Enhancement of BOLD-contrast sensitivity by single-shot multi-echo functional MR imaging

. (2010) The change in cerebrovascular reactivity between 3T and 7T measured using graded hypercapnia. NeuroImage, 51 (1 A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk 1 NeuroImage 51(1), 274-279 (2010) The change in cerebrovascular reactivity between 3T and 7T measured using graded hypercapnia AbstractMapping cerebrovascular reactivity (CVR) to hypercapnia is important both clinically and for improved understanding of the haemodynamic properties of the BOLD effect. In this work BOLD/R 2 * CVR was investigated by using a device which provided small, repeatable and stable steps in P ET CO 2 , whilst maintaining a steady P ET O 2 level.

Purpose: To acquire high spectral and spatial resolution (HiSS) MR images of the water resonance in rat brain, evaluate the lineshape of the water resonance in small voxels, and compare images derived from HiSS data with conventional images. Materials and Methods:Spectroscopic images of rat brain were obtained at 4.7 Tesla using phase encoding gradients only. Spectral resolution in each voxel was ϳ8 Hz and bandwidth was 1000 Hz. Spatial resolution was ϳ250 microns in 1-mm slices. Images were synthesized to show the water signal integral, peak height, linewidth, resonance frequency, and asymmetry.Results: Two or more resolved components of the water resonance were detected in ϳ14% Ϯ 6% of voxels in the brains of eight rats. The water resonances in ϳ20% Ϯ 10% of voxels (n ϭ 8) were highly asymmetric. Images with intensity proportional to water signal peak height, T 2 *, or to selected components of the water resonance showed features that were not evident in conventional images. Conclusions:The complexity of the water signal reflects the anatomy and physiology of the sub-voxelar environment, and may be a useful source of image contrast. HiSS imaging of brain provides accurate anatomic information, and may improve image contrast and delineation of subtle anatomic features.

This paper gives an overview of the recent literature on methodological developments of functional magnetic resonance imaging (fMRI) and recent trends in clinical applications. With the recent introduction of high-field systems and methodological developments leading to more robust signal behavior, fMRI is in a transition state from a research modality for use by experts to a standard procedure with useful applications in patient management. Compared to the use in neuroscientific research, which is often based on BOLD techniques alone, the application in patients is distinguished by a multiparametric characterization of the brain using a combination of several techniques. Neuronal fiber tracking based on diffusion anisotropy measurements, in particular, has already turned out to provide relevant supplementary information to the BOLD-based cortical activation maps.