title: Assessment of 3D proton MR echo-planar spectroscopic imaging using automated spectral analysis.
abstract: For many clinical applications of proton MR spectroscopic imaging (MRSI) of the brain, diagnostic assessment is limited by insufficient coverage provided by single- or multislice acquisition methods as well as by the use of volume preselection methods. Additionally, traditional spectral analysis methods may limit the operator to detailed analysis of only a few selected brain regions. It is therefore highly desirable to use a fully 3D approach, combined with spectral analysis procedures that enable automated assessment of 3D metabolite distributions over the whole brain. In this study, a 3D echo-planar MRSI technique has been implemented without volume preselection to provide sufficient spatial resolution with maximum coverage of the brain. Using MRSI acquisitions in normal subjects at 1.5T and a fully automated spectral analysis procedure, an assessment of the resultant spectral quality and the extent of viable data in human brain was carried out. The analysis found that 69% of brain voxels were obtained with acceptable spectral quality at TE = 135 ms, and 52% at TE = 25 ms. Most of the rejected voxels were located near the sinuses or temporal bones and demonstrated poor B0 homogeneity and additional regions were affected by stronger lipid contamination at TE = 25 ms.
authors.affiliation: Department of Radiology, University of California San Francisco, MR Unit (114M), DVA Medical Center, San Francisco, California 94121, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ebel
authors.forename: B J
authors.initials: BJ
authors.lastname: Soher
authors.forename: A A
authors.initials: AA
authors.lastname: Maudsley
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D017352:Echo-Planar Imaging; D006801:Humans; D021621:Imaging, Three-Dimensional; D009682:Magnetic Resonance Spectroscopy; D012815:Signal Processing, Computer-Assisted