionally, the controller acquires
electrical signals for determining a medical state of the patient
automatically responsive to the signal to noise level having a sufficient
level.
There is further provided in accordance with an embodiment of the
invention, a method of breast examination of an asymptomatic patient,
comprising providing electrical signals to a patient, sensing electrical
signals from a plurality of non-adjacent breast areas of the patient,
responsive to the provided electrical signals, combining the sensed
electrical signals without comparing the signals sensed in different
areas, determining a value of a characteristic dielectric parameter
for the breast, responsive to the combined sensed electrical signals,
determining a cancer risk score responsive to the value of the characteristic
dielectric parameter and providing an indication related to the
cancer risk score.
There is further provided in accordance with an embodiment of the
invention, a method of breast examination of a patient, comprising
providing electrical signals to a patient, sensing electrical signals
from a plurality of breast areas of the patient, responsive to the
provided electrical signals, determining a value of a characteristic
dielectric parameter for each of the breast areas, responsive to
the sensed electrical signals of the respective area, combining
the values of the characteristic dielectric parameters without comparing
the values of different areas, determining a cancer risk score responsive
to the combined value of the characteristic dielectric parameter;
and providing an indication related to the cancer risk score.
There is further provided in accordance with an embodiment of the
invention, a method of breast examination of a patient, comprising
providing electrical signals to a patient, sensing electrical signals
from a plurality of breast areas of the patient, responsive to the
provided electrical signals, determining a value of a characteristic
dielectric parameter for each of the breast areas, responsive to
the sensed electrical signals of the respective area, determining
a cancer risk score for at least some of the areas responsive to
the value of the characteristic dielectric parameter of the area,
combining the scores of the different areas; and providing an indication
related to the combined score.
Optionally, combining comprises combining using an additive function.
Optionally, combining comprises averaging or summing. Optionally,
combining comprises combining using a weighted average. Optionally,
the characteristic dielectric parameter comprises a characteristic
frequency. Optionally, the characteristic dielectric parameter comprises
an impedance or admittance value. Optionally, the characteristic
dielectric parameter comprises an impedance phase. Optionally, providing
the score comprises providing a binary indication of whether the
patient should be referred for further diagnostic testing. Optionally,
providing the score comprises providing a score on a multi-level
scale. Optionally, the plurality of areas comprise different pixels
corresponding to sensing elements of a multi-element surface probe
through which the signals are sensed. Optionally, the plurality
of areas comprise areas corresponding to different substantially
non-overlapping placements of a multi-element surface probe through
which the signals are sensed. Optionally, the areas comprise multi-pixel
areas.
Optionally, the areas comprise areas which differ in at least one
external parameter not related to whether the breast is cancerous.
Optionally, the plurality of areas comprise areas on a single breast.
Optionally, the plurality of areas comprise at least two areas on
different breasts of the patient. Optionally, the plurality of areas
comprise at least one areola area and at least one non-areola area.
Optionally, the patient is an asymptomatic patient.
There is farther provided in accordance with an embodiment of the
invention, apparatus for breast examination of a patient, comprising
a source electrode adapted to apply electrical signals to the patient,
a probe for sensing electrical signals from a plurality of non-adjacent
breast areas of the patient, responsive to signals applied by the
source electrode, a processor adapted to combine the sensed signals
from the plurality of areas, without comparing the signals sensed
from different areas and to calculate a cancer risk score responsive
to the combined signals; and an output unit operative to provide
an indication related to the cancer risk score.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast examination of a patient, comprising
a source electrode adapted to apply electrical signals to the patient,
a probe for sensing electrical signals from a plurality of breast
areas of the patient, responsive to signals applied by the source
electrode, a processor adapted to determine a value of a characteristic
dielectric parameter for each of the breast areas, responsive to
the sensed electrical signals of the respective area, to combine
the values of the characteristic dielectric parameters without comparing
the values of different areas, and to calculate a cancer risk score
responsive to the combined values; and an output unit operative
to provide an indication related to the cancer risk score.
Optionally, the characteristic dielectric parameter comprises a
characteristic frequency.
