Abstract
BACKGROUND:Besides mammography, breast ultrasound is the most important imaging modality for women with suspected breast cancer. New software tools bear high potential for improved detectability and specification of malignant breast lesions.OBJECTIVE:To compare the halo depicted around malignant breast lesions by ultrasound using Acoustic Structure Quantification (ASQ) of raw image data with the echogenic rim seen in B-mode ultrasound.METHODS:This retrospective study included 37 women for whom conventional B-mode ultrasound of the breast and ASQ were available as well as histopathology findings for comparison. Software tools were used to measure the halo area or echogenic rim and tumor area and calculate halo-to-lesion ratios for the two ultrasound modes. Six inexperienced readers characterized the breast lesions based on this information. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were determined. ANOVA, the Wilcoxon test, and ROC curve analysis were performed.RESULTS:There was a linear relationship between ASQ-based and B-mode-based halo-to-lesion ratios; however, a systematic error was also noted. ASQ-derived ratios tended to be higher for breast lesions with lymphangioinvasion (p = 0.051, n.s.) and higher N-stages (p > 0.925, n.s.), while there was no correlation with other markers. Because of the significantly greater conspicuity of peritumoral halos in the ASQ mode, inexperienced readers achieved greater sensitivity (78% vs. 74%) and specificity (75% vs. 71%) and higher NPVs (75% vs. 71%) and PPVs (78% vs. 74%) compared with B-mode images. Greater halo conspicuity affected the identification of malignant lesions with both modes; ASQ was found to be particularly well suited (FBimage (1,100) = 19.253, p < 0.001; FASQ (1,100) = 52.338, p < 0.001). The inexperienced readers were significantly more confident about their diagnosis using the ASQ maps (z = –3.023, p = 0.003).CONCLUSIONS:We conclude that the halo in ASQ and the echogenic rim in B-mode ultrasound are attributable to different morphologic correlates. ASQ improves diagnostic accuracy and confidence of inexperienced examiners because of improved halo visibility.
Highlights
Besides mammography, breast ultrasound is the most important imaging modality for women with suspected breast cancer
Size ratios differ between the Acoustic Structure Quantification (ASQ) and B-mode. These results suggest that the halo identified with the ASQ technique depends on a different underlying mechanism than the echogenic rim seen in conventional B-mode ultrasound
Since the interpretation of breast ultrasound findings was not standardized in the past, the American College of Radiology (ACR) proposed a BI-RADS classification for ultrasound based on the well-established BI-RADS classification for mammography
Summary
Breast ultrasound is the most important imaging modality for women with suspected breast cancer. According to publications of the German Society for Ultrasound in Medicine (Deutsche Gesellschaft fur Ultraschall in der Medizin, DEGUM), an echogenic rim surrounding an echolucent center is another sign of malignancy [6,7,8] Such a rim was first described in the early 1990s [9] and is most likely attributable to tissue changes around a lesion due to displacement, tumoral invasion, microvascularisation [10,11,12] and/or or lymphangioinvasion. Because of the significantly greater conspicuity of peritumoral halos in the ASQ mode, inexperienced readers achieved greater sensitivity (78% vs 74%) and specificity (75% vs 71%) and higher NPVs (75% vs 71%) and PPVs (78% vs 74%) compared with B-mode images. ASQ improves diagnostic accuracy and confidence of inexperienced examiners because of improved halo visibility
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