Relative apparent diffusion coefficient (rADC) in breast lesions of uncertain malignant potential (B3 lesions) and pathologically proven breast carcinoma (B5 lesions) following breast biopsy

Purpose: To assess relative apparent diffusion coefficient (rADC) and ADC in B3 and B5 lesions in premenopausal female patients, added to standard morpho-dynamic breast contrast-enhanced MRI. Methods: 104 patients with histologically confirmed B3 (N1 = 52) and matched B5 lesions (N2 = 52), were examined on MRI (1.5 T, full diagnostic protocol, diffusion weighted imaging – b50, b850) in a retrospective analysis following the IRB approval: Atypical ductal hyperplasia (ADH, n1 = 20), Flat epithelial atypia (FEA, n2 = 11), Classic lobular neoplasia (CLN, n3 = 8), Papillary lesion (PL, n4 = 6) and Phyllodes tumor (PT, n5 = 7). rADC and ADC were computed for each lesion. The two-tailed Mann-Whitney U test was used for comparison with B5 lesions. Results: Mean rADC value for B3 lesions, (N1 = 52): 0.81+/-0.08 mm2/s x 10-3 and B5 lesions, (N2 = 52): 0.58+/-0.07 mm2/s x 10-3 is statistically different (p < 0.00001). Mean rADC values [mm2/s x 10-3], per entity in B3 are: ADH, 0.82+/-0.06; FEA, 0.75+/-0.03; CLN, 0.73+/-0.03; PL, 0.94+/-0.02; PT 0.86+/-0.05. Conclusions: Although morpho-dynamic features of borderline and malignant lesions may overlap, the initial results in this research, suggest the highly significant difference in both ADC and rADC between B3 and B5 lesions. Larger trials are needed to confirm the initial data.