[123I]5-I-A-85380 ([123I]5-IA) is a ligand specific for the α4β2 nicotinic acetylcholine receptor (nAChR) subtype. It was reported that distribution volume (DV) is an appropriate measurement for α4β2 nAChR density in baboon [123I]5-IA dynamic SPECT studies. To evaluate the kinetics obtained from human [123I]5-IA dynamic SPECT, three different methods were applied to region of interest (ROI) kinetics analysis as folows: A: a 2-compartment 3-parameters model, B: 3-compartment 5-parameter model, and C: same model as in B but fitting with a constraint of ratio of K1/k2e estimated by fitting occipital kinetics to model in A. The DV was estimated as DV = K1/k2 for A, and DV=(K1/k2)(1+k3/k4) for B and C. Nonlinear least squares fitting using Marquardt algorithm was performed for A-C. Akaike information criterion (AIC) and R2 were used for evaluation of fitting results. A linear parametric imaging algorithm derived from model in method A was used for generating images of K1 and DV. Four normal human [123I]5-IA dynamic studies were evaluated by A-C. In each study, after a bolus of [123I]5-IA (5∼10 mCi, specific activity>10 Ci/umol) was injected intravenously, a dynamic scanning with 20 acquisitions over 6 hour was started immediately on a Trionix TriadXLT scanner. 30-40 arterial plasma samples were taken during the study and HPLC was performed to determine the metabolite-corrected arterial plasma radioactivity as input function. The ROI regions (cerebellum, frontal cortex, occipital cortex, pones, and thalamus) were drawn on co-registered MRI images. Results show that A fits to all ROI kinetics very well (R2>0.99), and paired T-test for AIC showed there is no statistical significantly improvement of model fitting from B, C methods The K1 and DV images are of good image quality. Conclusion: A is best for ROI kinetic analysis and parametric imaging for DV and K1.
|Number of pages||6|
|State||Published - 2001|
|Event||2001 IEEE Nuclear Science Symposium Conference Record - San Diego, CA, United States|
Duration: Nov 4 2001 → Nov 10 2001
|Conference||2001 IEEE Nuclear Science Symposium Conference Record|
|City||San Diego, CA|
|Period||11/4/01 → 11/10/01|