The use of 18F-fluoro-2-deoxy-D-glucose positron emission tomography with multiple slice spiral computed tomography scanners provides the opportunity to integrate morphologic information and functional information. It may allow the definition of new parameters for assessment of the treatment response of the tumor in one patient sitting. This will also facilitate the use of PET/CT in research studies as well as in clinical practice. This paper summarizes the results of recent studies with 18F-FDG PET/CT after chemotherapy or before and after surgery of metastatic colorectal carcinoma, and its impact on patient management. The purpose of this study was to evaluate the possible contribution of 18F-FDG PET/CT as compared to contrast-enhanced computerized tomography alone as a surrogate marker to evaluate liver metastases in vivo. Information retrieval for this review was through computerized literature search. Comparison of the results of each study was through statistical analysis. Results show that 18F-FDG PET/CT is better than CT as a diagnostic modality in the evaluation of the status of metastatic colorectal carcinoma. The review concludes with a position on how 18F-FDG-PET/CT could make a difference in drug development and clinical management for patients.