Implementation issues of multivoxel STEAM-localized 1H spectroscopy.
Single-voxel STEAM-localized spectroscopy studies of neuropsychiatric patients yield high-quality data at short echo times, but are often limited to only a few regions of interest due to the linear increase of acquisition time with the number of regions examined. A multivoxel STEAM approach increases the number of regions of interest examined with a less than linear increase in acquisition time. Several implementation issues were considered, especially the signal contribution of outer voxel stimulated echoes (OVSE), which can lead to systematic errors in the quantification of relative metabolite concentrations. The relative signal contribution of OVSEs was found to be as great as 30% in phantoms. Gradient polarity switching completely canceled the contribution of OVSEs. A two-voxel STEAM approach produces phantom and in vivo data quality comparable to single-voxel STEAM in practically half the time. Quantification precision and accuracy are preserved in phantoms and in vivo.
Théberge
Jean
J
Department of Nuclear Medicine and Magnetic Resonance, St. Joseph's Health Care, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada. jtheberg@lri.sjhc.london.on.ca
Menon
Ravi S
RS
Williamson
Peter C
PC
Drost
Dick J
DJ
D000704:Analysis of Variance; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging