Focal nodular hyperplasia: typical and atypical MRI findings with emphasis on the use of contrast media.

Focal nodular hyperplasia is a benign hypervascular hepatic tumour, frequently detected in asymptomatic patients undergoing imaging studies for unrelated reasons. Magnetic resonance imaging (MRI) generally allows a confident differential diagnosis with other hypervascular liver lesions, either benign or malignant. In addition, due to the recent development of hepatospecific MRI contrast agents, MRI concomitantly enables functional and morphological information to be obtained, thus providing important clues for the detection and characterization of focal nodular hyperplasia lesions.