Using Flow Relaxography to Elucidate Flow Relaxivity

Lee, Jing Huei; Li, Xin; Sammi, Manoj K.; Springer, Charles S.

doi:10.1006/jmre.1998.1629

Cited by 24 publications

(28 citation statements)

References 27 publications

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“…with E 1b ϵ exp(-t R ⅐ R * 1b ), and the S b0 (from the pre-CR R 10 map) includes inflow effects (36). These values are plotted as circles in Fig.…”

Section: Rat Cerebral Gliosarcomamentioning

confidence: 99%

Variation of the relaxographic “shutter‐speed” for transcytolemmal water exchange affects the CR bolus‐tracking curve shape

Yankeelov

Rooney

et al. 2003

Magnetic Resonance in Med

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“…with E 1b ϵ exp(-t R ⅐ R * 1b ), and the S b0 (from the pre-CR R 10 map) includes inflow effects (36). These values are plotted as circles in Fig.…”

Section: Rat Cerebral Gliosarcomamentioning

confidence: 99%

Variation of the relaxographic “shutter‐speed” for transcytolemmal water exchange affects the CR bolus‐tracking curve shape

Yankeelov

Rooney

et al. 2003

Magnetic Resonance in Med

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175

360

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“…The in vivo brain PCr:Cr ratio is near unity (7; 15-18). For the shortest TE of our 3T 1 H data for these six subjects, the SNR of the 3.0 ppm methyl resonances of tCr was 26 ± 8 (range 18-41), the SNR of the 3.2 ppm methyl resonances of tCho was 20.5 ± 6.4 (range [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], and the SNR of the 2.0 ppm methyl resonance of NAA was 47.5 ± 10.0 (range 36-65). Thus bi-exponential fitting of PCr and Cr components with relaxation times differing threefold or more should be possible for tCr.…”

Section:  Experimental Results For Bi-exponential T 2 For Tcr (And Omentioning

confidence: 81%

“…Optimal data conditions for successful and reliable fitting of bi-exponential data have been explored and defined (10)(11)(12) and determined to be a signal contribution ratio of 1:1, at least a three-fold difference in relaxation times, and a signal-to-noise ratio (SNR) of at least 20 and preferably 50 or more. A logarithmic rather than linear spacing of TE values is preferred (12)(13)(14) as more efficient. The in vivo brain PCr:Cr ratio is near unity (7; 15-18).…”

Section:  Experimental Results For Bi-exponential T 2 For Tcr (And Omentioning

confidence: 99%

Abnormalities in Human Brain Creatine Metabolism in Gulf War Illness Probed with MRS

Briggs¹

2014

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION / AVAILABILITY STATEMENTApproved for Public Release; Distribution Unlimited SUPPLEMENTARY NOTES ABSTRACTAbnormal levels of total creatine (tCr) in veterans with Gulf War Illness have been observed in prior studies. The goal of this research is to estimate amounts and 1 H transverse relaxation times (T2s) of the methyl peaks of the molecules phosphocreatine (PCr) and free creatine (Cr) in brains of ill and well control) Gulf War veterans using phosphorus ( 31 P) and proton ( 1 H) magnetic resonance spectroscopy (MRS). This will add more detailed and specific information about the previous preliminary reports of abnormal levels of these metabolites in brains of ill Gulf War veterans, validating this potential diagnostic marker and providing better understanding of underlying pathophysiology. Secondary goals are to measure amounts of adenosine triphosphate (ATP), inorganic phosphate (P i ), and magnesium ion (Mg 2+ ) and to estimate intracellular pH from 31 P MRS data. Year 1 progress and achievements included testing of a new dual-tuned 31 P-1 H head coil for 3T MRS, developing and optimizing protocols and parameters for 31 P and 1 H MRS, performing theoretical calculations using parameter estimates from the literature to characterize the creatine phosphokinase (CPK)-catalyzed chemical exchange of phosphate between PCr and Cr, and doing normal volunteer experiments to explore and determine the best 3T parameters for measuring biexponential 1 H T 2 relaxation of the methyl peak of tCr at 3.0 ppm. SUBJECT TERMS

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“…Developments in quantitative MR measurement of blood flow can generally be placed in either of two branches-the time-of-flight (TOF) and phase-contrast (PC) methods [1,2]. The former is based on the inflow effect, as is the approach [3] presented in this work. However, most TOF methods provide for blood vessel visualization by suppression the tissue signal and even partially the blood 1 H 2 O signal and usually provide no direct quantitative flow rate information [1].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we have shown that techniques, termed longitudinal relaxography and relaxographic imaging [23,24], which can quantitatively discriminate isochronous NMR signals according to their 1 T  values, have potential in this area. We also applied this powerful method for practical and accurate determination of relaxation time distributions that obtain for the NMR signals from a phantom having a mixture of flowing and non-flowing water [3]. We refer to this method as flow relaxography and thus to the distribution as a flow relaxogram-the distribution of the 1 values and, consequently, flow velocity values if flow relaxivity (r 1F ) is known.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Flow Relaxographic Angiography

Lee¹

2012

OJRad

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A powerful method, termed flow relaxography, allowing the practical and accurate determination of the water proton MR signal relaxation time distributions has been recently introduced with a phantom, having both flowing and nonflowing water. It was demonstrated that this method can discriminate the signals from the flowing and non-flowing spins, since flow affects the apparent T 1 ( T ) value. In this report, it is demonstrated that this technique is effective also in the human leg in vivo. Flow relaxographic angiography is presented for the first time. This technique promises to accomplish the twin goals of flow studies in medical MRI, to display vascular anatomy and measure its blood flow rate, in the same image.

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Using Flow Relaxography to Elucidate Flow Relaxivity

Cited by 24 publications

References 27 publications

Variation of the relaxographic “shutter‐speed” for transcytolemmal water exchange affects the CR bolus‐tracking curve shape

Variation of the relaxographic “shutter‐speed” for transcytolemmal water exchange affects the CR bolus‐tracking curve shape

Abnormalities in Human Brain Creatine Metabolism in Gulf War Illness Probed with MRS

Quantitative Flow Relaxographic Angiography

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