title: Optical bedside monitoring of cerebral perfusion: technological and methodological advances applied in a study on acute ischemic stroke.
abstract: We present results of a clinical study on bedside perfusion monitoring of the human brain by optical bolus tracking. We measure the kinetics of the contrast agent indocyanine green using time-domain near-IR spectroscopy (tdNIRS) in 10 patients suffering from acute unilateral ischemic stroke. In all patients, a delay of the bolus over the affected when compared to the unaffected hemisphere is found (mean: 1.5 s, range: 0.2 s to 5.2 s). A portable time-domain near-IR reflectometer is optimized and approved for clinical studies. Data analysis based on statistical moments of time-of-flight distributions of diffusely reflected photons enables high sensitivity to intracerebral changes in bolus kinetics. Since the second centralized moment, variance, is preferentially sensitive to deep absorption changes, it provides a suitable representation of the cerebral signals relevant for perfusion monitoring in stroke. We show that variance-based bolus tracking is also less susceptible to motion artifacts, which often occur in severely affected patients. We present data that clearly manifest the applicability of the tdNIRS approach to assess cerebral perfusion in acute stroke patients at the bedside. This may be of high relevance to its introduction as a monitoring tool on stroke units.
authors.affiliation: Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany. Oliver.Steinkellner@ptb.de
authors.forename: Oliver
authors.initials: O
authors.lastname: Steinkellner
authors.forename: Clemens
authors.initials: C
authors.lastname: Gruber
authors.forename: Heidrun
authors.initials: H
authors.lastname: Wabnitz
authors.forename: Alexander
authors.initials: A
authors.lastname: Jelzow
authors.forename: Jens
authors.initials: J
authors.lastname: Steinbrink
authors.forename: Jochen B
authors.initials: JB
authors.lastname: Fiebach
authors.forename: Rainer
authors.initials: R
authors.lastname: Macdonald
authors.forename: Hellmuth
authors.initials: H
authors.lastname: Obrig
mesh_terms: D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis* / Q000503:physiopathology*; D007834:Lasers; D010363:Pattern Recognition, Automated / Q000379:methods*; D055420:Perfusion Imaging / Q000295:instrumentation*; D010783:Photometry / Q000295:instrumentation*; D019095:Point-of-Care Systems; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity