Detection of hepatic metastases using dual-time-point FDG PET/CT scans in patients with colorectal cancer

Purpose: The purpose of this study was to determine the most useful parameter of dual-time-point 2-deoxy-2-[¹⁸F]fluoro-d-glucose positron emission tomography/computed tomography (PET/CT) for detection of hepatic metastases in patients with colorectal cancer. Procedures: 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. Results: 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. Conclusions: 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.