A flow velocity zeugmatographic interlace for NMR imaging in humans

Moran, P. R.

doi:10.1016/0730-725x(82)90170-9

Cited by 698 publications

(344 citation statements)

References 6 publications

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“…To provide a noninvasive estimate of PWV, phase contrast (PC) MRI has been applied in a number of in vivo studies determining blood flow based on flow waveform measurements in single two-dimensional (2D) planes transecting the aorta (8)(9)(10). For PWV estimation, typically transit-time methods are employed estimating temporal differences of specific features of blood flow waveforms, e.g., time from foot to foot or peak to peak, between two locations of the vessel with known distance (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”

mentioning

confidence: 99%

Estimation of global aortic pulse wave velocity by flow‐sensitive 4D MRI

Markl

Wallis

Brendecke

et al. 2010

Magnetic Resonance in Med

114

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The aim of this study was to determine the value of flow-sensitive four-dimensional MRI for the assessment of pulse wave velocity as a measure of vessel compliance in the thoracic aorta. Findings in 12 young healthy volunteers were compared with those in 25 stroke patients with aortic atherosclerosis and an age-matched normal control group (n 5 9). Results from pulse wave velocity calculations incorporated velocity data from the entire aorta and were compared to those of standard methods based on flow waveforms at only two specific anatomic landmarks. Global aortic pulse wave velocity was higher in patients with atherosclerosis (7.03 6 0.24 m/ sec) compared to age-matched controls (6.40 6 0.32 m/sec). Both were significantly (P < 0.001) increased compared to younger volunteers (4.39 6 0.32 m/sec). Global aortic pulse wave velocity in young volunteers was in good agreement with previously reported MRI studies and catheter measurements. Estimation of measurement inaccuracies and error propagation analysis demonstrated only minor uncertainties in measured flow waveforms and moderate relative errors below 16% for aortic compliance in all 46 subjects. These results demonstrate the feasibility of pulse wave velocity calculation based on fourdimensional MRI data by exploiting its full volumetric coverage, which may also be an advantage over standard two-dimensional techniques in the often-distorted route of the aorta in patients with atherosclerosis. Magn Reson Med 63:1575-1582, 2010. V C 2010 Wiley-Liss, Inc. Key words: pulse wave velocity; compliance; phase contrast; atherosclerosis; aorta Increased pulse wave velocity (PWV) as a measure of aortic stiffness is an important marker for both agerelated changes in aortic compliance and the presence of atherosclerosis (1,2) and is an independent predictor of cardiovascular mortality and stroke (3,4). Reliable measurement of PWV is of particular interest for monitoring the progression or regression of vessel compliance during therapy (5,6).Pressure catheter measurements can be considered the gold standard for the assessment of the development of aortic pressure wave, but their use is limited due to the invasiveness of the procedure (7). To provide a noninvasive estimate of PWV, phase contrast (PC) MRI has been applied in a number of in vivo studies determining blood flow based on flow waveform measurements in single two-dimensional (2D) planes transecting the aorta (8-10). For PWV estimation, typically transit-time methods are employed estimating temporal differences of specific features of blood flow waveforms, e.g., time from foot to foot or peak to peak, between two locations of the vessel with known distance (11-24). However, the precision of this method highly depends on the exact calculation of flow difference and distance between only two measuring points (16,25,26).Methodological improvements include a more continuous evaluation along a vessel center line and cross-correlation (XCor) analysis for the estimation of waveform delays, which improved the accuracy of PWV...

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confidence: 99%

Estimation of global aortic pulse wave velocity by flow‐sensitive 4D MRI

Markl

Wallis

Brendecke

et al. 2010

Magnetic Resonance in Med

114

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“…PHASE CONTRAST (PC) methods permit the in vivo measurement of blood velocities (1)(2)(3). With a slice oriented orthogonal to a vessel of interest, volume flow rate can be computed for through-plane flow (4,5).…”

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Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo

Wentland

Korosec

Vigen

et al. 2006

Magnetic Resonance Imaging

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Purpose:To assess the accuracy of flow measurements in vitro and in vivo during scan times shorter than a breathhold using a 2D cine phase contrast (PC) undersampled radial acquisition method, which may be useful for measuring flow, especially in vessels subject to motion during respiration. Materials and Methods:For in vitro assessment, a flow phantom was imaged at various flow rates and undersampling factors. For in vivo assessment, five normal subjects were imaged and the flow rate in the aorta was compared with the sum of the flow rates in the iliac arteries. Results:For results in vitro, the accuracy of flow measurements was maintained with scan times as low as 13-17 seconds. For results in vivo, scans acquired in less than 25 seconds provided flow measurements in the aorta that corresponded well to the sum of flow measurements in the iliac arteries. Conclusion:The undersampled radial acquisition cine PC technique provided accurate flow measurements in a flow phantom and in healthy human volunteers in scan times shorter than a typical breath-hold.

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“…Early work in estimating flow with MRI was based on a single phase measurement (3,4); subsequent developments lead to the phase-difference technique known as PC-MRI velocity mapping (5-7). The theoretical framework underlying PC-MRI was developed by Moran (8).…”

Section: Introductionmentioning

confidence: 99%

“…and u add is an additional phase-shift caused by factors other than spin motion, such as magnetic field inhomogeneities. In Fourier velocity encoding (8), S(k v ) is sampled using a range of k v values, and an inverse Fourier transform of the resulting k vspace gives the distribution of spin velocities within a voxel. As a complete spatiotemporal k-t space is required for each step in k v -space, many potential applications of Fourier velocity encoding are infeasible due to prohibitive scan times.…”

Section: Introductionmentioning

confidence: 99%

A novel MRI framework for the quantification of any moment of arbitrary velocity distributions

Dyverfeldt

Sigfridsson

Knutsson

et al. 2010

Magnetic Resonance in Med

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MRI can measure several important hemodynamic parameters but might not yet have reached its full potential. The most common MRI method for the assessment of flow is phasecontrast MRI velocity mapping that estimates the mean velocity of a voxel. This estimation is precise only when the intravoxel velocity distribution is symmetric. The mean velocity corresponds to the first raw moment of the intravoxel velocity distribution. Here, a generalized MRI framework for the quantification of any moment of arbitrary velocity distributions is described. This framework is based on the fact that moments in the function domain (velocity space) correspond to differentials in the Fourier transform domain (k v -space). For proof-of-concept, moments of realistic velocity distributions were estimated using finite difference approximations of the derivatives of the MRI signal. In addition, the framework was applied to investigate the symmetry assumption underlying phase-contrast MRI velocity mapping; we found that this assumption can substantially affect phase-contrast MRI velocity estimates and that its significance can be reduced by increasing the velocity encoding range. Magn Reson Med 65:725-731,

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A flow velocity zeugmatographic interlace for NMR imaging in humans

Cited by 698 publications

References 6 publications

Estimation of global aortic pulse wave velocity by flow‐sensitive 4D MRI

Estimation of global aortic pulse wave velocity by flow‐sensitive 4D MRI

Cine flow measurements using phase contrast with undersampled projections: In vitro validation and preliminary results in vivo

A novel MRI framework for the quantification of any moment of arbitrary velocity distributions

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