[Typical and atypical features of focal nodular hyperplasia of the liver on helical CT images].

Background & Objective: Focal nodular hyperplasia (FNH) is a rare hepatic neoplastic lesion. This study was to evaluate the typical and atypical features of FNH of the liver on helical computed tomography (CT) images to improve the diagnosis accuracy.

Methods: Helical CT images of 32 patients with 37 lesions were reviewed in Cancer Center, Sun Yat-sen University retrospectively, who were confirmed as FNH by histopathologic or clinic examinations. The number, size, margin status, density, enhancing type, presence of a center scar, and presence of a pseudocapsule of FNH lesions were analyzed.

Results: The largest diameters of 14 lesions were < or = 3 cm, of 23 lesions were > 3 cm; 20 lesions were subcapsular; pseudocapsule was presented in 7 lesions with the largest diameters of > 3 cm; 22 lesions had center scars, among them, the largest diameters of 20 lesions was > 3 cm. All lesions were hyperattenuated to the liver in hepatic arterial phase; 31 lesions were enhanced homogeneously in hepatic arterial phase; abnormally thickened vessels were presented at the border of 17 lesions.

Conclusions: Typical helical CT features of FNH include homogeneous enhancement in hepatic arterial phase, presence of central scar, and delayed enhancement. Atypical helical CT features of FNH include heterogeneous enhancement in hepatic arterial phase, absence of central scar, and presence of pseudocapsule. The various CT features are related to the pathologic type and the largest diameter of the lesion.