A method to correct background phase offset for phase‐contrast MRI in the presence of steady flow and spatial wrap‐around artifact

Pruitt, Aaron A.; Jin, Ning; Liu, Yingmin; Simonetti, Orlando P.; Ahmad, Rizwan

doi:10.1002/mrm.27572

Cited by 7 publications

(11 citation statements)

References 30 publications

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“…VNR is inversely proportional to the magnitude of Venc, hence when Cine-PC is performed to measure flow with a low velocity dynamic range (cerebrovascular blood or CSF), The prescribed Venc produces relatively high VNR in the targeted flow region [24]. In this investigation, The two different coverages demonstrated that there was no statistical difference in VNR, thus fold-over should not be selected solely for the purpose of increasing VNR value.…”

Section: Discussionmentioning

confidence: 82%

Fold-Over Oversampling Effects in the Measurements of Cerebral Cerebrospinal Fluid and Blood Flows with 2D Cine Phase-Contrast MRI

et al. 2020

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This prospective study investigated the effects of fold-over oversampling on phase-offset background errors with 2D-Cine phase contrast (Cine-PC) magnetic resonance imaging (MRI). It was performed on brain MRI and compared to conventional Full-field of view FOV coverage and it was tested with two different velocity encoding (Venc) values. We chose Venc = 100 mm/s to encode cerebrospinal fluid (CSF) flows in the aqueduct and 600 mm/s to encode blood flow in the carotid artery. Cine-PC was carried out on 10 healthy adult volunteers followed simultaneously by an acquisition on static agar-gel phantom to measure the phase-offset background errors. Pixel-wise correction of both the CSF and the blood flows was calculated through 32 points of the cardiac-cycle. We compared the velocity-to-noise ratio, the section area, the absolute and the corrected velocity (peak; mean and minimum), the net flow, and the stroke volume before and after correction. We performed the statistical T-test to compare Full-FOV and fold-over and Bland–Altman plots to analyze their differences. Our results showed that following phase-offset error correction, the blood stroke-volume was significantly higher with Full-FOV compared to fold-over. We observed a significantly higher CSF mean velocity and net flow values in the fold-over option. Compared to Full-FOV, fold-over provides a significantly larger section area and significantly lower peak velocity-offset in the aqueduct. No significant difference between the two coverages was reported before and after phase-offset in blood flow measurements. In conclusion, fold-over oversampling can be chosen as an alternative to increase spatial resolution and accurate cerebral flow quantification in Cine-PC.

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Section: Discussionmentioning

confidence: 82%

Fold-Over Oversampling Effects in the Measurements of Cerebral Cerebrospinal Fluid and Blood Flows with 2D Cine Phase-Contrast MRI

et al. 2020

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“…The comparative insensitivity of flow‐volume measurement to the amount of static tissue used for polynomial fitting shows that automated static tissue‐segmentation routines would benefit from accurate and evenly dispersed static tissue definition, whereas the omission of a large proportion of the available static tissue is acceptable, with negligible impact on measurement results. By combining this knowledge with other techniques of automated static‐tissue identification, artifact detection and weighted‐fitting algorithms, 4D‐flow MRI can be more accessible as a clinical tool …”

Section: Discussionmentioning

confidence: 99%

“…By combining this knowledge with other techniques of automated static-tissue identification, artifact detection and weighted-fitting algorithms, 4D-flow MRI can be more accessible as a clinical tool. 11,13,25 While other studies have investigated background-phase offsets in 4D-flow MRI, this is the first study to provide a comprehensive analysis of the influence of different correction techniques on vascular flow-volume measurements. Lorenz et al performed a streamline and pathline tracking analysis that showed improvement with second order, compared with linear background phase fitting in phantom experiments, but no discernable difference in in vivo tracking, F I G U R E 7 Percentage change in flow-volume measurement compared with using manually defined static tissue as a function of nonstatic tissue inclusion.…”

Section: F I G U R Ementioning

confidence: 97%

Flow quantification dependency on background phase correction techniques in 4D‐flow MRI

Callaghan

Burkhardt

Geiger

et al. 2019

Magnetic Resonance in Med

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Purpose To analyze the dependence of flow volume measurements on 3D cine phase‐contrast MRI (4D‐flow MRI) background phase correction. Methods In 31 subjects scanned on a 1.5T MRI scanner, flow volume measurements at 4 vessels were made using phantom corrected 2D phase contrast and 4D flow with background phase correction performed by linear, second, third, and fourth‐order polynomial fitting to static tissue. Variations in the amount and distribution of static tissue were made to investigate the influence on flow volume measurements. Results Bland Altman comparison of 2D phase‐contrast and 4D‐flow measurements showed low bias (2.3%‐4.8%) and relatively large limits of agreement (13.5%‐17.6%). Approximately half of this was attributable to sequence and physiological differences between the 2 scan sequences, demonstrated by smaller limits of agreement (5.3%‐10.0%) when comparing 4D‐flow measurements with differing background phase corrections. Using only 20% of available static tissue points for polynomial fitting resulted in only 1% difference in flow volume measurements. Using asymmetrically distributed static tissue or including nonstatic tissue for polynomial fitting yielded highly variable differences in flow volume measurements, which became more variable with increased polynomial order. Completely asymmetric static tissue selection resulted in high deviations in flow volume measurements (mean > 7%, max = 345%). Conclusion Comparisons between 2D phase‐contrast and 4D‐flow volume measurements should consider influences from sequence and physiological differences. A subset of static tissue points may be used with low impact on flow measurements, but should avoid the inclusion of nonstatic tissue and avoid asymmetric distribution. Higher‐order polynomial fits are more susceptible to inaccurate static tissue selection.

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“…Prior to flow quantification, all images were corrected using a recently proposed background phase correction method 39 . Phase‐aliasing correction was performed when necessary.…”

Section: Methodsmentioning

confidence: 99%

“…Prior to flow quantification, all images were corrected using a recently proposed background phase correction method. 39 Phase-aliasing correction was performed when necessary. Net volumetric flow, peak through-plane velocity, and peak volumetric flow rate were calculated as the flow indices of interest.…”

Section: Postprocessing and Analysismentioning

confidence: 99%

Fully self‐gated whole‐heart 4D flow imaging from a 5‐minute scan

Pruitt

Rich

Liu

et al. 2020

Magnetic Resonance in Med

Self Cite

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To develop and validate an acquisition and processing technique that enables fully self-gated 4D flow imaging with whole-heart coverage in a fixed 5-minute scan. Theory and Methods: The data are acquired continuously using Cartesian sampling and sorted into respiratory and cardiac bins using the self-gating signal. The reconstruction is performed using a recently proposed Bayesian method called ReVEAL4D. ReVEAL4D is validated using data from 8 healthy volunteers and 2 patients and compared with compressed sensing technique, L1-SENSE. Results: Healthy subjects-Compared with 2D phase-contrast MRI (2D-PC), flow quantification from ReVEAL4D shows no significant bias. In contrast, the peak velocity and peak flow rate for L1-SENSE are significantly underestimated. Compared with traditional parallel MRI-based 4D flow imaging, ReVEAL4D demonstrates small but significant biases in net flow and peak flow rate, with no significant bias in peak velocity. All 3 indices are significantly and more markedly underestimated by L1-SENSE. Patients-Flow quantification from ReVEAL4D agrees well with the 2D-PC reference. In contrast, L1-SENSE markedly underestimated peak velocity. Conclusions: The combination of highly accelerated 5-minute Cartesian acquisition, self-gating, and ReVEAL4D enables whole-heart 4D flow imaging with accurate flow quantification.

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A method to correct background phase offset for phase‐contrast MRI in the presence of steady flow and spatial wrap‐around artifact

Cited by 7 publications

References 30 publications

Fold-Over Oversampling Effects in the Measurements of Cerebral Cerebrospinal Fluid and Blood Flows with 2D Cine Phase-Contrast MRI

Fold-Over Oversampling Effects in the Measurements of Cerebral Cerebrospinal Fluid and Blood Flows with 2D Cine Phase-Contrast MRI

Flow quantification dependency on background phase correction techniques in 4D‐flow MRI

Fully self‐gated whole‐heart 4D flow imaging from a 5‐minute scan

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