Velocity Measurement of Fast Flows Inside Small Structures with Tagged MRI

Ahmadi, Shahla; Mastikhin, Igor V.

doi:10.1007/s00723-020-01194-1

Cited by 3 publications

(6 citation statements)

References 27 publications

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“…This was described by the measured displacement (∆x) of a point of the tag over a fixed period of time (∆t)-the delay of 250 ms between the application of the tag lines and acquisition of each image-as shown by Equation (2). Different parts of a tag can travel different velocities [33]. The average velocity of the tagged contents was calculated by measuring the displacement of the centroid of each tag between consecutive images, whilst the peak velocity was measured using the maximum displacement of each tag between consecutive images, i.e., tracking the displacement of the leading edge of each tag.…”

Section: Mr Data Analysismentioning

confidence: 99%

“…In the future, this could be solved through optimisation of the scanning parameters prior to the scan, based on the expected flow rates, for example, increasing the distance between the tags or decreasing the delay time between the application of the tag lines and acquisition of the image in order to capture higher velocity flows. In previous studies, MR tagging has been used to measure flows that are magnitudes stronger [33], using a single tag. Therefore, the use of a multiple tagged scan to identify regions of extreme flow due to erratic motility with pathological roots, followed by the application of a single tag to quantify the extent of the flows, could form a valuable clinical or research tool.…”

Section: Velocimetry Of Fluid Motion In Vitro Using Mr Taggingmentioning

confidence: 99%

“…The precision of the measurements must be scrutinised by delving into the characteristics of the tagged technique, since measurements inside the DCM were consistently higher than those found using PC cine-MRI. Tagged methods have been reported to measure velocities accurately in phantoms [18,19,33,55], including low flows [19], pulsatile flow [55], and in vivo [55]. Contrarily, when compared with PC cine-MRI, Moser et al [18] found that only 50 and 79% of tagged velocity measurements agreed, to within 10% of CFD velocity measurements for Reynolds numbers of 100 and 258, respectively, compared to 90 and 94% for PC cine-MRI.…”

Section: Scrutininsation Of Tagging Versus Phase Contrast Cine-mri Velocity Measurementsmentioning

confidence: 99%

“…To minimise errors in future tagged experiments, small evolution times can be chosen since the estimated velocity of a tag is given by u x = ∆x/∆t; however, this causes the error in measuring displacement to become more significant. Additionally, a decrease in the evolution time at a constant voxel size has been shown to improve accuracy of tagged velocity measurements from 0.30 m•s −1 to 0.13 m•s −1 [33]. PC cine-MRI has been reported to be more accurate than tagged TOF for steady, laminar Poiseuille flow [56].…”

Section: Scrutininsation Of Tagging Versus Phase Contrast Cine-mri Velocity Measurementsmentioning

confidence: 99%

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Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

et al. 2021

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Knowledge of luminal flow inside the human colon remains elusive, despite its importance for the design of new colon-targeted drug delivery systems and physiologically relevant in silico models of dissolution mechanics within the colon. This study uses magnetic resonance imaging (MRI) techniques to visualise, measure and differentiate between different motility patterns within an anatomically representative in vitro dissolution model of the human ascending colon: the dynamic colon model (DCM). The segmented architecture and peristalsis-like contractile activity of the DCM generated flow profiles that were distinct from compendial dissolution apparatuses. MRI enabled different motility patterns to be classified by the degree of mixing-related motion using a new tagging method. Different media viscosities could also be differentiated, which is important for an understanding of colonic pathophysiology, the conditions that a colon-targeted dosage form may be subjected to and the effectiveness of treatments. The tagged MRI data showed that the DCM effectively mimicked wall motion, luminal flow patterns and the velocities of the contents of the human ascending colon. Accurate reproduction of in vivo hydrodynamics is an essential capability for a biorelevant mechanical model of the colon to make it suitable for in vitro data generation for in vitro in vivo evaluation (IVIVE) or in vitro in vivo correlation (IVIVC). This work illustrates how the DCM provides new insight into how motion of the colonic walls may control luminal hydrodynamics, driving erosion of a dosage form and subsequent drug release, compared to traditional pharmacopeial methods.

