"Iron dot” lesion in left frontal lobe

"Iron dot” lesion in the left frontal lobe on 3D T2*-weighted (T2*w) coronal (top left), sagittal (lower left), and axial (right) 7 Tesla MRI sequences. T2*-weighted imaging is an MRI sequence to quantify observable or effective T2 (T2* or "T2-star"); in this sequence, hemorrhages and hemosiderin deposits become hypointense (Chavhan GB, Babyn PS, Thomas B, Shroff MM, Haacke EM. Principles, techniques, and applications of T2*-based MR imaging and its special applications. Radiographics 2009;29[5]:1433-49). Note the strong but punctate and sharply delineated intralesional signal loss. This type of intralesional T2*w signal loss differs from that of more recent multiple sclerosis lesions where central T2*w hypointensities appear larger and are more diffuse. They are also distinct from (enlarged) venules present in multiple sclerosis lesions as “iron dot” lesions do not show a tubular appearance following the course of a vessel. (Source: Strunk D, Sinnecker T, Kleffner I, et al. Central intra-lesional iron deposits as a possible novel imaging marker at 7 Tesla MRI in Susac Syndrome: an exploratory study. BMC Med Imaging 2024;24[1]:4. Creative Commons Attribution 4.0 International [CC BY 4.0] license, creativecommons.org/licenses/by/4.0.)