title: Effect of scatter correction on the compartmental measurement of striatal and extrastriatal dopamine D2 receptors using [123I]epidepride SPET.
abstract: Prior studies with anthropomorphic phantoms and single, static in vivo brain images have demonstrated that scatter correction significantly improves the accuracy of regional quantitation of single-photon emission tomography (SPET) brain images. Since the regional distribution of activity changes following a bolus injection of a typical neuroreceptor ligand, we examined the effect of scatter correction on the compartmental modeling of serial dynamic images of striatal and extrastriatal dopamine D(2) receptors using [(123)I]epidepride. Eight healthy human subjects [age 30+/-8 (range 22-46) years] participated in a study with a bolus injection of 373+/-12 (354-389) MBq [(123)I]epidepride and data acquisition over a period of 14 h. A transmission scan was obtained in each study for attenuation and scatter correction. Distribution volumes were calculated by means of compartmental nonlinear least-squares analysis using metabolite-corrected arterial input function and brain data processed with scatter correction using narrow-beam geometry micro (SC) and without scatter correction using broad-beam micro (NoSC). Effects of SC were markedly different among brain regions. SC increased activities in the putamen and thalamus after 1-1.5 h while it decreased activity during the entire experiment in the temporal cortex and cerebellum. Compared with NoSC, SC significantly increased specific distribution volume in the putamen (58%, P=0.0001) and thalamus (23%, P=0.0297). Compared with NoSC, SC made regional distribution of the specific distribution volume closer to that of [(18)F]fallypride. It is concluded that SC is required for accurate quantification of distribution volumes of receptor ligands in SPET studies.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine and VA Connecticut Healthcare System, West Haven, CT, USA. FujitaM@intra.nimh.nih.gov
authors.forename: Masahiro
authors.initials: M
authors.lastname: Fujita
authors.forename: Andrea
authors.initials: A
authors.lastname: Varrone
authors.forename: Kyeong Min
authors.initials: KM
authors.lastname: Kim
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watabe
authors.forename: Sami S
authors.initials: SS
authors.lastname: Zoghbi
authors.forename: Nicholas
authors.initials: N
authors.lastname: Seneca
authors.forename: Dnyanesh
authors.initials: D
authors.lastname: Tipre
authors.forename: John P
authors.initials: JP
authors.lastname: Seibyl
authors.forename: Robert B
authors.initials: RB
authors.lastname: Innis
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Iida
mesh_terms: D000328:Adult; D001549:Benzamides / Q000493:pharmacokinetics*; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D011759:Pyrrolidines / Q000493:pharmacokinetics*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017447:Receptors, Dopamine D1 / Q000378:metabolism*; D050641:Receptors, Dopamine D5; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D001549:Benzamides; C493605:DRD5 protein, human; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D019275:Radiopharmaceuticals; D017447:Receptors, Dopamine D1; C063525:epidepride; D050641:Receptors, Dopamine D5