Human biodistribution and dosimetry of iodine-123-fluouoalkyl analogs of beta-CIT

Two new N-omega-fluoroalkyl analogs of [I-123]2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane ([I-123]FE-CIT), the fluoroethyl and fluoropropyl compounds ([I-123]FE-CIT and [(123)]FP-CIT, respectively): have been shown to have faster kinetics and better selectivity for the dopamine transporter than [I-123]beta-CIT. We examined the organ biodistribution and radiation safely of these two compounds in six healthy volunteers who received an injection with each of the two compounds 2 weeks spare, Data were obtained on the Strichman 860 whole-body scanner, Transmission scans were obtained in all subjects prior to the injection of the radiotracer with a line source and used, to derive organ-specific attenuation correction factors, Whole-body planar images were acquired every hour for the first 6 h, and at 24 h, Attenuation-corrected regional conjugate counts were converted into units of activity using a calibration factor obtained for each subject by dividing whole-body conjugate decay-corrected counts from die first acquisition by the injected activity, Radiation dose estimates were on average higher for [I-123]CIT-FE than for [I-123]CIT-FP, with the lower large intestine receiving the highest exposure: 0.15+/-13% mGy/MBq (mean +/-COV) and 0.12+/-14% mGy/MBq for [I-123]FE-CIT and [I-123]FP-CIT, respectively, followed by the upper large intestine and the spleen.