There is further provided in accordance with an embodiment of the
invention, apparatus for breast examination of a patient, comprising
a source electrode adapted to apply electrical signals to the patient,
a probe for sensing electrical signals from a plurality of breast
areas of the patient, responsive to signals applied by the source
electrode, a processor adapted to determine a cancer risk score,
indicating a probability of the patient having breast cancer, for
each of the breast areas, responsive to the sensed electrical signals
of the respective area, and to calculate a combined cancer risk
score responsive to the cancer risk scores of the areas and an output
unit operative to provide an indication related to the cancer risk
score.
There is further provided in accordance with an embodiment of the
invention, a method of determining a value of a dielectric parameter,
characteristic of a medical state of a patient, comprising placing
a multi-element probe on the breast of the patient, acquiring electrical
signals at one or more first frequencies, from the patient through
the probe, selecting a sub-group of elements of the probe responsive
to the acquiring electrical signals at the one or more first frequencies;
and determining a value of a dielectric parameter, based on signals
acquired by the selected sub-group of elements, at one or more second
frequencies, the first and second frequencies are not all the same.
There is further provided in accordance with an embodiment of the
invention, a method of determining a dielectric parameter of a patient,
comprising applying electrical signals of a plurality of frequencies
to the patient, acquiring electrical signals from the patient responsive
to the applied electrical signals, determining a value of a dielectric
parameter, for each of the plurality of frequencies, responsive
to the acquired electrical signals, calculating an average of the
values of the dielectric parameter over the plurality of frequencies
and providing a cancer risk score to the patient responsive to the
calculated average.
Optionally, determining the value of the dielectric parameter comprises
determining a value of a parameter not requiring analyzing an image.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary non-limiting embodiments of the invention will be described
with reference to the following description of the embodiments,
in conjunction with the figures. Identical structures, elements
or parts which appear in more than one figure are preferably labeled
with a same or similar number in all the figures in which they appear,
and in which:
FIG. 1 is a schematic illustration of a breast examination system,
in accordance with an exemplary embodiment of the present invention;
FIG. 2 is a flowchart of acts performed by a scanning operator
during a cancer screening procedure, in accordance with an exemplary
embodiment of the present invention;
FIG. 3 is a schematic illustration of a patient's breasts and the
positions thereon for placing an impedance probe, in accordance
with an exemplary embodiment of the invention;
FIG. 4 is a schematic flowchart of acts performed by a breast examination
system in determining a breast screening score, in accordance with
a first exemplary embodiment of the invention;
FIG. 5 is a schematic graph of the ratio of background region to
areola region admittance as a function of frequency, as determined
in clinical tests;
FIG. 6A is a schematic comparative graph of the real part of the
admittance of healthy and cancerous breasts, based on simulations
and field tests;
FIG. 6B is a schematic comparative graph of the imaginary part
of the admittance of healthy and cancerous breasts, based on simulations
and field tests; and
FIG. 7 is a bottom view of a breast examination probe, in accordance
with an exemplary embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
FIG. 1 is a schematic illustration of a breast examination system
100, in accordance with an exemplary embodiment of the present invention.
Breast examination system 100 comprises a source electrode 104 adapted
to apply electrical signals to a patient and a surface probe 102
adapted to sense electrical signals, induced by the applied signals,
from a breast of a patient. Electrode 104 may comprise, for example,
a hand held cylinder which is held by the patient and provides electrical
signals to the patient through the hand.
Surface probe 102 optionally comprises a multi-element probe which
includes a plurality of sensing elements 106. For clarity of FIG.
1, only a limited number of sensing elements 106 are shown. Although
in some embodiments of the invention, only such a limited number
of elements is used, in other embodiments of the invention more
elements are used. The term surface probe refers herein to a probe,
which fits on a single continuous surface of the breast. The element
of a multi-element surface probe fit on a continuous surface of
the breast, such that the elements are optionally distanced from
each other by no more than about 2 4 times the size of the elements,
usually by less than the size of the elements. Surface probe 102
is optionally of a size that covers a small portion of an average
breast, for example 5 20%, since as described below, probe 102 optionally
collects signals from one or more representative regions of the
breast, rather than imaging the entire breast. Imaging the entire
breast generally requires a relatively long procedure. Sensing elements
106 optionally have a small area, smaller than required for the
accuracy of the procedure described below. The small area elements
are optionally used in order to allow examination of their contact
to the breast, before their values are used in the calculation procedure.
For example, local contact problems may be due to small air bubbles.
Alternatively or additionally, measurements from the small elements
may be used to delineate the areola. In an exemplary embodiment
of the invention, sensing elements 106 have an area of about 4.times.4
millimeters and are distanced from each other by about 0.4 mm.
In an exemplary embodiment of the present invention, surface probe
102 comprises a square, e.g., 8.times.8 or 16.times.16, array of
sensing elements 106. Alternatively, surface probe 102 comprises
a rectangular array of sensing elements. Further alternatively,
the elements of surface probe 102 are organized in other shapes,
for example in a circular shape.
In some embodiments of the invention, an additional electrode 108
is placed on the trunk of the patient's body closer to the breast
than the source electrode 104. The additional electrode is optionally
used to measure the voltage at a point close to the breast and thus
cancel the effect of the path from source electrode 102 to the breast,
and the contact impedance of source electrode 104, from the calculations.
Alternatively or additionally, any other normalization methods are
used, for example those described in U.S. patent application Ser.
No. 10/033,017, entitled Diagnosis probe, filed 22 Oct. 2001, the
disclosure of which is incorporated by reference.
In some embodiments of the invention, system 100 further comprises
an electrical impedance scanning device 58 which controls the sensing
of the impedance signals by sensing elements 106 and/or the applying
of electrification signals to the patient from electrode 104. Scanning
device 58 may be substantially any suitable electrical impedance
scanning device known in the art, for example, a T-Scan.TM. 2000
Impedance Scanner marketed by TransScan, Israel, or any of the scanners
described in U.S. Pat. Nos. 5,810,742, 4,458,694, PCT applications
PCT/IL00/00127, PCT/IL00/00839 and/or U.S. patent application Ser.
No. 09/460,699, the disclosures of which documents are incorporated
herein by reference.
A processor 110 optionally receives the signals sensed by sensing
elements 106 and determines therefrom, a malignancy score of the
examined breast, as described below. An output unit 116 optionally
provides an indication of the malignancy score to the operator.
In some embodiments of the invention, output unit 116 provides a
binary score having only two possible values (e.g., "OK"
or "high risk"). Optionally, output unit 116 includes
an indicator which lights up, for example, an indicator light, stating
that the tested patient is in a high risk group. Alternatively or
additionally, output unit 116 includes different color indicators,
which indicate different test results. For example a green light
may indicate that the patient is not classified as belonging to
a high risk group and a red light indicates that the patient belongs
to a high risk group. In some embodiments of the invention, output
unit 116 includes a LED display that states, for example, "additional
tests" or "OK", as appropriate. Alternatively or
additionally, output unit 116 includes other output interfaces,
such as a speaker that provides sound indications. Alternatively
or additionally, the malignancy score is selected from a multi-value
scale.
In an exemplary embodiment of the invention, the malignancy score
does not indicate the location of a possible anomaly. In some embodiments
of the invention, system 100 does not attempt to determine the location
of an anomaly but only to provide a general indication as to whether
such an anomaly exists. Alternatively or additionally, system 100
does not relate directly to whether an anomaly exists but rather
identifies a high risk population group, which requires periodic
tests for breast cancer.
In addition to a score output, output unit 116 optionally provides
one or more indications of the quality of the contact between surface
probe 102 and the examined breast, as discussed in detail below.
In some embodiments of the invention, processor 110 is included
in a single housing 112 with surface probe 102, output unit 116
and impedance scanning device 58. Optionally, housing 112 includes
a socket adapted to connect to electrode 104. In some embodiments
of the invention, housing 112 includes a compartment not shown)
adapted to receive electrode 104 when not in use. Alternatively
to including surface probe 102 in housing 112, housing 112 includes
a socket adapted to connect to surface probe 102. Thus, the replacement
of surface probe 102 is simplified, for example, if one-time surface
probes 102 are used. Further alternatively, housing 112 includes
a permanently connected cable for attachment to surface probe 102
or permanently connected to surface probe 102. Alternatively, scanning
device 58 is included with probe 102, separate from processor 110.
Optionally, system 100 is light weight and/or portable, allowing
simple movement of the system between locations. In some embodiments
of the invention, housing 112 requires a relatively small space
volume, such that it may be used, for example, in every physician's
office, without requiring a large amount of storage space. System
100 is optionally of relatively low cost to further facilitate its
wide distribution.
It is noted that the measurements performed using system 100 do
not use ionizing radiation and are not significantly painful. Therefore,
these tests are not expected to be objected to by patients. By having
system 100 widely distributed, for example, in every women physician's
clinic, the tests of system 100 may be applied to a relatively large
percentage of the population, which visits physicians for periodic
checkups and/or for other reasons.
FIG. 2 is a flowchart of acts performed by a scanning operator
during a cancer screening procedure, in accordance with an exemplary
embodiment of the present invention. Surface probe 102 is optionally
pressed (200) against a central surface of breast 120, including
the nipple. In some embodiments of the invention, the operator actuates
(202) a testing of the contact quality of the probe. As discussed
below, the contact quality testing optionally includes measuring
electrical signals through the elements of probe 102 and checking
that the measured values adhere to one or more predetermined requirements.
The results of the contact quality testing are optionally displayed
by output unit 116.
The operator optionally adjusts (204) the placement of probe 102,
if necessary, until the contact quality is sufficient and stable.
When a sufficient and stable contact quality is achieved, the operator
actuates (206) a screening impedance measurement from the current
position of probe 102. Alternatively, the screening impedance measurement
is actuated automatically by system 100, when the contact quality
is suitable. In some embodiments of the invention, probe 102 is
moved (208) to one or more additional positions on the breast, and
the actuating of the contact quality testing (202), the adjusting
of the position (204) and the actuation of the screening impedance
measurement (206) are repeated for each position of probe 102. Based
on the measurements from the positioning on the nipple and the one
or more other positions, an indication on whether the patient belongs
to a high risk group for breast cancer, is optionally provided (210)
through output unit 116.
In some embodiments of the invention, the method of FIG. 2 is used
in conjunction with palpation. Optionally, a physician first performs
palpation and if the palpation does not indicate a need of further
tests, impedance tests in accordance with the method of FIG. 2 are
carried out. Alternatively or additionally, impedance testing is
performed before the palpation, so that the unrest of the breast
in the first few minutes after palpation does not affect the impedance
testing. In some embodiments of the invention, the impedance tests
are performed twice or more and the highest cancer risk score from
all the tests is used. Alternatively, the lowest score or the average
score is used.
The method of FIG. 2 is optionally applied to asymptomatic women,
who have a low probability of having cancer. The group of asymptomatic
women is so large that it is generally not feasible to apply more
expensive modalities (X-ray mammography, ultrasound) to all the
women in the group. Using the method of FIG. 2, a high risk group
can be identified which has a probability of having cancer higher
by a factor of between about 2 20 than asymptomatic women. Alternatively
or additionally, the method of FIG. 2 is applied to other groups
of women who have low probabilities of having cancer, even if greater
than the probability of asymptomatic women. Such groups may include
women of specific ages, races, genetic data, disease family history,
etc. The groups to which the impedance screening methods are applied
are optionally groups which are too large to undergo X-ray mammography
or which otherwise do not generally undergo mammography testing.
The fact that a significant percentage of women who have cancer
are missed, is offset by the numbers of women who would never undergo
testing who are referred to such testing based on the present methodology.
While an impedance test is used in the exemplary embodiments of
the invention, the idea of using a low sensitivity, relatively high
selectivity test on low risk asymptotic women can be applied in
other modalities in which thresholds can be set to provide a significant
sensitivity (>30, 35, 40 or 50%) and a relatively high selectivity
(>90 95%). While such tests would not be definitive, they would
increase the risk factor so that further testing would be indicated.
In some embodiments of the invention, the method of FIG. 2 is applied
to young women as tests show that it is more effective on young
women. In preliminary test results it has been found that the sensitivity
for women below age 40 is about 60%, for women between 40 45 is
about 29% and for women above 45 is only about 8%. On the other
hand, the number of very young women (e.g., below 20 years) with
breast cancer is very small such that it mat not be effective to
scan all the women below age 20, even with system 100 which allows
simple use. Therefore, in some embodiments of the invention, the
method of FIG. 2 is recommended for women between the ages 20 45
or ages 25 40. It is noted, however, that the method of the present
invention may be used on groups of older women who do not go for
screenings of other modalities, provided that they will go for such
screening if so recommended by system 100. If used for older women,
the thresholds discussed below may be set to a lowest specificity
that will still cause women to go for further tests if they are
identified as belonging to a high risk group, so as to increase
the sensitivity of the system.
FIG. 3 is a schematic illustration of a patient's breasts and the
positions thereon for placing an impedance probe, in accordance
with an exemplary embodiment of the invention. Optionally, the right
breast 302 and the left breast 304 are each virtually divided into
nine sectors (marked 306A, 306B, . . . , 306I) of substantially
the same surface area as probe 102. Optionally, measurements are
acquired from a central sector 306E covering nipple 310. In some
embodiments of the invention, measurements are gathered from one
or more of the other sectors, for example from 3 4 out of 8 sectors.
Optionally, the operator may select the additional sectors according
to their convenience and/or according to where high contact testing
scores are achieved. Alternatively, a predetermined set of sectors,
for example, the three top sectors 306A, 306B and 306C and the external
center sector 306D, are used for all patients, in order to achieve
comparison between patients in similar conditions. The use of the
top and central external sectors is generally easier, as these sectors
allow easier access for probe 102.
In those embodiments in which measurements are acquired from a
plurality of placements of probe 102 on different locations of the
breast, the operator is optionally instructed to use a predetermined
order of measurements so that the compared test results are acquired
in as similar as possible conditions. Alternatively, the operator
may actuate the measurements in any order. Optionally, an input
interface receives from the operator an indication of the location
on which probe 102 is placed. Alternatively, processor 110 automatically
determines whether probe 102 was placed on central sector 306E,
which includes the nipple, based on the impedance differences between
the nipple and other breast areas.
It is noted that in accordance with some embodiments of the present
invention it is not necessary to measure signals from the entire
breast, as signals indicating that the examined patient belongs
to a high risk group would appear throughout the entire breast and/or
in a specific locality, such as around the nipple, and not necessarily
in an area in which a malignant tumor develops.
In some embodiments of the invention, the procedure of FIG. 2 is
performed for both breasts, and a separate score is given for each
breast. Alternatively, a single score is provided for both breasts,
the score being additive of the effects of both breasts or being
a maximum or other function of the effects of both breasts. This
alternative is based on the fact that the impedance effects which
are indicative of having a high risk of breast cancer appear in
some cases in both breasts in parallel, regardless of the breast
in which a malignant tumor may develop. Further alternatively or
additionally, the procedure of FIG. 2 is performed on only one of
the breasts. Optionally, the patient or operator may select which
breast is to be tested. Alternatively, the tests are always applied
to a specific one of the breasts, e.g., the right breast.
Referring in more detail to pressing (200) probe 102 against the
breast, optionally, a disposable gel interface, for example as described
in PCT patent publication WO 01/64102, entitled Uniform, Disposable,
Interface for Multi-Element Probe (the disclosure of which is incorporated
by reference) is placed between probe 102 and the breast, so as
to provide good electrical contact between probe 102 and the breast,
while preventing direct contact between the probe and the breast,
allowing safe use of probe 102 with a plurality of patients. Alternatively
or additionally, probe 102 comprises a disposable breast interface,
as described for example in U.S. Pat. No. 5,810,742 to Pearlman.
Further alternatively or additionally, probe 102 in its entirety
comprises a disposable probe, which is replaced for each patient.
