A New Technology for Detecting Cerebral Blood Flow: A Comparative Study of Ultrasound Tagged NIRS and 133Xe-SPECT
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There is a need for real-time non-invasive, continuous monitoring of cerebral blood flow (CBF) during surgery, in intensive care units and clinical research. We investigated a new non-invasive hybrid technology employing ultrasound tagged near infrared spectroscopy (UT-NIRS) that may estimate changes in CBF using a cerebral blood flow index (CFI). Changes over time for UT-NIRS CFI and 133Xenon single photon emission computer tomography (133Xe-SPECT) CBF data were assessed in 10 healthy volunteers after an intravenous bolus of acetazolamide. UT-NIRS CFI was measured continuously and SPECT CBF was measured at baseline, 15 and 60 min after acetazolamide. We found significant changes over time in CFI by UT-NIRS and CBF by SPECT after acetazolamide (P ≤ 0.001). Post hoc tests showed a significant increase in CFI (P = 0.011) and SPECT CBF (P < 0.001) at 15 min after acetazolamide injection. There was a significant correlation between CFI and SPECT CBF values (r = 0.67 and P ≤ 0.033) at 15 min, but not at 60 min (P ≥ 0.777). UT-NIRS detected an increase in CFI following an acetazolamide bolus, which correlated with CBF measured with 133Xe-SPECT. This study demonstrates that UT-NIRS technology may be a promising new technique for non-invasive and real-time bedside CBF monitoring.
KeywordsCerebral blood flow Ultrasound tagged near infrared spectroscopy 133Xenon single photon emission computer tomography Acetazolamide Monitoring
The authors wish to thank lab technicians Annette Foldager for her dedicated and excellent assistance and to Zmira Silman for advise on the statistical analysis. The study was supported by the Lundbeck Foundation via the Lundbeck Foundation Center for Neurovascular Signaling (LUCENS) and the Augustinus Foundation, Denmark. The study was funded by Ornim Medical Ltd. (Lod, Israel).
Conflict of interest
Dr. Schytz, Dr. Guo, Dr. Jensen and Dr. Ashina report no disclosures in any relation to this study. Dr. Kamar is vice president of medical affairs at Ornim Medical. Dr. Gress is a member of Ornim Medical Inc.’s scientific advisory board and holds stock options of the company. Dr. Nini is a medical advisor of Ornim.
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