title: Real-time animal functional magnetic resonance imaging and its application to neuropharmacological studies.
abstract: In pharmacological magnetic resonance imaging (phMRI) with anesthetized animals, there is usually only a single time window to observe the dynamic signal change to an acute drug administration since subsequent drug injections are likely to result in altered response properties (e.g., tolerance). Unlike the block-design experiments in which fMRI signal can be elicited with multiple repetitions of a task, these single-event experiments require stable baseline in order to reliably identify drug-induced signal changes. Such factors as subject motion, scanner instability and/or alterations in physiological conditions of the anesthetized animal could confound the baseline signal. The unique feature of such functional MRI (fMRI) studies necessitates a technique that is able to monitor MRI signal in a real-time fashion and to interactively control certain experimental procedures. In the present study, an approach for real-time MRI on a Bruker scanner is presented. The custom software runs on the console computer in parallel with the scanner imaging software, and no additional hardware is required. The utility of this technique is demonstrated in manganese-enhanced MRI (MEMRI) with acute cocaine challenge, in which temporary disruption of the blood-brain barrier (BBB) is a critical step for MEMRI experiments. With the aid of real-time MRI, we were able to assess the outcome of BBB disruption following bolus injection of hyperosmolar mannitol in a near real-time fashion prior to drug administration, improving experimental success rate. It is also shown that this technique can be applied to monitor baseline physiological conditions in conventional fMRI experiments using blood oxygenation level-dependent (BOLD) contrast, further demonstrating the versatility of this technique.
authors.affiliation: Neuroimaging Research Branch, National Institute on Drug Abuse (NIDA), Intramural Research Program, NIH, Baltimore, MD 21224, USA. luha@intra.nida.nih.gov
authors.forename: Hanbing
authors.initials: H
authors.lastname: Lu
authors.forename: Shaolin
authors.initials: S
authors.lastname: Yang
authors.forename: Yantao
authors.initials: Y
authors.lastname: Zuo
authors.forename: Steven
authors.initials: S
authors.lastname: Demny
authors.forename: Elliot A
authors.initials: EA
authors.lastname: Stein
authors.forename: Yihong
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D003042:Cocaine / Q000494:pharmacology*; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012984:Software
chemical_list: D003042:Cocaine