Diagnostic performance of dual-tracer positron emission tomography-CT with 18F-fluorodeoxyglucose and 11C-acetate versus modified response evaluation criteria in solid tumors in the assessment of residual viable tumours in HCC that received loco-regional therapy

Abstract

Purpose: Dual-tracer positron emission tomography (DT-PET) with 11C-acetate (Ac) and 18F-fluorodeoxyglucose (FDG) have shown to be highly sensitive in the detection of HCC although thus far, it has only been applied to treatment-naïve patients. The aim of this study was to evaluate the diagnostic performance DT-PET in assessing HCC that had undergone loco-regional treatment. Material and methods: Patients with HCC who received loco-regional treatment were retrospectively identified and included if they underwent CT or MRI and DT-PET within 3 months of resection of the lesion. All lesions were evaluated on cross-sectional imaging using the modified response evaluation criteria in solid tumours (mRECIST) and radiotracer uptake on PET were recorded and compared with histology. Results: Fourteen patients with 30 HCC fulfilled the inclusion criteria; 11 underwent transarterial chemoembolization (TACE), 2 radiofrequency ablation (RFA) and 1 both RFA and TACE (median time from previous intervention 3 months, range 1-43 months). Residual tumour was present in 24 lesions on histology. Using mRECIST criteria, 16/30 lesions had complete response, 14 partial response/stable disease. FDG was avid in 15/30, Ac in 20/30 and DT PET in 22/30 lesions. The positive predictive values for both modalities were 100% and the sensitivities in detecting residual disease were 54.2% and 83.3% (p<0.05) for cross-sectional imaging and DT-PET, respectively. Conclusion: mRECIST criteria on cross-sectional imaging under-detect residual viable tumour in HCC that had undergone loco-regional treatment. DTPET is a sensitive modality that can be used as an alternative modality for the treatment reassessment especially in cases where patients’ management may be altered.