ActivSight laser speckle contrast imaging compared to indocyanine green in renal perfusion of an animal model

Abstract BACKGROUND: Assessment of the vasculature is critical for overall success in cranial vascular neurological surgery procedures. Although several methods of monitoring cortical perfusion intraoperatively are available, not all are appropriate or convenient in a surgical environment. Recently, 2 optical methods of care have emerged that are able to obtain high spatial resolution images with easily implemented instrumentation: indocyanine green (ICG) angiography and laser speckle contrast imaging (LSCI). OBJECTIVE: To evaluate the usefulness of ICG and LSCI in measuring vessel perfusion. METHODS: An experimental setup was developed that simultaneously collects measurements of ICG fluorescence and LSCI in a rodent model. A 785-nm laser diode was used for both excitation of the ICG dye and the LSCI illumination. A photothrombotic clot model was used to occlude specific vessels within the field of view to enable comparison of the 2 methods for monitoring vessel perfusion. RESULTS: The induced blood flow change demonstrated that ICG is an excellent method for visualizing the volume and type of vessel at a single point in time; however, it is not always an accurate representation of blood flow. In contrast, LSCI provides a continuous and accurate measurement of blood flow changes without the need of an external contrast agent. CONCLUSION: These 2 methods should be used together to obtain a complete understanding of tissue perfusion.

Download Full-text

Laser speckle contrast imaging for visualizing blood flow during cerebral aneurysm surgery: A comparison with indocyanine green angiography

10.1101/2021.04.29.21254954 ◽

2021 ◽

Author(s):

David R. Miller ◽

Ramsey Ashour ◽

Colin T. Sullender ◽

Andrew K. Dunn

Keyword(s):

Blood Flow ◽

Indocyanine Green ◽

Real Time ◽

Indocyanine Green Angiography ◽

Laser Speckle ◽

Normal Operation ◽

Contrast Imaging ◽

Laser Speckle Contrast Imaging ◽

Speckle Contrast ◽

Aneurysm Clipping

AbstractLaser speckle contrast imaging (LSCI) has emerged as a promising tool for intraoperative cerebral blood flow (CBF) monitoring because it produces real-time full-field blood flow maps non-invasively and label-free. In this study, we compare LSCI with indocyanine green angiography (ICGA) to assess CBF during aneurysm clipping surgery in humans. LSCI hardware was attached to the surgical microscope prior to the start of each surgery and did not interfere with the sterile draping of the microscope or normal operation of the microscope. LSCI and ICGA were performed simultaneously to visualize CBF in n=4 aneurysm clipping cases, and LSCI was performed throughout each surgery when the microscope was positioned over the patient. To more easily visualize CBF in real-time, LSCI images were overlaid on the built-in microscope white light camera images and displayed to the neurosurgeon in real-time. Blood flow changes before, during, and after an aneurysm clipping were visualized with LSCI and later verified with ICGA. LSCI was performed continuously throughout the aneurysm clipping process, providing the surgeon with immediate actionable information on the success of the clipping. The results demonstrate that LSCI and ICGA provide different, yet complementary information about vessel perfusion.

Download Full-text

Nephron blood flow dynamics measured by laser speckle contrast imaging

AJP Renal Physiology ◽

10.1152/ajprenal.00417.2010 ◽

2011 ◽

Vol 300 (2) ◽

pp. F319-F329 ◽

Cited By ~ 34

Author(s):

Niels-Henrik Holstein-Rathlou ◽

Olga V. Sosnovtseva ◽

Alexey N. Pavlov ◽

William A. Cupples ◽

Charlotte Mehlin Sorensen ◽

...

Keyword(s):

Blood Flow ◽

Signal Transmission ◽

Experimental Studies ◽

Flow Dynamics ◽

Laser Speckle ◽

Tubuloglomerular Feedback ◽

Contrast Imaging ◽

Laser Speckle Contrast Imaging ◽

Speckle Contrast ◽

Blood Flow Dynamics

Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50–100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic techniques for extracting the desired data and for examining them for evidence of nephron synchronization. Synchronized TGF oscillations were detected in pairs or triplets of nephrons. The amplitude and the frequency of the oscillations changed with time, as did the patterns of synchronization. Synchronization may take place among nephrons not immediately adjacent on the surface of the kidney.

Download Full-text