Echo-planar BOLD fMRI of mice on a narrow-bore 9.4 T magnet.
The feasibility of BOLD fMRI in association with electrical somatosensory stimulation on spontaneously breathing, isoflurane-anesthetized mice was investigated using spin-echo, echo-planar imaging (EPI) on a vertical narrow-bore 9.4 T magnet. Three experiments were performed to derive an optimal fMRI protocol. In Experiment 1 (n = 9), spin-echo BOLD responses to 10% CO2 challenge under graded isoflurane (0.25-1.25%) ranged from 10 +/- 2% to 3.5 +/- 0.9%; the optimal BOLD contrast-to-noise ratio peaked at 0.75% isoflurane. In Experiment 2 (n = 6), hindpaw somatosensory stimulations using 1-7 mA under 0.75% isoflurane revealed the optimal BOLD response was at 6 mA. In Experiment 3 (n = 5), BOLD responses to 4 and 6 mA stimulation under 0.75% and 1% isoflurane were evaluated in detail, confirming the optimal conditions in Experiment 2. These results demonstrated that BOLD fMRI using single-shot, spin-echo EPI in a mouse somatosensory stimulation model could be routinely performed on high-field, vertical, narrow-bore magnets. This protocol might prove useful for fMRI studies of transgenic mice.
Center for Comparative NeuroImaging, Department of Psychiatry, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA.
Govind
G
Nair
Timothy Q
TQ
Duong
D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000818:Animals; D017352:Echo-Planar Imaging / Q000379:methods*; D004558:Electric Stimulation; D005240:Feasibility Studies; D006614:Hindlimb / Q000294:innervation; D006935:Hypercapnia / Q000503:physiopathology; D007530:Isoflurane / Q000008:administration & dosage; D051379:Mice; D008807:Mice, Inbred BALB C
D018685:Anesthetics, Inhalation; D007530:Isoflurane