The choice of embedding media affects image quality, tissue R , and susceptibility behaviors in post-mortem brain MR microscopy at 7.0T.

Petr Dusek, Vince Istvan Madai, Till Huelnhagen, Erik Bahn, Radoslav Matej, Jan Sobesky, Thoralf Niendorf, Julio Acosta-Cabronero, Jens Wuerfel

Journal: Magnetic resonance in medicine 2020;81(4):2688-2701

PMID: 30506939

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Abstract

PURPOSE

The quality and precision of post-mortem MRI microscopy may vary depending on the embedding medium used. To investigate this, our study evaluated the impact of 5 widely used media on: (1) image quality, (2) contrast of high spatial resolution gradient-echo (T and T -weighted) MR images, (3) effective transverse relaxation rate (R ), and (4) quantitative susceptibility measurements (QSM) of post-mortem brain specimens.

METHODS

Five formaldehyde-fixed brain slices were scanned using 7.0T MRI in: (1) formaldehyde solution (formalin), (2) phosphate-buffered saline (PBS), (3) deuterium oxide (D O), (4) perfluoropolyether (Galden), and (5) agarose gel. SNR and contrast-to-noise ratii (SNR/CNR) were calculated for cortex/white matter (WM) and basal ganglia/WM regions. In addition, median R and QSM values were extracted from caudate nucleus, putamen, globus pallidus, WM, and cortical regions.

RESULTS

PBS, Galden, and agarose returned higher SNR/CNR compared to formalin and D O. Formalin fixation, and its use as embedding medium for scanning, increased tissue R . Imaging with agarose, D O, and Galden returned lower R values than PBS (and formalin). No major QSM offsets were observed, although spatial variance was increased (with respect to R behaviors) for formalin and agarose.

CONCLUSIONS

Embedding media affect gradient-echo image quality, R , and QSM in differing ways. In this study, PBS embedding was identified as the most stable experimental setup, although by a small margin. Agarose and Galden were preferred to formalin or D O embedding. Formalin significantly increased R causing noisier data and increased QSM variance.

Address: Department of Neurology, Charles University, 1st Faculty of Medicine and General University Hospital in Prague, Praha, Czech Republic.; Department of Radiology, Charles University, 1st Faculty of Medicine and General University Hospital in Prague, Praha, Czech Republic.; Department of Neurology and Center for Stroke Research Berlin (CSB), Charité-Universitaetsmedizin, Berlin, Germany.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.; Institute of Neuropathology, University Medicine Göttingen, Göttingen, Germany.; Department of Pathology and Molecular Medicine, Thomayer Hospital, Praha, Czech Republic.; Department of Pathology, Charles University, 1st Faculty of Medicine and General University Hospital in Prague, Praha, Czech Republic.; Department of Neurology and Center for Stroke Research Berlin (CSB), Charité-Universitaetsmedizin, Berlin, Germany.; Experimental and Clinical Research Center (ECRC), Charité-Universitaetsmedizin and Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.; Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.; Experimental and Clinical Research Center (ECRC), Charité-Universitaetsmedizin and Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany.; Wellcome Centre for Human Neuroimaging, UCL Institute of Neurology, University College London, London, United Kingdom.; German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany.; NeuroCure Clinical Research Center, Charité-Universitaetsmedizin, Berlin, Germany.; Medical Imaging Analysis Center AG, Basel, Switzerland.; Department of Biomedical Engineering, University Basel, Switzerland.

DOI: 10.1002/mrm.27595

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MeSH Terms: Aged, Autopsy, Brain, Brain Mapping, Contrast Media, Deuterium Oxide, Ethers, Female, Fluorocarbons, Formaldehyde, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Middle Aged, Phosphates, Sepharose, Signal-To-Noise Ratio, Specimen Handling, Tissue Embedding