Focal nodular hyperplasia of the liver: assessment with contrast-enhanced TurboFLASH MR imaging.

Twenty-two patients with 25 cases of focal nodular hyperplasia (FNH) proved with pathologic study were imaged with a TurboFLASH (fast low angle shot) sequence combined with bolus administration of gadolinium tetraazacyclododecanetetraacetic acid (DOTA), spin-echo (SE) T2-weighted sequences, and postcontrast T1-weighted sequences. FNH-liver signal-difference-to-noise ratios were quantified; the features of the central scar were qualitatively analyzed. On SE T2-weighted images, all FNHs were hyperintense; in two cases the central scar exhibited a high signal intensity associated with hypointense areas corresponding to fibrous tissue within the branches of the scar. Unenhanced TurboFLASH images always demonstrated the FNHs as hypointense and always depicted the central scar as a hypointense area within the lesion. After bolus injection, arterial enhancement of FNH was clearly seen, and in 10 of 25 lesions, enhancement within the scar was seen 40-80 seconds after injection. Both unenhanced and enhanced TurboFLASH sequences produced the best signal-difference-to-noise ratios in comparison with T2-weighted images.