Correction for displacement artifacts in 3D phase contrast imaging

Thunberg, Per; Wigström, Lars; Ebbers, Tino; Karlsson, Matts

doi:10.1002/jmri.10187

Cited by 16 publications

(19 citation statements)

References 25 publications

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“…One common approach to minimize this is to place any phase-encoding between the alternating gradient pulses used for encoding motion [13]. In aerodynamic studies with a heavier (less MRI sensitive) gas this approach is so affective that the idea of apparent transport is unnecessary and good agreement between PC-MRI and straight CFD (i.e.…”

Section: Discussionmentioning

confidence: 99%

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Phase-contrast MRI and CFD modeling of apparent 3He gas flow in rat pulmonary airways

Minard¹,

Kuprat²,

Kabilan³

et al. 2012

Journal of Magnetic Resonance

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Phase-contrast (PC) magnetic resonance imaging (MRI) with hyperpolarized 3He is potentially useful for developing and testing patient-specific models of pulmonary airflow. One challenge, however, is that PC-MRI provides apparent values of local 3He velocity that not only depend on actual airflow but also on gas diffusion. This not only blurs laminar flow patterns in narrow airways but also introduces anomalous airflow structure that reflects gas-wall interactions. Here, both effects are predicted in a live rat using computational fluid dynamics (CFD), and for the first time, simulated patterns of apparent 3He gas velocity are compared with in-vivo PC-MRI. Results show 1) that correlations (R2) between measured and simulated airflow patterns increase from 0.23 to 0.79 simply by accounting for apparent 3He transport, and 2) that remaining differences are mainly due to uncertain airway segmentation and partial volume effects stemming from relatively coarse MRI resolution. Higher-fidelity testing of pulmonary airflow predictions should therefore be possible with future imaging improvements.

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Section: Discussionmentioning

confidence: 99%

“…Equation 4 therefore correctly describes so-called “displacement artifacts” that occur in Fig. 1 when upstream dynamics is inevitably mapped to downstream image locations [13]. …”

Section: Theorymentioning

confidence: 99%

Phase-contrast MRI and CFD modeling of apparent 3He gas flow in rat pulmonary airways

Minard¹,

Kuprat²,

Kabilan³

et al. 2012

Journal of Magnetic Resonance

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“…One of the scan segments had zero first gradient moment and the other three had a first gradient moment such that VENC was somewhat larger than the expected SD. The frequency-encoding direction was perpendicular to the flow in order to avoid displacement artifacts (30). Measurements were performed at three flow settings (Table 2) characterized by different Re's upstream of the stenosis of 500, 1000, and 2000, respectively.…”

Section: Data Acquisitionsmentioning

confidence: 99%

Quantification of intravoxel velocity standard deviation and turbulence intensity by generalizing phase‐contrast MRI

Dyverfeldt

Sigfridsson

Kvitting

et al. 2006

Magnetic Resonance in Med

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134

188

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“…The accuracy and reproducibility of phase contrast imaging have been thoroughly investigated, and a number of factors that influence the measured phase values have been identified (16). With compensation for these known artifacts, the phase contrast method has been shown to be very accurate (12,17,18). The acquisition time of phase contrast imaging can be relatively long, however, especially when all three velocity components are measured.…”

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confidence: 99%

Accuracy and reproducibility in phase contrast imaging using SENSE

Thunberg

Karlsson

Wigström

2003

Magnetic Resonance in Med

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The purpose of this study was to evaluate the accuracy and reproducibility of phase contrast imaging using the sensitivity encoding (SENSE) method at different reduction factors. Analytical expressions were derived that state how reproducibility is influenced for velocity and flow measurements. Computer simulations, and in vitro and in vivo studies were performed in order to validate these expressions and to assess how accuracy is affected when different reduction factors are applied. It was shown that reproducibility depends on the reduction and geometry factors. Since the geometry factor varies spatially, so does the reproducibility for phase contrast imaging. In areas with high geometry factors, the standard deviation (SD) may become so large that aliasing occurs. The accuracy of phase contrast imaging is not influenced directly when SENSE is used, but may be indirectly influenced due to high SDs of the measured phase that may subsequently cause aliasing. The current results show that it is possible to achieve accurate flow measurements even at high reduction factors. By taking the geometry factor into account, it may be possible to find areas where phase contrast imaging is accurate even at high reduction factors. The development of parallel acquisition strategies in magnetic resonance imaging (MRI) has created a potential for dramatic decreases in scan times. Several approaches for reconstructing images from individual coil elements have been proposed, based on combining the signal from individual coil elements in either the Fourier (1,2) or spatial (3,4) domain. The sensitivity encoding (SENSE) method has been shown to be a robust approach to image reconstruction (5), and has been implemented in many different pulse sequences, including non-Cartesian sampling patterns (6). With SENSE, the reduction in scan time can be selected depending on the number of coils used for parallel data acquisition. The SENSE method can also be used to suppress pulsation artifacts, with the same scan times as used in conventional acquisition methods (7).Phase contrast imaging is an established method that allows the velocities of moving spins to be measured (8 -12), and is widely used to quantify blood flow (13) and cardiac motion (14,15). The accuracy and reproducibility of phase contrast imaging have been thoroughly investigated, and a number of factors that influence the measured phase values have been identified (16). With compensation for these known artifacts, the phase contrast method has been shown to be very accurate (12,17,18). The acquisition time of phase contrast imaging can be relatively long, however, especially when all three velocity components are measured. Significant reductions in scan time would be highly useful, and may be achieved by using SENSE in combination with phase contrast imaging.The aim of this study was to determine what impact the use of SENSE at different reduction factors would have on the accuracy and reproducibility of phase contrast imaging. Computer simulations, and in vitro and in vivo s...

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Correction for displacement artifacts in 3D phase contrast imaging

Cited by 16 publications

References 25 publications

Phase-contrast MRI and CFD modeling of apparent 3He gas flow in rat pulmonary airways

Phase-contrast MRI and CFD modeling of apparent 3He gas flow in rat pulmonary airways

Quantification of intravoxel velocity standard deviation and turbulence intensity by generalizing phase‐contrast MRI

Accuracy and reproducibility in phase contrast imaging using SENSE

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