Functional marrow identification by PET/CT and MRI to assess organ reserve

Bone marrow plays an important role in cancer progression, treatment response, and therapy-related toxicity. Advances in molecular and quantitative imaging enable non-invasive assessment of marrow metabolism, proliferation, and composition. A systematic review identified studies investigating quantitative imaging biomarkers, which were evaluated according to imaging modality, biomarker type, clinical application, and temporal trends. In addition, an automated literature landscape analysis using citation-network expansion and semantic clustering was developed to characterize broader research structures and thematic communities. Research activity increased over time, with positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) representing the predominant imaging modalities. The automated analysis identified interconnected research domains including metabolic PET imaging, quantitative MRI of marrow composition, hematologic toxicity, multiple myeloma, transplantation, and proliferative PET imaging. $^{18}$F-fluorodeoxyglucose (FDG) PET was the most frequently investigated approach, whereas $^{18}$F-fluorothymidine (FLT) PET and Dixon-based MRI reflected growing interest in proliferation and marrow composition. Longitudinal studies demonstrated that imaging biomarkers can characterize therapy-induced marrow suppression, recovery, changes in tracer uptake, and increases in marrow fat fraction. Imaging-based assessment of hematologic toxicity remains less developed but shows promise for evaluating functional marrow reserve. Overall, quantitative imaging biomarkers provide valuable insight into marrow function, treatment response, and toxicity risk. Further standardization of imaging methodologies, terminology, and clinical endpoints, together with prospective validation and integration with clinical outcomes, is required to establish their role in oncology.