Contribution of diffusion-weighted MRI to the differential diagnosis of hepatic masses.

PURPOSE: To evaluate the diagnostic contribution of diffusion-weighted magnetic resonance imaging (MRI) using apparent diffusion coefficient (ADC) values to the characterization of hepatic masses and differentiation of benign and malignant lesions.

MATERIALS AND METHODS: The study included 30 patients that underwent upper abdominal MRI examinations because of hepatic masses that were found to be > or =1 cm in size with conventional sequences, and were additionally evaluated with diffusion-weighted MRI. Diffusion-weighted images and ADC maps in the axial plane were obtained using a 1.5 Tesla MRI device, single shot echo-planar spin echo sequences on 3 axes (x, y, z), and diffusion sensitive gradients with 2 different b values (b = 0 and b = 1000 s/mm (2)). Mean ADC measurements were calculated among the 30 cases involving 41 hepatic masses.

RESULTS: Of the 41 hepatic masses, 24 were benign and 17 were malignant. Benign lesions included 6 cysts, 14 hemangiomas, 2 abscesses, and 2 hydatid cysts. Malignant masses included 8 metastases, 4 hepatocellular carcinomas, 4 cholangiocellular carcinomas, and 1 gall bladder adenocarcinoma. The highest ADC values were for cysts and hemangiomas. The mean ADC value of benign lesions was 2.57 +/- 0.26 x 10(-3)mm(2)/s, whereas malignant lesions had a mean ADC value of 0.86 +/- 0.11 x 10(-3)mm(2)/s. The mean ADC value of benign lesions was significantly higher than that of malignant lesions (P < 0.01).

CONCLUSION: Diffusion-weighted MRI with quantitative ADC measurements can be useful in the differentiation of benign and malignant liver lesions.