ABSTRACT
Functional methods are primarily based on nuclear medicine procedures. Current systems are hybrid Positron Emission Tomography (PET)/CT or PET/MRI systems, which combine the advantages of functional PET imaging and high-resolution morphological images obtained by CT or MRI. The most common radiopharmaceutical used for oncological PET studies is F-18 labelled Deoxyglucose (FDG). Different morphological imaging modalities are used for initial staging in order to assess the extent of the disease, including primarily CT and MRI studies. The detection of tumour recurrence is a prime domain for PET-CT with FDG. In a meta-analysis, the pooled sensitivity and specificity in detecting pelvic metastases or local recurrence were 94% each, and for detecting distant metastases 91% and 83%, respectively. FDG PET-CT is recommended for staging when CEA is rising, but some studies demonstrate that it is helpful for the detection of recurrent colorectal cancer regardless of the serum CEA level. One major aim of functional imaging is the individualisation of therapy.
