Imaging Opiate Receptors in the Human Brain by Positron Tomography

Quantification of brain μ-opioid receptors with [11C]carfentanil: reference-tissue methods

“…Following bolus injection of CFN, blood was sampled from a radial arterial catheter as fast as possible for the first 2 min, then at times of 3,4,5,6,7,8,10,12,14,16,20,25,30,35,40,50,60,75, and 90 min post-injection. The blood sampling volume was 1.5 ml, with larger samples (8 ml) taken at 5, 10, 20, 30, 40, 60, and 90 min to provide additional blood for radioactive metabolite analysis.…”

“…The model parameters for this method are R 1 ϭK 1 /K 1 r , k 2 Ј, and BPϭk 3 Ј/k 4 . An alternative approach uses twotissue compartments (model B) for the reference region with parameters R 1 , k 2 Ј, k 5 , k 6 and BP (Watabe et al, 2000). implementation, the regression equations were expressed in terms of the five parameters R 1 , k 2 r , k 5 , nsϭk 5 /k 6 , and BP R2TM.…”

“…[ 11 C]Carfentanil (CFN) is a reversible -opioid agonist and is one of the first receptor binding ligands to be studied with positron emission tomography (PET) [6]. An early evaluation of CFN kinetics showed that a simple tissue-ratio method provides estimates of CFN binding that are highly correlated (r ϭ 0.98) with specific binding estimates obtained using a more rigorous blood-input modeling technique [7].…”

Buprenorphine Reduces Cerebral Glucose Metabolism in Polydrug Abusers

“…Effects of buprenorphine on rCMRglc follow the distribution of opioid receptors in the human brain only to some extent (Kuhar et al 1973;Frost et al 1985). For example, some subcortical brain regions (e.g., pons) ex hibited decreased metabolism in response to buprenor phine, despite low to negligible levels of opioid recep tors.…”

Comment on Hsiao et al.: Correlation of early-phase 18F-florbetapir (AV-45/Amyvid) PET images to FDG images: preliminary studies

“…It has long been recognized that the early cerebral distribution of lipophilic tracers reflects regional perfusion [2][3][4] and indeed it was suggested many years ago that a single injection might provide both perfusion and receptor binding information by imaging at two time points [5,6].…”