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352
Color Doppler Sonography in the Diagnosis of Breast Cancer
Fig. 37.8 Color Doppler image of an invasive ductal carcinoma
15 mm in diameter (Acuson 128, 7 MHz).
been published in recent years on the color Doppler evaluation
of breast lesions
discrepant results. These discrepancies are due largely to the
use of different type of equipment
tors are the examination technique and especially the equip-
37
ment settings and transducer selection.
Comparison of different types of equipment. We have tested a
number of different color Doppler systems since the early
1990s. In many of the systems used at that time, only 5 MHz
linear transducers were available for breast ultrasound, and
their operating frequency for color Doppler imaging was only
3 MHz. To provide a standard for comparison, we examined 70
breast carcinomas with high-frequency CW Doppler (10 MHz).
We found that in some of the tumors that showed definite
blood flow by CW Doppler, no color flow signals were detected.
Since malignant tumors can vary greatly in their degree of
vascularity, we classified them into different groups. In the
cancers that showed particularly high vascularity when examined by CW Doppler, more or less conspicuous flow signals
could be detected with all the color Doppler instruments.
Often this was not possible in tumors that had a moderate to
low degree of vascularity.
Comparison of different transducers. When the same instruments are operated with different transducers, such as the
Acuson 128, we were unable to detect blood flow in some
tumors using a 5 MHz linear transducer, but we detected definite flow when using a 7 MHz transducer with a 5 MHz Doppler
frequency. This illustrates the frequency-dependence of Doppler sensitivity in duplex systems.
Equipment characteristics. The individual characteristics of an
ultrasound machine are often difficult to define objectively
and can be tested only in examinations on patients. There are,
of course, Doppler flow phantoms for measuring the velocity
calibration of a Doppler machine, and the technical specifications of the unit provide information on the minimum detectable flow velocity. But there are no technical specifications
on the lower size limit of blood vessels that the unit can detect.
Consequently, the only wayto decide whether a unit is suitable
for a particular application is by practical experience. For color
1, 10
. These studies have yielded some highly
8
, but other important fac-
Doppler studies, it is important that all patients be examined
with the same machine using standardized projections, because differences in these parameters will lead to different results.
Equipment Settings
Frequency, power output, gain, and wall filter. Maximum sen-
sitivity is crucial in Doppler systems used for tumor diagnosis.
This depends on various equipment settings. With some transducers, the operating frequency is adjustable over a broad
range. The highest possible frequency setting should be used in
the Doppler mode. The power output and gain should be set as
high as possible, i.e., to levels that are just below the noise
threshold. The wall filter,which suppresses vascular pulsations
and other motion artifacts, should be set as low as possible. A
filter setting of 200 Hz or higher would cause too much sensitivity loss, while a low filter setting (e.g., 25 Hz) would not give
adequate suppression of motion artifacts. A filter setting of
50–100Hz is ideal.
Pulse repetition frequency and aliasing. The pulse repetition
frequency (PRF) also has a major effect on sensitivity. While a
very high PRF setting, like that used in echocardiography, allows the precise detection of high-velocity flows, it greatly reduces the sensitivity of the Doppler system. On the other hand,
a very low PRF leads to a very slow frame rate in the Doppler
mode and makes real-time scanning difficult. A PRF of 800–
1000 MHz has proved to be an ideal trade-off between a high
frame rate and high sensitivity. It should be noted that the flow
velocities in malignant tumors can reach values of more than
1 m/s, despite small vessel lumina. When a low PRF is used, this
high-velocity flow leads to aliasing—a color reversal that distorts direction and velocity information in the color-flow
image. This artifact must be tolerated, because the small vessel
lumina make it necessary to use the highest possible sensitivity setting. The artifact itself does not compromise the examination, since the unit must be switched to duplex mode anyway for the quantification of blood flow.
Angle correction. Before duplex is switched on, the direction of
the vessel should be checked in the color-flow image. Because
the breast is very mobile, it is easy to angle and rotate the transducer to obtain an optimum beam–vessel angle and optimum
Doppler signal. Since the probe can be moved about freely on
the breast surface, angle corrections are easily accomplished.
