Sunnybrook Health Sciences Centre

En Face Optical Coherence Tomography in Diagnosis of Persistent Subretinal Fluid & Outer Retinal Folds after Rhegmatogenous Retinal Detachment Repair

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Purpose To evaluate the role of en face optical coherence tomography (OCT) as a diagnostic tool for the detection of persistent subretinal fluid (PSRF) and outer retinal folds (ORF) following successful rhegmatogenous retinal detachment (RRD) repair. Design Observational post hoc analysis of two prospective surgical trials. Participants All patients with gradable (signal strength ≥ 5 and no segmentation error) 6x6 mm macular cube scans using spectral-domain OCT (SD-OCT) (Carl Zeiss Meditec, Jena, Germany) obtained between 1 and 2 months postoperatively were included in this study. Methods Scans were assessed for the presence or absence of PSRF or ORFs using en face OCT and cross-sectional B scans by two masked graders with any disagreements adjudicated by the third senior masked grader. Main Outcome Measure Sensitivity, specificity and predictive accuracy {using area under curve (AUC)} of en face OCT in comparison to cross-sectional OCT as the gold standard Results Two hu...

Prognostic Features of Preoperative Optical Coherence Tomography in Retinal Detachments: A systematic review and meta-analysis

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Topic: To evaluate the prognostic association between preoperative features seen on optical coherence tomography (OCT) imaging and postoperative visual acuity (VA) outcomes in rhegmatogenous retinal detachments (RRD). Clinical relevance: Currently, there is limited literature on the prognostic value of preoperative RRD OCT features. Methods: A literature search was conducted on Ovid MEDLINE, EMBASE and Cochrane CENTRAL from inception through September 15, 2022. A meta-analysis was performed using a random-effects model. Quality of studies and evidence was assessed using the JBI tools and GRADE framework, respectively. Results: A total of 1,671 eyes of 1,670 patients from 29 observational studies were included. Eighty-nine percent of eyes had a macula-off RRD at presentation. The mean average duration of detachment was 15±10 days. The majority of eyes (62%) underwent pars plana vitrectomy. Six preoperative OCT features were analyzed: height of retinal detachment (HRD) at the f...

Imaging probe with rotatable core

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The present disclosure provides for an imaging probe with a rotatable core which allows for rotating imaging assembly that is larger in diameter than the lumen in which the rotatable core resides, as well as methods to construct said probes. The imaging probes are generally elongate flexible imaging catheters for use in cardiovascular procedures. ( Read Full Article )

Conavi Medical’s Novasight Hybrid System Now In Use at Sunnybrook Health Sciences Centre

Conavi Medical Inc. ( www.conavi.com ), a leader of hybrid imaging guidance for common minimally invasive heart procedures, and Sunnybrook Health Sciences Centre , today announced that the Novasight Hybrid System is now being used for clinical procedures by interventional cardiologists as part of the Schulich Heart Program. Sunnybrook’s Schulich Heart Program is one of Canada’s leading cardiac and vascular care centres with an international reputation for pioneering some of the world’s most innovative ways to diagnose and treat the heart and damaged blood vessels. The hybrid intravascular ultrasound (IVUS) and optical coherence tomography (OCT) imaging platform, now called Novasight Hybrid System, was initially invented at Sunnybrook Research Institute (SRI) by Dr. Brian Courtney, a scientist and interventional cardiologist. It is the first and only clinical system available on the market that enables simultaneous and co-registered imaging of coronary arteries with...

Time interval optimized optical coherence tomographic angiography for bulk motion suppression on human skin

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Bulk motions occurred during in vivo scanning could modulate the backscattered light signals with the same mechanism of moving scatterers (such as red blood cells), so bulk motion suppression plays a key role for optical coherence tomographic angiography (OCTA) applications. One classic method to overcome this issue is to compensate the bulk motions with image registration algorithms before calculating vascular signals, which is however computationally intensive and makes real-time screening (a key feature for clinical devices) challenging. In this work, we investigated the influence of the time interval (between consecutive B-scans) on the microvascular images calculated with the recently proposed differential standard deviation of log-scale intensity (DSDLI) algorithm. An optimized time interval was successfully found and in vivo experiments were implemented for performance verification. The results showed that bulk-motion-suppressed high-contrast microvascular images could be obt...

