Average CT in PET studies of colorectal cancer patients with metastasis in the liver and esophageal cancer patients

Abstract

Average CT (ACT) is similar to PET in temporal resolution for PET/CT imaging of the thorax. This study is to quantify effect of ACT on PET gross tumor volume (GTV) delineation with standardized uptake value (SUV) for colorectal cancer with liver metastasis and esophageal cancer patients. We studied 48 colorectal cancer patients with metastasis in the liver and 52 esophageal cancer patients. Routine PET/CT scan with free breathing protocol was followed by a cine CT scan of the thoracic region for ACT. We analyzed the difference between the two PET data sets corrected with helical CT (HCT) and ACT in image alignment, SUVmax, and GTV. The 67% of the colorectal and 73% of the esophageal studies demonstrated respiratory artifacts in PETHCT. Majority of the artifacts were removed in PETACT. The SUVmax change of over 20% between PETHCT and PETACT was found in 15% of the colorectal and 17% of the esophageal cancer cases. The effect of misregistration was more pronounced for the smaller lesions (