Go Akamatsu1, Akihito Ohnishi2, Kazuki Aita2, Hiroyuki Nishida2, Yasuhiko Ikari2, Masahiro Sasaki2, Nobuo Kohara3, Michio Senda4. 1. Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. akamatsu@fbri.org. 2. Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. 3. Department of Neurology, Kobe City Medical Center General Hospital, Kobe, Japan. 4. Division of Molecular Imaging, Institute of Biomedical Research and Innovation, 2-2 Minatojima-Minamimachi, Chuo-ku, Kobe, 650-0047, Japan. senda@fbri.org.
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 previous 18F-FDOPA PET studies were carried out many years ago with a PET scanner of lower resolution and with 18F-FDOPA of low specific activity synthesized from 18F-F2, we used a newer PET/CT scanner with a high-resolution condition and 18F-FDOPA synthesized from 18F-F- to re-evaluate this technique on normal subjects and patients with PD, together with D2 receptor imaging with 11C-raclopride (RAC). METHODS: PET scans were carried out with 18F-FDOPA for 120 min and with 11C-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 of 18F-FDOPA was as high as 4000 MBq/nmol. We empirically determined appropriate reconstruction parameters to obtain high-resolution PET images with enough quantitative accuracy. Both 18F-FDOPA and 11C-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. CONCLUSION: Quantitative 18F-FDOPA and 11C-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 with 18F-FDOPA and 11C-RAC enhances the clinical utility of these dopaminergic PET as imaging biomarkers of PD.
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 previous 18F-FDOPA PET studies were carried out many years ago with a PET scanner of lower resolution and with 18F-FDOPA of low specific activity synthesized from 18F-F2, we used a newer PET/CT scanner with a high-resolution condition and 18F-FDOPA synthesized from 18F-F- to re-evaluate this technique on normal subjects and patients with PD, together with D2 receptor imaging with 11C-raclopride (RAC). METHODS: PET scans were carried out with 18F-FDOPA for 120 min and with 11C-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 of 18F-FDOPA was as high as 4000 MBq/nmol. We empirically determined appropriate reconstruction parameters to obtain high-resolution PET images with enough quantitative accuracy. Both 18F-FDOPA and 11C-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. CONCLUSION: Quantitative 18F-FDOPA and 11C-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 with 18F-FDOPA and 11C-RAC enhances the clinical utility of these dopaminergic PET as imaging biomarkers of PD.
Entities:
Keywords:
11C-raclopride; 18F-FDOPA; High resolution; PET; Quantification