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Section: Mr Data Analysismentioning

confidence: 99%

Section: Velocimetry Of Fluid Motion In Vitro Using Mr Taggingmentioning

confidence: 99%

Section: Scrutininsation Of Tagging Versus Phase Contrast Cine-mri Velocity Measurementsmentioning

confidence: 99%

Section: Scrutininsation Of Tagging Versus Phase Contrast Cine-mri Velocity Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

et al. 2021

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“…When MRI is applied in presence of flow, translational motion information can be extracted combining an imaging sequence with a spatially resolved measurement of molecular displacement. In many flow MRI studies, the velocity of a fluid media is measured by time-of-flight (TOF) [ 16 , 17 , 18 ] and phase shift methods [ 19 ]. A comprehensive review of non-medical flow MRI methods can be found in the articles by Gladden and Sederman [ 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Multiphase Flow Regime Characterization and Liquid Flow Measurement Using Low-Field Magnetic Resonance Imaging

Tromp

Cerioni²

2021

Molecules

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Multiphase flow metering with operationally robust, low-cost real-time systems that provide accuracy across a broad range of produced volumes and fluid properties, is a requirement across a range of process industries, particularly those concerning petroleum. Especially the wide variety of multiphase flow profiles that can be encountered in the field provides challenges in terms of metering accuracy. Recently, low-field magnetic resonance (MR) measurement technology has been introduced as a feasible solution for the petroleum industry. In this work, we study two phase air-water horizontal flows using MR technology. We show that low-field MR technology applied to multiphase flow has the capability to measure the instantaneous liquid holdup and liquid flow velocity using a constant gradient low flip angle CPMG (LFA-CPMG) pulse sequence. LFA-CPMG allows representative sampling of the correlations between liquid holdup and liquid flow velocity, which allows multiphase flow profiles to be characterized. Flow measurements based on this method allow liquid flow rate determination with an accuracy that is independent of the multiphase flow profile observed in horizontal pipe flow for a wide dynamic range in terms of the average gas and liquid flow rates.

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Counter-flow phenomena studied by nuclear magnetic resonance (NMR) velocimetry and flow simulations

et al. 2022

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Flow patterns including counter-flow and flow reversal effects have been studied by a combination of nuclear magnetic resonance flow imaging and numerical modeling using the finite volume method in the open-source computational fluid mechanics package OpenFOAM. Two cylindrical geometries have been used: In a concentric double-cylinder system the flow reversal under oscillatory rotation of the inner cylinder has been followed, and the time evolution of the flow reversal has been studied. We find extended periods of counter-rotating flow in the gap where fluid in the inner part of the gap follows the new direction of the rotor, while the outer part takes a longer time until the viscous forces transmit the reverted flow direction outwards. The radial position of the reversal of flow direction has been monitored as a function of the oscillation angle after the turning point. In the second cylindrical geometry, the rotating bob is placed off the center and a counter-rotating vortex is detected in the wider part of the gap. At constant viscosity and eccentricity, the position of the center of the vortex was found to depend on the rotation frequency of the bob. Qualitative and quantitative agreement between experiment and laminar (nonturbulent) flow simulations has been obtained for both steady-state flow using the Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm and time-dependent flow using the Pressure Implicit with Splitting of Operators (PISO) algorithm.

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Velocity Measurement of Fast Flows Inside Small Structures with Tagged MRI

Cited by 3 publications

References 27 publications

Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

Luminal Fluid Motion Inside an In Vitro Dissolution Model of the Human Ascending Colon Assessed Using Magnetic Resonance Imaging

Multiphase Flow Regime Characterization and Liquid Flow Measurement Using Low-Field Magnetic Resonance Imaging

Counter-flow phenomena studied by nuclear magnetic resonance (NMR) velocimetry and flow simulations

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