Intraoperative Laser Speckle Contrast Imaging For Real-Time Visualization of Cerebral Blood Flow in Cerebrovascular Surgery: Results From Pre-Clinical Studies.

Cerebrovascular surgery can benefit from an intraoperative system that conducts continuous monitoring of cerebral blood flow (CBF). Such a system must be handy, non-invasive, and directly integrated into the surgical workflow. None of the currently available techniques, considered alone, meets all these criteria. Here, we introduce the SurgeON™ system: a newly developed non-invasive modular tool which transmits high-resolution Laser Speckle Contrast Imaging (LSCI) directly onto the eyepiece of the surgical microscope. In preclinical rodent and rabbit models, we show that this system enabled the detection of acute perfusion changes as well as the recording of temporal response patterns and degrees of flow changes in various microvascular settings, such as middle cerebral artery occlusion, femoral artery clipping, and complete or incomplete cortical vessel cautery. During these procedures, a real-time visualization of vasculature and CBF was available in high spatial resolution through the eyepiece as a direct overlay on the live morphological view of the surgical field. Upon comparison with indocyanine green angiography videoangiography (ICG-VA) imaging, also operable via SurgeON, we found that direct-LSCI can produce greater information than ICG-VA and that continuous display of data is advantageous for performing immediate LSCI-guided adjustments in real time.

Noninvasive Assessment of Retinal Blood Flow Using a Novel Handheld Laser Speckle Contrast Imager.

PURPOSE: We assessed the image quality and reproducibility of blood flow measurements from a novel handheld laser speckle imager in handheld and stabilized use cases. METHODS: Eleven dilated human subjects were imaged with the XyCAM Handheld Retinal Imager investigational device (XyCAM HRI) in the handheld and stabilized use case in nine consecutive imaging sessions. Subjects then underwent standard color fundus photography using a Topcon TRC 50DX. The vessel-to-background contrast of the XyCAM HRI red-free photo was compared to the fundus photograph, while the coefficient of variation of blood flow measurements in specific arteries and veins also was determined. RESULTS: Vessel-to-background contrast was statistically greater in the handheld use case when compared to the standard color fundus photographs (P = 0.01). Estimates of mean blood flow velocity (BFV) were highly correlated between the stabilized and handheld use case (r 2 = 0.96). Peak velocity estimates in arteries were significantly higher than those in veins (P < 0.05). CONCLUSIONS: The XyCAM HRI prototype can acquire fundus photographs with the same or better level of clarity as color fundus photographs, and reproducibly acquire functional blood flow information in the handheld use case. TRANSLATIONAL RELEVANCE: To our knowledge, this is the first human study of a handheld laser speckle retinal imaging device. Determination of retinal blood flow has applications to ophthalmic and systemic disease and a portable handheld retinal imager that determines blood flow may be widely adopted at the point of care.