1. Articles from Joel Ramjist

    1-13 of 13
    1. Optical coherence tomography–guided flow diversion for aneurysmal treatment

      Optical coherence tomography–guided flow diversion for aneurysmal treatment

      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 ...

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    2. Optical coherence tomography imaging after endovascular thrombectomy for basilar artery occlusion: report of 3 cases

      Optical coherence tomography imaging after endovascular thrombectomy for basilar artery occlusion: report of 3 cases

      Studies evaluating individuals for endothelial injury after endovascular thrombectomy (EVT) have been done by means of retrieved human thrombus, MR vessel-wall imaging, and animal histopathological studies. These techniques have limitations, because MR imaging has insufficient spatial resolution to directly visualize endothelium, and histopathological examinations are performed ex vivo and are unable to provide real-time patterns of injury. The purpose of the current study was to obtain in vivo intraluminal imaging after EVT by using optical coherence tomography (OCT), examining for evidence of endothelial injury in real time. Three consecutive patients with acute basilar artery occlusion underwent OCT imaging immediately after ...

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    3. Optical Coherence Tomography as an Adjunct During Carotid Artery Stenting for Carotid Atherosclerotic Disease

      Optical Coherence Tomography as an Adjunct During Carotid Artery Stenting for Carotid Atherosclerotic Disease

      Purpose Carotid artery stenting (CAS) has been proven to decrease the risk of stroke in symptomatic patients with moderate/high-grade carotid stenosis; however, there is an increased periprocedural risk of stroke with CAS compared to carotid endarterectomy. The goal of this article is to report the utilization of endovascular optical coherence tomography (OCT) during CAS to aid in the identification of stent malapposition, plaque prolapse, and adjacent residual thrombus that could cause periprocedural stroke. Methods Approval was obtained for endovascular OCT imaging in patients undergoing CAS. Images were obtained before and after stenting. Images were acquired with proximal balloon occlusion ...

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    4. Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography

      Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography

      In this Letter, we propose a beam-shifting optical coherence tomography scheme for speckle reduction and blood flow rate calculation, where variations of the speckle pattern and Doppler angle were generated by parallel shifting of the sample beam incident on the objective lens. The resultant optical coherent tomography images could then be averaged for speckle noise reduction and simultaneously analyzed for flow rate measurement. The performance of the proposed technique was verified by both phantom and in vivo experiments.

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    5. Carotid artery stenting with optical coherence tomography

      Carotid artery stenting with optical coherence tomography

      A 61-year-old man underwent a left cervical internal carotid artery stenting following a recent ischemic stroke. Postoperative angiography was satisfactory and did not reveal any in-stent filling defect ( figure 1A ). Optical coherence tomography (OCT) probe was used to visualize the endoluminal area following stenting. OCT confirmed optimum placement of the stent and reveled a small plaque protrusion from the stent struts following deployment ( figure 1B ).

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    6. High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging

      High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging

      In this paper, a multi-beam scanning technique is proposed to optimize the microvascular images of human skin obtained with Doppler effect based methods and speckle variance processing. Flow phantom experiments were performed to investigate the suitability for combining multi-beam data to achieve enhanced microvascular imaging. To our surprise, the highly variable spot sizes (ranging from 13 to 77 μm) encountered in high numerical aperture multi-beam OCT system imaging the same target provided reasonably uniform Doppler variance and speckle variance responses as functions of flow velocity, which formed the basis for combining them to obtain better microvascular imaging without scanning penalty ...

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    7. Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo

      Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo

      In this paper, a multi-beam optical coherence tomography (OCT) was used to reconstruct the microvascular image of human skin in vivo with phase resolved Doppler OCT (PRDOCT), phase resolved Doppler variance (PRDV) and speckle variance OCT (svOCT), in which the blood flow image was calculated by averaging the four blood flow images obtained by the four beams. In PRDOCT method, it is difficult to detect the blood flow perpendicular to optical axis of the probe beam for single beam OCT, but the multi-beam scanning method can solve this because the input angles of the four probe beams are slightly different ...

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    8. Evaluation of hemodynamics changes during interventional stent placement using Doppler optical coherence tomography

      Evaluation of hemodynamics changes during interventional stent placement using Doppler optical coherence tomography

      Carotid atherosclerosis is a critical medical concern that can lead to ischemic stroke. Local hemodynamic patterns have also been associated with the development of atherosclerosis, particularly in regions with disturbed flow patterns such as bifurcations. Traditionally, this disease was treated using carotid endarterectomy, however recently there is an increasing trend of carotid artery stenting due to its minimally invasive nature. It is well known that this interventional technique creates changes in vasculature geometry and hemodynamic patterns due to the interaction of stent struts with arterial lumen, and is associated with complications such as distal emboli and restenosis. Currently, there is ...