This should be done before performing spectral analysis in the
duplex mode, as it increases the accuracy of flow velocity
measurements.
Duplex mode. The duplex mode is used for the quantification
of blood flow (Fig. 37.
ment settings can be made. The optimum PRF setting will depend on the flow velocity that is encountered. If the PRF is set
too low, high-velocity flow will cause aliasing and the flow
cannot be quantified. As a rule, the power output and gain
should be set as high as possible, making certain that background noise does not occur. Generally a low wall filter setting
can be used, since the transducer is held stationary during
9). No fixed recommendations on equip-
Color Doppler
Fig. 37.9 Color Doppler
image of an invasive ductal
carcinoma 12 mm in diame-
ter with flow quantitation in
the duplex mode (Acuson
128, 7 MHz).
spectral sampling and there should be very little wall motion in
the parenchymal and tumor vessels. The ideal filter setting is
between 25 and 50 Hz. The flow spectrum should be sampled
at the site that yields the best color Doppler flow signal. This is
generally the case when the most favorable beam–vessel angle
has been achieved. The smaller the beam–vessel angle, the
greater the accuracy of the measurement. When the angle
exceeds approximately 40⬚, small inaccuracies begin to cause
large changes in the cosine value, and the flow measurement
becomes less precise. Generally, however, the examiner can
adjust the transducer position to obtain a more favorable insonation angle and a very precise measurement.
Examination Technique
Patient position. The supine position is standard for breast ul-
trasound examinations, as this position flattens the breast
tissue against the chest wall. Raising the arms and clasping the
hands behind the neck tightens the pectoralis major muscle,
further flattening the breast and holding it in place. Pressure
from the transducer additionally flattens the glandular tissue.
This is helpful because a thinner tissue layer significantly improves the sound conduction properties of the glandular tissue
and permits the use of high ultrasound frequencies. A thicker
tissue layer is more resistant to high-frequency ultrasound
penetration, causing the image to appear darker. One difficulty
is that the attenuation of sound energy cannot be seen in the
color Doppler mode. Thus, when a tumor is located deep
within the breast, the beam may be so strongly attenuated by
the intervening tissues that blood vessels are not detected even
though the tumor is heavily vascularized.
B-mode and color Doppler. Before a breast is examined with
color Doppler, it should be systematically surveyed in overlapping planes by B-mode scanning. Color Doppler itself is not
useful for whole-breast screening because the motion of the
transducer causes color artifacts to appear throughout the tissues. After the breast has been completely surveyed by B-mode
scanning, any suspicious foci should again be located and
selectively scanned for abnormal vessels using color Doppler
ultrasound. At this time the transducer should be moved very
slowly so that color artifacts are minimized and can be distin-
guished from small, fluctuating vascular signals. When vessels
are detected, it should be determined whether they are normal
anatomical vessels. A main supply vessel runs from the axillary
artery through the upper outer quadrant and increasingly
branches as it approaches the center of the breast (Fig. 37.
Another large supply vessel arises from the internal mammary
artery and passes through the upper inner quadrant to the
nipple region. Measurements in these vessels indicate high
flow velocities. This can be confusing if there is a tumor nearby
and the vessels are misinterpreted as tumor vessels. They
should be positively identified by tracing the course of the vessels with ultrasound, rotating the transducer if necessary,
before an actual detailed flow analysis is performed.
Tumor vessels. All vessels that are seen entering a tumor are
classified as tumor vessels. It should be noted that the tissue in
breast cancer is often very firm, and many vessels become oc-
10).
Gynecological Ultrasound
353
Color Doppler Sonography in the Diagnosis of Breast Cancer
Fig. 37.10 Color Doppler and duplex
image of a main supply vessel in the breast
parenchyma. It is important to recognize
these normal anatomical breast vessels
and distinguish them from tumor vessels
to avoid false-positive findings (ATL UM9-
HDI, 10 MHz).
37
Fig. 37.11 Color Doppler and duplex
image of an invasive carcinoma 25 mm in
diameter. The vessels are most conspicuous at the periphery of the tumor and
radiate into the tumor mass. Inside the
tumor, they collapse due to the surrounding tissue pressure. As a result, the diastolic flow is frequently low or interrupted.
