title: 11C-acetate PET imaging in hepatocellular carcinoma and other liver masses.
abstract: It is well known that (18)F-FDG PET has a high average false-negative 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 (11)C-acetate and (18)F-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 (11)C-acetate and (18)F-FDG.
  
  
  RESULTS
  In the subgroup of HCC patients with the number of lesions < or = 3 (32 patients; 55 lesions; mean size +/- SD, 3.5 +/- 1.9 cm), the sensitivity of detection by (11)C-acetate is 87.3% ((11)C-acetate maximum SUV [SUV(max)] = 7.32 +/- 2.02, with a lesion-to-normal liver ratio of 1.96 +/- 0.63), whereas the sensitivity of detection by (18)F-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 (11)C-acetate and the poorly differentiated types are detected by (18)F-FDG. All 16 non-HCC malignant (cholangiocarcinoma and metastatic) liver lesions do not show abnormal (11)C-acetate metabolism. Of the benign liver lesions, only FNH shows mildly increased (11)C-acetate activities ((11)C-acetate SUV(max) = 3.59, with a lesion-to-normal liver ratio of 1.25).
  
  
  CONCLUSIONS
  (11)C-Acetate has a high sensitivity and specificity as a radiotracer complementary to (18)F-FDG in PET imaging of HCC and evaluation of other liver masses.
authors.affiliation: Department of Nuclear Medicine and PET, Hong Kong Sanatorium and Hospital, Hong Kong, China. garrettho@hksh.org.hk
authors.forename: Chi-Lai
authors.initials: CL
authors.lastname: Ho
authors.forename: Simon C H
authors.initials: SC
authors.lastname: Yu
authors.forename: David W C
authors.initials: DW
authors.lastname: Yeung
mesh_terms: D000085:Acetates / Q000493:pharmacokinetics; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology; D002250:Carbon Radioisotopes; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000556:secondary; D018281:Cholangiocarcinoma / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D003110:Colonic Neoplasms / Q000473:pathology; D005188:False Negative Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000556:secondary; D008175:Lung Neoplasms / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18