Simultaneous imaging of cortical partial oxygen pressure and anatomic structures using a transparent optical sensor foil.
OBJECTIVE
Reliable information of cerebral oxygenation is-besides the monitoring of the intracranial pressure-of eminent interest when treating patients with brain injuries. In this study, we introduce a new, fast, and sensitive method capable of determining the cortical partial oxygen pressure on the surface of the cortex using a special sensor foil.


METHODS
The introduced method exploits the O2-dependent phosphorescence of a thin sensor foil, which is excited by a short light-emitting diode flash. The optical signal is registered by a charge-coupled device camera and analyzed with PC-based software. The adequacy of this method was tested in 10 animals. The sensor device was placed directly over the cortex after craniotomy and removal of the dura. Arterial oxygen pressure was systematically varied by modifying the ventilation gas mixture. A total of 225 measurements were performed within 4 regions of interest.


RESULTS
Obtained results were sufficient in each case. The pO2 over the cortex correlated well with arterial pO2. Measurements over arteries showed a correlation coefficient of 0.72 (P<0.001), over veins 0.58 (P<0.001), over cortical parenchyma 0.46 (P<0.001), and in a larger region of interest containing vessels and cortical tissue 0.59 (P<0.001). The frequency of the measurements was 7 Hz with a single measurement covering an area of 30 x 30 microm.


CONCLUSIONS
For the first time, nearly online pO2 maps of a brain cortex can be generated, allowing simultaneously also separate measurements over distinct anatomic structures yielding a good spatial resolution.
Warnat
Jan
J
Department of Neurosurgery, University of Regensburg, Regensburg, Germany. Jan.Warnat@klinik.uni-regensburg.de
Liebsch
Gregor
G
Stoerr
Eva-Maria
EM
Brawanski
Alexander
A
Woertgen
Chris
C
D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism*; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods; D002560:Cerebrovascular Circulation; D005240:Feasibility Studies; D021621:Imaging, Three-Dimensional / Q000379:methods; D008163:Luminescent Measurements / Q000295:instrumentation* / Q000379:methods*; D010100:Oxygen / Q000032:analysis*; D010313:Partial Pressure; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
D010100:Oxygen