Diffusion magnetic resonance imaging of breast lesions: Initial experience at Alexandria University

ObjectiveThe purpose of our study was to investigate whether adding diffusion weighted imaging (DWI) to dynamic contrast-enhanced MRI (DCE-MRI) could improve specificity and the positive predictive value (PPV) of breast MRI in differentiating benign and malignant focal breast mass lesions.Materials and methodsThe prospective study included 71 females with 103 focal breast lesions on DCE-MRI who underwent subsequent biopsy. DWI was acquired during diagnostic breast MRI using b = 0, 400 and 800 s/mm2. Apparent diffusion coefficient (ADC) values were compared for benign and malignant lesions. Sensitivity and PPV were calculated for DCE-MRI alone (based on biopsy recommendations) and DCE-MRI plus DWI (adding an ADC threshold) for the same set of lesions.ResultsOn pathological basis, 57 out of 103 focal lesions were benign and the remaining revealed, 45 were malignant and one borderline. Malignant lesions exhibited lower mean ADC (<1.3 × 10−3 mm2/s) than benign lesions (>1.3 × 10−3 mm2/s). Applying an ADC threshold of 1.3 × 10−3 mm2/s sensitivity increased (on conventional DCE-MRI basis) from 86.95% up to 93.47% and the specificity from 91.22% to 96.49% in detection of malignancy with PPV of 95.55% in comparison to 86.95% for enhancement kinetics alone, which would have avoided biopsy for 10.5% (6/57) of benign lesions without missing any cancers.ConclusionDWI shows potential for improving the PPV of breast MRI for detection of malignant breast lesions.RecommendationFurthermore, larger studies should be made to use it as a monitor for tumor response to chemotherapy.