Longitudinal rotating frame relaxation time measurements in infarcted mouse myocardium in vivo

2012 ◽  
Vol 69 (5) ◽  
pp. 1389-1395 ◽  
Author(s):  
Haja-Sherief N. Musthafa ◽  
Galina Dragneva ◽  
Line Lottonen ◽  
Mari Merentie ◽  
Lyubomir Petrov ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Rotating Frame ◽  
Rotating Frame Relaxation

scholarly journals Balanced spin‐lock preparation for B 1 ‐insensitive and B 0 ‐insensitive quantification of the rotating frame relaxation time T 1ρ

2020 ◽  
Author(s):  
Maximilian Gram ◽  
Michael Seethaler ◽  
Daniel Gensler ◽  
Johannes Oberberger ◽  
Peter M. Jakob ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Rotating Frame ◽  
Spin Lock ◽  
Rotating Frame Relaxation

scholarly journals Frequency offset dependence of adiabatic rotating frame relaxation rate constants: relevance to MRS investigations of metabolite dynamics in vivo

2011 ◽  
Vol 24 (7) ◽  
pp. 807-814 ◽  
Author(s):  
Silvia Mangia ◽  
Timo Liimatainen ◽  
Michael Garwood ◽  
Ivan Tkac ◽  
Pierre-Gilles Henry ◽  
...  
Keyword(s):  
Relaxation Rate ◽  
Rate Constants ◽  
Frequency Offset ◽  
Rotating Frame ◽  
Rotating Frame Relaxation

scholarly journals Quantitative Assessment of Water Pools by T1p and T2p MRI in Acute Cerebral Ischemia of the Rat

2008 ◽  
Vol 29 (1) ◽  
pp. 206-216 ◽  
Author(s):  
Kimmo T Jokivarsi ◽  
Juha-Pekka Niskanen ◽  
Shalom Michaeli ◽  
Heidi I Gröhn ◽  
Michael Garwood ◽  
...  
Keyword(s):  
Correlation Time ◽  
Continuous Wave ◽  
Vasogenic Edema ◽  
Free Water ◽  
Rotating Frame ◽  
Mri Contrast ◽  
Water Fraction ◽  
Acute Cerebral Ischemia ◽  
Rotating Frame Relaxation

The rotating frame longitudinal relaxation magnetic resonance imaging (MRI) contrast, T1ρ, obtained with on-resonance continuous wave (CW) spin-lock field is a sensitive indicator of tissue changes associated with hyperacute stroke. Here, the rotating frame relaxation concept was extended by acquiring both T1ρ and transverse rotating frame ( T2ρ) MRI data using both CW and adiabatic hyperbolic secant (HSn; n = 1, 4, or 8) pulses in a rat stroke model of middle cerebral artery occlusion. The results show differences in the sensitivity of spinlock T1ρ and T2ρ MRI to detect hyperacute ischemia. The most sensitive techniques were CW- T1ρ and T1ρ using HS4 or HS8 pulses. Fitting a two-pool exchange model to the T1ρ and T2ρ MRI data acquired from the infarcting brain indicated time-dependent increase in free water fraction, decrease in the correlation time of water fraction associated with macromolecules, and increase in the exchange correlation time. These findings are consistent with known pathology in acute stroke, including vasogenic edema, destructive processes, and tissue acidification. Our results show that the sensitivity of the spinlock MRI contrast in vivo can be modified using different spinlock preparation blocks, and that physicochemical models of the rotating frame relaxation may provide insight into progression of ischemia in vivo.

Rotating-frame relaxation time study of hydrogen diffusion in ZrHx

1984 ◽  
Vol 17 (19) ◽  
pp. L477-L482 ◽  
Author(s):  
R C Bowman ◽  
B D Craft
Keyword(s):  
Relaxation Time ◽  
Hydrogen Diffusion ◽  
Rotating Frame ◽  
Time Study ◽  
Rotating Frame Relaxation

Proton Rotating Frame Relaxation in Lithium Hydrazinium Sulfate, Li(N2H5)SO4

1971 ◽  
Vol 49 (7) ◽  
pp. 870-875 ◽  
Author(s):  
R. R. Knispel ◽  
H. E. Petch
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Temperature Dependence ◽  
Rotating Frame ◽  
Kcal Mole ◽  
Second Moment ◽  
Rotating Frame Relaxation ◽  
And Diffusion

The temperature dependence of the rotating frame relaxation time T1ρ for protons in powdered lithium hydrazinium sulfate, Li(N2H5)SO4, has been determined from 140 to 495 °K. These measurements indicate that the –NH2 part of the N2H5+ ion executes 180° flips about the bisectrix of the H–N–H angle with activation energy of 10.7 ± 0.5 kcal/mole. Evidence for motion of the entire N2H5+ ion with activation energy of 17.4 ± 1.1 kcal/mole was also obtained. Separate reorientation and diffusion motions of the N2H5+ ion could not be distinguished, although evidence that the N2H5+ motion detected in the T1ρ measurements includes diffusion is obtained by comparing the T1ρ results with the temperature dependence of the proton second moment.

scholarly journals B0dependence of the on-resonance longitudinal relaxation time in the rotating frame (T1ρ) in protein phantoms and rat brain in vivo

