Hepatic Cavernous Hemangiomas: Relationship between Speed of Intratumoral Enhancement during Dynamic MRI and Apparent Diffusion Coefficient on Diffusion-Weighted Imaging

To investigate the relationships between the apparent diffusion coefficients (ADCs) on diffusion-weighted imaging (DWI) and the speed of contrast-enhancement in hepatic hemangiomas. Sixty-nine hepatic hemangiomas (≥ 1 cm) were evaluated with DWI, by using multiple b values (b = 50, 400, 800 s/mm2), followed by a gadolinium-enhanced dynamic MRI. The lesions were classified into three groups, according to the speed of contrast-enhancement on the portal phase. ADCs were measured on the ADC map automatically, and were calculated by using the two different b values (mADC50-400 with b values = 50 and 400; mADC400-800 with b values = 400 and 800 s/mm2). The mean ADCs (X 10-3 mm2/s) were significantly higher in the rapid group (1.9 ± 0.44) than in the intermediate (1.7 ± 0.35, p = 0.046) or the slow groups (1.4 ± 0.34, p = 0.002). There were significant differences between the rapid and the slow groups in mADC50-400 (2.12 vs. 1.48; p 0.008) and mADC400-800 (1.68 vs. 1.22, p = 0.010), and between the rapid and the intermediate groups in mADC50-400 (2.12 vs. 1.79, p 0.049). Comparing mADC50-400 with mADC400-800, there was a significant difference only in the rapid group (p = 0.001). Higher ADCs of rapidly-enhancing hemangiomas may be related to richer intralesional vascular perfusion. Also, the restricted diffusion may be attributed to the difference of structural characteristics of hemangioma.