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Suwalski M, Shoemaker LN, Shoemaker JK, Diop M, Murkin JM, Chui J, St. Lawrence K, Milej D. Assessing the Sensitivity of Multi-Distance Hyperspectral NIRS to Changes in the Oxidation State of Cytochrome C Oxidase in the Brain. Metabolites 2022; 12:metabo12090817. [PMID: 36144221 PMCID: PMC9502461 DOI: 10.3390/metabo12090817] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/16/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are frequently used during vascular and cardiac surgeries as a non-invasive means of assessing brain health; however, signal contamination from extracerebral tissues remains a concern. As an alternative, hyperspectral (hs)NIRS can be used to measure changes in the oxidation state of cytochrome c oxidase (ΔoxCCO), which provides greater sensitivity to the brain given its higher mitochondrial concentration versus the scalp. The purpose of this study was to evaluate the depth sensitivity of the oxCCO signal to changes occurring in the brain and extracerebral tissue components. The oxCCO assessment was conducted using multi-distance hsNIRS (source-detector separations = 1 and 3 cm), and metabolic changes were compared to changes in StO2. Ten participants were monitored using an in-house system combining hsNIRS and diffuse correlation spectroscopy (DCS). Data were acquired during carotid compression (CC) to reduce blood flow and hypercapnia to increase flow. Reducing blood flow by CC resulted in a significant decrease in oxCCO measured at rSD = 3 cm but not at 1 cm. In contrast, significant changes in StO2 were found at both distances. Hypercapnia caused significant increases in StO2 and oxCCO at rSD = 3 cm, but not at 1 cm. Extracerebral contamination resulted in elevated StO2 but not oxCCO after hypercapnia, which was significantly reduced by applying regression analysis. This study demonstrated that oxCCO was less sensitive to extracerebral signals than StO2.
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Affiliation(s)
- Marianne Suwalski
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
| | - Leena N. Shoemaker
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - J. Kevin Shoemaker
- Department of Kinesiology, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
| | - Mamadou Diop
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - John M. Murkin
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Jason Chui
- Department of Anesthesiology and Perioperative Medicine, London Health Science Centre, 339 Windermere Rd, London, ON N6A 5A5, Canada
| | - Keith St. Lawrence
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
| | - Daniel Milej
- Department of Medical Biophysics, Western University, 1151 Richmond St, London, ON N6A 3K7, Canada
- Imaging Division, Lawson Health Research Institute, Imaging Program, 268 Grosvenor St, London, ON N6A 4V2, Canada
- Correspondence: (M.S.); (D.M.)
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