Tomohisa Okada, M.D., Ph.D.

Research Overview

Equipped with a 3-Tesla and a 7-Tesla MRI systems, this unit supports non-invasive functional MRI (fMRI) studies on human subjects and anatomical scans on animals conducted by laboratories within RIKEN. Besides fMRI studies, we also have the capability to perform DTI, MRA, MRS, and simultaneous EEG/fMRI measurements. We have installed a number of peripheral devices for fMRI studies, such as stimulus presentation devices (video projectors, an LCD display, headphones, an electrical stimulation device, etc), to meet researchers’ various needs for experiments. Subject condition (heartbeat, respiration, eye movement, pupil size, EMG, button press response, etc), stimulus timing, and the shape of gradient pulses can be recorded together with the acquisition trigger timing signal, enabling this information to be used for post-processing and analysis of the MRI data. We have unique, in-house developed pulse sequences, data analyzing processes and peripheral equipment. Multi-shot EPI for high spatial resolution imaging, software for regressing out noises due to respiration and cardiac pulsation, and a bite-bar system for minimizing subject motion are all available for users. We have put special emphasis on developing software to process k-space (raw) data so that we are not limited by the vendor’s processing stream, which is optimized for clinical applications rather than research. We have developed software for reconstruction, noise reduction, and visualization of data in variety of formats. Using these cutting-edge technologies, users can perform many types of experiments and optimally process the data according to their needs.

For companies and researchers outside of RIKEN

For researchers from outside RIKEN, MRI experiments can be performed as Commissioned tests. For more details, please refer to the following website:
Commissioned tests (only available in Japanese).

Main Research Fields

Medicine, Dentistry & Pharmacy

Related Research Fields

Biology / Functional neuroimaging / Diagnostic imaging / Medical imaging

Keywords

• Functional magnetic resonance imaging
• Noninvasive measurement of the brain

Research Resources Division(RRD)

• Support Unit for Animal Resources Development (Kimie Niimi, D.V.M., Ph.D.)
• Support Unit for Bio-Material Analysis (Nobuhiko Miyasaka, Ph.D.)
• Support Unit for Functional Magnetic Resonance Imaging (Tomohisa Okada, M.D., Ph.D.)
• Support Unit for Electron Microscopy Techniques (Yoshiyuki Kubota, Ph.D.)

Selected Publications

Papers with an asterisk(*) are based on research conducted outside of RIKEN.

1. *Okada T, Kuribayashi H, Urushibata Y, Fujimoto K, Akasaka T, Seethamraju RT, Ahn S, Isa T.
   "GABA, glutamate and excitatory-inhibitory ratios measured using short-TE STEAM MRS at 7-Tesla: Effets of macromolecule basis sets and baseline parameters."
   "Heliyon. 2023 Jul 15;9(7):e18357.
2. *Oi Y, Hirose M, Togo H, Yoshinaga K, Akasaka T, Okada T, Aso T, Takahashi R, Glasser MF, Hayashi T, Hanakawa T.
   "Identifying and reverting the adverse effects of white matter hyperintensities on cortical surface analyses."
   Neuroimage. 2023 Nov 1;281:120377.
3. *Kose R, Kose K, Fujimoto K, Okada T, Tamada D, Motosugi U.
   "Nonlinear Gradient Field Mapping Using a Spherical Grid Phantom for 3 and 7 Tesla MR Imaging Systems Equipped with High-performance Gradient Coils."
   Magn Reson Med Sci. 2023 Sep 9.
4. *Son S, Arai M, Toriumi K, Andica C, Matsuyoshi D, Kamagata K, Aoki S, Kawashima T, Kochiyama T, Okada T, Fushimi Y, Nakamoto Y, Kobayashi Y, Murai T, Itokawa M, Miyata J.
   "Association between enhanced carbonyl stress and decreased apparent axonal density in schizophrenia by multimodal white matter imaging."
   Sci Rep. 2023 Jul 27;13(1):12220.
5. *Kuribayashi H, Urushibata Y, Imai H, Ahn S, Seethamraju RT, Isa T, Okada T.
   "Quantification of Cerebral Glucose Concentrations via Detection of the H1-α-Glucose Peak in 1 H MRS at 7 T."
   J Magn Reson Imaging. 2024 Feb;59(2):661-672.
6. *Shima A, Inano R, Tabu H, Okada T, Nakamoto Y, Takahashi R, Sawamoto N.
   "Altered functional connectivity associated with striatal dopamine depletion in Parkinson's disease."
   Cereb Cortex Commun. 2023 Feb 20;4(1):tgad004.
7. *Okada T, Fujimoto K, Fushimi Y, Akasaka T, Thuy DHD, Shima A, Sawamoto N, Oishi N, Zhang Z, Funaki T, Nakamoto Y, Murai T, Miyamoto S, Takahashi R, Isa T.
   "Neuroimaging at 7 Tesla: a pictorial narrative review."
   Quant Imaging Med Surg. 2022 Jun;12(6):3406-3435.
8. *Kondo T, Hara N, Koyama S, Yada Y, Tsukita K, Nagahashi A, Ikeuchi T, Ishii K, Asada T, Arai T, Yamada R; Alzheimer’s Disease Neuroimaging Initiative (ADNI); Japanese Alzheimer’s Disease Neuroimaging Initiative (J-ADNI); Inoue H.
   "Dissection of the polygenic architecture of neuronal Aβ production using a large sample of individual iPSC lines derived from Alzheimer's disease patients."
   Nat Aging. 2022 Feb;2(2):125-139.
9. *Okada T, Handa S, Ding B, Urayama SI, Fujimoto K, Shima A, Yoshii D, Ayaki T, Sawamoto N, Takahashi R, Onoe H, Isa T, Petropoulos L.
   "Insertable inductively coupled volumetric coils for MR microscopy in a human 7T MR system."
   Magn Reson Med. 2022 Mar;87(3):1613-1620.
10. *Okada T, Kuribayashi H, Kaiser LG, Urushibata Y, Salibi N, Seethamraju RT, Ahn S, Thuy DHD, Fujimoto K, Isa T.
    "Repeatability of proton magnetic resonance spectroscopy of the brain at 7 T: effect of scan time on semi-localized by adiabatic selective refocusing and short-echo time stimulated echo acquisition mode scans and their comparison."
    Quant Imaging Med Surg. 2021 Jan;11(1):9-20.