1. Articles from Jamil Jivraj

    1-12 of 12
    1. Optical coherence tomography for dynamic axial correction of an optical end-effector for robot-guided surgical laser ablation

      Optical coherence tomography for dynamic axial correction of an optical end-effector for robot-guided surgical laser ablation

      Robot-guided laser ablation for surgical applications potentially offers many advantages compared to by-hand mechanical tissue cutting. However, given that tissue can be rough and/or uneven, ablation quality can be compromised if the beam waist deviates significantly from the target tissue surface. Therefore, we present a method that uses optical coherence tomography (OCT) for dynamic refocusing of robot-guided surgical laser ablation. A 7-DOF robotic manipulator with an OCT-equipped optical payload was used to simulate robotic guided laser osteotomy. M-mode OCT feedback is used for continuous surface detection to correct for axial deviations along the ablation path due to surface nonuniformity ...

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    2. 2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography

      2D MEMS-based high-speed beam-shifting technique for speckle noise reduction and flow rate measurement in optical coherence tomography

      In this manuscript, a two-dimensional (2D) micro-electro-mechanical system (MEMS)-based, high-speed beam-shifting spectral domain optical coherence tomography (MHB-SDOCT) is proposed for speckle noise reduction and absolute flow rate measurement. By combining a zigzag scanning protocol, the frame rates of 45.2 Hz for speckle reduction and 25.6 Hz for flow rate measurement are achieved for in-vivo tissue imaging. Phantom experimental results have shown that by setting the incident beam angle to ϕ = 4.76° (between optical axis of objective lens and beam axis) and rotating the beam about the optical axis in 17 discrete angular positions, 91% of speckle ...

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    3. 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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    4. Intraoperative optical coherence tomography of the cerebral cortex using a 7 degree-of freedom robotic arm

      Intraoperative optical coherence tomography of the cerebral cortex using a 7 degree-of freedom robotic arm

      Optical Coherence Tomography (OCT) provides a high-resolution imaging technique with limited depth penetration. The current use of OCT is limited to relatively small areas of tissue for anatomical structure diagnosis or minimally invasive guided surgery. In this study, we propose to image a large area of the surface of the cerebral cortex. This experiment aims to evaluate the potential difficulties encountered when applying OCT imaging to large and irregular surface areas. The current state-of-the-art OCT imaging technology uses scanning systems with at most 3 degrees-of-freedom (DOF) to obtain a 3D image representation of the sample tissue. We propose the use ...

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    5. Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography imaging

      Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography imaging

      Endovascular Optical Coherence Tomography (OCT) has previously been used in both bench-top and clinical environments to produce vascular images, and can be helpful in characterizing, among other pathologies, plaque build-up and impedances to normal blood ow. The raw data produced can also be processed to yield high- resolution blood velocity information, but this computation is expensive and has previously only been available a posteriori using post-processing software. Real-time Doppler OCT (DOCT) imaging has been demonstrated before in the skin and eye, but this capability has not been available to vascular surgeons. Graphics Processing Units (GPUs) can be used to dramatically ...

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    6. 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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    7. Cadaveric in-situ testing of optical coherence tomography system-based skull base surgery guidance

      Cadaveric in-situ testing of optical coherence tomography system-based skull base surgery guidance

      Optical Coherence Tomography (OCT) has extensive potential for producing clinical impact in the field of neurological diseases. A neurosurgical OCT hand-held forward viewing probe in Bayonet shape has been developed. In this study, we test the feasibility of integrating this imaging probe with modern navigation technology for guidance and monitoring of skull base surgery. Cadaver heads were used to simulate relevant surgical approaches for treatment of sellar, parasellar and skull base pathology. A high-resolution 3D CT scan was performed on the cadaver head to provide baseline data for navigation. The cadaver head was mounted on existing 3- or 4-point fixation ...

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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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    1-12 of 12
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  2. Topics in the News

    1. (12 articles) Ryerson University
    2. (7 articles) Sunnybrook Health Sciences Centre
    3. (7 articles) University of Toronto
    4. (3 articles) Nanjing University of Science and Technology
    5. (1 articles) Harvard University
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    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 Cadaveric in-situ testing of optical coherence tomography system-based skull base surgery guidance Multi-beam optical coherence tomography for microvascular imaging of human skin in vivo Graphics processor unit acceleration enables realtime endovascular Doppler optical coherence tomography 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 Optical coherence tomography for dynamic axial correction of an optical end-effector for robot-guided surgical laser ablation Post-Doctoral and Graduate Student Research Positions at the University of Illinois Urbana-Champaign Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy