Dataset Information

Highly-accelerated volumetric brain examination using optimized wave-CAIPI encoding.

ABSTRACT:

Background

Rapid volumetric imaging protocols could better utilize limited scanner resources.

Purpose

To develop and validate an optimized 6-minute high-resolution volumetric brain MRI examination using Wave-CAIPI encoding.

Study type

Prospective.

Population/subjects

Ten healthy subjects and 20 patients with a variety of intracranial pathologies.

Field strength/sequence

At 3 T, MPRAGE, T₂ -weighted SPACE, SPACE FLAIR, and SWI were acquired at 9-fold acceleration using Wave-CAIPI and for comparison at 2-4-fold acceleration using conventional GRAPPA.

Assessment

Extensive simulations were performed to optimize the Wave-CAIPI protocol and minimize both g-factor noise amplification and potential T₁ /T₂ blurring artifacts. Moreover, refinements in the autocalibrated reconstruction of Wave-CAIPI were developed to ensure high-quality reconstructions in the presence of gradient imperfections. In a randomized and blinded fashion, three neuroradiologists assessed the diagnostic quality of the optimized 6-minute Wave-CAIPI exam and compared it to the roughly 3× slower GRAPPA accelerated protocol using both an individual and head-to-head analysis.

Statistical test

A noninferiority test was used to test whether the diagnostic quality of Wave-CAIPI was noninferior to the GRAPPA acquisition, with a 15% noninferiority margin.

Results

Among all sequences, Wave-CAIPI achieved negligible g-factor noise amplification (g_avg ≤ 1.04) and burring artifacts from T₁ /T₂ relaxation. Improvements of our autocalibration approach for gradient imperfections enabled increased robustness to gradient mixing imperfections in tilted-field of view (FOV) prescriptions as well as variations in gradient and analog-to-digital converter (ADC) sampling rates. In the clinical evaluation, Wave-CAIPI achieved similar mean scores when compared with GRAPPA (MPRAGE: Ø_W = 4.03, Ø_G = 3.97; T₂ w SPACE: Ø_W = 4.00, Ø_G = 4.00; SPACE FLAIR: Ø_W = 3.97, Ø_G = 3.97; SWI: Ø_W = 3.93, Ø_G = 3.83) and was statistically noninferior (N = 30, P < 0.05 for all sequences).

Data conclusion

The proposed volumetric brain exam retained comparable image quality when compared with the much longer conventional protocol.

Level of evidence

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:961-974.

SUBMITTER: Polak D

PROVIDER: S-EPMC6687581 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Publications

Highly-accelerated volumetric brain examination using optimized wave-CAIPI encoding.

Polak Daniel D Cauley Stephen S Huang Susie Y SY Longo Maria Gabriela MG Conklin John J Bilgic Berkin B Ohringer Ned N Raithel Esther E Bachert Peter P Wald Lawrence L LL Setsompop Kawin K

Journal of magnetic resonance imaging : JMRI 20190208 3

<h4>Background</h4>Rapid volumetric imaging protocols could better utilize limited scanner resources.<h4>Purpose</h4>To develop and validate an optimized 6-minute high-resolution volumetric brain MRI examination using Wave-CAIPI encoding.<h4>Study type</h4>Prospective.<h4>Population/subjects</h4>Ten healthy subjects and 20 patients with a variety of intracranial pathologies.<h4>Field strength/sequence</h4>At 3 T, MPRAGE, T<sub>2</sub> -weighted SPACE, SPACE FLAIR, and SWI were acquired at 9-fold ...[more]

PMID: 30734388

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Project description:PurposeTo develop an accelerated 3D intracranial time-of-flight (TOF) magnetic resonance angiography (MRA) sequence with wave-encoding (referred to as 3D wave-TOF) and to evaluate two variants: wave-controlled aliasing in parallel imaging (CAIPI) and compressed-sensing wave (CS-wave).MethodsA wave-TOF sequence was implemented on a 3 T clinical scanner. Wave-encoded and Cartesian k-space datasets from six healthy volunteers were retrospectively and prospectively undersampled with 2D-CAIPI sampling and variable-density Poisson disk sampling. 2D-CAIPI, wave-CAIPI, standard CS, and CS-wave schemes were compared at various acceleration factors. Flow-related artifacts in wave-TOF were investigated, and a set of practicable wave parameters was developed. Quantitative analysis of wave-TOF and traditional Cartesian TOF MRA was performed by comparing the contrast-to-background ratio between the vessel and background tissue in source images, and the structural similarity index measure (SSIM) between the maximum intensity projection images from accelerated acquisitions and their respective fully sampled references.ResultsFlow-related artifacts caused by the wave-encoding gradients in wave-TOF were eliminated by properly chosen parameters. Images from wave-CAIPI and CS-wave acquisitions had a higher SNR and better-preserved contrast than traditional parallel imaging (PI) and CS methods. Maximum intensity projection images from wave-CAIPI and CS-wave acquisitions had a cleaner background, with vessels that were better depicted. Quantitative analyses indicated that wave-CAIPI had the highest contrast-to-background ratio, SSIM, and vessel-masked SSIM among the sampling schemes studied, followed by the CS-wave acquisition.Conclusion3D wave-TOF improves the capability of accelerated MRA and provides better image quality at higher acceleration factors compared to traditional PI- or CS-accelerated TOF, suggesting the potential use of wave-TOF in cerebrovascular disease.

Dataset Information

Highly-accelerated volumetric brain examination using optimized wave-CAIPI encoding.

Background

Purpose

Study type

Population/subjects

Field strength/sequence

Assessment

Statistical test

Results

Data conclusion

Level of evidence

Publications

Highly-accelerated volumetric brain examination using optimized wave-CAIPI encoding.

Similar Datasets

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