354
cluded shortly after entering the tumor. Most tumor vessels
are found directly adjacent to the tumor and in the peripheral
part of the lesion. With malignancies, the vessels enter the
tumor in a radial pattern (Fig. 37.
broadenomas usually exhibit no vessels or, at most, one or two.
It is common to find vessels in the normal parenchyma surrounding the lesion. Because fibroadenomas grow by expansion and compress the surrounding tissue, the vessels in that
tissue tend to curve around the periphery of the tumor
(Fig. 37.
12). They are not classified as tumor-associated vessels.
11). Benign tumors such as fi-
Blood Flow Analysis
Tumor vessel count. The color Doppler mode permits a visual
assessment of whether there is an abnormal increase of blood
flow in the focal lesion. This qualitative assessment is subject
to large errors, however, and it does not allow us to compare
the results of different examiners. A more objective evaluation
is needed. The easiest way to do this is by counting the tumor
vessels in the color Doppler mode. In our prospective studies of
color Doppler breast imaging, we have found the tumor vessel
count to be a useful parameter for benign–malignant discrimi-
10
nation
.
Color Doppler
Fig. 37.12 Color Doppler and duplex
image of a fibroadenoma. Intratumoral
vessels usually appear sparse or absent.
Vessels often skirt the periphery of the
tumor, as shown here.
Resistance index. Vascular findings can also be quantified by
analyzing the Doppler spectrum. It is known from gynecological Doppler ultrasound that ovarian and endometrial carcinomas have low flow resistance, which is manifested by low RI
values in the tumor vessels. High RI values in gynecological
masses are suggestive of benignancy. This principle has not
been confirmed in CW Doppler or color Doppler studies,
however. On visual inspection of the image, the blood vessels
in the peripheral part of the tumor show an apparent “cutoff”
because they are usually constricted by the firm surrounding
tumor (Fig. 37.
11). Since the tumor vessels lack a muscular coat,
the increased flow impedance is caused by pressure from the
growing tumor tissue. As a result of this, breast cancers tend to
show elevated RI values. We performed RI measurements for
comparison with other study results. Because the blood vessels
in a tumor are heterogeneous, it is necessary to measure all the
vessels. Only a complete survey of tumor blood flow can reveal
distinctive impedance features. Also, sampling many different
spectra provides a database for analyzing extreme values, such
as the minimum resistance index as an extreme value for all
the tumor vessels.
Flow velocity. The measurement of flow velocity provides better information on tumor blood flow. The mean blood flow can
be determined from the multiplicity of tumor vessels. The
problem with this method is that the meticulous measurement
of all tumor vessels will include many small vessels that are
perfused by slow flow. When these vessels are averaged along
with the few large mainstem vessels, they result in a relatively
low mean value. Since different examiners differ in how carefully and completely they sample small tumor vessels, the calculated mean value is subject to large variations, which is why
this parameter must be handled very carefully. An easier
method is to identify the vessel with the highest flow velocity
in the color Doppler image. Generally this is the vessel that is
seen most clearly in the flow image and has the brightest color.
The measurement of this extreme value in the duplex mode
provides better discrimination between benign and malignant
lesions than determining the mean value.
Flow velocity sum. Total blood flow is an even better benignmalignant discriminator. This cannot be determined by a precise volume flow calculation, but it is possible to add together
all the blood flow velocities in all tumor vessels. This “flow
velocity sum” is a relatively good indicator of the total blood
flow in a tumor, and its calculation is not subject to measurement errors. Even when some small vessels with lower velocities are measured, this will cause little percentage change in
the velocity sum if the sum is already high due to the presence
of heavily perfused vessels. As a result, this measured value
provides a good parameter for differential diagnosis. Its main
disadvantage is that the measurement of all vessels can be very
time-consuming.
Total blood flow is particularly useful in monitoring the effect of chemotherapy on tumor vascularity. Mean tumor blood
flow is an unsatisfactory parameter for this purpose because
when tumor blood flow initially decreases in response to
chemotherapy, the smaller vessels with low flow velocities will
disappear first while the mainstem vessels are still perfused.
