The Usefulness Of Breast MRI In The Diagnosis And Differential Strategy For Lesions Showing Ductal And Segmental Enhancement

Objective:To characterize the ductal enhancement and segmental enhancement lesions on breast MRI, the usual nonmass-like lesions, correlate with histopathology and differ from benign and malignant breast lesions.Materials and Methods:The MRI findings of 112 ductal and segmental enhancement lesions proved by pathology were restrospectively analyzed, according to the lexicon of Breast Imaging Reporting and Data System-Magnetic Resonance Imaging(BI-RADS-MRI) designed by American College of Radiology(ACR), including morphology, internal structure after enhancement, kinetic curve pattern on dynamic study, signal intensity on fat-suppression T2WI before enhancement, and the mean value of apparent diffusion coefficients (ADC) on DWI. The pathologic diagnosis was made according to the standard of the World Health Organization Classification of Tumors (2003), characterize the correlation between MRI findings and histopathology. MRI imaging of the breast was performed on 1.5 Tesla scanner (Signa Infinity, GE), application of 4-channel phased array dedicated breast surface coil, all of the data measurement and imaging observation were collected with FunctoolⅡsoftware in GE AW 4.2 work station. SPSS16.0 software was used to make the following statistic analysis:(1) b value=1000 s/mm2, the t-test was used for testing the difference of ADC between malignant and benign breast lesions in two groups. (2) Grouping three parameters of both ductal enhancement and segmental enhancement lesions:Time-signal intense curve(typeⅠ, typeⅡ, typeⅢ), internal structure after enhancement(homogeneous/heterogeneous), fat-suppression T2WI signal intensity (isointense/hyperintense),χ2-test was used for testing the difference of each group.Results:All 112 cases included 37 ductal enhancement and 75 segmental enhancement, and malignant and benign lesions accounted for 85%(95/112) and 15% (17/112), respectively.Histopathological diagnosis in 37 ductal enhancement lesions were 8 benign, including 3 cystic hyperplasia with multiple papilloma, 2 ductal hyperplasia, 1 atypical ductal hyperplasia, and chronic inflammation in one and 29 malignant lesions including invasive ductal carcinoma (IDC) in 16, ductal carcinoma in situ (DCIS) in 11 (including one with lobular carcinoma in situ), invasive micropapillary carcinoma in one, and mixed mucinous adenocarcinoma in one.37 patients with lesions in the b value=1000 s/mm2 DWI imaging shown higher or as high signal, the average ADC values of 8 cases of benign lesions and 29 cases of malignant lesions were (1.24±0.21)×10-3mm2/s and (1.33±0.26)×10-3mm2/s, there were no significant differences for the mean ADC values between benign and malignant lesions (t=1.653, P= 0.105). TIC type:The group of 27 cases in the TIC showed typeⅠ(73%), of which 20 were malignant lesions,7 were benign.5 cases in the TIC showed typeⅡ(13.5%), of which 4 were malignant lesions,1 were benign and 5 cases in the TIC showed typeⅢ(13.5%), all malignant lesions (χ2=0.564, P=0.56). Internal enhancement characteristic:The lesions were 25 cases of lesions showed homogeneous enhancement, with 21 cases of malignant lesions, benign lesions in 4.12cases of lesions showed heterogeneous enhancement, including malignant lesions in 8 cases,4 cases of benign lesions(χ2= 0.394, P=0.39). Fat-suppression T2WI signal strength: The group of lesions were 22 cases in FS T2WI imaging showed isointense signal, of which 17 were malignant lesions,5 cases of benign lesions.15 cases showed high signal, of which 12 were malignant lesions,3 cases of benign lesions (χ2=1.0, P= 1.0).Segmental enhancement accounted for 75 of 112 nonmass-like lesions. Pathological finding in these 75 lesions were 9 benign lesions including chronic inflammation in four, cystic hyperplasia in three (one with multiple papilloma), apocrine metaplasia in one, adenosis in one and 66 malignant lesions including invasive ductal carcinoma (IDC) in 37 (four mainly composed of DCIS and two with invasive micropapillary carcinoma), ductal carcinoma in situ (DCIS) in 23 (five with microinvasive component and one with lobular carcinoma in situ), papilloma canceration in two(one limited intraduct), invasive lobular carcinoma in two (one with DCIS), invasive cribriform carcinoma (with DCIS) and invasive micropapillary carcinoma in one.75 patients with lesions in the b value=1000 s/mm2 DWI imaging shown higher or as high signal, the average ADC values of 9 cases of benign lesions and 66 cases of malignant lesions were (1.26±0.21)×10-3mm2/s and (1.28±0.31)×10-3mm2/s, there were no significant differences for the mean ADC values between benign and malignant lesions (t=1.245, P=1.115). TIC type:The group of 41 cases in the TIC showedⅠtype (54.6%), of which 35 were malignant lesions,6 were benign.17 cases in the TIC showedⅡtype (22.7%), of which 16 were malignant lesions,1 were benign.17 cases in the TIC showedⅢtype (22.7%),15 malignant lesions and 2 benign lesions (χ2=1.0, P=0.81). Internal enhancement characteristic: The lesions were 9 cases of lesions showed homogeneous enhancement, with 8 cases of malignant lesions, benign lesions in 1.66 cases of lesions showed heterogeneous enhancement, including malignant lesions in 58 cases,8 cases of benign lesions (χ2 =1.0, P=1.0). Fat-suppression T2WI signal strength: The group of lesions were 38 cases in FS T2WI imaging showed isointense signal, of which 32 were malignant lesions,6 cases of benign lesions.37 cases showed high signal, of which 34 were malignant lesions,3 cases of benign lesions (χ2=0.481, P=0.46).Both breast ductal and segmental enhancement had high positive predictive value for malignant lesions, about 78% and 88%, respectively.Conclusion:The wide used diagnostic principle of mass lesions, such as time-signal intense curve types (TIC) or ADC value, could not be used to distinguish benign from malignant lesions for ductal or segmental enhancement lesions on breast MRI. Whereas, the morphology of ductal or segmental enhancement is of more usefulness. Our study showed ductal or segmental enhancement more potentially suggestting malignant lesions (95 malignancy in all 112 cases), and DCIS accounted for 43.1% of all malignant lesions. The PPV of segmental enhancement was higher than ductal enhancement lesions for predicting malignancy.