Value of the hypointensive internal septation on MR for the differentiation between benign and malignant breast lesions

Objective: To investigate the diagnostic value of internal septation for differentiating benign from malignant breast lesions. Methods: A total of 26 patients were included in the study, in which 12 patients had 20 lesions of breast carcinoma and 14 patients had 25 lesions of fibroadenoma diagnosed either pathologically or clinically. The differential diagnoistic value of the hypointensive internal septation was analyzed. Results: The signal intensity of fibroadenomas and malignant lesions on T₂-weighted fat-suppressed images could be classified as iso- to hyper- intensity, hypointensity and mixed intensity. According to the signal intensity classification, there were 5, 11 and 4 cases in patients with breast carcinoma respectively, while 11, 10, 4 cases in patients with fibroadenoma respectively. There was no statistical difference in the distribution between the two patient groups (χ²=1.764, P=0.414). The shape of fibroadenomas and malignant lesions could be classified as irregular, roundish or lobulated. According to the morphological classification, there were 12, 7 and 1 case in patients with breast carcinoma respectively, while 1, 7, 17 cases in patients with fibroadenoma respectively. There was statistical difference in the distribution between the two patient groups (χ²=23.262, P=0.000). The typical features of fibroadenomas were as follows: lobulated shape, hypointensive internal septations on T₂-weighted or postcontrast images. The diagnostic sensitivity of the three imaging features for fibroadenoma was 68%(17/25), 52%(13/25), and 72%(18/25) respectively; and the diagnostic specificity was 95%(19/20), 90%(18/20), 95% (19/20) respectively. Conclusion: The internal septation is a rather specific sign for diagnosis of fibroadenomas. (authors)