The role of 18F-FDG PET/CT in the diagnosis of recurrent colorectal cancer

Abstract

Colorectal cancer is one of the most common cancers worldwide, including Poland. PET/CT is a relatively new diagnostic imaging method which has gained wide acceptance in oncology. The combination of anatomical imaging (CT) and metabolic imaging (PET) enables early identification of proliferative changes and thus an accurate staging of cancer. In the diagnosis of recurrent colorectal cancer, PET/CT with fluorodeoxyglucose (¹⁸F-FDG) has proven to be of high clinical value. The information obtained in this study has a significant impact on patient management. When there is suspicion of relapse, it is important to use an effective restaging tool to accurately define the extent of the recurrence and to plan the proper therapy. In the standard protocol for the ¹⁸F-FDG PET/CT study, fused images of low dose CT (without intravenous contrastagent) and PET are performed. This approach does not provide sufficient information of local tumor or invasion to adjacent organs and vessels to enable assessment of the suitability for resectability. This information is, however, available from computed tomography when intravenous contrast agent is used. Implementation of the PET/CT protocol consisting of low dose CT, with PET followed by CT with intravenous contrast agent in the corresponding region, provides in a single study all the necessary information required to qualify patients for surgery. It may in the future become the modality of choice in the diagnosis of colorectal cancer recurrence.