Differential diagnosis of breast mass image-forming lesions based on changes in depth-width ratio and internal echo intensity by hand-held probe compression.

Abstract

Regarding mass image-forming lesions, the 2005 Guidelines for Ultrasonic Diagnosis of Breast Diseases, published by the Japan Society of Ultrasonics in Medicine (JSUM), includes the evaluation of tumor compressibility, which is visually assessed by the degree of deformation caused by applying external pressure to the tumor. However, this is only a subjective estimation under real-time observation; consequently, quantitative evaluation of tumor deformation and the percentage change in internal echo intensity was attempted based on changes in the depth-width ratio and in the internal echo intensity on hand-held probe compression. We evaluated the usefulness of these measurements in the differential diagnosis of benign and malignant tumors. The subjects were 139 patients (89 benign and 50 malignant cases) who underwent breast ultrasonography with a 10-MHz (from 4-to 10-MHz) linear probe. The deformation index (D.I.) of the tumor was defined as: [1 - (depth-width ratio with 3.0 ± 0.6-kg-weighted compression)/(depth-width ratio without compression)] × 100 (%). The rate of change in internal echo intensity was defined as the echo intensity with compression divided by the echo intensity without compression × 100 (%). There was a significant difference in the D.I. between benign lesions (35.5% ± 14.7%) and malignant lesions (15.4% ± 6.2%) (P < 0.001). The cut-off ratio in differentiating benign from malignant lesions was approximately 25%. The rate of change in echo intensity of benign lesions (149.7% ± 34.3%) was significantly higher than that of malignant lesions (122.9% ± 19.9%) (P < 0.001). Using an electronic linear probe, quantitative indexes including the D.I. and the rate of change in internal echo intensity could be obtained with the help of a weight meter, and could prove effective for the differential diagnosis of breast mass-image forming lesions.