Value of pre-operative breast MRI for the size assessment of ductal carcinoma in situ.

Objective: To retrospectively evaluate the accuracy of pre-operative breast MRI and mammography in determining the size of ductal carcinoma in situ (DCIS) compared with the histopathological results.

Methods: 79 patients [mean age: 56.5 (standard deviation 10.2) years] with pathologically proven DCIS (79 lesions) obtained a bilateral mammogram and a pre-operative contrast-enhanced MRI. The accuracy of MRI and mammography to detect tumour size were estimated and compared, using histopathological size as the gold standard, on the subjects with measurements with both modalities (n = 60).

Results: MRI detected 67 (85%) lesions, mammography detected 72 (91%) and both modalities detected 60 (76%). Median DCIS size detected by mammography vs MRI was smaller (1.55 vs 1.65 cm). Out of these 60 cases, compared with the histopathological size, the accuracy of MRI and mammography was 0.66 and 0.56, respectively (p = 0.045). MRI showed better accuracy than mammography for younger patients (age ≤ 50 years, p = 0.003). For tumour nuclear grade, there was a statistically significant difference for the intermediate level, with higher accuracy for MRI (p = 0.03).

Conclusion: MRI was more accurate than mammography in DCIS size assessment when visible, particularly in lesions of intermediate grade and in patients less than 50 years of age.

Advances In Knowledge: Breast MRI may help in management of DCIS of intermediate grade and in females less than 50 years of age.