Diffusion-weighted imaging of the breast. Comparison of B-values 1000 s/mm2 and 1500 s/mm2

We compared diffusion-weighted imaging (DWI) of the breast using 2 different b-values to determine the optimal b-value for greatest signal contrast between tumors and normal tissue of the breast. We performed DWI of the breast at b-values of 1000 s/mm2 and 1500 s/mm2 in 120 patients (121 lesions, 19 benign, 102 malignant) and visually scored image quality with regard to artifact and visibility of tumors. We quantitatively evaluated the signal-to-noise ratio (SNR) of the tumor and contrast-to-noise ratio (CNR) and contrast ratio (CR) between the tumor and normal breast parenchyma. The CR of invasive carcinoma (IC), ductal carcinoma in situ (DCIS), and benign tumors significantly improved with b=1500 s/mm2 compared with b=1000 s/mm2. The SNR and CNR were significantly lower with b=1500 s/mm2 than b=1000 s/mm2 despite the increasing number of excitations at b=1500 s/mm2. At b=1500 s/mm2, the difference in SNR, CNR, and CR between IC and DCIS and benign tumors was statistically significant. DWI may depict breast tumors more clearly with b=1500 s/mm2 than b=1000 s/mm2. (author)