Postmortem analyses of brain tissue offer the unique opportunity to improve our understanding of MRI contrast mechanisms by performing chemical and immunohistological correlation analyses. We are currently running a variety of postmortem studies. The frequently applied formalin fixation extracts free water and consequently changes the magnetic susceptibility and nearly all relaxation properties. Therefore, image contrast in fixed brain slices differs from the contrast acquired under in vivo conditions. To circumvent these limitations, we recently started a post mortem analyses with fresh and unfixed brain (please see below).
|Figure: Workflow of our fresh postmortem study: The entire (unfixed) brain is embedded in agarose gel to maintain its structure and stiffness (A). Fiberglas rods arranged in 1cm spacing provide additional stability and enable precise cutting into 1 cm thick slices (B). Several Plexiglas trays holding the brain slices (C) are mounted inside the a plastic container which is filled with a buffer solution (D). The MRI (E) then is used as a reference to guide sample extraction for further histological and chemical analysis (F).|
** Birkl, C., Langkammer, C., Haybaeck, J., Ernst, C., Stollberger, R., Fazekas, F., Ropele, S.
Temperature-induced changes of magnetic resonance relaxation times in the human brain: A postmortem study.
Magn Reson Med. 2013, doi: 10.1002/mrm.24799
** Langkammer, C; Krebs, N; Goessler, W; Scheurer, E; Yen, K; Fazekas, F; Ropele, S.
Susceptibility induced gray-white matter MRI contrast in the human brain.
Neuroimage. 2012; 59(2):1413-1419
** Langkammer, C; Schweser, F; Krebs, N; Deistung, A; Goessler, W; Scheurer, E; Sommer, K; Reishofer, G; Yen, K; Fazekas, F; Ropele, S; Reichenbach, JR
Quantitative susceptibility mapping (QSM) as a means to measure brain iron? A post mortem validation study.
Neuroimage. 2012; 62(3):1593-1599
** Langkammer, C; Krebs, N; Goessler, W; Scheurer, E; Ebner, F; Yen, K; Fazekas, F; Ropele, S
Quantitative MR imaging of brain iron: a postmortem validation study.
Radiology. 2010; 257(2):455-462