Intraoperative monitoring of cerebral blood flow by laser speckle contrast analysis

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Currently, reliable low-cost and noninvasive techniques to assess cerebral perfusion in the operating room are not available. The authors report on their first clinical experience with laser speckle contrast analysis (LASCA) as a complementary imaging tool for the noninvasive and dynamic assessment of cerebral blood flow (CBF) during neurovascular surgery. The purpose of this preliminary study was to address the general feasibility of LASCA in terms of handling and image quality and to provide an example of its clinical implications.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Laser speckle contrast analysis was performed in patients undergoing cerebral revascularization procedures for the treatment of hemodynamic compromise and complex aneurysms. The portable LASCA device was centered over the surgical field, and continuous 5-minute recordings of relative CBF were obtained. In the case of flow augmentation for hemodynamic compromise, CBF monitoring was performed before and after completion of the anastomosis. In the case of flow replacement for parent artery sacrifice, CBF monitoring was performed during consecutive 30-second test occlusions of the radial artery graft after proximal internal carotid artery sacrifice and the subsequent initiation of blood flow through the bypass.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>In all cases, the authors achieved good visualization of relative CBF in addition to flow imaging in both the bypass graft and the cortical vasculature. During a sudden CBF decrease after test occlusion of the radial artery graft and subsequent flow initiation through the bypass, LASCA allowed immediate visualization and measurement of relative CBF in excellent spatiotemporal resolution.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>In this study LASCA offered noninvasive and rapid intraoperative assessment of relative CBF, which can be used for optimizing neurovascular procedures.</jats:p></jats:sec>

Intraoperative optical imaging of intrinsic signals: a reliable method for visualizing stimulated functional brain areas during surgery

“…11,17,22 By use of a wide field laser Doppler imaging setup mounted to a neurosurgical microscope, changes in the perfusion of the cortex caused by finger tapping in an awake patient have been demonstrated. 22 In a few patients, the feasibility of imaging general brain perfusion by using laser speckle imaging was also shown.…”

“…22 In a few patients, the feasibility of imaging general brain perfusion by using laser speckle imaging was also shown. 11,17 However, both methods need an additional laser source integrated into the surgical microscope, which increases complexity of the imaging setup and requires additional expenditure for the medical approval by regulatory boards. Instead, optical imaging can easily be performed by using a standard surgical microscope.…”

Infarct prediction by intraoperative laser speckle imaging in patients with malignant hemispheric stroke

“…23 For this purpose, intraoperative laser speckle contrast imaging was recently shown suitable for continuous realtime blood flow and perfusion monitoring in a simple, fast and cost-effective manner with minimal disruption of surgical workflow and reduced infrastructure requirements. [14][15][16][17]24,25 To date, however, the potential of iLSI to deliver quantitative information on relative perfusion with the possibility of immediately identifying tissue in danger of irreversible infarction during neurosurgical procedures has not yet been explored. Therefore, the present study was designed to characterize the prognostic value of iLSI by identifying critical iLSI-specific perfusion thresholds for prediction or exclusion of cortical infarction in the human brain.…”

“…[9][10][11][12][13] More recently, intraoperative Laser Speckle Imaging (iLSI) was shown sensitive to blood flow changes in the human brain and feasible for non-invasive real-time monitoring of relative cerebral blood flow (CBF) within the cortical parenchyma. [14][15][16][17] Importantly, iLSI can also be smoothly integrated into surgical workflow without requiring demanding logistics. At present, however, clinical validation of iLSI remains challenging due to the complex physics that relate the measured cerebral perfusion values to the underlying absolute CBF 18 and because information on perfusion is only obtained on the surface of the brain.…”

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

“…Beyond bench-side physiological research, there are direct implications for prognostic, diagnostic, and intraoperative imaging applications, as speckle imaging of microcirculatory flows is increasingly becoming applied for gauging local and systemic tissue health [8,9]. Consequently, laser speckle flowmetry studies are expanding in dermatological [10][11][12][13][14], ophthalmological [15][16][17], and neurosurgical settings [18][19][20].…”