Footnotes

• Contributors TA and KO: guarantor of integrity of the entire study. KO: study concepts. TA, MK and KO: study design. TA, MK and KY: literature research. TA, YS, SF, YK, KT, SA and KY: data acquisition. SF, YK, KT and SA: data analysis. TA, KO and KY: manuscript preparation. SF, YK and KT: manuscript editing.

• Funding This study was funded by Scientific Research from Japan Society for the Promotion of Science (grant number: JP18K09002) and Grant-in-Aid for Strategic Medical Science Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (grant number: S1491001, 2014–2018).

• Competing interests The corresponding author (KO) declared the following potential conflict of interest with respect to the research, authorship, and/or publication of this article: Consigned research funds from Nihon Medi-Physics Co., Ltd.

• Patient consent for publication Obtained.

• Provenance and peer review Not commissioned; externally peer reviewed.