Hematologic imaging

Blood cancers are among the malignancies for which hybrid imaging is most frequently used. Current guidelines recommend [18F]Fluorodeoxyglucose (FDG)-positron emission tomography (PET) for staging and treatment response assessment in most cases. However, some indolent non-Hodgkin lymphomas such as marginal zone lymphomas small lymphocytic lymphoma/chronic lymphocytic leukemia show variable, sometimes very low FDG uptake. Here, PET/magnetic resonance imaging (MRI) seems to outperform PET/CT, because diffusion-weighted imaging (DWI) is highly sensitive for lymphomas. In myelomas, FDG-PET is also recommended by current guidelines, although >10% of cases are non-FDG-avid. Given that MRI, and in particular DWI, are well established for myeloma evaluation, and especially diffuse marrow infiltration, PET/MRI may be a logical choice, although currently not officially endorsed. A promising novel PET tracer in blood cancers—including non-FDG-avid lymphomas and precursor myeloma—is [68Ga]Pentixafor, which targets CXCR4, a chemokine with a key function for cell migration.