title: Characterization of contrast changes in functional MRI of the human spinal cord at 1.5 T.
abstract: Contrast changes observed in functional magnetic resonance imaging in the human spinal cord were investigated with both motor and sensory tasks over a range of echo times. Data were acquired using a single-shot fast spin-echo sequence at 1.5 Tesla. Data were analyzed with two different correlation thresholds and the effects of altering the order of repeated experiments was also investigated. Plots of the fractional signal change as a function of echo time yielded linear functions with slopes corresponding to relaxation rate changes of -0.30 sec(-1) with sensory stimulation and approximately -0.50 sec(-1) with a motor task. However, the fractional signal change extrapolated to an echo time of zero was significantly greater than zero in each case and was roughly 2.5%. This suggests that in addition to the BOLD effect there is a baseline signal change which occurs concomitant to neuronal activation in the spinal cord.
authors.affiliation: MR Technology Group, Institute for Biodiagnostics, National Research Council of Canada, 435 Ellice Avenue, R3B 1Y6, Winnipeg, Manitoba, Canada. stroman@ibd.nrc.ca
authors.forename: P W
authors.initials: PW
authors.lastname: Stroman
authors.forename: V
authors.initials: V
authors.lastname: Krause
authors.forename: K L
authors.initials: KL
authors.lastname: Malisza
authors.forename: U N
authors.initials: UN
authors.lastname: Frankenstein
authors.forename: B
authors.initials: B
authors.lastname: Tomanek
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010812:Physical Stimulation; D013116:Spinal Cord / Q000033:anatomy & histology* / Q000502:physiology; D013647:Task Performance and Analysis; D013997:Time Factors