<i>k‐t</i> GRAPPA accelerated four‐dimensional flow MRI in the aorta: Effect on scan time, image quality, and quantification of flow and wall shear stress

Schnell, Susanne; Markl, Michael; Entezari, Pouya; Mahadewia, Riti J; Semaan, Edouard; Stanković, Zoran; Collins, Jeremy D.; Carr, James C.; Jung, Bernd

doi:10.1002/mrm.24925

Cited by 77 publications

(72 citation statements)

References 37 publications

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“…Even in healthy individuals, shorter acquisition times will result in fewer scans degraded by inadvertent respiratory motion artifact or degradation of a slice due to an ectopic beat. Moreover, there is a continued clinical interest in improved spatial and temporal resolution for advanced cardiac functional assessment such as coronary evaluation, flow quantification, and valvular imaging [22][23][24][25][26]. Accelerated imaging allows for the large data acquisition required for these advanced scans with minimal increases in scan time.…”

Section: Discussionmentioning

confidence: 99%

Highly accelerated cardiac MRI using iterative SENSE reconstruction: initial clinical experience

Allen

Carr

Botelho

et al. 2016

Int J Cardiovasc Imaging

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To evaluate the qualitative and quantitative performance of an accelerated cardiovascular MRI (CMR) protocol that features iterative SENSE reconstruction and spatio-temporal L1-regularization (IS SENSE). Twenty consecutively recruited patients and 9 healthy volunteers were included. 2D steady state free precession cine images including 3-chamber, 4-chamber, and short axis slices were acquired using standard parallel imaging (GRAPPA, acceleration factor = 2), spatio-temporal undersampled TSENSE (acceleration factor = 4), and IS SENSE techniques (acceleration factor = 4). Acquisition times, quantitative cardiac functional parameters, wall motion abnormalities (WMA), and qualitative performance (scale: 1-poor to 5-excellent for overall image quality, noise, and artifact) were compared. Breath-hold times for IS SENSE (3.0 ± 0.6 s) and TSENSE (3.3 ± 0.6) were both reduced relative to GRAPPA (8.4 ± 1.7 s, p < 0.001). No difference in quantitative cardiac function was present between the three techniques (p = 0.89 for ejection fraction). GRAPPA and IS SENSE had similar image quality (4.7 ± 0.4 vs. 4.5 ± 0.6, p = 0.09) while, both techniques were superior to TSENSE (quality: 4.1 ± 0.7, p < 0.001). GRAPPA WMA agreement with IS SENSE was good (κ > 0.60, p < 0.001), while agreement with TSENSE was poor (κ < 0.40, p < 0.001). IS SENSE is a viable clinical CMR acceleration approach to reduce acquisition times while maintaining satisfactory qualitative and quantitative performance.

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Section: Discussionmentioning

confidence: 99%

Highly accelerated cardiac MRI using iterative SENSE reconstruction: initial clinical experience

Allen

Carr

Botelho

et al. 2016

Int J Cardiovasc Imaging

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“…Methods such as k-t SENSE and k-t GRAPPA have been used to reduce scan times for Cartesian PC MRI, reaching net acceleration factors of around 5 [105][106][107]. While some temporal smoothing remains for k-t approaches, especially for high reduction factors, principal component analysis has shown promising results for reduction factors of up to 8 for 4D flow (k-t PCA) [108].…”

