RT Journal Article
SR Electronic
T1 Comparison of [18F]fluoroflumazenil and [18F]flumazenil for in vivo PET imaging of GABAA/cBZR density in a rat brain
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 62P
OP 62P
VO 48
IS supplement 2
A1 Stefanie Dedeurwaerdre
A1 Marie-Claude Gregoire
A1 Lucy Vivash
A1 Peter Roselt
A1 David Binns
A1 Tien Pham
A1 Andrew Katsifis
A1 Rod Hicks
A1 Terence O'Brien
A1 Damian Myers
YR 2007
UL http://jnm.snmjournals.org/content/48/supplement_2/62P.1.abstract
AB 206 Objectives: Animal models offer the distinct advantage of allowing the assessment of pre-, developing and chronic epileptic states. However, traditional techniques (e.g. histology) can only examine the brain at one time point during epileptogenesis. Recent advances in dedicated small animal PET (saPET) now allow the study of in vivo changes in brain function during epileptogenesis by means of serial acquisitions in the same animal. The aim of this study was to choose the best radioligand which would allow us to study the GABAA/cBZR complex in rats utilizing saPET. Two radiotracers were available: 2`-[18F]fluoroflumazenil ([18F]FFMZ) and [18F]flumazenil ([18]FMZ). Methods: Non-epileptic rats underwent 60-minutes PET scans after injection of: (i) Tracer dose of radioligand; (ii) Pre-treatment with cold radiotracer (100 μg), then injection of a tracer amount of radioligand; and, (iii) Tracer dose of radioligand, followed by a displacement (100 μg of cold compound) bolus injection. Results: [18F]FFMZ: In the hippocampus (high GABAA/cBZR density) the signal intensity was higher (10%) than in the whole brain during the first 10 min of uptake. In the pons (low GABAA/cBZR density), it was approximately 20% lower than in the whole brain during 25-30 min of the scan. The pre-saturation and displacement studies showed a high non-specific component in the measured signal. [18F]FMZ: At tracer dose, as compared to the whole brain, the kinetic uptake into hippocampus was 30% higher and the pons displayed a decrease of 40% after 10 minutes post-injection. Pre-saturation data confirmed that non-specific uptake is low and very similar among most of the brain structures. The displacement study showed a quick and major signal decrease: 90% for hippocampus; 79% in the pons. Conclusions: This data shows that [18F]FMZ is the best candidate for imaging and quantification of benzodiazepine receptors in the rat brain using saPET. Research Support (if any): Australian CRC for Biomedical Imaging Development