Repeated fMRI using iron oxide contrast agent in awake, behaving macaques at 3 Tesla.
Iron oxide contrast agents have been employed extensively in anesthetized rodents to enhance fMRI sensitivity and to study the physiology of cerebral blood volume (CBV) in relation to blood oxygen level-dependent (BOLD) signal following neuronal activation. This study quantified the advantages of exogenous agent for repeated neuroimaging in awake, nonhuman primates using a clinical 3 Tesla scanner. A monocrystalline iron oxide nanoparticle (MION) solution was injected at iron doses of 8 to 10 mg/kg in two macaque monkeys. Adverse behavioral effects due to contrast agent were not observed in either monkey using cumulative doses in excess of 60 mg/kg. Relative to BOLD imaging at 3 Tesla, MION increased functional sensitivity by an average factor of 3 across the brain for a stimulus of long duration. Rapid stimulus presentation attenuated MION signal changes more than BOLD signal changes, due to the slower time constant of the blood volume response relative to BOLD signal. Overall, the contrast agent produced a dramatic improvement in functional brain imaging results in the awake, behaving primate at this field strength. (c) 2002 Elsevier Science (USA).
Leite
Francisca P
FP
Massachusetts Institute of Technology, Department of Nuclear Engineering, Cambridge, Massachusetts 02139, USA.
Tsao
Doris
D
Vanduffel
Wim
W
Fize
Denis
D
Sasaki
Yuka
Y
Wald
Larry L
LL
Dale
Anders M
AM
Kwong
Ken K
KK
Orban
Guy A
GA
Rosen
Bruce R
BR
Tootell
Roger B H
RB
Mandeville
Joseph B
JB
D000818:Animals; D001810:Blood Volume; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D052203:Ferrosoferric Oxide; D006439:Hemodynamics; D007501:Iron; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D010087:Oxides; D010100:Oxygen / Q000097:blood*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time; D012680:Sensitivity and Specificity
D003287:Contrast Media; D010087:Oxides; D007501:Iron; D010100:Oxygen; D052203:Ferrosoferric Oxide