In some embodiments of the invention, probe 102 is cleaned and/or
sterilized between test procedures. It is noted that the procedure
of FIG. 2 is relatively simple, such that the procedure may be carried
out by substantially any user, nearly without any training. The
procedure of FIG. 2 may be carried out by a gynecologist, by any
other physician, by a nurse, a technician or optionally even by
the patient.
The measuring of the admittance from the nipple, provides a better
indication of the malignancy of the breast, at least partially due
to the lower impedance of the skin surrounding the nipple relative
to other outer surfaces of the breast. By having a lower impedance,
the nipple attracts currents from throughout the breast, thus providing
from a single point an indication on the entire breast. Additionally,
the high surface impedance of the skin, which generally masks the
tissue impedance for low frequencies, is at least partially avoided.
Furthermore, the nipple is at one end of the ducts. Since most cancers
start at the ducts or the lobula, nipple conductivity is a good
example of breast condition. In some embodiments of the invention,
surface probe 102 includes a marking defining a point that is to
be placed on the nipple.
Alternatively to using the same probe for measuring signals from
the nipple and from other breast areas, a different probe is used
for measuring impedance signals from the nipple. For example, a
small probe may be used for the nipple while a larger probe is used
for other breast areas. Alternatively, a circular probe with a narrow
guard ring is used to limit the measurements from the probe of the
nipple to the nipple area. Alternatively or additionally, a fixed
annular area, i.e., having a ring electrode, is used as a standardized
probe which covers only an annular portion of the nipple, i.e.,
a portion of the areola. In some embodiments of the invention, a
probe having a depression at the tip of the nipple is used. This
reduces or avoids the pressing of the nipple into the breast. While
the tip is thus not generally imaged, the amount of the areola that
is imaged is greatly increased. The probe may include an imaging
capability to aid in placement. Alternatively, the probe is a single
electrode probe and the score is determined based on the impedance
measured by the single electrode. In some embodiments of the invention,
a voltage is applied to the guard ring to at least partly cancel
cupping effects.
Referring now to the contact quality testing as performed by system
100, in some embodiments of the invention, in response to actuation
(202) of the testing, a signal of a plurality of frequencies is
applied to electrode 104. Optionally, the applied frequencies are
included in a wide band, for example ranging from 100 Hz to above
100 kHz. Alternatively, several frequencies in a relatively narrow
band are used, so that the measurements of one frequency do not
override other frequencies. In an exemplary embodiment of the invention,
the frequencies 200 Hz, 1000 Hz, and 2000 Hz. Alternatively or additionally,
a group of higher frequencies are used. The use of a plurality of
frequencies together allows for a more accurate testing of the contact
in a short time, since different frequencies may indicate different
faults in the contact between the breast and probe 102. Optionally,
responsive to the applied wide band frequencies, signals are sensed
by each of sensing elements 106. In some embodiments of the invention,
signals are also sensed while no signal is applied through electrode
104, for determination of the signal to noise ratio (SNR).
In some embodiments of the invention, the signals used for contact
quality determination have at least one characteristic different
from signals used for the cancer risk tests. For example, while
the signals applied to the patient for contact quality determination
include a plurality of frequencies concurrently, in order to save
time, the signals applied to the patient for the cancer risk tests
are applied each frequency at a separate time in order to maximize
the SNR of the tests. Alternatively or additionally, the signals
used for the tests have a different amplitude, optionally a higher
amplitude, or a higher amplitude per frequency.
Alternatively to applying a signal including all the test frequencies
at once, a few signals, each including one or more test frequencies,
are applied sequentially through electrode 104. Optionally, in this
alternative, the measurements for no applied signal may be taken
from the measurements when signals of other frequencies are applied.
Further alternatively, the contact testing is performed at a single
frequency, for example the frequency (or one of the frequencies)
at which the screening measurements are acquired.
