Dataset Information

Efficient spiral in-out and EPI balanced steady-state free precession cine imaging using a high-performance 0.55T MRI.

ABSTRACT:

Purpose

Low-field MRI offers favorable physical properties for SNR-efficient long readout acquisitions such as spiral and EPI. We used a 0.55 tesla (T) MRI system equipped with high-performance hardware to increase the sampling duty cycle and extend the TR of balanced steady-state free precession (bSSFP) cardiac cine acquisitions, which typically are limited by banding artifacts.

Methods

We developed a high-efficiency spiral in-out bSSFP acquisition, with zeroth- and first-gradient moment nulling, and an EPI bSSFP acquisition for cardiac cine imaging using a contemporary MRI system modified to operate at 0.55T. Spiral in-out and EPI bSSFP cine protocols, with TR = 8 ms, were designed to maintain both spatiotemporal resolution and breath-hold length. Simulations, phantom imaging, and healthy volunteer imaging studies (n = 12) were performed to assess SNR and image quality using these high sampling duty-cycle bSSFP sequences.

Results

Spiral in-out bSSFP performed favorably at 0.55T and generated good image quality, whereas EPI bSSFP suffered motion and flow artifacts. There was no difference in ejection fraction comparing spiral in-out with standard Cartesian imaging. Moreover, human images demonstrated a 79% ± 21% increase in myocardial SNR using spiral in-out bSSFP and 50% ± 14% increase in SNR using EPI bSSFP as compared with the reference Cartesian acquisition. Spiral in-out acquisitions at 0.55T recovered 69% ± 14% of the myocardial SNR at 1.5T.

Conclusion

Efficient bSSFP spiral in-out provided high-quality cardiac cine imaging and SNR recovery on a high-performance 0.55T MRI system.

SUBMITTER: Restivo MC

PROVIDER: S-EPMC7402011 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

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Publications

Efficient spiral in-out and EPI balanced steady-state free precession cine imaging using a high-performance 0.55T MRI.

Restivo Matthew C MC Ramasawmy Rajiv R Bandettini W Patricia WP Herzka Daniel A DA Campbell-Washburn Adrienne E AE

Magnetic resonance in medicine 20200414 5

<h4>Purpose</h4>Low-field MRI offers favorable physical properties for SNR-efficient long readout acquisitions such as spiral and EPI. We used a 0.55 tesla (T) MRI system equipped with high-performance hardware to increase the sampling duty cycle and extend the TR of balanced steady-state free precession (bSSFP) cardiac cine acquisitions, which typically are limited by banding artifacts.<h4>Methods</h4>We developed a high-efficiency spiral in-out bSSFP acquisition, with zeroth- and first-gradien ...[more]

PMID: 32291845

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Project description:BackgroundThere is a growing interest in the development and application of mid-field (0.55T) for cardiovascular magnetic resonance (CMR), including flow imaging. However, aortic flow imaging at 0.55T has limited signal-to-noise ratio (SNR), especially in diastolic phases where there is reduced inflow-driven contrast for spoiled gradient recalled echo (GRE) sequences. The low SNR can limit the accuracy of flow and regurgitant fraction measurements.MethodsIn this work, we developed a two-dimensional phase contrast (PC) acquisition with balanced steady-state free precession (bSSFP), termed PC-SSFP, for flow imaging and quantification at 0.55T. This PC-SSFP approach precisely nulls the zeroth and first gradient moments at both the echo time (TE) and repetition time, except for the flow-encoded acquisition, for which the first gradient moment at the TE is determined by the velocity encoding. Our proposed sequence was tested in both phantoms and in healthy volunteers (n = 11), to measure aortic flow. In volunteers, both a breath-hold (bh) and a free-breathing (fb) protocol, with averaging to increase SNR, were obtained. Total flow, peak flow, cardiac output, and SNR were compared for PC-SSFP and PC-GRE. Stroke volumes were also measured and compared to planimetry method.ResultsIn a phantom, SNR was significantly higher using PC-SSFP compared to PC-GRE (25.5 ± 9.6 vs 8.2 ± 2.9), and the velocity measurements agreed well (R = 1.00). In healthy subjects, for both bh and fb protocols, PC-SSFP measured accurate peak flow (fb: R = 0.99, bh: R = 0.96) and cardiac output (fb: R = 0.98, bh: R = 0.88), compared to PC-GRE, accurate stroke volume (fb: R = 0.94, bh: R = 0.97), compared to planimetry measurement, and offered constant high SNR (fb: 28 ± 9 vs 18 ± 6, bh: 24 ± 7 vs 11 ± 3) over the cardiac cycle in 11 subjects.ConclusionPC-SSFP is a more reliable evaluation tool for aortic flow quantification, when compared to the conventional PC-GRE method at 0.55T, providing higher SNR, and thus potentially more accurate flows.

Project description:BackgroundBalanced steady-state free precession (bSSFP) is important in cardiac MRI but suffers from off-resonance artifacts. The interpretation-limiting artifacts in patients with cardiac implants remain an unsolved issue.PurposeTo develop an interleaved radial linear combination bSSFP (lcSSFP) method with partial dephasing (PD) for improved cardiac cine imaging when implanted cardiovascular devices are present.Study typeProspective.Phantom and subjectsFlow phantom adjacent to a pacemaker and 10 healthy volunteers (mean age ± standard deviation: 31.9 ± 2.9 years, 4 females) with a cardioverter-defibrillator (ICD) positioned extracorporeally at the left chest in the prepectoral region.Field strength/sequenceA 3-T, 1) Cartesian bSSFP, 2) Cartesian gradient echo (GRE), 3) Cartesian lcSSFP, and 4) radial lcSSFP cine sequences.AssessmentFlow artifacts mitigation using PD was validated with phantom experiments. Undersampled radial lcSSFP with interleaving across phase-cyclings and cardiac phases (RLC-SSFP), combined with PD, was then employed for achieving improved quality of cine images from left ventricular short-axis view. The image quality in the presence of cardiac devices was qualitatively assessed by three independent raters (1 = worst, 5 = best), regarding five criteria (banding artifacts, streak artifacts, flow artifacts, cavity visibility, and overall image quality).Statistical testsWilcoxon rank-sum test for the five criteria between Cartesian bSSFP cine and RLC-SSFP with PD. Fleiss kappa test for inter-reader agreement. A P value < 0.05 was considered statistically significant.ResultsBased on simulations and phantom experiments, 60 projections per phase cycling and 1/6 PD were chosen. The in vivo experiments demonstrated significantly reduced banding artifacts (4.8 ± 0.4 vs. 2.7 ± 0.7), fewer streak artifacts (3.7 ± 0.6 vs. 2.6 ± 0.7) and flow artifacts (4.4 ± 0.4 vs. 3.7 ± 0.6), therefore improved cavity visibility (4.1 ± 0.4 vs. 2.9 ± 0.9) and overall quality (4.0 ± 0.4 vs. 2.7 ± 0.7).Data conclusionRLC-SSFP method with PD may improve cine image quality in subjects with cardiac devices.Evidence level2.Technical efficacyStage 1.

Dataset Information

Efficient spiral in-out and EPI balanced steady-state free precession cine imaging using a high-performance 0.55T MRI.

Purpose

Methods

Results

Conclusion

Publications

Efficient spiral in-out and EPI balanced steady-state free precession cine imaging using a high-performance 0.55T MRI.

Similar Datasets

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