Mr. Rasa Eskandari Profile

Rasa Eskandari

at Western University

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Author

Publications (2)

SPIE Journal Paper | 3 May 2024 Open Access

Assessing changes in regional cerebral hemodynamics in adults with a high-density full-head coverage time-resolved near-infrared spectroscopy device

Farah Kamar, Leena Shoemaker, Rasa Eskandari, Daniel Milej, Darren Drosdowech, John Murkin, Keith St. Lawrence, Jason Chui, Mamadou Diop

JBO, Vol. 29, Issue S3, S33302, (May 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.S3.S33302

KEYWORDS: Surgery, Brain, Hemodynamics, Near infrared spectroscopy, Oxygenation, Tunable filters, Head, Skin, Bandpass filters, Wavelets

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SignificanceCerebral oximeters have the potential to detect abnormal cerebral blood oxygenation to allow for early intervention. However, current commercial systems have two major limitations: (1) spatial coverage of only the frontal region, assuming that surgery-related hemodynamic effects are global and (2) susceptibility to extracerebral signal contamination inherent to continuous-wave near-infrared spectroscopy (NIRS).AimThis work aimed to assess the feasibility of a high-density, time-resolved (tr) NIRS device (Kernel Flow) to monitor regional oxygenation changes across the cerebral cortex during surgery.ApproachThe Flow system was assessed using two protocols. First, digital carotid compression was applied to healthy volunteers to cause a rapid oxygenation decrease across the ipsilateral hemisphere without affecting the contralateral side. Next, the system was used on patients undergoing shoulder surgery to provide continuous monitoring of cerebral oxygenation. In both protocols, the improved depth sensitivity of trNIRS was investigated by applying moment analysis. A dynamic wavelet filtering approach was also developed to remove observed temperature-induced signal drifts.ResultsIn the first protocol (28±5 years; five females, five males), hair significantly impacted regional sensitivity; however, the enhanced depth sensitivity of trNIRS was able to separate brain and scalp responses in the frontal region. Regional sensitivity was improved in the clinical study given the age-related reduction in hair density of the patients (65±15 years; 14 females, 13 males). In five patients who received phenylephrine to treat hypotension, different scalp and brain oxygenation responses were apparent, although no regional differences were observed.ConclusionsThe Kernel Flow has promise as an intraoperative neuromonitoring device. Although regional sensitivity was affected by hair color and density, enhanced depth sensitivity of trNIRS was able to resolve differences in scalp and brain oxygenation responses in both protocols.

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Proceedings Article | 7 March 2023 Presentation + Paper

Ideal light scatterer for near-infrared spectroscopy tissue mimicking phantoms

Rasa Eskandari, Mamadou Diop

Proceedings Volume 12376, 1237605 (2023) https://doi.org/10.1117/12.2649524

KEYWORDS: Dyes, Near infrared spectroscopy, Microspheres, Tissues, Chromophores, Light scattering, Titanium dioxide

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