SNR and total acquisition time analysis of multi-echo FLASH pulse sequence for current density imaging


Sadighi M., Şişman M., Eyüboğlu B. M.

Journal of Magnetic Resonance, vol.333, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 333
  • Publication Date: 2021
  • Doi Number: 10.1016/j.jmr.2021.107098
  • Title of Journal : Journal of Magnetic Resonance
  • Keywords: Magnetic resonance current density imaging (MRCDI), FLASH, SNR analysis, Noise analysis, Magnetohydrodynamic (MHD) flow imaging, ELECTRICAL-IMPEDANCE TOMOGRAPHY, MAGNETIC-FLUX DENSITY, DIRECT-CURRENT STIMULATION, NMR RELAXATION-TIMES, HUMAN BRAIN, METALLIC IMPLANTS, NOISE-ANALYSIS, STEADY-STATE, TISSUE, FIELD

Abstract

© 2021 Elsevier Inc.Magnetic Resonance Current Density Imaging (MRCDI) is an imaging modality providing cross-sectional current density (J¯) information inside the body. The clinical applicability of MRCDI is highly dependent on the sensitivity of the acquired noisy current-induced magnetic flux density (B∼z) distributions. Here, a novel analysis is developed to investigate the combined effect of relevant parameters of the RF spoiled gradient echo (FLASH) pulse sequence on the SNR level and the total acquisition time (TAT) of the acquired B∼z images. The proposed analysis then is expanded for a multi-echo FLASH (ME-FLASH) pulse sequence to take advantage of combining the multiple echoes to achieve B∼zcomb distribution with a higher SNR than the one achievable with a single echo acquisition. The optimized sequence parameters to acquire a B∼z distribution with the highest possible SNR for a given acquisition time or the desired SNR in the shortest scan time are estimated using the proposed analysis. The analysis also provides different sets of sequence parameters to acquire B∼z distributions with the same SNR at almost the same TAT. Furthermore, the effects of intensive utilization of the gradients and the magnetohydrodynamic (MHD) flow velocity on the acquired B∼z distribution in MRCDI experiments is investigated. The analytical results of the proposed analysis are validated experimentally using an imaging phantom having the conductivity and the relaxation parameters of the brain white matter tissue.