PIXSIC: A Wireless Intracerebral Radiosensitive Probe in Freely Moving Rats

Abstract

The aim of this study was to demonstrate the potential of a wireless pixelated β+-sensitive intracerebral probe (PIXSIC) for in vivo positron emission tomographic (PET) radiopharmacology in awake and freely moving rodents. The binding of [(11)C]raclopride to D2 dopamine receptors was measured in anesthetized and awake rats following injection of the radiotracer. Competitive binding was assessed with a cold raclopride injection 20 minutes later. The device can accurately monitor binding of PET ligands in freely moving rodents with a high spatiotemporal resolution. Reproducible time-activity curves were obtained for pixels throughout the striatum and cerebellum. A significantly lower [(11)C]raclopride tracer-specific binding was observed in awake animals. These first results pave the way for PET tracer pharmacokinetics measurements in freely moving rodents.

MAPSSIC, a communicating MAPS-based intracerebral positrons probe for deep brain imaging in awake and freely-moving rats

“…This difference arises from the fact that positrons have a larger range in water for 11 C and 15 O than for 18 F. Nevertheless 18 F is the most used isotope and has the best definition in terms of brain structure due to the lower range of its positrons. In addition sensitivity with 18 F has been proven sufficient with the previous probe version [2]. Indirect detection sensitivity Sindirect continuously increases because of the high penetration of 511 keV annihilation γ-rays in water.…”

“…Therefore, we have started the development of a miniaturized and real-time intracerebral positrons probe for awake and freely moving small animals, typically rats. Taking advantage of the availability of new technologies and of the expertise we have acquired from former developments [1], [2], we propose a novel, robust, wireless, autonomous and lightweight active pixel positron probe.…”

MAPSSIC, a Novel CMOS Intracerebral Positrons Probe for Deep Brain Imaging in Awake and Freely Moving Rats: A Monte Carlo Study

“…This complementarity is a critical step for comparing animal to human behavior and consequently assess the validity of preclinical studies in drug development. For example, as explained in [2], behavior neuroimaging shows applications for the study of addiction in animal models, using 18 F-FDG for associating brain metabolism to a particular behavior or 11 Craclopride to study the dynamic changes in the dopaminergic system in real-time.…”

“…A first intracerebral wireless probe named PIXSIC was previously developed [10]. Although successfully validated in various biological contexts [11], providing promising results for behavioral neuroimaging, this probe design suffered from several issues. The probe sensitivity to γ-rays led on to substantial noise.…”

“…We present the results obtained for a probe into a large homogeneous volume of radioactive water ( 18 F) leading to a sensitivity of 0.88 cps • Bq −1 • mm 3 and a mean energy deposition by positrons of 15.1 keV. Simulation in simplified brain-shaped sources modeling a 11 C-raclopride experiment shows that the implanted volume modeling the left putamen contribute to 92.4 % of the signal from positrons. We also investigate the effects of the thickness of the sensitive layer, the energy threshold and pixel dimensions on the detection capacities of the sensor.…”