1.5 Tesla MRI of focal nodular hyperplasia. A report of 7 cases and a review of the literature

Six patients with 7 focal nodular hyperplasia lesions were investigated with 1.5 Tesla magnetic resonance imagery (MRI). Surgical specimens were obtained in all cases and histological examination confirmed the diagnosis of focal nodular hyperplasia. In all cases, the tumour was isointense on the T1 weighted sequences. On the T2 weighted sequences in six cases, the tumour gave a hypersignal compared with the surrounding healthy liver tissue. Central scar tissue was found in all the lesions. One the T2 weighted images, the center gave a hypersignal 4 times and a hyposignal 3 times. Gadolinium injection on the echo gradient sequences (GRASS) showed product uptake suggestive of vessels within the central scar in one case. The report in the literature confirms the variability of focal nodular hyperplasia depending on the magnetic field used. In 1.5 Tesla MRI an isointense signal on at least one sequence would appear to be sufficient for the diagnosis of focal nodular dysplasia if the tumour is homogeneous and if the central scar is hyperintense in T2 sequences. (authors). 18 refs., 5 figs., 2 tabs