Pushing functional MRI spatial and temporal resolution further: High‐density receive arrays combined with shot‐selective 2D CAIPIRINHA for 3D echo‐planar imaging at 7 T. (3rd March 2020)

• Record Type: Journal Article
• Authors: Hendriks, Arjan D.; D'Agata, Federico; Raimondo, Luisa; Schakel, Tim; Geerts, Liesbeth; Luijten, Peter R.; Klomp, Dennis W.J.; Petridou, Natalia
• Is Part Of: NMR in biomedicine. Volume 33:Number 5(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-03-03
• Subjects: 3D EPI -- 7T -- CAIPI -- high resolution -- receive arrays -- shot selective -- visual cortex; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4281
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : To be able to examine dynamic and detailed brain functions, the spatial and temporal resolution of 7 T MRI needs to improve. In this study, it was investigated whether submillimeter multishot 3D EPI fMRI scans, acquired with high‐density receive arrays, can benefit from a 2D CAIPIRINHA sampling pattern, in terms of noise amplification (g‐factor), temporal SNR and fMRI sensitivity. High‐density receive arrays were combined with a shot‐selective 2D CAIPIRINHA implementation for multishot 3D EPI sequences at 7 T. In this implementation, in contrast to conventional inclusion of extra kz gradient blips, specific EPI shots are left out to create a CAIPIRINHA shift and reduction of scan time. First, the implementation of the CAIPIRINHA sequence was evaluated with a standard receive setup by acquiring submillimeter whole brain T2 *‐weighted anatomy images. Second, the CAIPIRINHA sequence was combined with high‐density receive arrays to push the temporal resolution of submillimeter 3D EPI fMRI scans of the visual cortex. Results show that the shot‐selective 2D CAIPIRINHA sequence enables a reduction in scan time for 0.5 mm isotropic 3D EPI T2 *‐weighted anatomy scans by a factor of 4 compared with earlier reports. The use of the 2D CAIPIRINHA implementation in combination with high‐density receive arrays, enhances the image quality of submillimeter 3D EPI scans of the visual cortex at high acceleration as compared to conventional SENSE. Both the g‐factor and temporal SNR improved, resulting in a method that is more sensitive to the fMRI signal. Using this method, it is possible to acquire submillimeter single volume 3D EPI scans of the visual cortex in a subsecond timeframe. Overall, high‐density receive arrays in combination with shot‐selective 2D CAIPIRINHA for 3D EPI scans prove to be valuable for reducing the scan time of submillimeter MRI acquisitions. Abstract : This study investigated whether submillimeter 3D EPI fMRI scans acquired with high‐density receive arrays can still benefit from a CAIPI sampling pattern, in terms of scan time per volume and (temporal) SNR. A shot‐selective 2D CAIPIRINHA acceleration scheme for multishot 3D EPI scans was implemented and evaluated with submillimeter 3D T2 *‐weighted anatomical scans. When combining this implementation with high‐density receive coil arrays at 7 T, it enabled substantial reduction in scan time for submillimeter fMRI scans of the visual cortex.