KEYWORDS: Surgery, Laser speckle contrast imaging, Arteries, Laser therapeutics, Animal model studies, Brain, Cerebral blood flow, Simulation of CCA and DLA aggregates, Lutetium, Cranial windows
Rodent middle cerebral artery occlusion (MCAO) model is commonly used in stroke research. Creating a stable infarct volume has always been challenging for technicians due to the variances of animal anatomy and surgical operations. The depth of filament suture advancement strongly influences the infarct volume as well. We investigated the cerebral blood flow (CBF) changes in the affected cortex using laser speckle contrast imaging when advancing suture during MCAO surgery. The relative CBF drop area (CBF50, i.e., the percentage area with CBF less than 50% of the baseline) showed an increase from 20.9% to 69.1% when the insertion depth increased from 1.6 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 significantly improve the stability of MCAO with a more consistent infarct volume and less mortality.
In experimental stroke research, anesthesia is common and serves as a major reason for translational failure. Real-time cerebral blood flow (CBF) monitoring during stroke onset can provide important information for the prediction of brain injury; however, this is difficult to achieve in clinical practice due to various technical problems. We created a photothrombotic focal ischemic stroke model utilizing our self-developed miniature headstage in conscious and freely moving rats. In this model, a high spatiotemporal resolution imager using laser speckle contrast imaging technology was integrated to acquire real-time two-dimensional CBF information during thrombosis. The feasibility, stability, and reliability of the system were tested in terms of CBF, behavior, and T2-weighted magnetic resonance imaging (MRI) findings. After completion of occlusion, the CBF in the targeted cortex of the stroke group was reduced to 16±9% of the baseline value. The mean infarct volume measured by MRI 24 h postmodeling was 77±11 mm3 and correlated well with CBF (R2=0.74). This rodent model of focal cerebral ischemia and real-time blood flow imaging opens the possibility of performing various fundamental and translational studies on stroke without the influence of anesthetics.
Stroke is a worldwide medical emergency and an important issue in stroke research is looking for the early pathophysiological markers which can predict the severity of brain injury. Decreased cerebral blood flow (CBF) has been serving as the most important indicator of ischemic stroke. Particular attention is paid to study the spatio-temporal CBF changes immediately after the onset of stroke in a rat intraluminal filament middle cerebral artery occlusion (MCAO) model and investigation of its correlation with brain infarct volume after 24 h. We implement an on-line laser speckle imaging (LSI) system, which could provide real time high spatio-temporal resolution CBF information before, during, and immediately after the rat MCAO surgery. We found a significant correlation between the affected area with 50% CBF reduction (CBF 50 ) at the first minute after occlusion with the infarct volume. To the best of our knowledge, this is the earliest CBF marker for infarct volume prediction. Based on such a CBF–infarct volume correlation, LSI may be used as a real time guidance for improving the consistency of intraluminal filament MCAO model since the depth of filament insertion could be adjusted promptly and those unsuccessful models could be excluded in the earliest stage.
Optical intrinsic signals (OIS) and laser speckle contrast imaging (LSCI) have been used for years in
the study of the cerebral blood flow (CBF) and hemodynamic responses to the neural activity under
functional stimulation. So far, most in vivo rodent experiments are based on the anesthesia model when
the animals are in unconscious and restrained conditions. The influences of anesthesia on the neural
activity have been documented in literature. In this study, we designed a miniature head-mounted
dual-modal imager in freely moving animals that could monitor in real time the coupling of local
oxygen consumption and blood perfusion of CBF by integrating different imaging modalities of OIS
and LSCI. The system facilitates the study the cortical hemodynamics and neural-hemodynamic
coupling in real time in freely moving animals.
We designed a miniature laser speckle imager that weighs ∼20 g and is 3.1-cm high for full-field high-resolution imaging of cerebral blood flow (CBF) in freely moving animals. Coherent laser light illuminates the cortex through a multimode optical fiber bundle fixed onto the supporting frame of the imager. The reflected lights are then collected by a miniature macrolens system and imaged by a high-resolution CMOS camera at a high frame rate (50 fps). Using this miniature imager, we achieve high spatiotemporal resolution laser speckle contrast imaging of CBF in freely moving animals in real time.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.