The use of dual-tracer PET/CT in selection of HCC patients based on Milan criteria before liver transplant

Objectives Selection of HCC patients for liver transplant (LT) is crucial for prognosis and survival. The conventional tool for assessment is contrast CT but its accuracy is suboptimal for detection of early HCC in cirrhotic livers and for metastatic survey. We evaluated the accuracy of dual-tracer (¹¹C-acetate: ACT and ¹⁸F-FDG: FDG) PET/CT in selecting candidates for LT based on Milan criteria.

Methods HCC patients status post LT or partial hepatectomy (HCC lesion<7 cm) with both preoperative dual-tracer PET/CT and contrast CT within 1 month were recruited into this study. Dual-tracer PET/CT and contrast CT were reviewed independently based on the parameters specified by Milan criteria: HCC lesion size and number, presence/absence of vascular invasion and extrahepatic metastasis, with postoperative pathology as the gold standard. Statistical analysis was performed using Chi-square test.

Results Forty three HCC patients (M: 34, F: 9, mean: 57±10.1 years) were included. Postoperative pathology confirmed 31 patients satisfying and 12 not satisfying Milan criteria. ACT (29/31: 93.5%) and dual-tracer (30/31: 96.8%) PET/CT were significantly more accurate in patient selection for LT than FDG (8/31: 25.8%) or contrast CT (13/31: 41.9%; all p<0.05). ACT (11/12: 91.7%) and dual-tracer (11/12: 91.7%) PET/CT were also more concordant with pathology in patient exclusion for LT than FDG (6/12: 50.0%) or contrast CT (4/12: 33.3%; all p<0.05). The discordance between contrast CT and pathology was due to: false negative diagnosis (n=17), HCC lesion size (n=6) and number (n=1), and overstaging by false positive diagnosis of vascular (n=2) and extrahepatic metastases (n=2). The discordance between dual-tracer PET/CT and pathology was found in 2 false negative cases with post-treatment necrosis.

Conclusions Dual-tracer PET/CT is significantly more accurate in preoperative assessment and selection of HCC patients for LT. Implementation of this imaging for transplant work-up may be considered