scholarly journals Quantitative Multi-Parameter Mapping Optimized for the Clinical Routine

2020 ◽  
Vol 14 ◽  
Author(s):  
Graham Cooper ◽  
Sebastian Hirsch ◽  
Michael Scheel ◽  
Alexander U. Brandt ◽  
Friedemann Paul ◽  
...  
Keyword(s):  
White Matter ◽  
Relaxation Rate ◽  
Bias Field ◽  
Brain Atlas ◽  
Transverse Relaxation Rate ◽  
Post Processing ◽  
Clinical Routine ◽  
Parameter Mapping ◽  
Bias Field Correction ◽  
Subject Variability

Using quantitative multi-parameter mapping (MPM), studies can investigate clinically relevant microstructural changes with high reliability over time and across subjects and sites. However, long acquisition times (20 min for the standard 1-mm isotropic protocol) limit its translational potential. This study aimed to evaluate the sensitivity gain of a fast 1.6-mm isotropic MPM protocol including post-processing optimized for longitudinal clinical studies. 6 healthy volunteers (35±7 years old; 3 female) were scanned at 3T to acquire the following whole-brain MPM maps with 1.6 mm isotropic resolution: proton density (PD), magnetization transfer saturation (MT), longitudinal relaxation rate (R1), and transverse relaxation rate (R2*). MPM maps were generated using two RF transmit field (B1+) correction methods: (1) using an acquired B1+ map and (2) using a data-driven approach. Maps were generated with and without Gibb's ringing correction. The intra-/inter-subject coefficient of variation (CoV) of all maps in the gray and white matter, as well as in all anatomical regions of a fine-grained brain atlas, were compared between the different post-processing methods using Student's t-test. The intra-subject stability of the 1.6-mm MPM protocol is 2–3 times higher than for the standard 1-mm sequence and can be achieved in less than half the scan duration. Intra-subject variability for all four maps in white matter ranged from 1.2–5.3% and in gray matter from 1.8 to 9.2%. Bias-field correction using an acquired B1+ map significantly improved intra-subject variability of PD and R1 in the gray (42%) and white matter (54%) and correcting the raw images for the effect of Gibb's ringing further improved intra-subject variability in all maps in the gray (11%) and white matter (10%). Combining Gibb's ringing correction and bias field correction using acquired B1+ maps provides excellent stability of the 7-min MPM sequence with 1.6 mm resolution suitable for the clinical routine.

scholarly journals Reduced white matter MRI transverse relaxation rate in cognitively normal H63D-HFE human carriers and H67D-HFE mice

2015 ◽  
Vol 10 (4) ◽  
pp. 1231-1242 ◽  
Author(s):  
Mark D. Meadowcroft ◽  
Jianli Wang ◽  
Carson J. Purnell ◽  
Douglas G. Peters ◽  
Paul J. Eslinger ◽  
...  
Keyword(s):  
White Matter ◽  
Relaxation Rate ◽  
Transverse Relaxation Rate ◽  
Transverse Relaxation ◽  
Cognitively Normal

scholarly journals Combining Navigator and Optical Prospective Motion Correction for High-Quality 500 μm Resolution Quantitative Multi-Parameter Mapping at 7T

2021 ◽  
Author(s):  
Lenka Vaculčiaková ◽  
Kornelius Podranski ◽  
Luke J. Edwards ◽  
Dilek Ocal ◽  
Thomas Veale ◽  
...  
Keyword(s):  
Relaxation Rate ◽  
Motion Correction ◽  
The Elderly ◽  
Proton Density ◽  
Young Cohort ◽  
Transverse Relaxation Rate ◽  
Spatial Homogeneity ◽  
Parameter Mapping ◽  
Dementia Patients ◽  
Elderly Cohort

AbstractPURPOSEHigh-resolution quantitative multi-parameter mapping shows promise for non-invasively characterizing human brain microstructure but is limited by physiological artifacts. We implemented corrections for rigid head movement and respiration-related B0-fluctuations and evaluated them in healthy volunteers and dementia patients.METHODSCamera-based optical prospective motion correction (PMC) and free-induction decay (FID) navigator correction were implemented in a gradient and RF-spoiled multi-echo 3D gradient echo sequence for mapping proton density (PD), longitudinal relaxation rate (R1) and effective transverse relaxation rate (R2*). We studied their effectiveness separately and in concert in young volunteers and then evaluated the navigator correction (NAVcor) with PMC in a group of elderly volunteers and dementia patients. We used spatial homogeneity within white matter (WM) and gray matter (GM) and scan-rescan measures as quality metrics.RESULTSNAVcor and PMC reduced artifacts and improved the homogeneity and reproducibility of parameter maps. In elderly participants, NAVcor improved scan-rescan reproducibility of parameter maps (coefficient of variation decreased by 14.7% and 11.9% within WM and GM respectively). Spurious inhomogeneities within WM were reduced more in the elderly than in the young cohort (by 9% vs 2%). PMC increased regional GM/WM contrast and was especially important in the elderly cohort, which moved twice as much as the young cohort. We did not find a significant interaction between the two corrections.CONCLUSIONNavigator correction and PMC significantly improved the quality of PD, R1 and R2* maps, particularly in less compliant elderly volunteers and dementia patients.

