PET/MR Imaging of the Gastrointestinal Tract.

PET/MR imaging combines molecular PET data with multiparametric MR imaging in a single reduced-radiation examination of the gastrointestinal tract. For oncologic indications, the hybrid modality adds value in hepatic metastasis detection, locoregional staging, and posttreatment response assessment. Radiotracers beyond fluorodeoxyglucose, including fibroblast activation protein inhibitor ligands and somatostatin receptor analogs, expand diagnostic reach in tumors with low glycolytic activity and in neuroendocrine disease. For inflammatory bowel disease, PET/MR enterography assists with selected questions such as differentiation of inflammatory from fibrotic strictures. This review evaluates current evidence supporting PET/MR imaging across oncologic and nononcologic gastrointestinal applications.