Magnetization‐prepared shells trajectory with automated gradient waveform design

Shu, Yunhong; Tao, Shengzhen; Trzasko, Joshua D.; Huston, John; Weavers, Paul T.; Bernstein, Matt A.

doi:10.1002/mrm.26863

Cited by 2 publications

(9 citation statements)

References 54 publications

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“…Denoting T as the user-specified constant representing the number of k-space samples along each interleave (e.g. T = 512 points per interleave/readout), the trajectory parameters (ω n and M n ) and the readout gradient waveforms corresponding to each interleave can be generated using a fully automated iterative gradient design scheme, as we developed previously for the fully sampled shells trajectory (Shu et al 2018). In this work, this scheme is adapted to partial Fourier asymmetric shells trajectory.…”

Section: Gradient Waveform Generationmentioning

confidence: 99%

“…T) as specified. To ensure a total of fixed T points for each interleave, the gradient generation can be repeated by iteratively adjusting ω n until a total of T samples are obtained (Shu et al 2018). Note that the trajectory parameter ω n for a partial Fourier shells acquisition implicitly depends on the partial Fourier factor κ, i.e.…”

Section: Gradient Waveform Generationmentioning

confidence: 99%

“…For example, in gadolinium-enhanced MR angiography, the inner shells can be acquired when the contrast agents cause peak enhancement of the arteries of interest, while suppressing the venous phase signal (Shu et al 2009). In a magnetization-prepared sequence, the inner k-space shells can be acquired when the peak contrast between the white and gray matters is achieved, following a magnetization-preparation pulse, as we demonstrated in Shu et al (2018).…”

Section: Introductionmentioning

confidence: 98%

“…The shells trajectory is a three-dimensional (3D) non-Cartesian MRI technique for efficient isotropic acquisition (Irarrazabal and Nishimura 1995, Shu et al 2006, 2018, Zahneisen et al 2012. It uses a series of concentric k-space shells to sample a 3D k-space, with each individual shell in turn sampled by a group of helical spiral interleaves traversing its surface from one pole to the other (Shu et al 2018). The shells trajectory offers several intrinsic advantages.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we have described an automated shells trajectory design (Shu et al 2018), which allows a fully sampled shells trajectory and its gradient waveforms to be automatically determined for a prescribed acquisition setting. In this work, a new asymmetric 3D shells trajectory design is presented.…”

Section: Introductionmentioning

confidence: 99%

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Partial fourier shells trajectory for non-cartesian MRI

Tao¹,

Shu²,

Trzasko³

et al. 2019

Phys. Med. Biol.

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Non-Cartesian MRI acquisition has demonstrated various advantages in many clinical applications. The shells trajectory is a 3D non-Cartesian MRI acquisition technique that samples the k-space using a series of concentric shells to achieve efficient 3D isotropic acquisition. Partial Fourier acquisition is an acceleration technique that is widely used in Cartesian MRI. It exploits the conjugate symmetry of k-space measurement to reduce the number of k-space samples compared to full-k-space acquisition, without loss of spatial resolution. For a Cartesian MRI acquisition, the direction of partial Fourier acceleration is aligned either with the phase encoded or frequency encoded direction. In those cases, the underlying image matrix can be reconstructed from the undersampled k-space data using a non-iterative, homodyne reconstruction framework. However, designing a non-Cartesian acquisition trajectory that is compatible with non-iterative homodyne reconstruction is not nearly as straightforward as in the Cartesian case. One reason is the non-iterative homodyne reconstruction requires (slightly over) half of the k-space to be fully sampled. Since the direction of partial Fourier acceleration varies throughout the acquisition in the non-Cartesian trajectory, directly applying the same partial Fourier acquisition pattern (as in Cartesian acquisitions) to a non-Cartesian trajectory does not necessarily yield a continuous, physically-achievable trajectory. In this work, we develop an asymmetric shells trajectory with fully-automated trajectory and gradient waveform design to achieve partial Fourier acquisition for the shells trajectory. We then demonstrate a non-iterative image reconstruction framework for the proposed trajectory. Phantom and in vivo brain scans based on spoiled gradient echo (SPGR) shells and magnetization-prepared shells (MP-shells) were performed to test the proposed trajectory design and reconstruction method. Our phantom and in vivo results demonstrate that the proposed partial Fourier shells trajectory maintains the desirable image contrast and high sampling efficiency from the fully sampled shells, while further reducing data acquisition time.

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Section: Gradient Waveform Generationmentioning

confidence: 99%

Section: Gradient Waveform Generationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Partial fourier shells trajectory for non-cartesian MRI

Tao¹,

Shu²,

Trzasko³

et al. 2019

Phys. Med. Biol.

Self Cite

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Evaluation of hearing loss in young adults after exposure to 3.0T MRI with standard hearing protection

Carr

Lane

Eckel

et al. 2022

The Journal of the Acoustical Society of America

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Standard clinical protocols require hearing protection during magnetic resonance imaging (MRI) for patient safety. This investigation prospectively evaluated the auditory function impact of acoustic noise exposure during a 3.0T MRI in healthy adults. Twenty-nine participants with normal hearing underwent a comprehensive audiologic assessment before and immediately following a clinically indicated head MRI. Appropriate hearing protection with earplugs (and pads) was used per standard of practice. To characterize noise hazards, current sound monitoring tools were used to measure levels of pulse sequences measured. A third audiologic test was performed if a significant threshold shift (STS) was identified at the second test, within 30 days post MRI. Some sequences produced high levels (up to 114.5 dBA; 129 dB peak SPL) that required hearing protection but did not exceed 100% daily noise dose. One participant exhibited an STS in the frequency region most highly associated with noise-induced hearing loss. No participants experienced OSHA-defined STS in either ear. Overall, OAE measures did not show evidence of changes in cochlear function after MRI. In conclusion, hearing threshold shifts associated with hearing loss or OAE level shifts reflecting underlying cochlear damage were not detected in any of the 3.0T MRI study participants who used the current recommended hearing protection.

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Magnetization‐prepared shells trajectory with automated gradient waveform design

Cited by 2 publications

References 54 publications

Partial fourier shells trajectory for non-cartesian MRI

Partial fourier shells trajectory for non-cartesian MRI

Evaluation of hearing loss in young adults after exposure to 3.0T MRI with standard hearing protection

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