Helical CT and MRI diagnosis of focal nodular hyperplasia (FNH) of the liver

Objective:To improve diagnosis accuracy of focal nodular hyperplasia (FNH) of the liver by studying helical CT and MRI multiphase scanning. Methods:A retrospective analysis was made on the unenhanced and dynamic enhanced helical CT and MRI images of 13 patients with surgically and pathologically proved FNH,including helical CT scan (n=8) and MRI (n=6). Results:On plain CT scans,8 FNH lesions showed hetrogeneous or homogeneous hypodense areas.In the arterial phase,all lesions were vigorously and homogeneously enhanced,except the central scar.Tortuous and dilated arteries were seen in the center or peripheral area in 4 cases.In the portal venous phase and delayed phase,4 of 8 lesions remained slightly hyperdense,4 of 8 lesions turned to isodense or slightly hypodense.Central scar was found in 4 FNH lesions and demonstrated late enhancement.MR images of 6 patients showed slightly low signal in T_1-weighted images and isointensity or slightly high intensity in T_2-weighted images.All lesions had apparent enhancement in the arterial phase and prolonged enhanced in the portal venous phase and delayed phase.Central scar was found in 4 FNH lesions and demonstrated late enhancement.Conclusion:The multiphase helical CT and MRI scanning can fully show the pathologic and blood supply characteristics of FNH and improve the ability to differentiate FNH from other malignant hypervascular tumors.