Value of dual phase 11C-Acetate (DP Ac) PET in the assessment of Hepatocellular Carcinoma (HCC) in dual tracer (DT) PET-CT

Purpose : The aim of this study is to evaluate the additional value DP Ac PET for differentiation between HCC and other liver lesions compared with conventional DT PET-CT. Material & Method Patients who underwent Dual Tracer PET-CT (Ac and 18F FDG) for suspected HCC in our centres from 2014-16 with histological confirmation were identified. Kinetics analysis were carried out on Ac positive lesions, defined as Ac uptake above liver background. The maximum standardised uptake value (SUVmax) of the lesion and normal liver on Ac PET, and their ratios at 2 mins and 11 mins after tracer injection were obtained. The Ac uptake ratio and difference between the two ratios (R) were calculated. A R>0 was deemed to be predictive of HCC using previously published data. The findings were compared with conventional DT PET-CT and histology. McNemar’s test was used to compare the two methods. Results Forty-eight hepatic lesions were identified on histology, mean size was 30 mm (range 8-112 mm). 34/46 were Ac avid including 28 HCC and 6 non-HCC. 40/46 lesions were DT positive including 33 HCC and 7 non-HCC. The sensitivity, specificity, PPV and NPV for diagnosing HCC based on DT avidity were 94%, 46%, 82% and 75% respectively. 20/34 Ac avid lesion had a positive R including 18 HCC and 2 non-HCC. The sensitivity, specificity, PPV and NPV for DT with DP Ac were 80%, 77%, 90% and 59% respectively (p = 0.0077). False positives were seen in one colon metastasis and one scar tissue. Conclusion: DP Ac significantly increased the specificity of DT PET-CT. Although sensitivity is reduced using this method, DT with DP Ac remains at a clinically acceptable level