Received: 6 April 2020
Accepted: 22 December 2020
First Online: 18 January 2021
Ethics approval and consent to participate
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the Institutional Review Board of the Kofu Neurosurgical Hospital and Yamanashi PET imaging clinic (approved on 7 March 2020) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The requirement for informed consent from each patient has been waived due to its retrospective nature.
: Not applicable.
: The authors declare that they have no conflict of interest.