A dual-tracer approach using [¹¹C]CH and [¹⁸F]FDG in HCC clinical decision making

Background: Early detection of recurrent or progressive HCC remains the strongest prognostic factor for survival. Dual tracer PET/CT imaging with [¹¹C]CH and [¹⁸F]FDG can further increase detection rates as both tracers entail different metabolic pathways involved in HCC development. We investigated dual-tracer PET/CT in clinical decision making in patients suspected of recurrent or progressive HCC. All HCC patients who underwent both [¹¹C]CH and [¹⁸F]FDG PET/CT in our institute from February 2018 to December 2021 were included. Both tracer PET/CT were within 4 weeks of each other with at least 6-month follow-up. Patients underwent dual tracer PET/CT because of unexplained and suspicious CT/MRI or sudden rise of serum tumour markers. A detected lesion was considered critical when the finding had prognostic consequences leading to treatment changes.

Results: Nineteen patients who underwent [¹¹C]CH and [¹⁸F]FDG PET/CT were included of which all but six patients were previously treated for HCC. Dual-tracer critical finding detection rate was 95%, with [¹⁸F]FDG 68%, and [¹¹C]CH 84%. Intrahepatic HCC recurrence finding rate was 65% for both tracers. [¹⁸F]FDG found more ablation site recurrences (4/5) compared to [¹¹C]CH (2/5). Only [¹¹C]CH found two needle tract metastases. Both tracers found 75% of the positive lymph nodes. Two new primary tumours were found, one by [¹⁸F]FDG and both by [¹¹C]CH.

Conclusions: Our study favours a dual-tracer approach in HCC staging in high-risk patients or when conventional imaging is non-conclusive.