Combined dual-tracer PET and NM imaging in the evaluation of focal nodular hyperplasia

Abstract

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Objectives: Focal nodular hyperplasia (FNH) is typically considered a benign entity related to a hyperplastic process. Our aim was to investigate the dual-tracer PET findings of FNH and incremental value of conventional NM imaging.

Methods: Nineteen patients (F: 10, M: 9; mean age: 40y) with 23 liver lesions (mean size of 4.0±2.5 cm) identified by other imaging studies were referred for PET studies. All patients had negative Hepatitis B or C status and normal alphafetoprotein concentration. Eight patients had histopathological proof of FNH in 9 lesions. The remaining 11 patients had stable follow-up imaging studies in 14 lesions within a median period of 21 months (6-36 mo), clinically compatible with FNH. Dual-tracer PET/CT protocol using C11-acetate followed by F18-FDG was employed. Seventeen patients also underwent Tc99m-sulfur colloid scintiscan, of which 5 patients had additional Tc99m-mebrofenin scintigraphy.

Results: All the liver lesions demonstrated increased C11-acetate metabolism (23/23) with a range of SUVmax ranging from 3.27 to 15.98 (lesion-to-liver SUVmax ratio 1.49±0.41, range 1.1-2.48) and they were all non-avid for F18-FDG (0/23). Tc99m-sulphur colloid scintiscan in 17 patients showed increased colloid uptake in 5 patients (6/21, 29%) and normal colloid uptake (same intensity as liver) in the remaining 12 patients (15/21, 71%), indicating at least some degree of intact Kuppfer function. Tc99m-mebrofenin scintiscan in all 5 patients demonstrated tracer retention, suggesting the presence of functioning hepatocytes but impaired biliary excretion.

Conclusions: All the FNH lesions showed no F18-FDG avidity but they demonstrated a variable degree of increased C11-acetate metabolism, as well as intact Kupffer cell and hepatocyte function.