CT and MRI in the diagnosis of focal nodular hyperplasia / 中华肝胆外科杂志

ABSTRACT

Objectives To study the value of CT and MRI in diagnosing focal nodular hyperplasia (FNH).Methods The CT and MRI findings of 16 patients with FNH confirmed histopathologically were analyzed retrospectively.Both plain and dynamic enhanced CT scannings were performed in all the patients.Plain and dynamic enhanced MRI were carried out in 9 patients.Results (1) There were 16 patients with 19 lesions,and 8 lesions were in the left lobe,5 lesions in the right lobe,4 lesions between the left/right lobes and 2 lesions in the caudate lobe.The morphology of the lesions showed 15 lesions to have clear boundaries and 4 lesions to have fuzzy boundaries.The tumor diameters varied from 2.2 to 9.6 cm,(average 4.3 cm).(2) Sixteen patients underwent CT examination.On plain CT,the lesions were isotonic (n＝ 5),or slightly low-density (n=11).In 7 lesions,there was a slit-like,stellate-shaped low density central scar.Nine patients underwent MRI examination.On T2WI,6 lesions showed slightly higher signal while the remaining 3 lesions showed iso-signal.On T1WI,4 lesions showed slightly lower signal,3 lesions showed iso-signal and 2 lesions showed slightly higher signal while in 1 lesion the local signal showed reduction in anti-phase 1.A central scar was seen in 6 lesions which showed high signal on T2WI,and low signal on T1WI.(3) Enhanced CT 15 lesions were significantly enhanced and 1 lesion showed mild enhancement at the arterial phase.For the patients with mild enhancement,the scar in the center of the lesion showed no enhancement.In all lesions,the central scar did not enhance.In 5 lesions,enhancements of thickened and torturous arteries were seen.In all the lesions with enhancement,the enhancement was reduced at the portal venous phase,with 12 lesions showing slightly higher density,3 lesions isodensity and 1 lesion low-density.Three lesions showed mild enhancement of the central scar.All the substantial parts of the lesions with enhancement declined at the delay phase,with 3 lesions showing slightly higher density,9 lesions of isodensity and 4 lesions slightly low density.In 7 lesions with central scar delayed enhancement,they showed slightly higher density.Nine patients underwent MRI enhancement and the enhancement characteristics were similar to CT,but the arterial phase magnitude was higher than that of CT.In 4 lesions,the central scar began to enhance at the portal venous phase,while 6 lesions continued to enhance,thus showing slightly higher signal at the delay phase.In a large lesion,there was persistent delayed enhancement in the capsule.(4) On DWI,6 lesions showed inhomogeneous,slightly hyperintensity with the center showing a slit-like low signal area.Three lesions showed iso-signal.The ADC values of the lesions were (1.31±0.08)× 10-3 mm2/s,and the normal liver parenchyma were (1.22± 0.14)× 10-3 mm2/s,(difference not statistically significant).Conclusions CT and MRI using plain and dynamic enhanced scans could show fully and accurately the pathological features and the characteristics of blood supply of FNH.The characteristic signs on both CT and MRI make an accurate diagnosis of FNH.MRI when compared with CT was slightly better.A combined use of both CT and MRI has an important value in the diagnosis of FNH.