Cardiac balanced steady-state free precession MRI at 0.35 T: a comparison study with 1.5 T

Rashid, Shams; Han, Fei; Gao, Yu; Sung, Kyunghyun; Cao, Minsong; Yang, Yingli; Hu, Peng

doi:10.21037/qims.2018.08.09

Cited by 23 publications

(37 citation statements)

References 24 publications

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“…The temporal resolution and scan time were matched across the three scanners, requiring slightly lower acquired spatial resolution at 0.35 T due to the lower gradient performance. Cine images acquired at 0.35 T with flip angles greater than 110° were shown recently by Rashid et al 27 to have comparable image quality with 1.5 T cine images with flip angle 90°. Based on this information, we set the flip angle at 110° for 0.35 T cine 27 .…”

Section: Methodsmentioning

confidence: 79%

“…Cine images acquired at 0.35 T with flip angles greater than 110° were shown recently by Rashid et al 27 to have comparable image quality with 1.5 T cine images with flip angle 90°. Based on this information, we set the flip angle at 110° for 0.35 T cine 27 . At 1.5 and 3 T, the flip angle was initially set to 90° and then reduced automatically to the maximum flip angle allowed by SAR limits for each subject to maximize blood‐myocardium contrast.…”

Section: Methodsmentioning

confidence: 79%

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Assessment of cardiac function, blood flow and myocardial tissue relaxation parameters at 0.35 T

et al. 2020

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A low field strength (B0) system could increase cardiac MRI availability for patients otherwise contraindicated at higher field. Lower equipment costs could also broaden cardiac MR accessibility. The current study investigated the feasibility of cardiac function with steady-state free precession and flow assessment with phase contrast (PC) cine images at 0.35 T, and evaluated differences in myocardial relaxation times using quantitative T1, T2 and T2* maps by comparison with 1.5 and 3 T results in a small cohort of six healthy volunteers. Signal-to-noise ratio (SNR) differences across systems were characterized with proton density-weighted spin echo phantom data. SNR at 0.35 T was lower by factors of 5.5 and 15.0 compared with the 1.5 and 3 T systems used in this study. All cine images at 0.35 T scored 3 or greater on a fivepoint image quality scale. Normalized blood-myocardium contrast in cine images, left ventricular volumes (end diastolic volume, end systolic volume) and function (ejection fraction and stroke volume) measures at 0.35 T matched 1.5 and 3 T results. Phase-to-noise ratio in 0.35 T PC images (11.7 ± 1.9) was lower than 1.5 T (18.7 ± 5.2) and 3 T (44.9 ± 16.5). Peak velocity and stroke volume determined from PC images were similar across systems. Myocardial T1 increased (564 ± 13 ms at 0.35 T, 955 ± 19 ms at 1.5 T and 1200 ± 35 ms at 3 T) while T2 (59 ± 4 ms at 0.35 T, 49 ± 3 ms at 1.5 T and 40 ± 2 ms at 3 T) and T2* (42 ± 8 ms at 0.35 T, 33 ± 6 ms at 1.5 T and 24 ± 3 ms at 3 T) decreased with increasing B0. Despite SNR deficits, cardiovascular function, flow assessment and myocardial relaxation parameter mapping is feasible at 0.35 T using standard cardiovascular imaging sequences. K E Y W O R D Sflow quantitation, heart function, human study, magnets, relaxometry

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Section: Methodsmentioning

confidence: 79%

Section: Methodsmentioning

confidence: 79%

Assessment of cardiac function, blood flow and myocardial tissue relaxation parameters at 0.35 T

et al. 2020

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“…The decreased T 1 and specific absorption rate (SAR) at this field strength compared with higher fields of 1.5T and 3T can also be leveraged to optimize steady‐state sequences, particularly for SAR‐intensive applications such as cardiac imaging. These advantages have been demonstrated in the work by Rashid et al Balanced SSFP‐based imaging of the heart at 0.35T on an MRI‐guided radiation therapy system (MRIdian, ViewRay, OH) with an actively shielded superconducting magnet, split bore, and 18 mT/m gradients was compared with corresponding images from a standard 1.5T. This balanced (b)SSFP study demonstrated that image quality at 0.35T approached that seen at 1.5T at high flip angles.…”

Section: Current State Of the Artmentioning

confidence: 88%

Accessible magnetic resonance imaging: A review

Geethanath

Vaughan

2019

Magnetic Resonance Imaging

137

139

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The role of MRI in diagnostics, prognostics, and discoveries in basic sciences has been well established. However, access to this life‐saving technology is largely restricted to countries in upper‐middle to high‐income groups. In this article, we collate recent global MR scanner density data and group them into six geographical regions based on the WHO classification. We then analyze these data with respect to demographic factors such as population size, life expectancy, the percentage of internet users, and World Bank income grouping. We map these demographic factors to five dimensions or characteristics of accessible MRI, adapting definitions from the healthcare literature. With this background, the study then reviews recent demonstrations of accessible MRI categorized based on main magnetic field strength. We describe demonstrated examples for each of these categories, ranging from ultralow‐field to ultrahigh‐field MRI. Lastly, we review MR methods and associated developments impacting accessible MRI such as increasing/augmenting MR awareness and local expertise, incorporating hardware‐cognizant methods, rapid quantitative imaging, and leveraging innovations from adjacent fields. Level of Evidence: 5 Technical Efficacy Stage: 6 J. Magn. Reson. Imaging 2019.

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“…Clinical MR for cardiac imaging typically uses 1.5 tesla (T) systems and, less commonly, 3T systems, despite the availability of higher field MRI. There are potential advantages to lower field (<1.5T) for cardiovascular applications, which has generated recent interest in low‐field cardiac MRI 1‐3 . Low field may offer reduced costs, reduced artifacts, and improved safety for cardiac imaging.…”

Section: Introductionmentioning

confidence: 99%

“…RF power scales quadratically with field strength, which leads to improved safety for cardiovascular implanted electronic devices and metallic devices used for MRI‐guided cardiovascular catheterization procedures 4,5 . The reduced specific absorption rate constraints also permit imaging with higher flip angles 2 . Increased main magnetic field (B 0 ) homogeneity at low field provides linear scaling of absolute susceptibility 6 .…”

Section: Introductionmentioning

confidence: 99%

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

Restivo

Ramasawmy

Bandettini

et al. 2020

Magnetic Resonance in Med

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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.

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Cardiac balanced steady-state free precession MRI at 0.35 T: a comparison study with 1.5 T

Abstract: This study demonstrates that cardiac bSSFP imaging is highly feasible at 0.35 T.

Cited by 23 publications

References 24 publications

Assessment of cardiac function, blood flow and myocardial tissue relaxation parameters at 0.35 T

Assessment of cardiac function, blood flow and myocardial tissue relaxation parameters at 0.35 T

Accessible magnetic resonance imaging: A review

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

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