PET/MR: Basics and new developments

Abstract

It has become evident that hybrid modalities are one of the most important technical and clinical achievements in clinical imaging over the last two decades. This has impacted significantly many aspects of patient diagnosis, stratification, prognosis, and treatment strategies. After the advent of SPECT/CT and PET/CT to the clinical arena, PET/MR was introduced shortly afterward with real simultaneous capabilities and additional features mainly characterized by the inherent differences between MR and CT imaging techniques. In this chapter, objectives were made to describe the technical challenges behind the hybridization of PET and MR in one imaging system especially if the aim is to produce a simultaneous data acquisition. Different commercially available PET/MR systems were also described along with their specific characteristics, geometry, and design. The use of new PET detector technology was one of the reasons beyond the success of hybrid PET/MR. Thus, some details were provided for different types of crystals and light photosensors along with other interfering variables with MR detector components. Attenuation and motion correction in PET/MR imaging were reviewed with recent tips on approaches devised and their relative merits. Small animal PET/MR was outlined as well. Challenges, opportunities, and future directions were highlighted at the end of the chapter.