System Design And Key Techniques For Intraoperatively Real-time Monitoring Of Cerebral Blood Flow

The intraoperative monitoring of cerebral blood flow (CBF) is ofinterest in neuroscience research with rodent model. Real time CBF offersthe assessment of hemodynamic responses throughout the process ofneurosurgery, including obliteration of intracranial aneurysms, resection ofbrain and spinal arteriovenous malformations and creation of extracranial-to-intracranial bypass grafts. In addition, intraoperative CBF can alsoprovide an early biomarker which can be used for guiding the surgery orimproving the surgical skills. Our lab has developed high spatio-temporalresolution Laser Speckle Contrast Imaging (LSCI) technology that can beused for acquiring2D CBF images. However, most current LSCI techniquesrequire the anesthetized experimental animals in prone position. Yet in manyexperiments, e.g. rodent suture-line model of stroke, the animal has to bepositioned in a supine position, and moved during the experiment, whichmakes the intraoperative LSCI impossible.In this study, we designed a novel operation bench for intraoperativelyreal-time monitoring of CBF during the surgery. A rotatable operation platewith a modified stereotaxic frame was designed for the CBF monitoring insupine position. LSCI imager was fixed under the plate and real-time CBFcan be monitored during the surgery. A graphic interface of software isavailable for real-time CBF acquisition, analysis, display and data saving atselected ROIs. The real-time registration of raw speckle image wasimplemented to correct the misalignment due to motion effects.To test the performance of intraoperative CBF monitoring, weimplemented a rat intraluminal filament MCAO model on the operationbench. Throughout the experiment, CBF of the contralateral cortex was computed and displayed simultaneously. The images were not affected fromthe motion introduced by surgery operation. Furthermore, we selected asegment of a major artery as ROI and the average CBF within it wascomputed as baseline data before we inserted the filament into the transectedexternal carotid artery. Then the quantitative CBF changes were shown in aseparate window to indicate the process of surgery, so that the operator canobserve the real time CBF responses during the surgery. All CBF data weresaved for post-operation processing.Such a design enables the intraoperative CBF monitoring in rodentexperimental study, e.g. MCAO model, neurovascular surgery, orcardiovascular surgery.