Proton magnetic relaxation of water sorbed by methaemoglobin crystals

1973 ◽  
Vol 331 (1587) ◽  
pp. 457-468 ◽  
Keyword(s):  
Relaxation Rate ◽  
Relaxation Times ◽  
Transverse Relaxation Rate ◽  
Ferric Ions ◽  
Transverse Relaxation ◽  
Water Binding ◽  
Adsorption Sites ◽  
Protein Molecules ◽  
Proton Magnetic Relaxation ◽  
Limiting Value

P. m. r. relaxation times ( T 1 and T 2 ) have been measured as a function of regain and temperature for water sorbed by lyophilized methaemoglobin. The purpose of the work was to gain information regarding the nature and extent of water binding by the protein molecules. The T 1 results are interpreted in terms of an exchange between the sixth ligand position of the Fe (III) and other adsorption sites on the protein. At high temperatures the relaxation rate at a given regain reaches a limiting value which allows the fraction of ferric ions hydrated to be calculated. Above 16% regain all the Fe (III) is hydrated. At 21 and 35% regains a maximum appears in the relaxation rate at about -46 °C indicating a contribution from a more mobile phase which produces a T 1 minimum at that temperature. The T 2 data are consistent with a model in which the main contribution to the transverse relaxation rate comes from a tightly bound fraction of the water with ω 0 Ƭ c ≫1. The temperature dependence of T 2 exhibits three different regions: ( a ) a low temperature region where lg T 2 ∝ T -1 ; ( b ) an intermediate region with a steeper increase of T 2 with temperature; and ( c ) a high temperature where T 2 levels off.

scholarly journals Apparent transverse relaxation rate in human brain varies linearly with tissue iron concentration at 4.7 T

2007 ◽  
Vol 58 (5) ◽  
pp. 1054-1060 ◽  
Author(s):  
Fumiyuki Mitsumori ◽  
Hidehiro Watanabe ◽  
Nobuhiro Takaya ◽  
Michael Garwood
Keyword(s):  
Human Brain ◽  
Relaxation Rate ◽  
Iron Concentration ◽  
Transverse Relaxation Rate ◽  
Transverse Relaxation ◽  
Tissue Iron

Robust Finger Vein Recognition Based on Deep CNN with Spatial Attention and Bias Field Correction

2021 ◽  
Vol 30 (01) ◽  
pp. 2140005
Author(s):  
Zhe Huang ◽  
Chengan Guo
Keyword(s):  
Spatial Attention ◽  
Transfer Learning ◽  
Learning Strategy ◽  
Bias Field ◽  
The Public ◽  
Finger Vein ◽  
Bias Field Correction ◽  
Training Samples ◽  
Vein Recognition ◽  
Finger Vein Recognition

As one of the biometric information based authentication technologies, finger vein recognition has received increasing attention due to its safety and convenience. However, it is still a challenging task to design an efficient and robust finger vein recognition system because of the low quality of the finger vein images, lack of sufficient number of training samples with image-level annotated information and no pixel-level finger vein texture labels in the public available finger vein databases. In this paper, we propose a novel CNN-based finger vein recognition approach with bias field correction, spatial attention mechanism and a multistage transfer learning strategy to cope with the difficulties mentioned above. In the proposed method, the bias field correction module is to remove the unbalanced bias field of the original images by using a two-dimensional polynomial fitting algorithm, the spatial attention module is to enhance the informative vein texture regions while suppressing the other less informative regions, and the multistage transfer learning strategy is to solve the problem caused by insufficient training for CNN-based model due to lack of labeled training samples in the public finger vein databases. Moreover, several measures, including a label smoothing scheme and data augmentation, are exploited to improve the performance of the proposed method. Extensive experiments have been conducted in the work on three public databases, and the results show that the proposed approach outperforms the existing state-of-the-art methods.

scholarly journals Brain structural changes in cannabis dependence: association with MAGL

2019 ◽  
Vol 25 (12) ◽  
pp. 3256-3266 ◽  
Author(s):  
Peter Manza ◽  
Kai Yuan ◽  
Ehsan Shokri-Kojori ◽  
Dardo Tomasi ◽  
Nora D. Volkow
Keyword(s):  
White Matter ◽  
Spatial Patterns ◽  
Cortical Thickness ◽  
Gray Matter ◽  
Acid Amide ◽  
Cannabis Use ◽  
Brain Atlas ◽  
Cannabis Dependence ◽  
Human Connectome Project ◽  
Postmortem Brain Tissue

AbstractCannabis use is rising, yet there is poor understanding of biological processes that might link chronic cannabis use to brain structural abnormalities. To lend insight into this topic, we examined white matter microstructural integrity and gray matter cortical thickness/density differences between 89 individuals with cannabis dependence (CD) and 89 matched controls (64 males, 25 females in each group) from the Human Connectome Project. We tested whether cortical patterns for expression of genes relevant for cannabinoid signaling (from Allen Human Brain Atlas postmortem tissue) were associated with spatial patterns of cortical thickness/density differences in CD. CD had lower fractional anisotropy than controls in white matter bundles innervating posterior cingulate and parietal cortex, basal ganglia, and temporal cortex. The CD group also had significantly less gray matter thickness and density in precuneus, relative to controls. Sibling-pair analysis found support for causal and graded liability effects of cannabis on precuneus structure. Spatial patterns of gray matter differences in CD were significantly associated with regional differences in monoacylglycerol lipase (MAGL) expression in postmortem brain tissue, such that regions with higher MAGL expression (but not fatty-acid amide hydrolase or FAAH) were more vulnerable to cortical thinning. In sum, chronic cannabis use is associated with structural differences in white and gray matter, which was most prominent in precuneus and associated white matter tracts. Regions with high MAGL expression, and therefore with potentially physiologically restricted endogenous cannabinoid signaling, may be more vulnerable to the effects of chronic cannabis use on cortical thickness.

Sign in / Sign up

Export Citation Format

Share Document