Evaluation of hepatic lesions and hepatic parenchyma using diffusion-weighted echo-planar MR with three values of gradient b-factor

PURPOSE: To determine whether diffusion-weighted echo-planar (EP) MR images with very small, small, and large gradient b-factors are useful in evaluating hepatic lesions and hepatic parenchyma. MATERIALS AND METHODS: Approximate values of the apparent diffusion coefficients for diffusion (D) and for flowing spins (D*) for 96 hepatic lesions (26 hepatocellular carcinomas HCCs], 28 metastases, 26 hemangiomas, and 16 cysts) and the non-lesion-bearing regions of parenchyma in 78 livers (50 noncirrhotic and 28 cirrhotic) were calculated from EP images (modified for gradient b-factors of 3, 50, and 300 second/mm(2)). RESULTS: Liver cysts and noncirrhotic livers showed statistically higher mean D* values than HCCs, hemangiomas, metastases, and cirrhotic livers (P < 0.05 on Scheffé post hoc analysis). Liver cysts showed statistically higher mean D values than HCCs, metastases, noncirrhotic livers, and cirrhotic livers (P < 0.05). Liver hemangiomas showed statistically higher mean D values than HCCs, noncirrhotic livers, and cirrhotic livers (P < 0.05). CONCLUSION: The D* value in addition to the D value may be useful for evaluating the nature of diffusion and flowing spins in hepatic lesions and hepatic parenchyma.