Quantification metrics for telangiectasia using optical coherence tomography

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Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder that causes vascular malformations throughout the body. The most prevalent and accessible of these lesions are found throughout the skin and mucosa, and often rupture causing bleeding and anemia. A recent increase in potential HHT treatments have created a demand for quantitative metrics that can objectively measure the efficacy of new and developing treatments. We employ optical coherence tomography (OCT)-a high resolution, non-invasive imaging modality in a novel pipeline to image and quantitatively characterize dermal HHT lesion behavior over time or throughout the course of treatment. This study is aimed at detecting detailed morphological changes of dermal HHT lesions to understand the underlying dynamic processes of the disease. We present refined metrics tailored for HHT, developed from a pilot study using 3 HHT patients and 6 lesions over the course of multiple imaging dates, totalling to 26 lesion...

Minimally invasive intrathecal spinal cord imaging with optical coherence tomography

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ignificance: Imaging of the spinal cord is challenging due to the surrounding bony anatomy, physiologic motion, and the small diameter of the spinal cord. This precludes the use of non-invasive imaging techniques in assessing structural changes related to trauma and evaluating residual function. Aim: The purpose of our research was to apply endovascular technology and techniques and construct a preclinical animal model of intrathecal spinal cord imaging using optical coherence tomography (OCT). Approach: Five animals (2 Yorkshire Swine and 3 New Zealand Rabbits) were utilized. Intrathecal access was gained using a 16-guage Tuohy, and an OCT catheter was advanced under roadmap technique into the cervical canal. The OCT catheter has a motorized pullback, and a total length of 54 mm of the spinal canal is imaged. Results: Image acquisition was successful for all animals. There were no instances of difficult catheter navigation, enabling OCT imaging rostrally to C2. The thecal sac provi...

Endovascular Cerebral Venous Sinus Imaging with Optical Coherence Tomography

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BACKGROUND AND PURPOSE: Imaging of the cerebral venous sinuses has evolved Substantially during the past 2 decades, and most recently intravascular sinus imaging with sonography has shed light on the pathophysiology of sinus thrombosis and intracranial hypertension. Optical coherence tomography is the highest resolution intravascular imaging technique available but has not been previously used in cerebral sinus imaging. The purpose of this study was to develop a preclinical animal model of endovascular optical coherence tomography cerebral venous sinus imaging and compare optical coherence tomography findings with histology. MATERIALS AND METHODS: Four consecutive Yorkshire swine were selected. The superior sagittal sinus was first catheterized with a microwire, and the optical coherence tomography catheter was delivered via a monorail technique into the sinus. Luminal blood was cleared with a single arterial injection. After structural and Doppler optical coherence tomography imagi...

Endovascular optical coherence tomography imaging in cerebrovascular disease

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Endovascular optical coherence tomography (OCT) is the highest resolution imaging modality currently available with spatial resolution of 10 µm. Although originally developed for interventional cardiology, the ability to visualize the luminal environment and anatomy, along with the stent-vessel interaction could be of great utility for various cerebrovascular diseases, and the adoption of endovascular OCT imaging in the evolving field of interventional neuroradiology seems instinctive. The purpose of this study is to conduct a systematic review of the literature regarding applications of endovascular OCT in the diagnosis and treatment of cerebrovascular diseases. In addition, the authors report their institutional experience with the use of OCT in carotid atherosclerotic disease, cerebral aneurysms, and acute ischemic stroke. A systematic review of the literature was undertaken. Peer-reviewed articles were collected through MEDLINE, Embase, Scopus, and Cochrane Central Registe...

30/80 MHz Bidirectional Dual-Frequency IVUS Feasibility Evaluated In Vivo and for Stent Imaging

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Although intravascular ultrasound (IVUS) is an important tool in guiding complex coronary interventions, the resolution of existing commercial IVUS devices is considerably poorer than that of optical coherence tomography. Dual-frequency IVUS (DF IVUS), incorporating a second, higher frequency transducer, has been proposed as a possible method of overcoming this limitation. Although preliminary studies have shown that DF IVUS can produce complementary images, including large-scale morphology and high detail of superficial features, it has not yet been determined that this approach would be feasible in a more clinically relevant environment. The purpose of this study was to demonstrate the first in vivo use of a 30/80 MHz DF IVUS catheter in visualizing coronary vessels in a porcine model. In addition, two commercially available stents were studied in vitro and in vivo. Clear subjective improvement of visualization of superficial structures is demonstrated, and sufficient dynamic rang...

