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ORIGINAL RESEARCH article

Front. Med. Technol.

Sec. Diagnostic and Therapeutic Devices

Intracranial Functional Near-Infrared Spectroscopy: an Animal Feasibility Study

Provisionally accepted
Netaniel ReinNetaniel Rein1,2,3*Sami HeymannSami Heymann2,4Marco ZuritaMarco Zurita2,4Revital ShechterRevital Shechter3,5Zvi IsraelZvi Israel2,4Michal BalbergMichal Balberg3,5Mordekhay MedvedovskyMordekhay Medvedovsky1,2,3Guy RosenthalGuy Rosenthal2,4
  • 1Department of Neurology and Agnes Ginges Center for Human Neurogenetics, Hadassah Medical Center, Jerusalem, Israel
  • 2Hebrew University of Jerusalem School of Medicine, Jerusalem, Israel
  • 3Neuro-Electro-Light Center (NELC), Hadassah Medical Organization and Holon Institute of Technology, Jerusalem, Israel
  • 4Department of Neurosurgery, Hadassah Medical Center, Jerusalem, Israel
  • 5Faculty of Engineering, Holon Institute of Technology, Holon, Israel

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Functional Near-Infrared Spectroscopy (fNIRS) is widely used to monitor cerebral hemodynamics, however, it is limited by shallow penetration depth and susceptibility to hemodynamic noise from the scalp. A novel intracranial fNIRS (ifNIRS) system, featuring depth optrodes (optode-electrodes) and optical anchor bolts (OABs), has been proposed to address these limitations. This study investigates the feasibility of ifNIRS in a swine model under controlled interventions. Three animals were implanted with ifNIRS. Each animal with three OABs, with depth optrodes (DO) inserted into two of the OABs. Hemodynamic changes were recorded using OAB-to-OAB (OAB-OAB) and DO-to-OAB (DO-OAB) channels. Two interventions were performed to generate hemodynamic changes: rapid infusion of hypotonic saline to induce cerebral edema and blood withdrawal. Postmortem assessment for tissue damage and hemorrhage was performed. Hemoglobin concentration changes were analyzed using the Beer-Lambert equation. A decrease in total hemoglobin (tHb) levels during blood withdrawal was observed in all channel configurations that displayed relevant signals. During hypotonic saline infusion, variable patterns of tHb were observed. Postmortem findings showed minor extra-axial hemorrhages near OABs, but no intracerebral or heat-related injuries. This study demonstrates the feasibility of the ifNIRS system in detecting hemodynamic changes in vivo. While technical refinements are needed, ifNIRS shows promise for improving cerebral hemodynamic monitoring and enhancing diagnostic accuracy in invasive monitoring of patients with epilepsy.

Keywords: Intracranial fNIRS (ifNIRS), optical anchor bolt (OAB), depth optrode (DO), Stereotactic EEG (SEEG), swine model

Received: 25 Aug 2025; Accepted: 30 Oct 2025.

Copyright: © 2025 Rein, Heymann, Zurita, Shechter, Israel, Balberg, Medvedovsky and Rosenthal. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Netaniel Rein, netanielrein@gmail.com

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Supplementary Material