Real‐time free‐breathing cardiac imaging with self‐calibrated through‐time radial GRAPPA

Sayin, Ozan; Saybasili, Haris; Zviman, Muz; Griswold, Mark A.; Halperin, Henry R.; Seiberlich, Nicole; Herzka, Daniel A.

doi:10.1002/mrm.26112

Cited by 9 publications

(6 citation statements)

References 48 publications

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“…Parallel computing can be harnessed to speed up computation and display images almost immediately after scanning. Such techniques have been explored in research settings for CG SENSE [90], non-Cartesian GRAPPA [91,92], and l 1 -SPIRiT [61]. …”

Section: Non-cartesian Parallel Imagingmentioning

confidence: 99%

Recent advances in parallel imaging for MRI

Hamilton

Franson

Seiberlich

2017

Progress in Nuclear Magnetic Resonance Spectroscopy

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175

125

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Magnetic Resonance Imaging (MRI) is an essential technology in modern medicine. However, one of its main drawbacks is the long scan time needed to localize the MR signal in space to generate an image. This review article summarizes some basic principles and recent developments in parallel imaging, a class of image reconstruction techniques for shortening scan time. First, the fundamentals of MRI data acquisition are covered, including the concepts of k-space, undersampling, and aliasing. It is demonstrated that scan time can be reduced by sampling a smaller number of phase encoding lines in k-space; however, without further processing, the resulting images will be degraded by aliasing artifacts. Nearly all modern clinical scanners acquire data from multiple independent receiver coil arrays. Parallel imaging methods exploit properties of these coil arrays to separate aliased pixels in the image domain or to estimate missing k-space data using knowledge of nearby acquired k-space points. Three parallel imaging methods—SENSE, GRAPPA, and SPIRiT—are described in detail, since they are employed clinically and form the foundation for more advanced methods. These techniques can be extended to non-Cartesian sampling patterns, where the collected k-space points do not fall on a rectangular grid. Non-Cartesian acquisitions have several beneficial properties, the most important being the appearance of incoherent aliasing artifacts. Recent advances in simultaneous multi-slice imaging are presented next, which use parallel imaging to disentangle images of several slices that have been acquired at once. Parallel imaging can also be employed to accelerate 3D MRI, in which a contiguous volume is scanned rather than sequential slices. Another class of phase-constrained parallel imaging methods takes advantage of both image magnitude and phase to achieve better reconstruction performance. Finally, some applications are presented of parallel imaging being used to accelerate MR Spectroscopic Imaging.

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Section: Non-cartesian Parallel Imagingmentioning

confidence: 99%

Recent advances in parallel imaging for MRI

Hamilton

Franson

Seiberlich

2017

Progress in Nuclear Magnetic Resonance Spectroscopy

Self Cite

175

125

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“…Therefore, these methods may not be suitable for real‐time cardiac imaging. Others use the geometric patterns of propeller and radial trajectories to overlap undersampled data into fully‐sampled regions, 28 interpolate GRAPPA weights, 29 or accumulate calibration data over undersampled k‐space 30 . However, these methods cannot be easily adapted to spiral trajectories.…”

Section: Discussionmentioning

confidence: 99%

“…Others use the geometric patterns of propeller and radial trajectories to overlap undersampled data into fully‐sampled regions, 28 interpolate GRAPPA weights, 29 or accumulate calibration data over undersampled k‐space. 30 However, these methods cannot be easily adapted to spiral trajectories. A recent method uses the Fourier transform phase shift property on fully‐sampled Cartesian data to estimate GRAPPA kernels for arbitrary trajectories.…”

Section: Discussionmentioning

confidence: 99%

“…One previous method for free‐breathing, ungated cardiac imaging achieves high spatiotemporal resolutions of up to 1.3 mm 2 × 1.3 mm 2 and 38 ms/frame. 30 However, it relied on the geometry of radial trajectories, and acceleration factors of 6–16 were needed for these resolutions. Here, a specially designed interleaved spiral trajectory is used to reach clinically relevant resolutions at R = 3.…”

Section: Discussionmentioning

confidence: 99%

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Self‐calibrated through‐time spiral GRAPPA for real‐time, free‐breathing evaluation of left ventricular function

