Abstract
Although multiple intraoperative cerebral blood flow (CBF) monitoring techniques are currently available, a quantitative method that allows for continuous monitoring and that can be easily integrated into the surgical workflow is still needed. Laser speckle contrast imaging (LSCI) is an optical imaging technique with a high spatiotemporal resolution that has been recently demonstrated as feasible and effective for intraoperative monitoring of CBF during neurosurgical procedures. This study demonstrates the impact of retrospective motion correction on the quantitative analysis of intraoperatively acquired LSCI images. LSCI images were acquired through a surgical microscope during brain tumor resection procedures from 10 patients under baseline conditions and after a cortical stimulation in three of those patients. The patient's electrocardiogram (ECG) was recorded during acquisition for postprocess correction of pulsatile artifacts. Automatic image registration was retrospectively performed to correct for tissue motion artifacts, and the performance of rigid and nonrigid transformations was compared. In baseline cases, the original images had [Formula: see text] noise across 16 regions of interest (ROIs). ECG filtering moderately reduced the noise to [Formula: see text], while image registration resulted in a further noise reduction of [Formula: see text]. Combined ECG filtering and image registration significantly reduced the noise to [Formula: see text] ([Formula: see text]). Using the combined motion correction, accuracy and sensitivity to small changes in CBF were improved in cortical stimulation cases. There was also excellent agreement between rigid and nonrigid registration methods (15/16 ROIs with [Formula: see text] difference). Results from this study demonstrate the importance of motion correction for improved visualization of CBF changes in clinical LSCI images.
Highlights
Because the brain relies on a constant supply of cerebral blood flow (CBF), any prolonged reduction of CBF can greatly increase the patient’s risk for irreversible ischemic brain injury
The speckle contrast images were thresholded to display only speckle contrast values less than 40% of the maximum and were overlaid on top of the color photographs. These image sets show excellent alignment of the anatomical vasculature and the blood flow maps seen in the Laser speckle contrast imaging (LSCI) images, confirming the performance of the microscope-integrated LSCI system
The overlay image highlights a major benefit of integrating LSCI into the surgical microscope: LSCI can provide blood flow maps for the tissue region in the microscope’s field of view (FOV) with the spatial resolution of the microscope
Summary
Because the brain relies on a constant supply of cerebral blood flow (CBF), any prolonged reduction of CBF can greatly increase the patient’s risk for irreversible ischemic brain injury. By monitoring CBF during neurosurgery, surgeons can be promptly warned about a reduction in blood flow, allowing quick intervention to minimize the risks of postoperative neurologic deficits. Optical flow measurement techniques based on dynamic light scattering have the potential to improve many of the shortcomings of the currently available methods. Laser speckle contrast imaging (LSCI) is an optical imaging technique that provides high spatiotemporal resolution and quantitative
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