Influence of scanning time window on the binding potentials of dopamine transporter in the brain of healthy volunteers with 11C-CFT PET imaging

Abstract

Objective To find the optimal scanning time window and then set up the normal binding potentials (BPs) of 2β-carbomethoxy-3β-(4-fluorophenyl)-(N-11C-methyl) tropane (11C-CFT) DAT PET/CT imaging.Methods Thirty-one healthy volunteers (20 males,11 females,average age:(55.7±2.3) years),who all gave written informed consent,were divided into three age and gender-matched groups according to block randomization.Each group underwent static PET/CT scan in different time windows from 40-60 min,60-80 min to 80-100 min after 11C-CFT injection.To determine the best scanning time window,the ratios of caudate and putamen of all volunteers were analyzed using automatic ROI method (caudate (putamen)/parieto-occipital cotex-1) and compared by one-way analysis of variance and the least significant difference (LSD) t test.The ratio of the same area between different age-groups and gender-groups was compared with independent two-sample t test.Results Ratios of left caudate (2.08±0.06,1.75±0.07and 1.77±0.12 respectively),right anterior putamen (2.33±0.06,1.95±0.09 and 2.08±0.12 respectively)and bilateral posterior putamen (left:1.88±0.66,1.55±0.88 and 1.72±0.09; right:1.98±0.07,1.61±0.09and 1.69±0.12) were all different in three time windows (F=3.588,3.345,4.479,3.557,all P＜0.05).There were significant differences in ratios of left caudate,right anterior and bilateral posterior putamen between 40-60 min and the 60-80 min (all P＜0.05),as well as the ratios of left caudate between 40-60 min and the 80-100 min group (P＜0.05).While no valid differences in ratios of those areas were shown between the groups of 60-80 min and 80-100 min scanning time window (all P＞0.05).DAT densities in right and left side of caudate,anterior and posterior putamen were significantly lower in the group over 60 years of age than those under 60 years (t=-3.260,-3.090,-3.270,-3.190,-2.270,-3.110,all P＜0.05),but were not different between gender-groups (t =0.367,0.522,0.144,0.524,0.166,0.004,all P＞0.05).Conclusions Sixty min after injection of 11C-CFT,the BPs achieve stable stage,so the best scanning time window of 11C-CFT DAT PET imaging was 60-80 min after injection.Identification of normal DAT distribution and understanding of normal BPs of 11C-CFF are necessary before its clinical application. Key words: Brain; Dopamine transporter; Tomography, emission-computed; Tomography, X-ray computed; CFT