Franson

Ahad

Liu

et al. 2022

Magnetic Resonance in Med

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Purpose Through‐time spiral GRAPPA is a real‐time imaging technique that enables ungated, free‐breathing evaluation of the left ventricle. However, it requires a separate fully‐sampled calibration scan to calculate GRAPPA weights. A self‐calibrated through‐time spiral GRAPPA method is proposed that uses a specially designed spiral trajectory with interleaved arm ordering such that consecutive undersampled frames can be merged to form calibration data, eliminating the separate fully‐sampled acquisition. Theory and Methods The proposed method considers the time needed to acquire data at all points in a GRAPPA calibration kernel when using interleaved arm ordering. Using this metric, simulations were performed to design a spiral trajectory for self‐calibrated GRAPPA. Data were acquired in healthy volunteers using the proposed method and a comparison electrocardiogram‐gated and breath‐held cine scan. Left ventricular functional values and image quality are compared. Results A 12‐arm spiral trajectory was designed with a temporal resolution of 32.72 ms/cardiac phase with an acceleration factor of 3. Functional values calculated using the proposed method and the gold‐standard method were not statistically significantly different (paired t‐test, p < 0.05). Image quality ratings were lower for the proposed method, with statistically significantly different ratings (Wilcoxon signed rank test, p < 0.05) for two of five image quality aspects rated (level of artifact, blood‐myocardium contrast). Conclusions A self‐calibrated through‐time spiral GRAPPA reconstruction can enable ungated, free‐breathing evaluation of the left ventricle in 71 s. Functional values are equivalent to a gold‐standard cine technique, although some aspects of image quality may be inferior due to the real‐time nature of the data collection.

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“…Combinations of data undersampling and self-gating are being explored for respiratory motion-state cine imaging [ 27 ]. Some of these approaches require contrast administration [ 18 , 24 , 28 ], or prospective cardiac gating [ 16 , 17 ] and undersampling methods may require considerably longer reconstruction times and/or advanced hardware capabilities [ 16 , 18 , 24 , 25 , 27 ]. The dual RF navigator gated approach was limited to partial acquisition of the cardiac cycle [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Two-center clinical validation and quantitative assessment of respiratory triggered retrospectively cardiac gated balanced-SSFP cine cardiovascular magnetic resonance imaging in adults

Pednekar

Wang

Flamm

et al. 2018

Journal of Cardiovascular Magnetic Resonance

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BackgroundBreath-hold (BH) requirement remains the limiting factor on the spatio-temporal resolution and coverage of the cine balanced steady-state free precession (bSSFP) cardiovascular magnetic resonance (CMR) imaging. In this prospective two-center clinical trial, we validated the performance of a respiratory triggered (RT) bSSFP cine sequence for evaluation of biventricular function.MethodsOur study included 23 asymptomatic healthy subjects and 60 consecutive patients from Institute A (n = 39) and Institute B (n = 21) referred for a clinically indicated CMR study. We implemented a RT sequence with a respiratory synchronized drive to steady state (SS) of bSSFP signal, before the commencement of image data acquisition with prospective cardiac arrhythmia rejection and retrospectively cardiac gated reconstruction in real-time. Left (LV) and right (RV) ventricular function and LV mass were evaluated by using RT-bSSFP and conventional BH-bSSFP sequences with one cardiac cycle for SS preparation keeping all the imaging parameters identical. The performance of the sequences was evaluated by using quantitative and semi-quantitative metrics.ResultsGlobal LV and RV functional parameters and LV mass obtained from the RT-bSSFP and BH-bSSFP sequences were in good agreement. Quantitative metrics designed to capture fluctuation in SS signal intensity showed no significant difference between sequences. In addition, blood-to-myocardial contrast was nearly identical between sequences. The combined clinical score for image quality was excellent or good for 100% of cases with the BH-bSSFP and 83% of cases with the RT-bSSFP sequence. The de facto image acquisition time for RT-bSSFP was statistically significantly longer than that for conventional BH-bSSFP (7.9 ± 3.4 min vs. 5.1 ± 2.6 min).ConclusionsCine RT-bSSFP is an alternative for evaluating global biventricular function with contrast and spatio-temporal resolutions that are similar to those attained by using the BH-bSSFP sequence, albeit with a modest time penalty and a small reduction in image quality.

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Real‐time free‐breathing cardiac imaging with self‐calibrated through‐time radial GRAPPA

Cited by 9 publications

References 48 publications

Recent advances in parallel imaging for MRI

Recent advances in parallel imaging for MRI

Self‐calibrated through‐time spiral GRAPPA for real‐time, free‐breathing evaluation of left ventricular function

Two-center clinical validation and quantitative assessment of respiratory triggered retrospectively cardiac gated balanced-SSFP cine cardiovascular magnetic resonance imaging in adults

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