Magnetic resonance imaging of hepatocellular carcinoma: a pictorial review of novel insights into pathophysiological features revealed by magnetic resonance imaging.

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Magnetic resonance (MR) imaging is one of the most powerful modalities for the assessment of HCC with sufficient sensitivity and specificity. In addition to its capacity for lesion detection, MR imaging delineates some unique in vivo pathophysiological features of tumors, which cannot be assessed by other modalities. Chemical shift imaging may depict steatosis of the tumor. Dynamic contrast-enhanced MR imaging is the most powerful tool to assess the vascularity of the tumor, which is closely related to malignant transformation in hepatocarcinogenesis. Diffusion-weighted imaging illustrates the cellularity of the tumor. Super-paramagnetic iron oxide, a liver-specific MR contrast agent accumulating in Kupffer cells, enables detection of the hepatocellular architecture in the lesion. Recently, a new liver-specific MR contrast agent, gadoxetic acid [gadolinium-ethoxybenzyl (Gd-EOB)-diethylenetriaminopentoacetic acid (DTPA)], has been introduced for clinical imaging. Gd-EOB-DTPA has a significant impact on the imaging of HCC, with potential capacity for the concurrent assessment of vascularity of the tumor and hepatocellular-specific properties within the tumor. Understanding the characteristics of MR imaging methods and contrast agents is essential for the optimal diagnosis and characterization of HCCs.