Section: Undersampling Of K-spacementioning

confidence: 99%

Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment

Petersson¹

2013

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The study of blood flow is essential in understanding the physiology and pathophysiology of the cardiovascular system. Small disturbances of the blood flow may over time evolve and contribute to cardiovascular pathology. While the blood flow in a healthy human appears to be predominately laminar, turbulent or transitional blood flow is thought to be involved in the pathogenesis of several cardiovascular diseases. Wall shear stress is the frictional force of blood on the vessel wall and has been linked to the pathogenesis of atherosclerosis and aneurysms. Despite the importance of hemodynamic factors, cardiovascular diagnostics largely relies on the indirect estimation of function based on morphological data.Time-resolved three-dimensional (3D) phase-contrast magnetic resonance imaging (MRI), often referred to as 4D flow MRI, is a versatile and non-invasive tool for cardiovascular blood flow assessment. The use of 4D flow MRI permits estimation of flow volumes, pressure losses, wall shear stress, turbulence intensity and many other unique hemodynamic parameters. However, 4D flow MRI suffers from long scan times, sometimes over 40 minutes. Furthermore, the accuracy of the many different 4D flow MRI-based applications and estimates have not been thoroughly examined.In this thesis, the accuracy of 4D flow MRI-based turbulence intensity mapping and wall shear stress estimation was investigated by using numerical simulations of MRI flow measurements. While the results from the turbulence intensity mapping agreed well with reference values from computational fluid dynamics data, the accuracy of the MRI-based wall shear stress estimates was found to be very sensitive to different parameters, especially to spatial resolution, and wall shear stress values over 5 N/m 2 were not well resolved.To reduce the scan time, a 4D flow MRI sequence using spiral k-space trajectories was implemented and validated in-vivo and in-vitro. The scan time of 4D flow MRI was reduced by more than two-fold compared to a conventional Cartesian acquisition already accelerated using SENSE factor 2, and the data quality was maintained. For a 4D flow scan of the human heart, the use of spiral k-space trajectories resulted in a scan time of around 13 min, compared to 30 min for the Cartesian acquisition. By combining parallel imaging and spiral trajectories, the total scan time of a 4D flow measurement of the entire heart may be further reduced. This scan time reduction may also be traded for higher spatial resolution.Numerical simulation of 4D flow MRI may act as an important tool for future optimization and validation of the spiral 4D flow sequence. The scan-time reductions offered by the spiral k-space trajectories can help to cut costs, save time, reduce discomfort for the patient as well as to decrease the risk for motion artifacts. These benefits may facilitate an expanded clinical and investigative use of 4D flow MRI, including larger patient research studies.v Populärvetenskaplig sammanfattningHjärt-och kärlsjukdom är fortfarande den ...

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“…The amount of the acceleration possible with these techniques is extremely high but requires substantial computational power to fully achieve high levels of acceleration [23]. More modest accelerations can be achieved utilizing lower computational burden of k-t acceleration techniques [19]. With the combination of parallel imaging and k-t acceleration techniques, the major arterial circulation can be imaged with 1 mm isotropic spatial resolution within 5-10 min.…”

Section: Intracranial 4dflow Mri Acquisitionmentioning

confidence: 99%

Neurovascular 4DFlow MRI (Phase Contrast MRA): emerging clinical applications

et al. 2016

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Recent advances in 4DFlow MRI (Phase Contrast MRA) acquisition and reconstruction enable high resolution exams to be obtained in practical imaging times. 4DFlow MRI provides images of vascular morphology and quantitative measurements of blood velocity throughout a 3D imaging volume. Hemodynamic parameters such as flow volume, relative wall shear stress, streamlines, vorticity and pressure gradients can be derived from the velocity data. The combination of anatomic vessel wall imaging, lumen visualization and physiologic data derived from accelerated 4DFlow MRI augments the characterization of intracranial arterial stenosis, aneurysms, vascular malformations and dural sinus pathology. This review provides an update for clinicians interested in 4DFlow MRI of the brain.

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k‐t GRAPPA accelerated four‐dimensional flow MRI in the aorta: Effect on scan time, image quality, and quantification of flow and wall shear stress

Cited by 77 publications

References 37 publications

Highly accelerated cardiac MRI using iterative SENSE reconstruction: initial clinical experience

Highly accelerated cardiac MRI using iterative SENSE reconstruction: initial clinical experience

Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment

Neurovascular 4DFlow MRI (Phase Contrast MRA): emerging clinical applications

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