RT Journal Article
SR Electronic
T1 Comparative PET imaging of D2/D3 receptors in the rodent spinal cord with [<sup>18</sup>F]fallypride and [<sup>11</sup>C]fallypride
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1193
OP 1193
VO 52
IS supplement 1
A1 Armen Khararjian
A1 Cristian Constantinescu
A1 Robert Coleman
A1 Min-Liang Pan
A1 Jogeshwar Mukherjee
YR 2011
UL http://jnm.snmjournals.org/content/52/supplement_1/1193.abstract
AB 1193 Objectives Our goal was to evaluate and compare the imaging capability of dopamine D2/D3 receptors in the rat spinal cord using PET ligands 18F-falllypride and 11C-fallypride. Methods Male Sprague-Dawley rats were used in all studies. For in vivo studies two different animals received a 150-min 18F-fallypride scan and a 90-min 11C-Fallypride scan using a Siemens Inveon dedicated PET scanner. The spinal cord and the brain were then harvested, flash-frozen and imaged ex vivo for 30-min. Further, the spine was then sectioned and analyzed in vitro using a Cyclone Phosphor Imager. Binding of radiotracer in the spinal cord (SC) was calculated relative to binding in the striatum (STR). Regions of interest (ROI) were drawn over the STR, cerebellum and two areas of the SC (lower and upper). For in vivo analysis Logan plots with cerebellum as a reference was used to evaluate binding potentials (BP). Tissue ratios were used for ex vivo analysis. Results In Vitro studies showed 18F-fallypride binding of 77.4% in the upper spinal cord and 89.8% in the lower spinal cord. In Vivo analysis yielded BP values of 4.2 (upper and lower SC) and 17.8 for the STR. For 11C-fallypride the values were 8.63 in the STR and 0.6 in the SC. Relative to striatum, ex vivo studies showed 18F-fallypride binding of 1.21% in the lower spinal cord, 1.15% in the upper spinal cord, and 1.07% for the total spinal cord. 11C Fallypride showed binding of 9.00% in the lower SC, 8.96% in the upper SC, and 9.24% for the total spinal cord. Conclusions Our micro PET studies showed quantifiable 18F-Fallypride and 11F-Fallypride binding in the spinal cord in vivo. Increased uptake was observed near sites of the various plexuses (lumbar/cervical). The binding pattern correlates well with lower extremity nerves and may suggest a possible use of D2/D3 receptor to study the restless leg syndrome. 11C-fallypride also showed reduced bone uptake compared to the 18F-fallypride. Research Support NIH R01 EB00611