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Proceedings Paper

Fast and accurate brain T2 relaxation time quantification in animal models calibrated using gel phantoms and in vivo data suitable for imaging at a biosafety level 4 environment
Author(s): Marcelo A. Castro; Joseph Laux; Harry Friel; Jeffrey Solomon; Russell Byrum; Oscar Rojas; David Thomasson; Laura Bollinger; Dima Hammoud; Ji Hyun Lee
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Paper Abstract

The brain is an organ of interest in high-consequence infectious disease. Subtle blood-brain-barrier disruption and edema can be identified and quantified using T2 relaxation time as a biomarker. Accuracy is required to correlate changes in imaging findings with biological processes and therapeutic effectiveness. Dual echo time Fluid-Attenuated Inversion Recovery images, which minimizes the partial volume effects from cerebrospinal fluid, can be used to quantify T2 relaxation. This sequence also meets the acquisition time requirements of biosafety level-4 facilities, where cohorts of animals are imaged on a tight schedule until terminal stages, when the animals may not survive long scans. However, the echo time used to compute T2 varies among slices due to k-space mapping in fast spin-echo sequence. Therefore, an effective echo time instead of the prescribed echo time should be considered. We hypothesize that accurate effective echo time can be estimated by optimization for each slice ordering. A longer and more accurate T2-weighted spin-echo (multiecho) sequence to compute T2 maps from mono-exponential fitting was validated using gel phantoms and used as ground truth. A brain of a non-human primate was imaged in vivo using both T2 sequences. T2 maps were generated using both methods and a correction factor was computed by linear fitting for each set of echo times and slice ordering. The coefficient of variation within phantoms and the Pearson’s correlation coefficient between in vivo ground truth T2 and each map were used to assess its accuracy and quality.

Paper Details

Date Published: 16 March 2020
PDF: 9 pages
Proc. SPIE 11312, Medical Imaging 2020: Physics of Medical Imaging, 1131233 (16 March 2020); doi: 10.1117/12.2548619
Show Author Affiliations
Marcelo A. Castro, National Institutes of Health (United States)
Joseph Laux, National Institutes of Health (United States)
Harry Friel, Philips Healthcare (United States)
Jeffrey Solomon, Frederick National Lab. for Cancer Research (United States)
Russell Byrum, National Institutes of Health (United States)
Oscar Rojas, National Institutes of Health (United States)
David Thomasson, National Institutes of Health (United States)
Laura Bollinger, National Institutes of Health (United States)
Dima Hammoud, National Institutes of Health (United States)
Ji Hyun Lee, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 11312:
Medical Imaging 2020: Physics of Medical Imaging
Guang-Hong Chen; Hilde Bosmans, Editor(s)

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