The sensed values of each sensing element 106 are optionally evaluated,
for some or all of the frequencies for which measurements were acquired,
to determine their signal to noise ratio (SNR). In some embodiments
of the invention, measurements are taken while signals are applied
to electrode 104 and while no signals (at all or at the applied
frequency) are applied to the breast. The SNR is optionally determined
as the ratio between the maximum amplitude while signals are applied
and while signals are not applied. Alternatively or additionally,
the SNR is determined based on average amplitudes. Further alternatively
or additionally, the SNR is determined based on a comparison of
the signal envelope to the deviation from the envelope. Further
alternatively or additionally, the SNR is determined based on a
comparison of the signals at the frequencies at which signals were
applied to the patient to the average signal values at the frequencies
not applied to the patient. The values of the signals at the different
frequencies may be determined based on a Fourier transform of the
acquired signals. Other known methods of determining SNR can be
used.
Alternatively or additionally to testing the contact based on the
SNR, the sensed signals are evaluated to determine a resultant impedance
value suitable for comparing to predetermined thresholds which define
the limits of reasonable values. Further alternatively or additionally,
a series of measurements are taken and the evaluation of the contact
is based on the stability of the measurements. In some embodiments
of the invention, the sensing of the contact testing signals is
performed repeatedly for a predetermined number of times (e.g.,
10 times) and/or for a predetermined interval, and the sensed values
and/or the SNR are tested to verify that they are stable. In an
exemplary embodiment of the invention, the reciprocal (1/.times.)
of the standard deviation of the predetermined number of measurements
serves as a contact quality indicator.
Alternatively, the contact quality test results are displayed to
the operator and the operator is instructed to perform the measurement
only when the contact test values were determined to be stable.
Alternatively or additionally, the repeated values are used to
provide a more accurate parameter value, for example by averaging
over time and/or providing the minimum or maximum. Optionally, the
minimal SNR value over time is used in determining the quality level.
Further alternatively or additionally, the contact quality is determined
by measuring the pressure of the contact between the sensing elements
and the breast surface. Optionally, the sensing elements are mounted
on pressure sensing pins that measure the pressure. Alternatively
or additionally, one or more pressure sensors are placed on the
probe dispersed between the sensing elements. Further alternatively
or additionally, any other method is used to measure the pressure
and/or to assure that a sufficient pressure is used, for example
as described in the above mentioned U.S. patent application Ser.
No. 10/033,017.
In some embodiments of the invention, for simplicity, the contact
tests are based on only one parameter, such as SNR, measured values
being within a suitable range (or above a predetermined value) or
stability. Alternatively, the contact-quality test results depend
on two or more parameters.
The parameter values from the different frequencies are optionally
averaged to provide a combined indication for each of the pixels.
Alternatively, a maximal or minimal value is found for one or more
of the parameters over the pixels. For example, the quality level
may be a function of the minimal SNR of any of the sensing elements.
Alternatively or additionally, separate scores are given for different
frequencies, for example requiring a suitable SNR for all, or a
predetermined number, of the applied frequencies and/or pixels.
In some embodiments of the invention, contact tests are performed
for each of the pixels separately. The parameter values of each
pixel are optionally compared to a threshold or expected range for
the parameter and accordingly an indication on the quality of the
contact is provided for the pixel. The indication for each pixel
may be a binary indication and/or may be a multi-scale indication.
When the contact tests are based on a plurality of parameters, each
pixel is optionally given a value that is a weighted average of
scores given to each of the parameters. Alternatively, each pixel
is given a score that depends on whether each of the parameters
has a suitable value.
Optionally, a go ahead signal is provided to the operator of probe
102 when the signals of all the pixels pass the tests (e.g., have
values within a given range, have a high SNR, etc.). Alternatively,
a multi-scale indication (i.e., on a scale including at least three
values), which depends on the number of pixels passing the test,
is provided to the operator. In an exemplary embodiment of the invention,
the operator is instructed to perform the screening test when at
least a predetermined number of pixels have suitable contact values.
Optionally, the operator may be allowed the discretion to carry
out tests with a lower number of pixels or only with a higher number
of pixels. The test results provided by system 100 optionally indicate
that a lower number of pixels were used. Optionally, measurements
from pixels not passing the contact tests are not used in the screening
tests, as described below.
In some embodiments of the invention, the results of the measurements
of each of the pixels are displayed to the operator in the form
of a map image. Thus, the operator can see where the contact is
not suitable and accordingly may adjust the positioning of probe
102 on the breast.
Alternatively to determining a separate score for each pixel, a |