The Value of Diffusion-Weighted Imaging in Characterizing Focal Liver Masses

Rationale and Objectives To determine if focal liver masses could be differentiated as benign or malignant on the basis of diffusion-weighted imaging (DWI). Methods and Materials A total of 104 patients with focal liver masses were scanned using 1.5 T magnetic resonance imaging (MRI). DWI was performed with b values of 0, 50, and 400 s/mm2 . Of these, 76 patients had lesions larger than 2 cm diameter, radiologic or pathologic characterization of the lesion, and diagnostic quality DWI. The apparent diffusion coefficient (ADC) of the largest liver lesion was measured. The liver masses were diagnosed on histology or had characteristic computed tomography/MRI findings and follow up of more than 6 months. The analyzed lesions were hemangioma ( n = 17), cysts ( n = 5), hepatocellular cancer (HCC) ( n = 41), adenoma ( n = 3), focal nodular hyperplasia (FNH) ( n = 6), and metastases ( n = 4). Results The mean (standard deviation) ADC values (10−5 mm2 /second) of hemangiomas, cysts, FNH, and HCC were 156.8 (54.1), 190.2 (43.0), 130.1 (81.9), and 107.6 (32.7). The ADC of cysts and hemangiomas were significantly higher than that of other lesions ( P = .0003, t -test). There was no significant difference between ADC values of solid, benign liver lesions (FNH, adenoma) and malignant lesions (HCC, metastases) ( P = .62). Conclusion Solid liver lesions have a lower ADC than cysts and hemangiomas. However, there is no significant difference in ADC between solid benign and malignant lesions. DWI appears to have only minimal additional value over currently used MRI sequences in characterizing liver masses.