Optical bedside monitoring of cerebral perfusion: technological and methodological advances applied in a study on acute ischemic stroke

• Published in: Journal of Biomedical Optics 2010-11, Vol.15 (6), p.061708-061708
• Main Authors: Steinkellner, Oliver, Gruber, Clemens, Wabnitz, Heidrun, Jelzow, Alexander, Steinbrink, Jens M, Fiebach, Jochen B, Macdonald, Rainer, Obrig, Hellmuth
• Format: Article
• Language: English
• Subjects: Blood Flow Velocity; Cerebrovascular Circulation; Contrast agents; Delay; Equipment Design; Equipment Failure Analysis; Humans; Ischemic Attack, Transient - diagnosis; Ischemic Attack, Transient - physiopathology; Lasers; Monitoring; Patients; Pattern Recognition, Automated - methods; Perfusion Imaging - instrumentation; Photometry - instrumentation; Point-of-Care Systems; Reproducibility of Results; Sensitivity and Specificity; Strokes; Tracking
• ISSN: 1083-3668; 1560-2281
• DOI: 10.1117/1.3505009

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.