title: Quantifying the blood oxygenation level dependent effect in cerebral blood volume-weighted functional MRI at 9.4T.
abstract: In cerebral blood volume (CBV)-weighted functional MRI (fMRI) employing superparamagnetic contrast agent, iron dose and blood oxygenation level dependent (BOLD) contamination are two important issues for experimental design and CBV quantification. Both BOLD and CBV-weighted fMRI are based upon the susceptibility effect, to which spin-echo and gradient-echo sequences have different sensitivities. In the present study, CBV-weighted fMRI was conducted using spin-echo and gradient-echo sequences at 9.4T by systematically changing the doses of contrast agent. Results suggest that BOLD contamination is a significant component in CBV-weighted fMRI at high field, particularly when relatively low dose of contrast agent is administered. A mathematical model was developed to quantify the extravascular (EV) BOLD effect. With a TE of 35 ms, the EV BOLD effect was estimated to account for 76+/-12% of the observed spin-echo fMRI signal at 9.4T. These data suggest that correcting BOLD effect may be necessary for accurately quantifying activation-induced CBV changes at high field.
authors.affiliation: Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland 21224, USA. luha@intra.nida.nih.gov
authors.forename: Hanbing
authors.initials: H
authors.lastname: Lu
authors.forename: Clara A
authors.initials: CA
authors.lastname: Scholl
authors.forename: Yantao
authors.initials: Y
authors.lastname: Zuo
authors.forename: Elliot A
authors.initials: EA
authors.lastname: Stein
authors.forename: Yihong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001810:Blood Volume / Q000502:physiology*; D001921:Brain / Q000098:blood supply* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003287:Contrast Media / Q000008:administration & dosage; D003911:Dextrans; D004558:Electric Stimulation; D052203:Ferrosoferric Oxide; D005528:Foot / Q000294:innervation; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007501:Iron / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008954:Models, Biological; D010087:Oxides / Q000008:administration & dosage; D010100:Oxygen / Q000097:blood*; D010525:Peripheral Nerves / Q000502:physiology; D051381:Rats
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D010100:Oxygen; D052203:Ferrosoferric Oxide