Fig. 3.

T1/T2* mixed-contrast FISP MRI detects post-traumatic iron in the choroid plexus. A Five consecutive 175 µm thick coronal MRI slices (centered at − 1.00 mm from bregma) of the sham-operated (top row) and TBI animal (bottom row) at 6 months post-operation. Note black signal-void areas (white arrows) in the TBI rat which are related to the presence of iron deposits in the choroid plexus. B Thionin-stained section of the same animal sectioned at the corresponding coronal level (7 months post-TBI). C Magnification of the MRI showing the choroidal iron (white arrows). Dashed box equals to that in B, and the corresponding area is shown in photomicrographs

taken from thionin D and Prussian blue F stained sections. Iron deposits (arrowheads) are robustly detected along the ependymal lining at ventricular wall adjacent to fimbria in D, E thionin and F, G adjacent Prussian blue preparations. Iron appears as both diffuse and intracellular deposits. Note the match in location of iron deposits in histologic sections and MRI. H Coronal thionin-stained section showing acute post-impact hemorrhages in the choroid plexus and fimbria at 6 h post-TBI (sections were available from the EPITARGET tissue bank; (Lapinlampi et al. 2017). I Higher magnification photomicrograph of the area indicated with a dashed box in panel H. Note detachment of the ependymal layer along the ventral aspect of the fimbria (fi). The bleeds extend to the “floating part” of the choroid plexus (arrowheads). Abbreviations: cp, choroid plexus; fi, fimbria of hippocampus; V, 3rd ventricle