The paradoxical result of this process is that the mean blood
flow may appear to increase even though the total blood flow is
decreased.
Study Results
Table 37.1 shows the principal flow data measured in our study. We
counted an average of 12 tumor vessels in each of 82 breast malignancies, as compared with only two vessels in 176 benign breast lesions. The mean and maximum flow velocities and flow velocity
sum were significantly higher in carcinomas than in benign lesions.
The mean RI was also significantly higher: 0.74 in carcinomas versus
Gynecological Ultrasound
355
Color Doppler Sonography in the Diagnosis of Breast Cancer
Table 37.1 Color Doppler and duplex flow data for 82 breast carcinomas and 176 benign breast lesions
Parameter Carcinomas
mean value/SD
Vessel count 12/11 2/2 ⬍ 0.0001
Mean flow 20/9 11/7 ⬍ 0.0001
Maximum
flow
Flow velocity
sum
Mean RI 0.74/0.10 0.68/0.10 ⬍ 0.0001
Minimum RI 0.62/0.11 0.63/0.10 ⬎ 0.1
0.68 in benign lesions, although the overlap of RI values between
benign and malignant lesions is too large for accurate differentia-
tion. Determination of the minimum RI for all the tumor vessels
shows a slightly lower value for carcinomas (0.62) than for benign
lesions (0.63), but there is an almost complete overlap of minimum
RI values between benign and malignant lesions, so the difference
is not significant. This demonstrates the variability of the flow data
37
in tumor vessels and shows how important it is to include all the
vessels in a flow data analysis.
As Table 37.1 indicates, the vessel count by color Doppler and
the flow velocity sum, as relative measures of total tumor blood
flow, reflect the greatest differences between benign and malig-
nant tumors. With the other parameters it will be noted that, while
most of the differences are highly significant, the standard devia-
tions show considerable overlap.
37/21 13/10 ⬍ 0.0001
285/361 29/39 ⬍ 0.0001
Benign lesions
mean value/SD
Statistical
significance
(p)
Discussion
Malignant tumors. In agreement with all previous study re-
sults, we found a marked increase of blood flow in malignant
tumors compared with benign lesions. Color Doppler sonogra-
phy combined with frequency spectrum analysis in the duplex
mode provides an effective method for the quantitative differentiation of these flow patterns. Malignant tumors are characterized by many blood vessels with high flow velocities
(Fig. 37.
11). This feature aids in the differential diagnosis of cir-
cumscribed masses. It can also improve the detection of diffuse
carcinomas, which are easy to miss in the B-mode image
(Fig. 37.
13).
Benign tumors and scars. Benign tumors usually exhibit little
or no measurable blood flow on Doppler ultrasound. Of course,
this depends strongly on the sensitivity of the equipment used
(Figs. 37.
useful after breast-conserving operations (Fig.37.
12,37.14). Doppler sonography can be particularly
15). Scars
frequently appear as spiculated densities on mammograms.
They also have suspicious ultrasound features, appearing as
hypoechoic focal lesions with irregular, ill-defined margins
and a posterior acoustic shadow. These cases demonstrate the
significant value of a noninvasive modality that can improve
the differentiation of scars and local recurrences in the previously operated, irradiated breast.
Proliferative and inflammatory lesions. Proliferative lesions
are still a problem. It is difficult to distinguish among proliferative fibroadenomas, atypical proliferative fibrocystic change,
mural proliferation in cysts, and mastitis (Figs. 37.
16–37.18 ).
With their increased blood flow, proliferative changes often
appear suspicious on color Doppler imaging. Dynamic MRI can
be problematic for the same reason. Inflammatory changes can
be quickly identified in most cases by treating the patient with
antibiotics and dopamine agonists. Regression of increased
blood flow should occur within a few days after treatment is
begun, thereby distinguishing the condition from inflammatory carcinoma.
356
Fig. 37.13 Diffusely infiltrating lobular
carcinoma. The tumor is not visible in the
color Doppler image. Dynamic examination with compression revealed an indu-
rated area within the breast. This area con-
tained several small vessels with high flow
velocities, which suggested the correct diagnosis.
