Dataset Information

Tilted-CAIPI for highly accelerated distortion-free EPI with point spread function (PSF) encoding.

ABSTRACT: PURPOSE:To develop a method for fast distortion- and blurring-free imaging. THEORY:EPI with point-spread-function (PSF) mapping can achieve distortion- and blurring-free imaging at a cost of long acquisition time. In this study, an acquisition/reconstruction technique, termed "tilted-CAIPI," is proposed to achieve >20× acceleration for PSF-EPI. The proposed method systematically optimized the k-space sampling trajectory with B0 -inhomogeneity-informed reconstruction, to exploit the inherent signal correlation in PSF-EPI and take full advantage of coil sensitivity. Susceptibility-induced phase accumulation is regarded as an additional encoding that is estimated by calibration data and integrated into reconstruction. Self-navigated phase correction was developed to correct shot-to-shot phase variation in diffusion imaging. METHODS:Tilted-CAIPI was implemented at 3T, with incorporation of partial Fourier and simultaneous multislice to achieve further accelerations. T2 -weighted, T2 * -weighted, and diffusion-weighted imaging experiments were conducted to evaluate the proposed method. RESULTS:The ability of tilted-CAIPI to provide highly accelerated imaging without distortion and blurring was demonstrated through in vivo brain experiments, where only 8 shots per simultaneous slice group were required to provide high-quality, high-SNR imaging at 0.8-1 mm resolution. CONCLUSION:Tilted-CAIPI achieved fast distortion- and blurring-free imaging with high SNR. Whole-brain T2 -weighted, T2 * -weighted, and diffusion imaging can be obtained in just 15-60 s.

SUBMITTER: Dong Z

PROVIDER: S-EPMC6258292 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Tilted-CAIPI for highly accelerated distortion-free EPI with point spread function (PSF) encoding.

Dong Zijing Z Wang Fuyixue F Reese Timothy G TG Manhard Mary Katherine MK Bilgic Berkin B Wald Lawrence L LL Guo Hua H Setsompop Kawin K

Magnetic resonance in medicine 20180905 1

<h4>Purpose</h4>To develop a method for fast distortion- and blurring-free imaging.<h4>Theory</h4>EPI with point-spread-function (PSF) mapping can achieve distortion- and blurring-free imaging at a cost of long acquisition time. In this study, an acquisition/reconstruction technique, termed "tilted-CAIPI," is proposed to achieve >20× acceleration for PSF-EPI. The proposed method systematically optimized the k-space sampling trajectory with B<sub>0</sub> -inhomogeneity-informed reconstruction, to ...[more]

PMID: 30229562

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Project description: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 (gavg ???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: ØW ?=?4.03, ØG ?=?3.97; T2 w SPACE: ØW ?=?4.00, ØG ?=?4.00; SPACE FLAIR: ØW ?= 3.97, ØG ?=?3.97; SWI: ØW ?=?3.93, ØG ?=?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.

Dataset Information

Tilted-CAIPI for highly accelerated distortion-free EPI with point spread function (PSF) encoding.

Publications

Tilted-CAIPI for highly accelerated distortion-free EPI with point spread function (PSF) encoding.

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