Response to Letter to the Editor: “Nomenclature for real‐time magnetic resonance imaging”

Nayak, Krishna S.

doi:10.1002/mrm.27770

Cited by 11 publications

(12 citation statements)

References 6 publications

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“…illustrated by a gray shaded bar, with fine spatial resolution and coarse temporal resolution on the upper left (e.g. 1x1mm 2 with 80 ms temporal resolution, 12.5 fps), and coarse spatial resolution and fine temporal resolution on the right (e.g. 3.5x3.5mm with ms temporal resolution, 50 fps).…”

mentioning

confidence: 99%

Cardiac magnetic resonance assessment of central and peripheral vascular function in patients undergoing renal sympathetic denervation as predictor for blood pressure response

et al. 2018

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mentioning

confidence: 99%

Cardiac magnetic resonance assessment of central and peripheral vascular function in patients undergoing renal sympathetic denervation as predictor for blood pressure response

et al. 2018

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“…The data consisted of multiple stacks of highly accelerated dynamic bSSFP imaging planes, with multiple time frames obtained for each slice. The temporal resolution of the acquisition (72 ms per frame) was sufficient to capture fetal cardiac motion in real-time without the requirement for periodic movement and electrocardiography-gating, however, note that the k-t SENSE acquisition itself was not interactive due to image reconstruction latency (on the order of minutes) 53 . The fetal heart rate was estimated from the frames of each acquired slice and used to assign cardiac phases to each successive frame.…”

Section: Methodsmentioning

confidence: 99%

Fetal whole heart blood flow imaging using 4D cine MRI

et al. 2020

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Prenatal detection of congenital heart disease facilitates the opportunity for potentially life-saving care immediately after the baby is born. Echocardiography is routinely used for screening of morphological malformations, but functional measurements of blood flow are scarcely used in fetal echocardiography due to technical assumptions and issues of reliability. Magnetic resonance imaging (MRI) is readily used for quantification of abnormal blood flow in adult hearts, however, existing in utero approaches are compromised by spontaneous fetal motion. Here, we present and validate a novel method of MRI velocity-encoding combined with a motion-robust reconstruction framework for four-dimensional visualization and quantification of blood flow in the human fetal heart and major vessels. We demonstrate simultaneous 4D visualization of the anatomy and circulation, which we use to quantify flow rates through various major vessels. The framework introduced here could enable new clinical opportunities for assessment of the fetal cardiovascular system in both health and disease.

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“…Optimization methods are inherently more computationally intensive than analytic approaches, and careful attention is needed to ensure that computation times are short enough to permit on‐the‐fly design while limiting delays due to latency 24 during patient‐specific protocol refinement 25 . Additionally, it is easy to check that a waveform meets all of the specified constraints imposed on the optimization, but it remains unclear if other constraints are needed.…”

Section: Theorymentioning

confidence: 99%

Optimization methods for magnetic resonance imaging gradient waveform design

et al. 2020

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The development and implementation of novel MRI pulse sequences remains challenging and laborious. Gradient waveforms are typically designed using a combination of analytical and ad hoc methods to construct each gradient waveform axis independently. This strategy makes coding the pulse sequence complicated, in addition to being time inefficient. As a consequence, nearly all commercial MRI pulse sequences fail to maximize use of the available gradient hardware or efficiently mitigate physiological effects. This results in expensive MRI systems that underperform relative to their inherent hardware capabilities. To address this problem, a software solution is proposed that incorporates numerical optimization methods into MRI pulse sequence programming. Examples are shown for rotational variant vs. invariant waveform designs, acceleration nulled velocity encoding gradients, and mitigation of peripheral nerve stimulation for diffusion encoding. The application of optimization methods to MRI pulse sequence design incorporates gradient hardware limits and the prescribed MRI protocol parameters (e.g. field-of-view, resolution, gradient moments, and/or b-value) to simultaneously construct time-optimal gradient waveforms. In many cases, the resulting constrained gradient waveform design problem is convex and can be solved on-the-fly on the MRI scanner. The result is a set of multi-axis time-optimal gradient waveforms that satisfy the design constraints, thereby increasing SNR-efficiency. These optimization methods can also be used to mitigate imaging artifacts (e.g. eddy currents) or account for peripheral nerve stimulation. The result of the optimization method is to enable easier pulse sequence gradient waveform design and permit on-the-fly implementation for a range of MRI pulse sequences. KEYWORDS acquisition methods, applications, diffusion methods, diffusion MR sequences, flow imaging methods, flow quantitation, methods and engineering, methods and engineering, methods and engineering, other applications 1 INTRODUCTION Magnetic resonance imaging (MRI) is driven by pulse sequences-a synchronized series of radiofrequency (RF) and gradient events that confer image contrast, echo formation, and spatio-temporal sampling. This enables the acquisition of anatomical and physiological measurements that contain the preferred image information. The design of pulse sequences remains at the core of advances in fast and quantitative MRI.

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Response to Letter to the Editor: “Nomenclature for real‐time magnetic resonance imaging”

Cited by 11 publications

References 6 publications

Cardiac magnetic resonance assessment of central and peripheral vascular function in patients undergoing renal sympathetic denervation as predictor for blood pressure response

Cardiac magnetic resonance assessment of central and peripheral vascular function in patients undergoing renal sympathetic denervation as predictor for blood pressure response

Fetal whole heart blood flow imaging using 4D cine MRI

Optimization methods for magnetic resonance imaging gradient waveform design

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