Quantitative brain relaxation atlases for personalized detection and characterization of brain pathology

Purpose To exploit the improved comparability and hardware independency of quantitative MRI, databases of MR physical parameters in healthy tissue are required, to which tissue properties of patients can be compared. In this work, normative values for longitudinal and transverse relaxation times in...

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Bibliographic Details
Published in:Magnetic resonance in medicine 2020-01, Vol.83 (1), p.337-351
Main Authors: Piredda, Gian Franco, Hilbert, Tom, Granziera, Cristina, Bonnier, Guillaume, Meuli, Reto, Molinari, Filippo, Thiran, Jean‐Philippe, Kober, Tobias
Format: Article
Language:English
Subjects:
Adult
Algorithms
Brain
Brain - diagnostic imaging
Brain Diseases - diagnostic imaging
Brain Mapping
Corpus callosum
Female
Healthy Volunteers
Humans
Image Processing, Computer-Assisted - methods
Lesions
Magnetic Resonance Imaging
Male
Middle Aged
Multiple sclerosis
Multiple Sclerosis - diagnostic imaging
Normalizing
normative atlases
Norms
Physical properties
quantitative MRI
Reference Values
Relaxation time
Reproducibility of Results
single‐subject comparisons
Substantia alba
T1 and T2 mapping
Telemetry
Tissues
Variability
White Matter - diagnostic imaging
Young Adult
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Summary:Purpose To exploit the improved comparability and hardware independency of quantitative MRI, databases of MR physical parameters in healthy tissue are required, to which tissue properties of patients can be compared. In this work, normative values for longitudinal and transverse relaxation times in the brain were established and tested in single‐subject comparisons for detection of abnormal relaxation times. Methods Relaxometry maps of the brain were acquired from 52 healthy volunteers. After spatially normalizing the volumes into a common space, T1 and T2 inter‐subject variability within the healthy cohort was modeled voxel‐wise. A method for a single‐subject comparison against the atlases was developed by computing z‐scores with respect to the established healthy norms. The comparison was applied to two multiple sclerosis and one clinically isolated syndrome cases for a proof of concept. Results The established atlases exhibit a low variation in white matter structures (median RMSE of models equal to 32 ms for T1 and 4 ms for T2), indicating that relaxation times are in a narrow range for normal tissues. The proposed method for single‐subject comparison detected relaxation time deviations from healthy norms in the example patient data sets. Relaxation times were found to be increased in brain lesions (mean z‐scores >5). Moreover, subtle and confluent differences (z‐scores ~2–4) were observed in clinically plausible regions (between lesions, corpus callosum). Conclusions Brain T1 and T2 quantitative norms were derived voxel‐wise with low variability in healthy tissue. Example patient deviation maps demonstrated good sensitivity of the atlases for detecting relaxation time alterations.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.27927