High spatio‐temporal resolution in functional MRI with 3D echo planar imaging using cylindrical excitation and a CAIPIRINHA undersampling pattern. Issue 5 (14th September 2017)

• Record Type: Journal Article
• Authors: van der Zwaag, Wietske; Reynaud, Olivier; Narsude, Mayur; Gallichan, Daniel; Marques, José P.
• Is Part Of: Magnetic resonance in medicine. Volume 79:Issue 5(2018)
• Page Start: 2589
• Page End: 2596
• Publication Date: 2017-09-14
• Subjects: fMRI -- fast imaging -- cylinder excitation -- 3D‐EPI -- CAIPIRINHA -- high resolution; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.26906
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: The combination of 3D echo planar imaging (3D‐EPI) with a 2D‐CAIPIRINHA undersampling scheme provides high flexibility in the optimization for spatial or temporal resolution. This flexibility can be increased further with the addition of a cylindrical excitation pulse, which exclusively excites the brain regions of interest. Here, 3D‐EPI was combined with a 2D radiofrequency pulse to reduce the brain area from which signal is generated, and hence, allowing either reduction of the field of view or reduction of parallel imaging noise amplification. Methods: 3D‐EPI with cylindrical excitation and 4 × 3‐fold undersampling in a 2D‐CAIPIRINHA sampling scheme was used to generate functional MRI (fMRI) data with either 2‐mm or 0.9‐mm in‐plane resolution and 1.1‐s temporal resolution over a 5‐cm diameter cylinder placed over both temporal lobes for an auditory fMRI experiment. Results: Significant increases in image signal‐to‐noise ratio (SNR) and temporal SNR (tSNR) were found for both 2‐mm isotropic data and the high‐resolution protocol when using the cylindrical excitation pulse. Both protocols yielded highly significant blood oxygenation level–dependent responses for the presentation of natural sounds. Conclusion: The higher tSNR of the cylindrical excitation 3D‐EPI data makes this sequence an ideal choice for high spatiotemporal resolution fMRI acquisitions. Magn Reson Med 79:2589–2596, 2018. © 2017 International Society for Magnetic Resonance in Medicine.