PET in Benign Bone Marrow Disorders

This review aims to describe the current status of benign bone marrow (BM) imaging using PET. BM imaging is important as the BM is not only involved in poiesis of different vital cell lines and can be affected by primary BM disorders, but it is also frequently affected by several extramedullary diseases. Indications for the use of PET in benign BM disorders are the detection of extramedullary hematopoiesis, evaluation of patients with a discrepancy between BM histology and clinical status, visualizing BM infarctions, location of the optimal site for BM biopsy, diagnosing and staging of other hematological BM disorders, evaluation of radiotherapy effect on BM, and evaluation of BM transplantation. The 3'-¹⁸F-fluoro-3'-deoxy-L-thymidine (FLT) and 2-¹⁸F-2-deoxy-D-glucose (FDG) are the current main PET tracers to image BM physiology and pathology. FLT is a DNA synthesis-related tracer that can be used effectively in primary BM disorders in both diagnosis and monitoring treatment response, for example, in aplastic anemia. In secondary benign BM disorders, FDG-PET reveals that the prevalence of BM involvement in several benign diseases is more common than thought before. Novel PET tracers, such as the proliferation marker 4DST and hypoxia markers FAZA, MISO, and ATSM, are promising to visualize (benign) BM pathology more specifically. PET/MRI using innovative MRI sequences is promising to improve BM imaging in the near future. Additional trials are recommended to evaluate possible clinical applications of these newer tracers and new applications of PET/MRI in daily practice. This should be followed by updated guidelines on the use of PET in benign BM diseases.