title: A revisit to quantitative PET with18F-FDOPA of high specific activity using a high-resolution condition in view of application to regenerative therapy.
abstract: OBJECTIVE
  With the advent of regenerative/cell therapy for Parkinson's disease (PD),18F-FDOPA has drawn new attention as a biomarker of the therapeutic that cannot be evaluated with radiopharmaceuticals for dopamine transporter. Since most previous18F-FDOPA PET studies were carried out many years ago with a PET scanner of lower resolution and with18F-FDOPA of low specific activity synthesized from18F-F2, we used a newer PET/CT scanner with a high-resolution condition and18F-FDOPA synthesized from18F-F-to re-evaluate this technique on normal subjects and patients with PD, together with D2receptor imaging with11C-raclopride (RAC).
  
  
  METHODS
  PET scans were carried out with18F-FDOPA for 120 min and with11C-RAC for 60 min on 10 patients clinically diagnosed with PD and on 10 normal control subjects. Image reconstruction parameters were optimized with phantom experiments. Graphical analysis and the ratio method for the late-phase images were performed to quantify the striatal uptakes.
  
  
  RESULTS
  The specific activity of18F-FDOPA was as high as 4000 MBq/nmol. We empirically determined appropriate reconstruction parameters to obtain high-resolution PET images with enough quantitative accuracy. Both18F-FDOPA and11C-RAC PET showed higher uptake values on normal subjects than those of the previous studies probably due to high-resolution. Quantified ratio values strongly correlated with the graphical values for both tracers. Furthermore,18F-FDOPA uptake in the substantia nigra was clearly visualized in most subjects.
  
  
  CONCLUSIONS
  Quantitative18F-FDOPA and11C-RAC PET scans using a high-resolution condition are considered to provide essential information for regenerative dopaminergic therapy. Furthermore, the ratio analysis for the late-phase PET scans with18F-FDOPA and11C-RAC enhances the clinical utility of these dopaminergic PET as imaging biomarkers of PD.
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. akamatsu@fbri.org.
authors.forename: Go
authors.initials: G
authors.lastname: Akamatsu
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Ohnishi
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Aita
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishida
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Ikari
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Sasaki
authors.affiliation: Department of Neurology, Kobe City Medical Center General Hospital, Kobe, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kohara
authors.affiliation: Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. senda@fbri.org.
authors.forename: Michio
authors.initials: M
authors.lastname: Senda
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000628:therapy*; D019047:Phantoms, Imaging; D000072078:Positron Emission Tomography Computed Tomography / Q000295:instrumentation / Q000379:methods*; D020891:Raclopride; D019275:Radiopharmaceuticals
chemical_list: D019275:Radiopharmaceuticals; C043437:fluorodopa F 18; D020891:Raclopride; D004295:Dihydroxyphenylalanine
keywords: 11C-raclopride; 18F-FDOPA; High resolution; PET; Quantification