Implementation of vascular-space-occupancy MRI at 7T

Research output: Contribution to journalArticlepeer-review

Abstract

Vascular-space-occupancy (VASO) MRI exploits the difference between blood and tissue T1 to null blood signal and measure cerebral blood volume changes using the residual tissue signal. VASO imaging is more difficult at higher field because of sensitivity loss due to the convergence of tissue and blood T1 values and increased contamination from blood-oxygenation- level-dependent (BOLD) effects. In addition, compared to 3T, 7T MRI suffers from increased geometrical distortions, e.g., when using echo-planar-imaging, and from increased power deposition, the latter especially problematic for the spin-echo-train sequences commonly used for VASO MRI. Third, non-steady-state blood spin effects become substantial at 7T when only a head coil is available for radiofrequency transmit. In this study, the magnetization-transfer-enhanced- VASO approach was applied to maximize tissue-blood signal difference, which boosted signal-to-noise ratio by 149% ± 13% (n = 7) compared to VASO. Second, a 3D fast gradient-echo sequence with low flip-angle (7°) and short echo-time (1.8 ms) was used to minimize the BOLD effect and to reduce image distortion and power deposition. Finally, a magnetization-reset technique was combined with a motion-sensitized-driven-equilibrium approach to suppress three types of non-steady-state spins. Our initial functional MRI results in normal human brains at 7T with this optimized VASO sequence showed better signal-to-noise ratio than at 3T.

Original languageEnglish (US)
Pages (from-to)1003-1013
Number of pages11
JournalMagnetic resonance in medicine
Volume69
Issue number4
DOIs
StatePublished - Apr 2013

Keywords

  • 7T
  • CBV
  • MRI
  • MT
  • VASO
  • cerebral blood volume
  • fMRI
  • high field
  • magnetization transfer
  • vascular-space-occupancy

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Fingerprint Dive into the research topics of 'Implementation of vascular-space-occupancy MRI at 7T'. Together they form a unique fingerprint.

Cite this