Combination of C-11-Acetate and F-18-DG PET for the diagnosis of hepatic neoplasms

Abstract

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Objectives: To evaluate the combined use of C-11-Acetate and F-18-DG PET for the diagnosis of hepatic neoplasms. Methods: 20 patients suspicious of hepatic neoplasms underwent both F-18-DG and C-11-Acetate PET within 1 week. 16 patients were proved pathologically and 15 cases were also classified by grading. 4 patients were confirmed by clinical follow-up (time>6 months). All patients also underwent CT, MRI, US or SPECT studies. A routine F-18-DG PET imaging was performed. C-11-Acetate studies consisted of an initial scan on upper abdomen for 10min, followed by a whole body scan. A lesion was classified “+” by both visual assessment and target-background ratio (T/B >1), “-” when T/B≤ 1. Results: In 16 of 20 patients the size of hepatic neoplasm was smaller than 5cm. The lesions of 12 patients could not be differentiated between malignant and benign by other imaging modalities. In PET studies, no C-11-Acetate and F-18-DG uptake were found in 3 benign hepatic lesions. 2 patients with precancerous lesions showed positive uptake of C-11-Acetate only. 5 patients (3 cholangiocarcinomas, 1 angiosarcoma and 1 metastatic lesion) demonstrated positive uptake with F-18-DG, but negative with C-11-Acetate. Of 10 HCC patients, 2 well-differentiated lesions were only positive with C-11-Acetate, 2 poorly differentiated lesions were positive only with F-18-DG and 6 cases (3 well-differentiated and 3 medially differentiated type) were positive with both. The C-11-Acetate positive lesions accumulated tracer both in initial and delayed images that indicated not only increased blood perfusion but also metabolism in the tumor. The highest uptake of C-11-Acetate was found in one of precancerous lesions, the SUV was being 11 in the initial image. However, no relationship between SUV of C-11-Acetate and grade of tumor was found. The F-18-DG -avidity increased when the tumor grade decreased. Conclusions: Combination of C-11-Acetate and F-18-DG PET is not only useful in increasing the accuracy of diagnosis, differentiating primary or secondary/ benign or malignant lesions, but also giving important information for the grading of hepatic carcinoma. F-18-DG is still the first choice for the diagnosis of hepatic carcinoma. C-11-Acetate PET should be applied to those who were negative with F-18-DG.