What does splenic iron deposition look like on MRI, and what are some major causes of iron deposition in the spleen?
Iron deposition leads to decreased T1-weighted and T2-weighted signal intensity of the spleen relative to normal splenic tissue, which is particularly accentuated on in-phase T1-weighted gradient recalled echo MR images. Punctate foci of iron deposition, known as Gamna Gandy bodies, result from intraparenchymal hemorrhages in the setting of portal hypertension. Focal iron deposition may also occur with prior splenic infarction. Diffuse iron deposition in the spleen is most commonly due to secondary hemosiderosis related to repeated blood transfusions, where iron is taken up by reticuloendothelial cells. Diffuse iron deposition in the liver and bone marrow is also commonly seen. In contrast, genetic (primary) hemochromatosis, an inherited condition leading to excess iron absorption from the bowel, leads to diffuse iron deposition in the liver, pancreas, and myocardium, with sparing of the spleen.