Fast accurate MR thermometry using phase referenced asymmetric spin-echo EPI at high field

2013 ◽  
Vol 71 (2) ◽  
pp. 524-533 ◽  
Author(s):  
Markus N. Streicher ◽  
Andreas Schäfer ◽  
Dimo Ivanov ◽  
Dirk K. Müller ◽  
Alexis Amadon ◽  
...  
Keyword(s):  
High Field ◽  
Spin Echo ◽  
Mr Thermometry ◽  
Asymmetric Spin Echo

Mapping of the cerebral response to acetazolamide using graded asymmetric spin echo EPI

2005 ◽  
Vol 23 (9) ◽  
pp. 907-920 ◽  
Author(s):  
Bhashkar Mukherjee ◽  
Mark Preece ◽  
Gavin C. Houston ◽  
Nikolas G. Papadakis ◽  
T. Adrian Carpenter ◽  
...  
Keyword(s):  
Spin Echo ◽  
Asymmetric Spin Echo

Improved MR Thermometry to Measure Brain Temperatures

2008 ◽  
Author(s):  
Devashish Shrivastava ◽  
Lance DelaBarre ◽  
Timothy Hanson ◽  
J. Thomas Vaughan
Keyword(s):  
High Field ◽  
Core Body Temperature ◽  
Temperature Response ◽  
Time History ◽  
Rf Heating ◽  
Mr Thermometry ◽  
Ultra High Field ◽  
High Fields ◽  
Rf Safety

An MR thermometry technique with sub-degree celsius accuracy is needed to measure in vivo temperatures vs. time in porcine brains at ultra-high fields. Porcine models are used to study thermoregulatory temperature response of the ultra-high field radiofrequency (RF) heating. The porcine hot critical temperature limit is comparable to and lower than that of humans. Also, porcine thermoregulatory mechanisms are similar to humans. Thus, conservative porcine thermoregulatory temperature responses can help develop new RF safety thresholds for ultra-high field human MRI. Sub-degree C temperature accuracy is needed since RF safety guidelines limit the maximum in vivo head temperature change due to RF heating to 1 °C over the core body temperature. Three-dimensional temperature maps over time are required since non-uniform RF power deposition at ultra-high fields and blood flow produce non-uniform in vivo temperatures with local hot spots. Thermogenic hazards are related to in vivo temperatures and temperature-time history — and not to the typically measured whole head average specific absorption rate.

SU-FF-I-70: Asymmetric Spin Echo in FMRI at 3T: A Quantitative Evaluation of BOLD Response and Signal Drop Off

2006 ◽  
Vol 33 (6Part4) ◽  
pp. 2013-2013
Author(s):  
P Hou ◽  
J Steinberg ◽  
D Chen ◽  
F moeller ◽  
P Narayana
Keyword(s):  
Quantitative Evaluation ◽  
Spin Echo ◽  
Bold Response ◽  
Asymmetric Spin Echo

Dynamics and spin relaxation of tempone in a host crystal. An ENDOR, high field EPR and electron spin echo study

1999 ◽  
Vol 1 (17) ◽  
pp. 4015-4023 ◽  
Author(s):  
Antonio Barbon ◽  
Marina Brustolon ◽  
Anna Lisa Maniero ◽  
Maurizio Romanelli ◽  
Louis-Claude Brunel
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
High Field ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Host Crystal

Asymmetric spin-echo (ASE) spiral improves BOLD fMRI in inhomogeneous regions

2009 ◽  
Vol 22 (6) ◽  
pp. 654-662 ◽  
Author(s):  
Kimberly D. Brewer ◽  
James A. Rioux ◽  
Ryan C. N. D'Arcy ◽  
Chris V. Bowen ◽  
Steven D. Beyea
Keyword(s):  
Spin Echo ◽  
Bold Fmri ◽  
Asymmetric Spin Echo

scholarly journals Variable appearances of subacute intracranial hematomas on high-field spin-echo MR

1988 ◽  
Vol 150 (1) ◽  
pp. 171-178 ◽  
Author(s):  
JM Gomori ◽  
RI Grossman ◽  
DB Hackney ◽  
HI Goldberg ◽  
RA Zimmerman ◽  
...  
Keyword(s):  
High Field ◽  
Spin Echo ◽  
Intracranial Hematomas

scholarly journals Simulations of the effect of diffusion on asymmetric spin echo based quantitative BOLD: An investigation of the origin of deoxygenated blood volume overestimation

2019 ◽  
Author(s):  
Alan J Stone ◽  
Naomi C Holland ◽  
Avery J L Berman ◽  
Nicholas P Blockley
Keyword(s):  
Blood Volume ◽  
Spin Echo ◽  
Oxygen Extraction Fraction ◽  
Parameter Estimates ◽  
Analysis Model ◽  
Extraction Fraction ◽  
Echo Time ◽  
Asymmetric Spin Echo ◽  
The Impact ◽  
The Relationship

AbstractQuantitative BOLD (qBOLD) is a technique for mapping oxygen extraction fraction (OEF) and deoxygenated blood volume (DBV) in the human brain. Recent measurements using an asymmetric spin echo (ASE) based qBOLD approach produced estimates of DBV which were systematically higher than measurements from other techniques. In this study, we investigate two hypotheses for the origin of this DBV overestimation using simulations and consider the implications for experimental measurements. Investigations were performed by combining Monte Carlo simulations of extravascular signal with an analytical model of the intravascular signal.Hypothesis 1DBV overestimation is due to the presence of intravascular signal which is not accounted for in the analysis model. Intravascular signal was found to have a weak effect on qBOLD parameter estimates.Hypothesis 2DBV overestimation is due to the effects of diffusion which are not accounted for in the analysis model. The effect of diffusion on the extravascular signal was found to result in a vessel radius dependent variation in qBOLD parameter estimates. In particular, DBV overestimation peaks for vessels with radii from 20 to 30 μm and is OEF dependent. This results in the systematic underestimation of OEF.ImplicationsThe impact on experimental qBOLD measurements was investigated by simulating a more physiologically realistic distribution of vessel sizes with a small number of discrete radii. Overestimation of DBV consistent with previous experiments was observed, which was also found to be OEF dependent. This results in the progressive underestimation of the measured OEF. Furthermore, the relationship between the measured OEF and the true OEF was found to be dependent on echo time and spin echo displacement time.The results of this study demonstrate the limitations of current ASE based qBOLD measurements and provide a foundation for the optimisation of future acquisition approaches.

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