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Wave‐CAIPI ViSTa: highly accelerated whole‐brain direct myelin water imaging with zero‐padding reconstruction
Author(s) -
Wu Zhe,
Bilgic Berkin,
He Hongjian,
Tong Qiqi,
Sun Yi,
Du Yiping,
Setsompop Kawin,
Zhong Jianhui
Publication year - 2018
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27108
Subject(s) - aliasing , voxel , computer science , padding , image quality , transverse plane , physics , acoustics , optics , artificial intelligence , anatomy , medicine , computer security , undersampling , image (mathematics)
Purpose This study introduces a highly accelerated whole‐brain direct visualization of short transverse relaxation time component (ViSTa) imaging using a wave controlled aliasing in parallel imaging (CAIPI) technique, for acquisition within a clinically acceptable scan time, with the preservation of high image quality and sufficient spatial resolution, and reduced residual point spread function artifacts. Methods Double inversion RF pulses were applied to preserve the signal from short T 1 components for directly extracting myelin water signal in ViSTa imaging. A 2D simultaneous multislice and a 3D acquisition of ViSTa images incorporating wave‐encoding were used for data acquisition. Improvements brought by a zero‐padding method in wave‐CAIPI reconstruction were also investigated. Results The zero‐padding method in wave‐CAIPI reconstruction reduced the root‐mean‐square errors between the wave‐encoded and Cartesian gradient echoes for all wave gradient configurations in simulation, and reduced the side‐main lobe intensity ratio from 34.5 to 16% in the thin‐slab in vivo ViSTa images. In a 4 × acceleration simultaneous‐multislice scenario, wave‐CAIPI ViSTa achieved negligible g‐factors (g mean /g max = 1.03/1.10), while retaining minimal interslice artifacts. An 8 × accelerated acquisition of 3D wave‐CAIPI ViSTa imaging covering the whole brain with 1.1 × 1.1 × 3 mm 3 voxel size was achieved within 15 minutes, and only incurred a small g‐factor penalty (g mean /g max = 1.05/1.16). Conclusion Whole‐brain ViSTa images were obtained within 15 minutes with negligible g‐factor penalty by using wave‐CAIPI acquisition and zero‐padding reconstruction. The proposed zero‐padding method was shown to be effective in reducing residual point spread function for wave‐encoded images, particularly for ViSTa.