FOCAL LIVER MASSES - CHARACTERIZATION WITH DIFFUSION-WEIGHTED ECHO-PLANAR MR-IMAGING

PURPOSE: To evaluate diffusion-weighted echo-planar magnetic resonance (MR) imaging for improving the specificity of characterization of liv er tumors. MATERIALS AND METHODS: Diffusion-weighted echo-planar imagi ng was performed with a 1.5-T whole-body imager with use of a body pha sed-array coil in 51 patients with 59 hepatic masses (41 malignant tum ors, nine hemangiomas, and nine cysts). Apparent diffusion coefficient (ADC) values were obtained with two motion-probing gradients (b = 30 and 1,200 sec/mm(2)) during each of the breath-hold periods, and an AD C map was constructed. The T2 was derived from spin-echo echo-planar i mages with echo times of 47 and 99 msec. RESULTS: The ADC value of mal ignant masses (1.04 x 10(-3) mm(2)/sec) was significantly lower (P < . 01) than that of benign masses (hemangiomas [1.95 x 10(-3) mm(2)/sec] and cysts [3.05 x 10(-3) mm(2)/sec]), although the T2s showed consider able overlap. A small amount of overlap in ADC values occurred among m alignant tumors, hemangiomas, and cysts. ADC values of two cystic mass es from ovarian carcinomas were within the range of those of hemangiom as. CONCLUSION: These preliminary results indicate that diffusion-weig hted MR imaging can be useful in characterizing focal liver masses. Wi th the exception of cystic metastatic tumors, the technique may be esp ecially useful in tumors that appear markedly hyperintense on T2-weigh ted images due to a long T2.