Color Doppler
Fig. 37.14 Color Doppler image of an intracystic papilloma shows no apparent abnormalities.
Fig. 37.15 Hypoechoic scar after breastconserving surgery for carcinoma. The scar
appears avascular in the color Doppler
image. A small vessel in the surrounding
parenchyma has a typically low flow velocity of 5.9 cm/s.
Gynecological Ultrasound
Fig. 37.16 Mural proliferation in a septated cyst. Color Doppler demonstrates a
circumscribed increase in blood flow.
357
Color Doppler Sonography in the Diagnosis of Breast Cancer
37
Fig. 37.17 Color Doppler appearance of a
proliferative, hyper vascular fibroadenoma.
FNA biopsy yielded proliferative cells. Be-
cause of the benign findings and for other
medical reasons, an expectant approach
was taken. Examination four months later
showed a marked increase in tumor size,
and local excision was performed. Histology confirmed a proliferative fibroade-
noma.
Fig. 37.18 Nonpuerperal mastitis. The
high vessel count by color Doppler sug-
gested an inflammatory carcinoma, but
the duplex scan showed relatively low arte-
rial flow velocities with a predominance of
venous vessels. Follow-up after anti-inflam-
matory therapy confirmed the benign na-
ture of the disease.
358
Conclusions
References
Although most breast masses can be differentiated by Doppler
sonography, this method should be used only by experienced
examiners. Due to a lack of standardization of measuring techniques and equipment parameters, not all scanners are equally
suitable. In addition, the measurements obtained with one
machine cannot be applied to other machines. Even switching
transducers can significantly alter the results. Moreover, the
biological differences that characterize tumor tissue are not
easily defined. In our experience, approximately 10% of malignant tumors exhibit low blood flow, and an examiner who does
not properly consider all available diagnostic information may
draw a false-negative conclusion. However, it is reasonable to
expect that technical improvements, standardized protocols,
and better training will help to establish Doppler flow assessment as a routine diagnostic test in the foreseeable future.
References
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noma: measurement of tumor response to primary medical therapy
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5 Madjar H, Sauerbrei W, Schillinger H: Aktueller Stand der Doppler-
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Berlin 1989
6 Madjar H, Sauerbrei W, Münch S, Schillinger H: Continuous-Wave And
Pulsed Doppler Studies Of The Breast: Clinical Results And Effect Of
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8 Madjar H: Breast examinations with continuous wave and color Dopp-
ler. Ultrasound Obstet. Gynecol. 2 (1992) 215
9 Madjar H, VetterM, Prömpeler HJ, Breckwoldt M, Pfleiderer A: Doppler
measurement of breast vascularity under pharmacological treatment
of benign breast disease. J. Reproduct. Med. 38(12) (1993) 935–940
10 Madjar H, Prömpeler HJ, Sauerbrei W, Wolfarth R, Pfleiderer A: Color
Doppler flow criteria of breast lesions. Ultrasound Med. Biol. 20(9)
(1994) 849–858
11 Minasian H, Bamber JC: A preliminary assessment of an ultrasonic
Doppler method for the study of blood flow in human breast cancer.
Ultrasound Med. Biol. 8 (1982) 357
12 Natsuki S, Kosuke Y: A study on the vascular proliferation in tissues
around the tumor in breast cancer. Jpn. J. Surg. 18 (1988) 235
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1
14 Wells PNT, Halliwell M, Skidmore R, Webb AJ, Woodcock JP: Tumour
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Gynecological Ultrasound
359
Usefulness of the Minimum Resistance Index in the
38
Benign–Malignant Discrimination of Breast Tumors
C. Villena-Heinsen, M. Friedrich, J. König, and W. Schmidt
Flow Resistance in Malignant Breast Tumors
Number of sampled vessels. Several Doppler flow studies
have shown that malignant breast tumors have greater blood
flow on average than benign tumors and normal breast tissue.
Significantly more vessels could be sampled from malignant
tumors, first using a high-frequency continuous-wave (CW)
Doppler pencil probe and later using duplex equipment and
color Doppler sonography. Despite the consistent results obtained with different technologies, all of these methods involve
an indirect assessment of the number of blood vessels actually
present. Because the vessels are not imaged in three dimen-
38
sions, some vessels are not sampled at all while others are inadvertently sampled more than once due to their course. Factors such as the sensitivity of the Doppler equipment, examination time, transducer pressure on the breast, and the
patience and experience of the examiner have a systematic influence in these examinations.
