Abstract
Background: The drawbacks of assessing cerebral ischemia using conventional methods such as SPECT or angiography are invasiveness and the inability to repeat measurements. Here, we describe the use of near infrared optical topography (OT) to overcome these disadvantages.
Methods: Twenty-five normal volunteers and 32 patients with cerebral ischemia were enrolled in this study of a 48-channel OT system covering the bilateral fronto-temporal areas. The participants inhaled pure oxygen for 2 minutes and fingertip SpO2 values were monitored. All of the patients with ischemia underwent IMP-SPECT.
Results: The concentration of oxy-hemoglobin determined by OT and the time course of SpO2 in normal individuals increased in a trapezoidal manner in accordance with oxygen inhalation, whereas the increase in oxy-hemoglobin was delayed and/or the peak was lower in ischemic areas. These findings suggested that transmission of the systemic SpO2 wave was delayed and/or reduced in areas of ischemia. Statistical evaluation of the data using principal component analysis showed that the weight of the principal component in the ischemic regions was reduced, findings that agreed with those of IMP-SPECT.
Conclusions: Our results suggested that regional attenuation of the oxy-hemoglobin wave reflects the status of cerebral ischemia, which can be noninvasively assessed using near infrared OT.
