C-Acetate PET Imaging in Hepatocellular Carcinoma and Other Liver Masses

Chi-Lai Ho, Simon C.H. Yu and David W.C. Yeung

Abstract

It is well known that 18F-FDG PET has a high average falsenegative rate of 40%–50% in the detection of hepatocellular carcinoma (HCC). This is not an acceptable accuracy, particularly in countries where this tumor is prevalent. In this study, we evaluated prospectively the characteristics of 11C-acetate and 18F-FDG metabolism in HCC and other liver masses.

Methods: Fifty-seven patients were recruited into this study, with masses consisting of 39 HCC; 3 cholangiocarcinomas; 10 hepatic metastases from lung, breast, colon, and carcinoid primary malignancies; and 5 benign pathologies, including focal nodular hyperplasia (FNH), adenoma, and hemangioma. All patients, except 2 with typical findings of hemangioma and 3 clinically obvious metastases, were confirmed histopathologically by liver biopsy or resection. All patients fasted for at least 6 h and blood glucose concentration was measured before they underwent dual PET radiopharmaceutical evaluation of the upper abdomen with 11C-acetate and 18F-FDG.

Results: In the subgroup of HCC patients with the number of lesions ≤ 3 (32 patients; 55 lesions; mean size ± SD, 3.5 ±1.9 cm), the sensitivity of detection by 11C-acetate is 87.3% ( 11C-acetate maximum SUV [SUVmax] =7.32 ± 2.02, with a lesion-to-normal liver ratio of 1.96 ±0.63), whereas the sensitivity of detection by 18F-FDG is only 47.3%, and 34% lesions show uptake of both tracers. None of the lesions was negative for both tracers (100% sensitivity using both tracers). In some lesions and in the subgroup of HCC patients (n = 7) with multifocal or diffuse disease, dual-tracer uptake by different parts of the tumor is demonstrated. Histopathologic correlation suggests that the well-differentiated HCC tumors are detected by 11C-acetate and the poorly differentiated types are detected by 18F-FDG. All 16 non-HCC malignant (cholangiocarcinoma and metastatic) liver lesions do not show abnormal 11C-acetate metabolism. Of the benign liver lesions, only FNH shows mildly increased 11C-acetate activities (11C-acetate SUVmax = 3.59, with a lesion-to-normal liver ratio of 1.25).

Conclusion: 11C-Acetate has a high sensitivity and specificity as a radiotracer complementary to 18F-FDG in PET imaging of HCC and evaluation of other liver masses.

Full Publications: http://jnm.snmjournals.org/content/44/2/213.full.pdf