Study Of The Cerebral Blood Flow Changes During Guided Rodent Surgery With Real-time Laser Speckle Imaging Technology

Middle cerebral artery occlusion?MCAO?by intraluminal suture is one of the most commonly used stroke models.Due to the variance of animal anatomy and surgical operation,creating a stable infarct volume has always been challenging for technicians.So far,the only intraoperative method for confirming the success of MCAO is to use the laser Doppler flowmetry?LDF?to check the cerebral blood flow?CBF?drop in MCA immediately after the surgery.However,because of the high sensitivity to motion and the lack in spatial resolution,LDF in most cases only could be used as a post-surgical confirmation.To ensure a successful and stable MCAO,the depth of filament insertion from the bifurcation of common carotid artery toward the middle cerebral artery?MCA?should be carefully controlled.Our previous work has reported the success of the two-dimensional technique of laser speckle imaging?LSI?of CBF as an early and real-time predictor of ischemic lesion after stroke in MCAO surgery.Compared with LDF,LSI provides full-field CBF information with high spatial and temporal resolution.Our experiments indicated that the changes of CBF at the first minute after the stroke was significantly correlated with the lesion size at 24 hours after the stroke.In order to compare the prognostic of different vessels,we analyzed the correlation between the CBF levels in major artery,vein and the capillary bed with the lesion volume at 24 hours post surgery,respectively.The results show that ipsilesional artery blood flow is of more prognostic value in MCAO lesion than the CBF in veins and capillaries.In this study,we further investigated CBF changes in the affected cortex using LSI when advancing suture during MCAO surgery.The area of more than 50%CBF drop(CBF₅₀)showed an increase from 20.9%to 69.1%when the insertion depth increased from 1.6 cm to 1.8 cm.Using the real-time CBF₅₀ marker to guide suture insertion during the surgery,our animal experiments showed that intraoperative CBF-guided surgery could improve the stability of MCAO significantly with a more consistent infarct volume?from 0.417±0.217 cm³ to 0.477±0.134 cm³?and less mortality?from 75%to 100%?.Cardiopulmonary bypass?CPB?and deep hypothermic circulatory arrest?DHCA?are important techniques often used in complex cardiac surgery for neonates and infants heart diseases.CBF serves as an important physiological parameter and provides valuable hemodynamic information during the surgery.In this study,we acquired the real-time CBF images during the whole CPB/DHCA rat model.Relative CBF velocity in veins and arteries in bilateral hemispheres dropped significantly during cooling period and reached to nearly zero during arrest period?n=5?.The real-time full-field CBF imaging during the CPB/DHCA surgery could add more insights into the operation and be utilized to study the surgical protocols with the ultimate goal of reducing neurologic injury after surgery.