Application of a time-resolved optical brain imager for monitoring cerebral oxygenation during carotid surgery

Abstract

Recent studies have shown that time-resolved optical measurements of the head can estimate changes in the absorption coefficient with depth discrimination. Thus, changes in tissue oxygenation, which are specific to intracranial tissues, can be assessed using this advanced technique, and this method allows us to avoid the influence of changes to extracerebral tissue oxygenation on the measured signals. We report the results of time-resolved optical imaging that was carried out during carotid endarterectomy. This surgery remains the "gold standard" treatment for carotid stenosis, and intraoperative brain oxygenation monitoring may improve the safety of this procedure. A time-resolved optical imager was utilized within the operating theater. This instrument allows for the simultaneous acquisition of 32 distributions of the time-of-flight of photons at two wavelengths on both hemispheres. Analysis of the statistical moments of the measured distributions of the time-of-flight of photons was applied for estimating changes in the absorption coefficient as a function of depth. Time courses of changes in oxy- and deoxyhemoglobin of the extra- and intracerebral compartments during cross-clamping of the carotid arteries were obtained. A decrease in the oxyhemoglobin concentration and an increase in the deoxyhemoglobin concentrations were observed in a large area of the head. Large changes were observed in the hemisphere ipsilateral to the site of clamped carotid arteries. Smaller amplitude changes were noted at the contralateral site. We also found that changes in the hemoglobin signals, as estimated from intracerebral tissue, are very sensitive to clamping of the internal carotid artery, whereas its sensitivity to clamping of the external carotid artery is limited. We concluded that intraoperative multichannel measurements allow for imaging of brain tissue hemodynamics. However, when monitoring the brain during carotid surgery, a single-channel measurement may be sufficient.

Systematic review of near-infrared spectroscopy determined cerebral oxygenation during non-cardiac surgery

“…rScO 2 and systemic blood pressure correlate, with higher pressures leading to better oxygenation values (Williams et al, 1994c; Ritter et al, 2011). The use of multichannel NIRS with 8 lightsource fibers and 8 detectors providing 24 source-detector pairs supports that following application of ICA cross clamp, HbO 2 , and Hb change in the border region between the right middle and posterior cerebral supply areas (Nakamura et al, 2009) with distinct changes in Hb and HbO 2 of the ipsilateral brain cortex (Kacprzak et al, 2012). …”

Frequency analysis of oscillations in cerebral hemodynamics measured by time domain near infrared spectroscopy

“…The tdNIRS technique was previously applied to cortex oxygenation assessment [37] and perfusion [38] successfully. Our present results demonstrate that tdNIRS used for the detection of autoregulatory deficiencies in patients with neurovascular disorders demonstrate significant final result.…”

Multi-channel medical device for time domain functional near infrared spectroscopy based on wavelength space multiplexing

“…It is worth mentioning that European research groups located in academic or public research centers have designed and built most of the existing TD fNIRS systems effectively employed in the clinics. In particular the most active in the field are the research groups at Physikalisch-Technische Bundesanstalt, Berlin, Germany [9][10][11][12][13][14][15], at the Institute of Biocybernetics and Biomedical Engineering, Warsaw, Poland [16][17][18], and at the the Department of Medical Physics and Bioengineering, University College London [19][20][21][22][23]. In the US we can mention the group at the Massachusetts General Hospital, Athinoula A. Martinos Center, Charlestown, Massachusetts [6,[24][25][26].…”