An introduction to PET/CT imaging

Since its introduction in 1998, dual-modality PET/CT imaging has received great attention in the medical community. Patients are examined with both CT and PET in a whole-body single examination in the same scanner and fusion can be obtained directly obviating the need for software registration. The CT images are used for anatomic reference of the tracer uptake patterns imaged in PET, as well as for attenuation correction of the PET data. This review discusses the technical background of PET with F-18-fluorodeoxyglucose, CT and combined PET/CT devices. Clinical applications in oncology are considered. Fusion of the anatomic information provided by CT and the metabolic information provided by PET in PET/CT imaging allows a higher diagnostic accuracy for lesion localisation than PET plus CT performed independently. Image artefacts can result from CT-based attenuation methodology that can overcorrect dense objects generating hot spot artefacts in attenuation correction PET images and mismatches in CT and PET studies due to respiratory movements and the different patient positioning between both examinations. (author)