FIG 3. Parasagittal non-contrast-enhanced T1-weighted MR image (600/12/1) in a 35-year-old man with a history of thalassemia and a chronic hemoglobin level of 7.7 mg/dL. The marrow in the diploic space is diffusely abnormal (arrows), because the normal fat has been replaced by hematopoietic tissue, with resultant signal that is hypointense relative that of the adjacent WM and GM.