Dual-Tracer PET/CT Better for Liver Transplant Selection

Staging of hepatocellular carcinoma for evaluation of liver transplant suitability may be more effective with dual-tracer PET/CT than with the traditional contrast-enhanced CT, according to a study published online in the Journal of Nuclear Medicine.

Researchers in Hong Kong noted that assessment with contrast CT could be affected by structural or architectural changes in cirrhotic livers. They undertook a retrospective study to compare preoperative contrast CT findings with those from dual tracer (11C-acetate and 18F-FDG) PET/CT to see if this would be a more effective screening method.

The study included 43 subjects with hepatocellular carcinoma (HCC) who had undergone both imaging exams within a one-month period before receiving a liver transplant (22 subjects) or undergoing a partial hepatectomy (21 subjects). The researchers compared the study findings with postoperative pathological analysis for accuracy in assessment of parameters specified by the Milan criteria, TNM staging, and patient selection for transplant.

The dual-tracer PET/CT performed equally well in detecting HCC for both transplant (94.1 percent) and partial hepatectomy (95.8 percent) groups, as well as with TNM staging (90.9 percent transplant; 90.5 percent partial hepatectomy). The contrast CT findings were lower, although the authors wrote that it “performed reasonably well,” with 67.6 percent for HCC detection in the transplant group and 37.5 percent in the partial hepatectomy group. TNM staging was 54.5 percent for the transplant group and 28.6 percent for the partial hepatectomy group.

Sources of error for contrast CT were related to cirrhosis or previous treatment. These errors included difficulty differentiating cirrhotic nodules from HCC (39 percent) and tumor size estimation (14 percent). Overestimation of vascular invasion and extrahepatic metastases were not common (4.6 percent, each).

According to the authors, “The overall sensitivity (96.8 percent) and specificity (91.7 percent) of dual-tracer PET/CT for patient selection for LT were significant higher than those of contrast CT (41.9 percent and 33.0 percent, respectively) (both Ps < 0.05).” The inclusion of the dual-contrast PET/CT in a pretransplant workup may warrant serious consideration, they concluded.