CT and MR diagnosis on focal nodular hyperplasia of the liver

Objective: To explore the appearances of the focal nodular hyperplasia (FNH) using CT and MR imaging, and to improve its diagnostic accuracy of the FNH. Methods: CT and MR scanning of pre- and post-contrast arterial phase, portal venous phase and delayed phase were performed on 20 patients with pathologically proved FNH. CT and MR imaging of 24 lesions in 20 cases was retrospectively analyzed, including 13 cases done by CT scan, 10 cases done by MR scan, among which 3 cases done by both CT and MR scan. Results: 18 solitary lesions and 2 multiple lesions were revealed. On pre-contrast CT scans, 9 of 14 FNH lesions were hypodense, the other five lesions were isodense. On pre-contrast MR scans, 10 of 14 FNH lesions showed hypointense, the other four lesions showed isointense on T1WI, and all 14 lesions showed hyperintense or slight hyperintense on T2WI. On the arterial phase scans, all lesions were markedly enhanced, except for the central scar area on CT and MR imaging. On the portal phase CT scans, 9 FNH lesions were isodense, 4 lesions were hyperdense, and 1 lesion was hypodense. On the delayed phase CT scans, 11 FNH lesions were isodense, 2 lesions were slight hyperdense, and 1 lesion was slight hypodense. On the portal phase MR scans, 11 FNH lesions showed hyperintense, the other three lesions showed isointense. On the delayed phase scans, 10 FNH lesions showed hyperintense, the other four lesions showed isointense. On multiphase CT scanning, central scar was found in 8 FNH lesions; tortuous and dilated arteries at the peripheral area in 7 lesions; and pseudocapsule sign in 3 lesions. On multiphase MR scanning, central scar was seen in 9 FNH lesions; tortuous and dilated arteries at the peripheral area in 6 lesions; and pseudocapsule sign in 5 lesions. Conclusion: Multiphase CT and MR scanning can fully reveal the blood supplying and histological characteristic of FNH, which will be very useful in diagnosing and differentiating FNH. (authors)