Lipiodol uptake after transarterial embolization in hepatocellular carcinoma can make false positive lesion on CT-based attenuation-corrected FDG PET

Abstract

106

Objectives: The transarterial embolization (TAE) is widely used in the therapy of hepatocellular carcinoma (HCC). After TAE, dense lipiodol uptake remains in HCC. The aim of the study was to investigate the effect of lipiodol uptake on CT-based attenuation corrected FDG PET.

Methods: Twenty-six patients with HCC underwent FDG PET/CT to evaluate the metabolic activity of the lesions after TAE. Thirty-one tumors in 26 patients which were stained by lipiodol were evaluated. All patients had received successful TAE therapy using lipiodol before the PET/CT study. The standardized uptake value (SUV) was used to evaluate FDG uptake in tumor and non tumor regions of the liver. The maximum Hounsfield unit (HU) was also measured in the plane of largest lesion shown on non-enhanced CT.

Results: The size of tumors ranged from 0.9 to 5.7 cm in diameter. Fourteen of the lesions showed hypermetabolism in tumors, and 17 lesions showed isometabolism. All the hypermetabolic lesions disappeared on attenuation non-corrected image. The average HUs of the lesions are 1244.4±659.8 in hypermetabolism and 1046.6±445.1 HU in isometabolism. The size of lesions was 2.5 ± 1.0 cm in hypermetabolism and 2.6 ± 1.2 cm in isometabolism.

Conclusions: We demonstrated that compact lipiodol uptake in hepatocellular carcinoma could make false positive lesion on FDG PET. Attenuation non-corrected image or cesium-correction image will be helpful to differentiate between false positive lesion and residual tumor.