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. J. Magn. Reson. Imaging 2006.