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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5791_Библиотеки_им_академика_М_И_Перельмана.pdf
1014.7 Ultrasound Elastography
Fig. 4.15 Breast carcinoma. Mixed type of color pattern. Grayscale US and elastography
102
4 Ultrasound Diagnosis of Breast Cancer
Fig. 4.15 (continued)
1034.7 Ultrasound Elastography
Fig. 4.15 (continued)
104
4 Ultrasound Diagnosis of Breast Cancer
Fig. 4.15 (continued)
1054.7 Ultrasound Elastography
Fig. 4.16 Sonoelastography. Irregular staining of the lesion. Grayscale US and elastography
106
4 Ultrasound Diagnosis of Breast Cancer
Fig. 4.16 (continued)
1074.7 Ultrasound Elastography
13 %
Fig. 4.17 Intensity of staining of malignant breast lesions
with US elastography
18%
Homogeneous color Heterogeneous color
Fig. 4.18 Homogeneity of staining of malignant breast
lesions with US elastography
Table 4.2 Diagnostic value of US elastography in diag-
nosis of breast carcinoma
Breast carcinoma
US+ 1,093 57
US– 174 5,376
Sensitivity 86 %
Speci fi city 99 %
Prognostic value of positive result 95 %
Prognostic value of negative result 97 %
Breast carcinoma
US and elastography+ 88 3
US and elastography– 4 1,134
Sensitivity 96 %
Speci fi city 99 %
Prognostic value of positive result 97 %
Prognostic value of negative result 99 %
11 %
76 %
Intensive color Poor color No color
82%
Positive
cancer with
histology
Positive
cancer with
histology
Negative
cancer with
histology
Negative
cancer with
histology
High operator dependency and intra- and •
interobserver variability
Certain limits of compression of the breast •
(discomfort), especially in patients with
anatomic, constitutional, psychological,
emotional, or physiological variants
“Noises” and artifacts •
Quantitative assessment of elasticity is much
more objective. So, numerical representation is
preferable to interpret tissue elasticity precisely.
Strain ratio, elastic modulus, and others are
offered.
Shear-wave elastography permits objective
de fi nition of the velocity of shear waves in tissues
and calculation of Young’s modulus of elasticity
in kPa. It enables quantitative elastographic
assessment of the status of breast tissue (Postnova
et al. 2011 ; Mitkov et al. 2011 ) .
The method utilizes focused US beam to
induce acoustic shear wave and works in real
time. The distinctive feature of the technology is
absence of direct tissue compression. The results
are more objective, well reproduced, and operator independent. Additionally, it permits to assess
the stiffness of deeply located lesions, which are
impossible to assess with compression elastography. An elastic index in normal tissues and in
benign dysplastic breast changes is 2–22 kPa. In
breast carcinoma, it ranges from 65 kPa to
297 kPa, in benign lesions 17–30 kPa, and in
cysts 1.7–10 kPa (Postnova et al. 2011 ) .
One example of the technology of shear-wave
elastography is Acoustic Radiation Force Impulse
(ARFI), which forms the basis of Virtual Touch
Tissue Quanti fi cation. Tissue elasticity is in
inverse relationship with the velocity of shear
wave generated with high-power acoustic
impulse. The measurement of this velocity, which
is done automatically and displayed in m/s,
enables to make an objective opinion about the
rigidity of examined structures (e.g., breast
lesions) (Zubarev 2009 ) (Fig.
4.22 ).
US probe during ARFI measurements is positioned over the lesion with sample volume gate in
its center. The time of measurement that passes in
108
4 Ultrasound Diagnosis of Breast Cancer
Fig. 4.19 Difference in dimensions of malignant breast lesions in grayscale mode and sonoelastography
1094.7 Ultrasound Elastography
Fig. 4.19 (continued)
110
4 Ultrasound Diagnosis of Breast Cancer
Fig. 4.19 (continued)