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    9. Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

      Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

      The use of gas assistance in laser machining hard materials is well established in manufacturing but not in the context of surgery. Laser cutting of osseous tissue in the context of neurosurgery can benefit from gas-assist but requires an understanding of flow and pressure effects to minimize neural tissue damage. In this study we acquire volumetric flow rates through a gas nozzle on the spinal cord, with dura and without dura

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    10. Feature Of The Week 01/18/15: An Integrated Optical Coherence Tomography-Gas Nozzle System for Surgical Laser Ablation Applications

      Feature Of The Week 01/18/15: An Integrated Optical Coherence Tomography-Gas Nozzle System for Surgical Laser Ablation Applications

      Gas assisted laser machining of materials is a common practice in the manufacturing industry. Advantages in using gas assistance include reducing the likelihood of flare-ups in flammable materials and clearing away ablated material in the cutting path. Current surgical procedures and research do not take advantage of this and in the case for resecting osseous tissue, gas assisted ablation can help minimize charring and clear away debris from the surgical site. In the context of neurosurgery, the objective is to cut through osseous tissue without damaging the underlying neural structures. Different inert gas flow rates used in laser machining could ...

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    11. Development of an integrated optical coherence tomography-gas nozzle system for surgical laser ablation applications: preliminary findings of in situ spinal cord deformation due to gas flow effects

      Development of an integrated optical coherence tomography-gas nozzle system for surgical laser ablation applications: preliminary findings of in situ spinal cord deformation due to gas flow effects

      Gas assisted laser machining of materials is a common practice in the manufacturing industry. Advantages in using gas assistance include reducing the likelihood of flare-ups in flammable materials and clearing away ablated material in the cutting path. Current surgical procedures and research do not take advantage of this and in the case for resecting osseous tissue, gas assisted ablation can help minimize charring and clear away debris from the surgical site. In the context of neurosurgery, the objective is to cut through osseous tissue without damaging the underlying neural structures. Different inert gas flow rates used in laser machining could ...

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    12. Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling

      Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling

      Hemodynamics plays a critical role in the development of atherosclerosis, specifically in regions of curved vasculature such as bifurcations exhibiting irregular blood flow profiles. Carotid atherosclerotic disease can be intervened by stent implantation, but this may result in greater alterations to local blood flow and consequently further complications. This study demonstrates the use of a variant of Doppler optical coherence tomography (DOCT) known as split spectrum DOCT (ssDOCT) to evaluate hemodynamic patterns both before and after stent implantation in the bifurcation junction in the internal carotid artery (ICA). Computational fluid dynamics (CFD) models were constructed to simulate blood velocity profiles ...

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    13. Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia

      Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia

      Speckle statistics of flowing scatterers have been well documented in the literature. Speckle variance optical coherence tomography exploits the large variance values of intensity changes in time caused mainly by the random backscattering of light resulting from translational activity of red blood cells to map out the microvascular networks. A method to map out the microvasculature malformation of skin based on the time-domain histograms of individual pixels is presented with results obtained from both normal skin and skin containing vascular malformation. Results demonstrated that this method can potentially map out deeper blood vessels and enhance the visualization of microvasculature in ...

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    1-13 of 13
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  2. Topics in the News

    1. (13 articles) Victor X. D. Yang
    2. (12 articles) Joel Ramjist
    3. (11 articles) Ryerson University
    4. (9 articles) Sunnybrook Health Sciences Centre
    5. (9 articles) University of Toronto
    6. (5 articles) Cuiru Sun
    7. (5 articles) Ronnie Wong
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    Histogram flow mapping with optical coherence tomography for in vivo skin angiography of hereditary hemorrhagic telangiectasia Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling Development of an integrated optical coherence tomography-gas nozzle system for surgical laser ablation applications: preliminary findings of in situ spinal cord deformation due to gas flow effects Feature Of The Week 01/18/15: An Integrated Optical Coherence Tomography-Gas Nozzle System for Surgical Laser Ablation Applications Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography Evaluation of hemodynamics changes during interventional stent placement using Doppler optical coherence tomography Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo High speed, wide velocity dynamic range Doppler optical coherence tomography (Part V): Optimal utilization of multi-beam scanning for Doppler and speckle variance microvascular imaging Carotid artery stenting with optical coherence tomography Beam-shifting technique for speckle reduction and flow rate measurement in optical coherence tomography Optical Coherence Tomography Angiography in Myopic Patients Quantification of retinal microvasculature and neurodegeneration changes in branch retinal vein occlusion after resolution of cystoid macular edema on optical coherence tomography angiography