PET/CT imaging: what radiologists need to know.

Positron emission tomography (PET)/computed tomography (CT) imaging is frequently requested in Oncology. Radiologists and nuclear medicine physicians are often asked to perform a panel of imaging examinations as part of the initial staging or follow-up of cancer patients. Medical imaging must therefore integrate polyvalent skills enabling imaging specialists to understand and interpret all types of images. In this context, PET imaging combined with non-enhanced CT, and diagnostic quality contrast-enhanced CT scan and optimisation of CT settings, is part of this multidisciplinary approach requiring the specific skills of a radiologist and a nuclear medicine physician. This approach must therefore be conducted in both directions: radiologists and nuclear medicine physicians should both know how to correlate PET and CT images, while preserving the specificities of each discipline. Radiologists need to be aware of several aspects of PET imaging: PET technology, the examination procedure and injection of iodinated contrast agent for high quality diagnostic CT, ideally followed by double interpretation of CT images, PET images and fused images. Radiologists should be familiar with PET imaging, as this procedure may be associated with several pitfalls and artefacts that need interpretation by a trained specialist. The authors analyse the examination technique of PET combined with non-enhanced and/or contrast-enhanced CT and the proposals for optimal interpretation of normal or pathological PET/CT fusion images.