Background: In acute stroke patients, there is a need for noninvasive measurement to monitor blood flow-based therapies. We investigated the utility of near-infrared spectroscopy (NIRS) to determine cerebral perfusion in these patients.
Methods: Eleven patients were investigated within 1.4 +/- 2.2 days after onset of an ischemic middle cerebral artery infarction by monitoring the kinetics of an intravenous bolus of indocyanine green (ICG). For ICG kinetics, bolus peak time, time to peak (TTP = time between 0 and 100% ICG maximum), maximum ICG concentration, rise time (time between 10 and 90% ICG maximum), slope (maximum ICG/TTP), and blood flow index (BFI = maximum ICG/rise time) were obtained. Perfusion-weighted MRI (PWI) and NIRS measurements were performed within 24 h, and the interhemispherical differences of TTP values were compared.
Results: Stroke patients showed an increased bolus peak time (p < 0.02), TTP (p < 0.01), and rise time (p < 0.01), whereas slope (p < 0.01) and BFI (p < 0.01) were diminished at the site of infarction as compared to the unaffected hemisphere. The interhemispherical differences of TTP as measured by PWI and NIRS were closely correlated (r = 0.86).
Conclusions: Noninvasive measurements of cerebral ICG kinetics by NIRS provide a useful means of detecting cerebral perfusion deficits in patients with acute stroke, which correlate well with those obtained by PWI.