A local multi‐transmit coil combined with a high‐density receive array for cerebellar fMRI at 7 T. (6th July 2021)

• Record Type: Journal Article
• Authors: Priovoulos, Nikos; Roos, Thomas; Ipek, Özlem; Meliado, Ettore F.; Nkrumah, Richard O.; Klomp, Dennis W. J.; van der Zwaag, Wietske
• Is Part Of: NMR in biomedicine. Volume 34:Number 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-06
• Subjects: 3D EPI -- 7 T, BOLD -- cerebellum -- parallel imaging -- receive arrays; Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.4586
• Languages: English
• ISSNs: 0952-3480

Abstract

Abstract : The human cerebellum is involved in a wide array of functions, ranging from motor control to cognitive control, and as such is of great neuroscientific interest. However, its function is underexplored in vivo, due to its small size, its dense structure and its placement at the bottom of the brain, where transmit and receive fields are suboptimal. In this study, we combined two dense coil arrays of 16 small surface receive elements each with a transmit array of three antenna elements to improve BOLD sensitivity in the human cerebellum at 7 T. Our results showed improved B 1 + and SNR close to the surface as well as g ‐factor gains compared with a commercial coil designed for whole‐head imaging. This resulted in improved signal stability and large gains in the spatial extent of the activation close to the surface (<3.5 cm), while good performance was retained deeper in the cerebellum. Modulating the phase of the transmit elements of the head coil to constructively interfere in the cerebellum improved the B 1 +, resulting in a temporal SNR gain. Overall, our results show that a dedicated transmit array along with the SNR gains of surface coil arrays can improve cerebellar imaging, at the cost of a decreased field of view and increased signal inhomogeneity. Abstract : Human cerebellar fMRI is hindered by B 1 + cancellation in ultra‐high fields and the need for high resolution. Using a dedicated 3Tx array improved the transmit field close to the cerebellar surface compared with a commercial 8Tx coil. The signal‐to‐noise and parallel imaging performance were further increased by the usage of a high‐density surface receive array. The combination of improved transmit and receive fields resulted in increased BOLD sensitivity close to the surface of the cerebellum.