Role of PET (Positron Emission Tomography) CT in detection of patients with colorectal carcinoma and staging of the tumor

Abstract

Colorectal cancer is one of the most common malignant tumors all over the world and one of the leading causes of death. Its highest incidence is found in advanced countries, and its lowest incidence is found in developing countries. Colorectal cancer is the fifth most common cause of cancer deaths in Egypt. Colon cancer is more common in women, and rectal cancer is more common in men, however, the percentage of young-onset colorectal cancer cases in Egyptians is strikingly high with more than one third of cases occurring under age 40 years, and the age-adjusted mortality rates in young Egyptians are likewise high. In addition, rectal cancer is frequent. The available modalities of investigation include : Fecal occult blood test, double contrast barium enema, and conventional colonoscopy, CT has been used to detect and stage primary and recurrent colorectal neoplasms and has been joined by MR imaging, trans-rectal sonography, scintigraphy with monoclonal antibody (MoAb) imaging, Positron Emission Tomography (PET) and recently PET/CT. PET using (18-FDG) is a unique form of imaging that allows in vivo analysis of tissue metabolic activity. 18-FDG exploits the native glucose transporter to enter the cell. Since many tumors have enhanced glucose uptake, FDG is readily accumulated in malignant cells and can be detected by a PET camera, thus by forming images based on functional rather than anatomic information, FDG-PET has the potential to show tumor foci at an early stage, before any structural abnormality becomes apparent. PET/CT scanners are actually twice as expensive as standard PET scanners because of the sophisticated technology required to create these machines. With these scanners, the