Cardiac Magnetic Resonance at High Field: Promises and Problems

Gharib, Ahmed M.; Elagha, Abdalla; Pettigrew, Roderic I.

doi:10.1067/j.cpradiol.2007.11.003

Cited by 17 publications

(9 citation statements)

References 54 publications

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“…For example, the use of high efficiency balanced imaging sequences is routine at 1.5 tesla, but has proved challenging to implement at 3 tesla [12] and is likely to require sophisticated higher order shimming to be even feasible at 7 tesla. The lack of a body-coil for uniform excitation also makes many standard preparation modules for imaging sequences difficult: for example, black-blood imaging or quantitative velocity measurements.…”

Section: Discussionmentioning

confidence: 99%

“…In terms of cardiac imaging, the pros and cons of moving from lower to higher magnetic fields have been discussed previously in [12] and references therein, comparing 1.5 and 3 tesla: such considerations are also pertinent when considering cardiac imaging at 7 tesla. Briefly, the advantages of higher fields include improved tagging due to the prolonged T 1 time of the myocardium, improved perfusion imaging both due to the increased signal-to-noise (S/N) and the longer myocardial T 1 values, and a higher velocity-to-noise ratio in blood velocity measurements.…”

Section: Introductionmentioning

confidence: 98%

“…Briefly, the advantages of higher fields include improved tagging due to the prolonged T 1 time of the myocardium, improved perfusion imaging both due to the increased signal-to-noise (S/N) and the longer myocardial T 1 values, and a higher velocity-to-noise ratio in blood velocity measurements. Specific challenges outlined in [12] included implementation of high efficiency balanced SSFP sequences without off-resonance banding artifacts, the detrimental effects of B 1 and B 0 inhomogeneity on inversion-recovery prepared sequences in particular, and the high potential specific absorption ratio (SAR). Although not mentioned, localized MR spectroscopy is also an area that should profit considerably from the higher field.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simple RF design for human functional and morphological cardiac imaging at 7tesla

Versluis

Tsekos

Smith

et al. 2009

Journal of Magnetic Resonance

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simple RF design for human functional and morphological cardiac imaging at 7tesla

Versluis

Tsekos

Smith

et al. 2009

Journal of Magnetic Resonance

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“…Pulse sequences are adapted to 3T due to Specific Absorption Rate (SAR) limits, susceptibility, and motion artifacts and relaxometries of tissue and thus contrast at 3T. Compared with 1.5T MR, the use of higher magnetic field strength with a lower T1 relaxation curve allows more accurate determination of inversion time and shortens the delay time from 20 min with 1.5T to 5 min before starting the IR prepared 3D while‐heart scan (16, 24). Moreover, the higher signal‐to‐noise ratio (SNR) inherent at 3T can be used to offset the relative SNR loss that results from reduction in voxel size and the use of parallel imaging to shorten scan times.…”

Section: Discussionmentioning

confidence: 99%

Pulmonary vein morphology by free‐breathing whole heart magnetic resonance imaging at 3 tesla versus breathhold multi‐detector computed tomography

Fodi¹,

McAreavey²,

Abd‐Elmoniem³

et al. 2012

Magnetic Resonance Imaging

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Purpose This study compares pulmonary vein and left atrial anatomy using 3D free-breathing whole-heart magnetic resonance imaging (MR) at 3T and multi-detector computed tomography (MDCT). Materials and Methods Thirty three subjects (19 male, age 49±12 years) underwent free-breathing 3T MR and contrast-enhanced MDCT during inspiratory breath hold. Pulmonary vein parameters (ostial areas, diameters, angles) were measured. Results All pulmonary veins and anomalies were identified by 3T MR and by MDCT. The right-sided pulmonary veins were directed more posteriorly, the right superior pulmonary vein more inferiorly, and the right inferior pulmonary vein more superiorly by 3T MR when compared with MDCT. The cross-sectional area, perimeters and minimum diameters of right-sided pulmonary vein ostia were significantly larger by MR, as were the maximum diameters of right and left inferior pulmonary veins. There were no significant differences between techniques in distance to first pulmonary vein branch. Conclusion Pulmonary vein measurements demonstrated significant differences in angulations and dimensions when 3T MR is compared with MDCT. These differences likely represent hemodynamic and respiratory variation during free-breathing with MR versus breath-holding with MDCT. MR imaging at 3T during free-breathing offers an alternate method to define pulmonary vein and left atrial anatomy without exposure to radiation.

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“…SNR increases for both coronary MRI and LGE have been reported when imaging at higher fields . Although SNR increases between 30% and 60% have been reported , these differences in SNR have not translated to improved diagnostic quality .…”

Section: Discussionmentioning

confidence: 99%

Utility of respiratory‐navigator‐rejected k‐space lines for improved signal‐to‐noise ratio in three‐dimensional cardiac MR

Akçakaya

Shaw

Hauser

et al. 2012

Magnetic Resonance in Med

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Purpose To develop and evaluate a technique that utilizes the k-space lines rejected by prospective respiratory navigator (NAV) to improve the signal-to-noise ratio (SNR) without increasing the scan time. Methods In conventional image reconstruction, the motion-corrupted k-space lines rejected by the NAV are not utilized. In this study, a set of translational motion parameters for the NAV-rejected lines and a phase-corrected average for the k-space line are estimated jointly using a maximum-likelihood approach and the information from the corresponding accepted k-space lines. Left coronary artery images were acquired in 10 healthy adult subjects, and the proposed approach incorporating the NAV-rejected lines was compared to the conventional dataset with NAV-accepted lines only, as well as a simple average of all k-space lines, in terms of SNR, normalized vessel sharpness and qualitative image scores on a 4-point scale (1 = poor, 4 = excellent). Late gadolinium enhancement (LGE) images of the left atrium were also acquired in 21 patients with atrial fibrillation pre- or post- pulmonary vein isolation. Images reconstructed with the proposed, conventional and simple averaging methods were compared in terms of SNR, and subjective image quality on a 4-point scale. Results For coronary MRI, there was a significant improvement in SNR with the proposed technique, but no significant difference in normalized vessel sharpness or qualitative image scores were observed with respect to the conventional method. Simple averaging resulted in an SNR gain, but significant loss in vessel sharpness and image quality. For LGE, there was a significant increase in SNR, but no significant differences were observed in subjective image quality scores between the proposed and conventional methods. There was an SNR gain, but image quality loss for simple averaging, when compared to the conventional technique. In both coronary MRI and LGE, the SNR gain of the proposed method was not significantly different than the maximum theoretical SNR gain. Conclusion The proposed technique improves SNR using the additional information from NAV-rejected k-space lines, while providing similar image quality to standard reconstruction using motion-free k-space data only, with no increase in scan time.

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Cardiac Magnetic Resonance at High Field: Promises and Problems

Cited by 17 publications

References 54 publications

Simple RF design for human functional and morphological cardiac imaging at 7tesla

Simple RF design for human functional and morphological cardiac imaging at 7tesla

Pulmonary vein morphology by free‐breathing whole heart magnetic resonance imaging at 3 tesla versus breathhold multi‐detector computed tomography

Utility of respiratory‐navigator‐rejected k‐space lines for improved signal‐to‐noise ratio in three‐dimensional cardiac MR

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