Imaging Analysis of HCC Using 18F-FDG-PET/CT

Within the month prior to the initiation of lenvatinib, ¹⁸F-FDG-PET/CT was performed using a dedicated whole-body PET scanner (Biograph mCT Flow40, Siemens Healthcare, Germany). Using SYNAPSE VINCENT v4 (Fujifilm Medical Systems, Japan) software for semiquantitative analysis, the volume of interest (VOI) was drawn along the outline of the tumor, and maximum standardized uptake value (SUV-max) and mean SUV (SUV-mean) in each intra- and extrahepatic target tumor were calculated. Of the lesions measured, that with the highest ¹⁸F-FDG up take was selected and used to calculate the TLR. Next, to measure normal liver activity, 3 non-overlapping spherical 1-cm³ VOIs were drawn in the liver (2 in the right lobe and 1 in the left) on the axial PET images, avoiding the HCC areas seen on dynamic CT. The TLR was calculated using the following equation: TLR = SUV-max of the tumor/SUV-mean of the normal liver. Based on previous reports [3, 6, 8], we selected a TLR ≥2 to indicate high malignant potential.