Fig. 1

“Iron dot” lesion in the left frontal lobe on 3D T2* weighted coronal (top left), sagittal (lower left), and axial (right) 7 Tesla magnetic resonance imaging sequences. Please note the strong but punctate and sharply delineated intra-lesional signal loss on T2*w. This type of intra-lesional T2*w signal loss differs from that of more recent multiple sclerosis (MS) lesions where central T2*w hypointensities appear larger and more diffuse. They are also distinct from (enlarged) venules present in MS lesions as “iron dot” lesions do not show a tubular appearance following the course of a vessel