2003 ◽  
Vol 51 (1) ◽  
pp. 4-8 ◽  
Author(s):  
Heidi I. Mäkelä ◽  
Enrico De Vita ◽  
Olli H.J. Gröhn ◽  
Mikko I. Kettunen ◽  
Martin Kavec ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Rat Brain ◽  
Rotating Frame ◽  
Longitudinal Relaxation Time ◽  
Longitudinal Relaxation

Evaluation of the Rotating-Frame Relaxation (T1ρ) Filter and Its Application in Metabolomics as an Alternative to the Transverse Relaxation (T2) Filter

2021 ◽  
Author(s):  
Elena Piersanti ◽  
Lamya Rezig ◽  
Fabrice Tranchida ◽  
Wael El-Houri ◽  
Seidou M. Abagana ◽  
...  
Keyword(s):  
Rotating Frame ◽  
Transverse Relaxation ◽  
Rotating Frame Relaxation

Reproducibility of in vivo magnetic resonance imaging T 1 rho and T 2 relaxation time measurements of hip cartilage at 3.0T in healthy volunteers

2017 ◽  
Vol 47 (4) ◽  
pp. 1022-1033 ◽  
Author(s):  
Angeline Nemeth ◽  
Lucy Marco ◽  
Florent Boutitie ◽  
Michael Sdika ◽  
Denis Grenier ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Healthy Volunteers ◽  
Resonance Imaging ◽  
Hip Cartilage

scholarly journals Alterations in articular cartilage T2 star relaxation time following mechanical disorders: in vivo canine supraspinatus tendon resection models

2020 ◽  
Author(s):  
Dokwan Lee ◽  
Ki-Taek Hong ◽  
Tae Seong Lim ◽  
Eugene Lee ◽  
Ye Hyun Lee ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Articular Cartilage ◽  
Motion Tracking ◽  
Supraspinatus Tendon ◽  
Quantitative Mri ◽  
Joint Mechanics ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Positive Correlations

Abstract Background: The role of altered joint mechanics on cartilage degeneration in in vivo models has not been studied successfully due to a lack of pre-injury information. We aimed 1) to develop an accurate in vivo canine model to measure the changes in joint loading and T2 star (T2*) relaxation time before and after unilateral supraspinatus tendon resections, and 2) to find the relationship between regional variations in articular cartilage loading patterns and T2* relaxation time distributions.Methods: Rigid markers were implanted in the scapula and humerus of tested dogs. The movement of the shoulder bones were measured by a motion tracking system during normal gaits. In vivo cartilage contact strain was measured by aligning 3D shoulder models with the motion tracking data. Articular cartilage T2* relaxation times were measured by quantitative MRI scans. Articular cartilage contact strain and T2* relaxation time were compared in the shoulders before and three months after the supraspinatus tendon resections.Results: Excellent accuracy and reproducibility were found in our in vivo contact strain measurements with less than 1% errors. Changes in articular cartilage contact strain exhibited similar patterns with the changes in the T2* relaxation time after resection surgeries. Regional changes in the articular cartilage T2* relaxation time exhibited positive correlations with regional contact strain variations three months after the supraspinatus resection surgeries.Conclusion: This is the first study to measure in vivo articular cartilage contact strains with high accuracy and reproducibility. Positive correlations between contact strain and T2* relaxation time suggest that the articular cartilage extracellular matrix may responds to mechanical changes in local areas.

Force reduction uncoupled from pH and H2PO 4 − in rat gastrocnemius in vivo with continuous 2-Hz stimulation

2001 ◽  
Vol 281 (2) ◽  
pp. R511-R518 ◽  
Author(s):  
Julie H. Cieslar ◽  
Geoffrey P. Dobson
Keyword(s):  
Relaxation Time ◽  
Atp Hydrolysis ◽  
Nerve Impulse ◽  
Force Transducer ◽  
Sprague Dawley ◽  
Glycogen Depletion ◽  
Cytosolic Ph ◽  
Twitch Force ◽  
Isometric Twitch

The aim of this study was to examine the effect of the products of ATP hydrolysis on the fatigue process in rat gastrocnemius in vivo. Adult male Sprague-Dawley rats (300–400 g) were anesthetized and ventilated in a custom-built cradle fitted with a force transducer that could be placed into a 7-T NMR magnet. The muscle was stimulated continuously at 2 Hz for 20 min ( n = 7). Isometric twitch force increased in the first 4 min of stimulation accompanied by changes in twitch duration (20% increase in relaxation time). Prolonged relaxation was associated with changes in cytosolic pH (6.91 to 6.58), lactate (1.8 to 12.6 μmol/g wet wt), and H2PO[Formula: see text] (7.57 to 13.99 mM). After 4 min, relaxation time, pH, lactate, and H2PO[Formula: see text] returned toward control values as twitch force progressively decreased. No correlation was found between force decline (or twitch broadening) and total phosphate (3 to 23 mM), free [ADP] (18 to 95 μM), free [Mg2+] (0.58 to 0.96 mM), or free energy of ATP hydrolysis (−65 to −55 kJ/mol). We conclude that force decline is not due to increased pH and/or H2PO[Formula: see text] but to fatigue of the fast-twitch fibers, possibly linked to glycogen depletion and/or failure of nerve impulse transmission in these fibers.

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