Residual breast cancer or post operative changes: Can Diffusion-weighted magnetic resonance imaging solve the case?

ObjectiveTo evaluate the ability of Diffusion weighted MR imaging (DWI), as a non-invasive sequence to differentiate between accepted post operative sequel and residual malignancy in breast cancer patients following different surgical procedures.Patients and methodsDWI in addition to the routine post contrast MRI was performed for follow up of 170 post operative breasts (6–24 months). DWI acquired using b values: 0, 850, 1000 and 1500. Analysis considered signal intensity (SI) at b 1000 and the ADC map and the mean ADC values.ResultsPost operative changes were: Edema (n = 17, 10%), skin thickening (n = 25, 15.9%), seroma (n = 17, 10%), hematoma (n = 5, 3%), fat necrosis (n = 13, 7.6%), fibrosis (n = 8, 4.7%), and combined (n = 83, 48.8%). Residual malignancy found in 16.5% (n = 28) of cases.No significant difference was noted between DWI SI at b 850 versus 1000 and b 1000 versus 1500 (P > 0.05). Also no difference (P > 0.05) was noted between the mean ADC values of residual malignant masses and post operative sequel of fibrosis and fat necrosis. ADC map showed low SI in 30% of cases. Statistical analysis yielded sensitivity, specificity and accuracy of 92.8%, 75.6% and 78% for contrast MRI and 92.8%, 82.6% and 83.4% for DWI respectively.ConclusionDWI enhanced the diagnostic performance of MRI in differentiating residual malignancy from post operative changes.