The significance of dual-mode elastography in the diagnosis of breast lesions by physicians with different levels of experience

Abstract

Background: This study aimed to assess the diagnostic value of dual-mode elastography for benign and malignant breast lesions and determine whether this technique can improve the diagnostic ability of physicians with different levels of experience.

Methods: One hundred and eighty-three breast lesions were analyzed retrospectively, and the following values were calculated for the lesions with various shells: shear modulus (G), Young's modulus (E), shear wave velocity (Cs), and strain ratio (SR). A random forest algorithm was used to select the optimal modes for elastography. A receiver operating characteristic curve was used to assess the diagnostic efficacy for benign and malignant breast lesions. Sensitivity and specificity values were calculated to evaluate any improvements in the diagnostic efficacy of physicians with different levels of experience (junior, intermediate-level, and senior) in the evaluation of malignant breast lesions using dual-mode elastography.

Results: The best-performing mode of shear wave elastography (SWE) in the diagnosis of breast lesions was the A'min 1.0 (Cs) mode (minimum shear wave velocity of the area of interest and 1.0 mm around the area of interest), and the best-performing mode of strain elastography (SE) was the B/A' 0.5 (ratio of fat to the elasticity of the area of interest and 0.5 mm around the area of interest). When the two methods were used in series, results showed high specificity (98%), positive likelihood ratio (PLR) (21.2), and positive predictive value (PPV) (95%). Series means that if SE and SWE were malignant, the result in series was malignant, and that if either SE or SWE was benign, the result in series was benign. When the methods were used in parallel, the results showed high sensitivity (91%), negative likelihood ratio (NLR) (0.15), and negative predictive value (NPV) (89%). Parallel means that if SE and SWE were benign, the result in parallel was benign, and that if either SE or SWE was malignant, the result in parallel was malignant. When conventional ultrasound was combined with dual-mode elastography, the intermediate-level and junior physicians' diagnoses of breast lesions showed a higher sensitivity, specificity, and area under the curve than conventional ultrasound diagnosis alone.

Conclusions: Dual-mode elastography is effective in the diagnosis of breast lesions. The sensitivity and specificity values in this study show that diagnoses made by junior and intermediate-level physicians improve when dual-mode elastography is used, although diagnoses made by senior physicians do not improve significantly.

Keywords: Breast cancer; diagnosis; elastography; ultrasound.

Figure 1

Mean decreases in the accuracy of elastography. (A) Top 10 modes for mean decrease in accuracy with shear wave elastography (SWE). (B) Top 10 modes for mean decrease in accuracy with strain elastography (SE).

Figure 2

Receiver operating characteristic (ROC) curves of the best modulus of elasticity. (A) ROC curves of A'min 1.0 (Cs) (minimum shear wave velocity of the area of interest and 1.0 mm around the area of interest). (B) ROC curves of B/A' 0.5 (ratio of fat to the elasticity of area of interest and 0.5 mm around the area of interest).

Figure 3

Receiver operating characteristic (ROC) curves and slope figures for the physicians with different levels of experience: (A,D) are for the senior physician, (B,E) are for the intermediate-level physician, and (C,F) are for the junior physician. Blue line: before dual-mode elastography. Green line: after dual-mode elastography. AUC, area under the curve; NLR, negative likelihood ratio; NPV, negative predictive value; PLR, positive likelihood ratio; PPV, positive predictive value.

Figure 4

Images of an irregular breast lesion in a 42-year-old woman with low echo and no flow. The senior physician classified the lesion as BI-RADS 4b, while the intermediate-level and junior physicians classified it as BI-RADS 3. The lesion’s A'min 1.0 (Cs) and B/A' 0.5 are 1.15 m/s and 5.75, respectively. Both elastography scans give a result of malignant. After the addition of dual-mode elastography, the intermediate-level and junior physicians reclassified the lesion as BI-RADS 4a, and the pathological result was invasive nonspecific carcinoma.