Vascular structure and flow resistance. As we know today, the
blood flow signals that are sampled with Doppler ultrasound
originate from relatively large-caliber supply vessels. Several
histopathological studies
the neovascularity of malignant tumors. It is common, for example, to find arteriovenous shunts and sites where the capillaries lack a muscular coat. These structural differences from
the neoangiogenesis of benign tumors result in a lower im-
2, 3
have described typical features of
1,4, 5, 7
pedance to blood flow. Because of this, the vessels supplying a
malignant tumor should also exhibit low flow resistance, and
all of the resistance indices—the minimum, mean, and maximum resistance index (RI)—should be decreased in proportion
to the number of tumor vessels that are present.
Number of tumor vessels. Our own study results
however, that as the number of tumor vessels increases, the
minimum RI progressively declines while the maximum RI increases. The mean RI remains unchanged. Two conclusions can
be drawn from this:
1 Neither the minimum RI nor the maximum RI is a satis-
factory parameter for characterizing the actual flow resistance of a tumor. They are the end products of a minimization and maximization effect that is proportional to the
number of tumor vessels. This means that the likelihood of
determining the lowest minimum RI and the highest maximum RI increases when more vessels are present.
2 If a resistance index is to be used in characterizing breast
tumors, the best choice would be the mean RI.
That the minimum (and maximum) RI is influenced by the
number of vessels sampled is a phenomenon observed not just
in breast tumors but also in healthy breast parenchyma.
6, 7
indicate,
360
Authors’ Studies
Patients and Methods
Study design. A total of 114 women with a focal breast lesion
detectable by preoperative ultrasound underwent a conventional B-mode examination with assessment of tumor size followed by detailed color Doppler scanning of both breasts. First
the tumor area and the healthy breast tissue were divided into
four quadrants per breast and examined with color Doppler ultrasound. The tumor area was scanned thoroughly and systematically with the goal of sampling as many tumor vessels as
possible. To save time, a maximum of two vessels were
sampled in each quadrant. Flow signals located more than 2 cm
from the tumor margin were assigned to the corresponding
quadrant. Figure 38.
the resistance indices for the tumor area, for each quadrant,
and for the healthy breast tissue. Two different systems were
1 explains the method used to calculate
used to calculate the different resistance indices in healthy
breast tissue.
Equipment and settings. The examinations were performed
with the model 128 XP10 ultrasound system from Acuson
(Mountain View, CA, USA). A 7 MHz linear transducer with a
38 mm acoustic window was used. For color Doppler, the
transducer automatically switched its operating frequency to
5 MHz. The color Doppler settings were adjusted to optimize
the detection of slow flows and weak color signals in the vascular network. Color Doppler sensitivity was set just below the
noise threshold to minimize artifacts, and transducer movements were limited to slow angulation. For maximum signal
yield, care was taken to maintain a constant transducer pressure throughout the examination.
Right Left
0.75
0.50
0.63
0.64
0.55
0.75
0.67
0.58
0.64
0.57
0.67
0.42
0.67
0.67
0.65
0.67
0.57
0.65
0.71
0.57
0.83
0.63
Fig. 38.1 Methods used to calculate the various resistance indices.
Right breast. Retroareolar mass in a 56-year-old woman, extending
predominantly into the upper outer quadrant, classified histologically
as invasive ductal carcinoma stage pT3, pN12/18, M0, G3, ER+, PR+,
20% Ki-67-positive cells, aneuploid. Six vascular segments were
sampled in the tumor area. The RI
RI
= 0.75. In the upper inner quadrant, the RI
max
were equal to 0.67. RI
min
,RI
mean
min
, and RI
= 0.42, the RI
were determined for each
max
= 0.57, and the
mean
,RI
min
mean
, and RI
max
quadrant. For example, the values for the right upper outer quadrant
were: RI
upper inner quadrant were: RI
Left breast. The resistance indices RI
breast tissue were calculatedin two ways. (1) Meanvalues for the RI
RI
mean
eight quadrants (in this case: RI
RI
max
16), the lowest RI was defined as RI
the RI
RI
max
min
, and RI
= 0.64, RI
determined for each quadrant were calculated for all
max
= 0.70, and RI
mean
min
=RI
= 0.75. The values for the
max
=RI
mean
min
min
= 0.67.
