18F FDG PET/CT for staging of colorectal carcinoma – literature review and case report
- Ilcheva, V. Hadzhiyska , V. Malla, T. Petrov, K. Mladenov, D. Zlatareva, M. Nedevska, V. Neychev
Colorectal cancer is the third most common cancer worldwide. The role of PET/CT in initial diagnosis of primary colorectal cancer is limited. PET is used for restaging of colorectal carcinoma or for evaluating the hepatic and pulmonary metastasis. On the other hand, MRI is used for T- and N- staging and also in the evaluation of liver metastasis. The aim of the study is to demonstrate the capabilities of the imaging modalities (PET/CT and MRI) as well as to show the importance of collaborative work of the units to determine the correct therapeutic decision. In this case, we present a 63 years old patient with rectal carcinoma. Confirmation of the disease was proven using colonoscopy and biopsy. Then we perform FDG-PET/CT on a GE Discovery 16T according to a standard protocol, using diuretic stimulation and oral contrast intake, followed by 3 Tesla MRI of the abdomen and pelvis with intravenous contrast. PET/CT: data on metabolic active tumor formation in the recto-sigmoid region, liver disseminaton and lesion near the navel as well as the presence of two metabolically active peritoneal lesions of small size. MRI: Rectal tumor data with a suspected infiltration of the wall of the ileum and bladder as well as dissemination in the liver and abdominal wall. Additionally, there was a thrombosis of the left branch of the portal vein. By applying both methods it is possible to accurately stage the disease and choose the most appropriate therapeutic behavior. Our impressions of the application of the two imaging methods PET/CT and MRI matches the science publications that each one has a specific application, capabilities and advantages. For example, PET/CT provide sufficient functional and morphological information for the initial staging and also for the peritoneal lesions, which are identified as non-specific and non-definite in MRI. On the other hand, after MRI we receive detailed information for the anatomic and topographic characteristic of the major tumor formation, its relationships with surrounding tissues and organs, as well as several small (less than 15 mm) liver lesions, which are not- definite in PET/CT. Our observations suggest that the independent use of each of the applied imaging methods was not enough for making diagnosis, while the result of the combination of PET/CT and MRI was the most pathognomonic.
Key words: COLORECTAL CANCER. STAGING. PET/CT. MRI. CT