Spin-echo and gradient-echo echoplanar functional magnetic resonance imaging (fMRI) studies at 1.5 Tesla (T) were used to obtain blood oxygenation level-dependent (BOLD) contrast images of the whole brain in seven strongly right-handed women during execution of a complex motor task. Five subjects underwent subsequent H215O positron emission tomography (PET) studies while performing the same task. Group-averaged results for changes in the MRI relaxation rates R2* and R2 at 1.5T in response to neuronal activation in nine cortical, subcortical, and cerebellar motor regions are reported. Results for each method are grouped according to tissue type - cerebral cortex (precentral gyrus and supplementary motor area), subcortical regions (thalamus and putamen), and cerebellar cortex (superior lobule). The observed changes in R2* from activation-induced oxygenation changes were more variable across brain regions with different tissue characteristics than observed changes in R2. The ratio of ΔR2 to ΔR2 was 3.3 ± 0.9 for cerebral cortex and 2.0 ± 0.6 for subcortical tissue. ΔR2* ΔR2, and relative blood flow changes were ΔR2* = -0.201 ± 0.040 s-1, ΔR2 = -0.064 ± 0.011 s-1, and Δf/f = 16.7 ± 0.8% in the cerebral cortex; ΔR2* = -0.100 ± 0.026 s-1, ΔR2 = -0.049 ± 0.009 s-1, and Δf/f = 9.4 ± 0.7% in the subcortical regions; and ΔR2* = -0.215 ± 0.093 s-1, ΔR2 = -0.069 ± 0.012 s-1, and Δf/f = 16.2 ± 1.2% in the cerebellar cortex.
- Basal ganglia
- Functional magnetic resonance imagin
- Motor cortex
- Positron emission tomography
- Spin-echo imaging
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism