title: Noninvasive measurement of cerebral blood flow and blood oxygenation using near-infrared and diffuse correlation spectroscopies in critically brain-injured adults.
abstract: BACKGROUND
  This study assesses the utility of a hybrid optical instrument for noninvasive transcranial monitoring in the neurointensive care unit. The instrument is based on diffuse correlation spectroscopy (DCS) for measurement of cerebral blood flow (CBF), and near-infrared spectroscopy (NIRS) for measurement of oxy- and deoxy-hemoglobin concentration. DCS/NIRS measurements of CBF and oxygenation from frontal lobes are compared with concurrent xenon-enhanced computed tomography (XeCT) in patients during induced blood pressure changes and carbon dioxide arterial partial pressure variation.
  
  
  METHODS
  Seven neurocritical care patients were included in the study. Relative CBF measured by DCS (rCBF(DCS)), and changes in oxy-hemoglobin (DeltaHbO(2)), deoxy-hemoglobin (DeltaHb), and total hemoglobin concentration (DeltaTHC), measured by NIRS, were continuously monitored throughout XeCT during a baseline scan and a scan after intervention. CBF from XeCT regions-of-interest (ROIs) under the optical probes were used to calculate relative XeCT CBF (rCBF(XeCT)) and were then compared to rCBF(DCS). Spearman's rank coefficients were employed to test for associations between rCBF(DCS) and rCBF(XeCT), as well as between rCBF from both modalities and NIRS parameters.
  
  
  RESULTS
  rCBF(DCS) and rCBF(XeCT) showed good correlation (r (s) = 0.73, P = 0.010) across the patient cohort. Moderate correlations between rCBF(DCS) and DeltaHbO(2)/DeltaTHC were also observed. Both NIRS and DCS distinguished the effects of xenon inhalation on CBF, which varied among the patients.
  
  
  CONCLUSIONS
  DCS measurements of CBF and NIRS measurements of tissue blood oxygenation were successfully obtained in neurocritical care patients. The potential for DCS to provide continuous, noninvasive bedside monitoring for the purpose of CBF management and individualized care is demonstrated.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA. meeri@sas.upenn.edu
authors.forename: Meeri N
authors.initials: MN
authors.lastname: Kim
authors.forename: Turgut
authors.initials: T
authors.lastname: Durduran
authors.forename: Suzanne
authors.initials: S
authors.lastname: Frangos
authors.forename: Brian L
authors.initials: BL
authors.lastname: Edlow
authors.forename: Erin M
authors.initials: EM
authors.lastname: Buckley
authors.forename: Heather E
authors.initials: HE
authors.lastname: Moss
authors.forename: Chao
authors.initials: C
authors.lastname: Zhou
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Yu
authors.forename: Regine
authors.initials: R
authors.lastname: Choe
authors.forename: Eileen
authors.initials: E
authors.lastname: Maloney-Wilensky
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Wolf
authors.forename: M Sean
authors.initials: MS
authors.lastname: Grady
authors.forename: Joel H
authors.initials: JH
authors.lastname: Greenberg
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Levine
authors.forename: Arjun G
authors.initials: AG
authors.lastname: Yodh
authors.forename: John A
authors.initials: JA
authors.lastname: Detre
authors.forename: W Andrew
authors.initials: WA
authors.lastname: Kofke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D002545:Brain Ischemia / Q000175:diagnosis* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D003422:Critical Care / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D012720:Severity of Illness Index; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis* / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D010100:Oxygen