Correlation between dual-time-point ¹⁸F-FDG PET/CT imaging and pathological grade in hepatocellular carcinoma

Dual-time-point (DTP) ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) imaging has been associated with an enhanced diagnostic yield in various malignancies. Nevertheless, there is a lack of data on the use of delayed imaging in patients with hepatocellular carcinoma (HCC). The aim of this study was to investigate the correlation between the semiquantitative parameters of DTP ¹⁸F-FDG PET/CT scan and histological grades of HCC.

The data of 40 patients with HCC who underwent DTP ¹⁸F-FDG PET/CT scan were retrospectively analyzed. The maximum standardized uptake value of tumor (SUVmax) and normal liver tissue (SUVavg) were measured for both time points. The tumor to normal liver tissue ratio (SUVratio) and changes in SUVratio (ΔSUVratio) between early and delayed images were calculated. These values were compared and evaluated for correlation between the semiquantitative parameters and histological grades of HCC (I, II, and III).

SUVmax [3.50 (2.80, 4.80) vs. 3.10 (2.70, 4.38), P=0.001] and SUVratio [1.89 (1.41, 2.49) vs. 1.67 (1.25, 2.22), P<0.001] on delayed images were significantly higher than those on early images. In contrast, SUVavg was significantly lower in delayed scan [1.90 (1.70, 2.10) vs. 2.10 (1.90, 2.40), P<0.001]. The delayed imaging had less influence on the SUV values of well-differentiated HCC. SUVratio2 and ΔSUVratio differed significantly across grades (all P<0.05), with good positive correlations to histological grades (r=0.660 and r=0.689, both P<0.001).

Delayed ¹⁸F-FDG PET/CT imaging significantly enhances tumor visualization and provides reliable semiquantitative metrics (SUVratio2 and ΔSUVratio) for HCC grading. These findings underline the clinical utility of DTP imaging in non-invasive tumor differentiation and treatment planning.