Detection of Hepatic Metastases Using Dual-Time-Point FDG PET/CT Scans in Patients with Colorectal Cancer

The purpose of this study was to determine the most useful parameter of dual-time-point 2-deoxy-2-[(18)F]fluoro-d-glucose positron emission tomography/computed tomography (PET/CT) for detection of hepatic metastases in patients with colorectal cancer. Thirty-nine patients had undergone a dual-time-point PET/CT scan and a subsequent histopathological confirmation for a workup of hepatic metastases. Detection rates were compared for visual analysis score, standardized uptake value (SUV), tumor-to-liver uptake ratio (TLR), and percent changes of the SUV and TLR. Of 91 liver lesions, 86 lesions were confirmed as metastases. The SUV and TLR of metastatic lesions on the delayed images were higher than those on the first scan (p < 0.001). The signal-to-noise ratio of the delayed PET scan was higher than that of the first scan (p < 0.0001). The TLR and SUV of the delayed scan showed the highest detection rates of 92% and 88%, whereas percent changes of SUV and TLR showed the lowest detection rates (51%, 67%). Visual analysis detected 87% on the delayed scan and 77% on the first scan. A delayed scan is more favorable for the detection of hepatic metastases of colorectal cancer, and the TLR on the delayed scan was the most useful parameter.