OBJECT: The recently developed vascular space occupancy (VASO) fMRI technique is gaining popularity as it facilitates the measurement of cerebral blood volume (CBV) changes concomitant with brain activation, without the use of contrast agents. Thus far, VASO fMRI has only been used in conjunction with a GE-EPI (gradient-echo echo planar imaging) sequence, which is proceeded by an inversion recovery (IR) experiment to selectively null the blood signal. The use of GE-EPI has potential disadvantages: (a) the non-zero TE may lead to BOLD contamination and (b) images suffer from the EPI-typical inhomogeneity artefacts.
MATERIALS AND METHODS: Here, we propose the use of VASO based on an IR-HASTE (inversion recovery half-Fourier acquisition single-shot turbo spin echo) sequence. Results Results from a visual stimulation study (n = 8) show a 43% higher functional contrast-to-noise (CNR) of HASTE compared to EPI, with a strongly increased count of active voxels at the same significance threshold. Sensitivity to inflow effects was investigated and found to be similar for both methods.
CONCLUSION: As HASTE VASO yields essentially artefact-free images, it appears to be the method of choice for measuring relative CBV changes with VASO.
|Number of pages
|Magnetic Resonance Materials in Physics Biology and Medicine
|Published - Apr 2007
- Blood Volume
- Cerebrovascular Circulation
- Echo-Planar Imaging
- Evoked Potentials, Visual
- Image Enhancement
- Image Interpretation, Computer-Assisted
- Visual Cortex