Diffusion-weighted imaging of the breast: Comparison of b-values 1000 s/mm2 and 1500 s/mm2

Abstract

Purpose: 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. Materials and Methods: 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. Results: 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. Conclusion: DWI may depict breast tumors more clearly with b=1500 s/mm2 than b=1000 s/mm2. © 2013 Japanese Society for Magnetic Resonance in Medicine.