Diffusion-Weighted Imaging Shows a False-Negative Finding for Bone Marrow Involvement on 18F-FDG PET/MRI in a Patient With Malignant Lymphoma After Blood Transfusion.

Iron overload is a major complication in blood transfusion procedures. This report presents a case of malignant lymphoma, in which the findings of bone marrow involvement were discordant between F-FDG PET imaging studies and MRI with diffusion-weighted imaging studies. In this case, the PET imaging studies were positive for malignant lymphoma, whereas the MRI studies were negative. Iron deposition in the reticuloendothelial system due to posttransfusion iron overload was considered to be the cause of the decrease in signal intensity on diffusion-weighted imaging, resulting in a false-negative finding on MRI.