Magnetic resonance mammography of invasive lobular versus ductal carcinoma: systematic comparison of 811 patients reveals high diagnostic accuracy irrespective of typing.

OBJECTIVE

Invasive lobular (ILC) and ductal carcinomas (IDC) are the most frequent subtypes of breast cancer. Diagnosis of ILC is often challenging. This study was conducted to (1) evaluate dynamic and morphologic profiles and to (2) compare the diagnostic accuracy of IDC and ILC in magnetic resonance mammography (MRM).

METHODS

Our database consisted of all consecutive MRMs over a 12-year period (standardized protocol: T1-weighted fast low-angle shot; 0.1-mmol gadolinium-diethylenetriaminepentaacetate per kilogram of body weight; T2-weighted turbo spin-echo, 1.5 T; histological verification after MRM), which were evaluated by experienced (>500 MRMs) radiologists in consensus, applying 17 predefined descriptors. All the patients gave written consent; this study was approved by the local institutional review board. Extracting all the ILCs (n = 108), IDCs (n = 347), and benign lesions (n = 436) from the database, the data set of the study was created.In ILC and IDC diagnostic accuracy of single descriptors was calculated and compared separately (chi test). Using all the descriptors, a combined binary logistic regression analysis was applied to calculate the overall diagnostic accuracy for ILC and IDC. The corresponding areas under the curve were compared.

RESULTS

ILC and IDC, showed wash-in and an irregular shape without difference (P = 1.0 and P = 0.4). Wash-out was more typical of IDC (72.6%; ILC, 57.4%; P = 0.007). Perifocal edema was diagnosed more frequently in IDC (45.5%; P = 0.05). For overall accuracy, the areas under the curve were 0.929 for ILC and 0.939 for IDC (P = 0.5).

CONCLUSIONS

The dynamic and morphologic profiles of ILC and IDC were overlapping, and minor differences between both subgroups could be identified. Accordingly, the overall diagnostic accuracy of MRM was high and without difference between both subtypes of breast cancer.