On the Measurement of Transverse Relaxation Rates in Complex Spin Systems

1972 ◽  
Vol 56 (7) ◽  
pp. 3210-3216 ◽  
Author(s):  
Robert L. Vold
Keyword(s):  
Spin Systems ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Complex Spin

scholarly journals Broadband measurement of true transverse relaxation rates in systems with coupled protons: application to the study of conformational exchange

2021 ◽  
Author(s):  
Peter Kiraly ◽  
Guilherme Dal Poggetto ◽  
Laura Castañar ◽  
Mathias Nilsson ◽  
Andrea Deák ◽  
...  
Keyword(s):  
Spin Systems ◽  
Conformational Exchange ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Coupled Spin Systems

Existing methods for measuring transverse relaxation give incorrect results in coupled spin systems. Measuring true relaxation rates extends their utility.

A convenient method for the measurements of transverse relaxation rates in homonuclear scalar coupled spin systems

2011 ◽  
Vol 47 (32) ◽  
pp. 9209 ◽  
Author(s):  
Caroline Barrère ◽  
Pierre Thureau ◽  
André Thévand ◽  
Stéphane Viel
Keyword(s):  
Convenient Method ◽  
Spin Systems ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Coupled Spin Systems

Fourier transform heteronuclear magnetic triple resonance in complex spin systems—III

Polyhedron ◽  
1983 ◽  
Vol 2 (8) ◽  
pp. 783-790 ◽  
Author(s):  
Geoffrey T. Andrews ◽  
Ian J. Colquhoun ◽  
William McFarlane
Keyword(s):  
Fourier Transform ◽  
Spin Systems ◽  
Triple Resonance ◽  
Complex Spin

scholarly journals Transverse relaxation rates of pulmonary dissolved‐phase Hyperpolarized 129 Xe as a biomarker of lung injury in idiopathic pulmonary fibrosis

2020 ◽  
Vol 84 (4) ◽  
pp. 1857-1867
Author(s):  
Jeff Kammerman ◽  
Andrew D. Hahn ◽  
Robert V. Cadman ◽  
Annelise Malkus ◽  
David Mummy ◽  
...  
Keyword(s):  
Idiopathic Pulmonary Fibrosis ◽  
Pulmonary Fibrosis ◽  
Lung Injury ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Dissolved Phase

scholarly journals In Vivo Quantification of Cerebral R2*-Response to Graded Hyperoxia at 3 Tesla

2015 ◽  
Vol 5 ◽  
pp. 1 ◽  
Author(s):  
Grigorios Gotzamanis ◽  
Roman Kocian ◽  
Pinar S. Özbay ◽  
Manuel Redle ◽  
Spyridon Kollias ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Relaxation Rate ◽  
Tumor Therapy ◽  
Cerebrovascular Reactivity ◽  
Oxygen Intake ◽  
Transverse Relaxation Rate ◽  
Dependent Manner ◽  
Relaxation Rates ◽  
Transverse Relaxation ◽  
Arterial Blood

Objectives: This study aims to quantify the response of the transverse relaxation rate of the magnetic resonance (MR) signal of the cerebral tissue in healthy volunteers to the administration of air with step-wise increasing percentage of oxygen. Materials and Methods: The transverse relaxation rate (R2*) of the MR signal was quantified in seven volunteers under respiratory intake of normobaric gas mixtures containing 21, 50, 75, and 100% oxygen, respectively. End-tidal breath composition, arterial blood saturation (SaO2), and heart pulse rate were monitored during the challenge. R2* maps were computed from multi-echo, gradient-echo magnetic resonance imaging (MRI) data, acquired at 3.0T. The average values in the segmented white matter (WM) and gray matter (GM) were tested by the analysis of variance (ANOVA), with Bonferroni post-hoc correction. The GM R2*-reactivity to hyperoxia was modeled using the Hill's equation. Results: Graded hyperoxia resulted in a progressive and significant (P < 0.05) decrease of the R2* in GM. Under normoxia the GM-R2* was 17.2 ± 1.1 s-1. At 75% O2 supply, the R2* had reached a saturation level, with 16.4 ± 0.7 s-1 (P = 0.02), without a significant further decrease for 100% O2. The R2*-response of GM correlated positively with CO2 partial pressure (R = 0.69 ± 0.19) and negatively with SaO2 (R = -0.74 ± 0.17). The WM showed a similar progressive, but non-significant, decrease in the relaxation rates, with an increase in oxygen intake (P = 0.055). The Hill's model predicted a maximum R2* response of the GM, of 3.5%, with half the maximum at 68% oxygen concentration. Conclusions: The GM-R2* responds to hyperoxia in a concentration-dependent manner, suggesting that monitoring and modeling of the R2*-response may provide new oxygenation biomarkers for tumor therapy or assessment of cerebrovascular reactivity in patients.

scholarly journals High-Resolution CMRO2 Mapping in Rat Cortex: A Multiparametric Approach to Calibration of BOLD Image Contrast at 7 Tesla

2000 ◽  
Vol 20 (5) ◽  
pp. 847-860 ◽  
Author(s):  
Ikuhiro Kida ◽  
Richard P. Kennan ◽  
Douglas L. Rothman ◽  
Kevin L. Behar ◽  
Fahmeed Hyder
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Echo ◽  
7 Tesla ◽  
Relaxation Rates ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Transverse Relaxation ◽  
Physiologic Parameters ◽  
Spin Echo Sequences

The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) method, which is sensitive to vascular paramagnetic deoxyhemoglobin, is dependent on regional values of cerebral metabolic rate of oxygen utilization (CMRO2), blood flow (CBF), and volume (CBV). Induced changes in deoxyhemoglobin function as an endogenous contrast agent, which in turn affects the transverse relaxation rates of tissue water that can be measured by gradient-echo and spin-echo sequences in BOLD fMRI. The purpose here was to define the quantitative relation between BOLD signal change and underlying physiologic parameters. To this end, magnetic resonance imaging and spectroscopy methods were used to measure CBF, CMRO2, CBV, and relaxation rates (with gradient-echo and spin-echo sequences) at 7 Tesla in rat sensorimotor cortex, where cerebral activity was altered pharmacologically within the autoregulatory range. The changes in tissue transverse relaxation rates were negatively and linearly correlated with changes in CBF, CMRO2, and CBV. The multiparametric measurements revealed that CBF and CMRO2 are the dominant physiologic parameters that modulate the BOLD fMRI signal, where the ratios of (ΔCMRO2/CMRO2)/(ΔCBF/CBF) and (ΔCBV/CBV)/(ΔCBF/CBF) were 0.86 ± 0.02 and 0.03 ± 0.02, respectively. The calibrated BOLD signals (spatial resolution of 48 μL) from gradient-echo and spin-echo sequences were used to predict changes in CMRO2 using measured changes in CBF, CBV, and transverse relaxation rates. The excellent agreement between measured and predicted values for changes in CMRO2 provides experimental support of the current theory of the BOLD phenomenon. In gradient-echo sequences, BOLD contrast is affected by reversible processes such as static inhomogeneities and slow diffusion, whereas in spin-echo sequences these effects are refocused and are mainly altered by extravascular spin diffusion. This study provides steps by which multiparametric MRI measurements can be used to obtain high-spatial resolution CMRO2 maps.

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