max
,RI
, and RI
mean
= 0.62, RI
mean
in healthy
max
= 0.66, and
min
= 0.70). (2) Of all the resistance indices determined (in this case
was calculated from all 16 values (RI
mean
min
and the highest RI as RI
= 0.57, RI
min
mean
, and
max
= 0.66,
= 0.83).
Results and Discussion
Number of vascular signals. One to nine vascular segments
weresample d fromthe area of malignant tumors and one tosix
vascular segments from benign tumors. Figure 38.
relative frequency of malignant and benign tumors plotted
against the number of vessels in the tumor area.
50
40
30
20
Relative frequency (%)
Malignant (n=63)
Benign (n=51)
2 shows the
Authors’ Studies
Table 38.1 Mean-value comparison of the number of vascular segments sampled in the tumor area, stratified by menopausal status,
benignancy, and malignancy
Nature and number of lesions Vascular
segments
All (n = 114) 3.3 (⫾ 1.8)
Benign (n = 51) 2.8 (⫾ 0.2) p = 0.008
Malignant (n = 63) 3.6 (⫾ 0.2)
Premenopausal, benign (n = 36) 2.9 (⫾ 0.3) p =0.14
Premenopausal, malignant (n = 23) 3.4 (⫾ 0.4)
Postmenopausal, benign (n = 15) 2.5 (⫾ 0.3) p = 0.03
Postmenopausal, malignant (n = 40) 3.7 (⫾ 0.3)
Standard deviation in parentheses
On average, 3.3 vascular signals were detected in each
tumor area. The vessels were more numerous in malignant
tumors than in benign tumors. This difference was statistically
significant only in postmenopausal patients, however (Table
38.
1).
,
Dependence of RI
min
and RI
on the Number of
max
Vessels in the Tumor Region
Presumably, an increasing number of blood flow signals would
correlate with an increase in blood flow and a decrease in
vascular resistance (Figs. 38.
that all the resistance indices—minimum, mean, and maximum—would show a more or less parallel decline. Paradoxically, an increase in the number of sampled tumor vessels was
associated with a statistically significant decrease in RI
(p = 0.004) and a statistically significant increase in RI
(p = 0.03). Meanwhile, the RI
the only blood flow parameter that showed no dependence on
the number of vessels sampled.
Figure 38.
5 shows the difference between the resistance in-
dices in the tumor area and the mean indices for the eight
breast quadrants for RI
as a function of the number of vascular segments sampled in
the tumor area. Tumor areas with more vessels display the
highest RI
and lowest RI
max
us to conclude that neither RI
sistance values that are actually present. They are, rather, the
products of a minimization and maximization process in
which the values are critically determined by the number of
potential measurements (vessels).
3, 38.4). It is reasonable to expect
remained constant and was
mean
(left), RI
min
. These paradoxical results force
min
(center) and RI
mean
nor RI
min
reflects the re-
max
p-value
(right)
max
Gynecological Ultrasound
min
max
10
0
123456 789
Number of vascular segments sampled in the tumor area
Fig. 38.2 Percentage frequency of benign and malignant tumors as a
function of the number of vascular segments sampled in the tumor
area (61 malignant tumors = 100 %, 53 benign lesions = 100%).
Dependence of RI
min
and RI
on the Number of
max
Vessels in Healthy Breast Tissue
This conclusion is supported by a subsequent analysis in which
a significantly lower RI
gardless of menopausal status or whether the tumors were
malignant or benign—compared with the mean value of RI
calculated from the eight RI
breast quadrants (p = 0.0001). On average, 3.3 vessels were
sampled in the tumor area and an RI
was found in the tumor area—re-
min
values in the eight healthy
min
of 0.62 ⫾ 0.11 SD was
min
min
361