Real-time en-face Gabor optical coherence tomographic angiography on human skin using CUDA GPU

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We recently proposed an optical coherence tomographic angiography (OCTA) algorithm, Gabor optical coherence tomographic angiography (GOCTA), which can extract microvascular signals from a spectral domain directly with lower computational complexity compared to other algorithms. In this manuscript, we combine a programmable swept source, an OCT complex signal detecting unit, and graphics process units (GPU) to achieve a real-time en-face GOCTA system for human skin microvascular imaging. The programmable swept source can balance the A-scan rate and the spectral tuning range; the polarization-modulation based complex signal detecting unit can double the imaging depth range, and the GPU can accelerate data processing. C++ and CUDA are used as the programming platform where five parallel threads are created for galvo-driving signal generation, data acquisition, data transfer, data processing, and image display, respectively. Two queues (for the raw data and en-face images, respectively)...

Optical coherence tomography as an adjunct during carotid artery stenting for carotid web

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Consider optical coherence tomography as an adjunct to visualize the membrane of a carotid web, the extent of the web, and aid in placement of a carotid stent. ( Read Full Article )

Gabor optical coherence tomographic angiography (GOCTA) (Part II): theoretical basis of sensitivity improvement and optimization for processing speed

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We previously proposed a Gabor optical coherence tomography angiography (GOCTA) algorithm for spectral domain optical coherence tomography (SDOCT) to extract microvascular signals from spectral fringes directly, with speed improvement of 4 to 20 times over existing methods. In this manuscript, we explored the theoretical basis of GOCTA with comparison of experimental data using solid and liquid displacement sample targets, demonstrating that the majority of the GOCTA sensitivity advantage over speckle variance based techniques was in the small displacement range (< 10 ∼ 20 µm) of the moving target (such as red blood cells). We further normalized GOCTA signal by root-mean-square (RMS) of original fringes, achieving a more uniform image quality, especially at edges of blood vessels where slow flow could occur. Furthermore, by transecting the spectral fringes and using skipped convolution, the data processing speed could be further improved. We quantified the trade-off in ...

Optical Coherence Tomography Guided Antithrombotic Treatment After Endovascular Thrombectomy of the Posterior Circulation

Evidence regarding the role of early (<24 hours) antithrombotics post-revascularization with either intravenous thrombolysis (IVT), endovascular thrombectomy (EVT), or a combination of both remains scarce. In 2018 the American Heart Association/American Stroke Association changed their recommendation, stating that the risk of antithrombotic therapy within the first 24 hours after treatment with IVT (with or without EVT) is uncertain. This was changed after data emerged that early antithrombotics may be safe and may improve outcomes in select patients undergoing EVT. Recently our group showed for the first time that significant residual basilar thrombus can exist after EVT despite complete angiographic revascularization using endovascular optical coherence tomography imaging. This residual thrombus could cause ongoing function-limiting strokes with occlusion of vital basilar perforators after EVT. Therefore, we propose a prospective,non-randomized safety study to evaluate optical ...

Optical coherence tomography–guided flow diversion for aneurysmal treatment

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A 28-year-old man presenting with right third nerve palsy was diagnosed with a giant unruptured aneurysm supplied by the right posterior communicating and cerebral arteries (figure 1, A and B). The aneurysm was treated with flow-diverting stent-assisted coiling. Two months later, he presented with new-onset left-sided weakness, and MRI showed increased edema in the thalamus (figure 1C) and increased aneurysm size and no filling. There was no evidence of stent malapposition with high-resolution cone-beam (VASO) CT (figure 2). Angiography and optical coherence tomography (OCT) imaging demonstrated no stent endothelialization over a patent portion of the aneurysm neck (figure 3). 1,2 A second stent was deployed under OCT guidance for complete aneurysmal embolization. In follow-up at 4 months, the patient was ambulating independently, and repeated MRI showed decrease in the amount of perilesional edema. In summary, OCT allowed for visualization of stent malapposition and small neck remn...

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