Dr. Raj Shekhar Profile

Dr. Raj Shekhar

Principal Investigator at Children's National Health System

SPIE Involvement:

Editorial Board Member: Journal of Medical Imaging | Author

Publications (27)

SPIE Journal Paper | 13 September 2024

Augmented reality for point-of-care ultrasound-guided vascular access in pediatric patients using Microsoft HoloLens 2: a preliminary evaluation

Gesiren Zhang, Trong Nguyen, Hadi Fooladi-Talari, Tyler Salvador, Kia Thomas, Daragh Crowley, R. Scott Dingeman, Raj Shekhar

JMI, Vol. 11, Issue 06, 062604, (September 2024) https://doi.org/10.1117/12.10.1117/1.JMI.11.6.062604

KEYWORDS: Ultrasonography, Augmented reality, Head, Tablets, Point-of-care devices, Displays, Image processing, Ultrasound transducers, Image compression, Frame grabbers

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SignificanceConventional ultrasound-guided vascular access procedures are challenging due to the need for anatomical understanding, precise needle manipulation, and hand–eye coordination. Recently, augmented reality (AR)-based guidance has emerged as an aid to improve procedural efficiency and potential outcomes. However, its application in pediatric vascular access has not been comprehensively evaluated.AimWe developed an AR ultrasound application, HoloUS, using the Microsoft HoloLens 2 to display live ultrasound images directly in the proceduralist’s field of view. We presented our evaluation of the effect of using the Microsoft HoloLens 2 for point-of-care ultrasound (POCUS)-guided vascular access in 30 pediatric patients.ApproachA custom software module was developed on a tablet capable of capturing the moving ultrasound image from any ultrasound machine’s screen. The captured image was compressed and sent to the HoloLens 2 via a hotspot without needing Internet access. On the HoloLens 2, we developed a custom software module to receive, decompress, and display the live ultrasound image. Hand gesture and voice command features were implemented for the user to reposition, resize, and change the gain and the contrast of the image. We evaluated 30 (15 successful control and 12 successful interventional) cases completed in a single-center, prospective, randomized study.ResultsThe mean overall rendering latency and the rendering frame rate of the HoloUS application were 139.30 ms (σ=32.02 ms) and 30 frames per second, respectively. The average procedure completion time was 17.3% shorter using AR guidance. The numbers of puncture attempts and needle redirections were similar between the two groups, and the number of head adjustments was minimal in the interventional group.ConclusionWe presented our evaluation of the results from the first study using the Microsoft HoloLens 2 that investigates AR-based POCUS-guided vascular access in pediatric patients. Our evaluation confirmed clinical feasibility and potential improvement in procedural efficiency.

SPIE Journal Paper | 3 February 2021 Open Access

Hybrid electromagnetic-ArUco tracking of laparoscopic ultrasound transducer in laparoscopic video

Xinyang Liu, William Plishker, Raj Shekhar

JMI, Vol. 8, Issue 01, 015001, (February 2021) https://doi.org/10.1117/12.10.1117/1.JMI.8.1.015001

KEYWORDS: Laparoscopy, Cameras, Transducers, Video, Ultrasonography, Zoom lenses, Detection and tracking algorithms, Sensors, Imaging systems, Augmented reality

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Proceedings Article | 8 March 2019 Paper

Segmentation of surgical instruments in laparoscopic videos: training dataset generation and deep-learning-based framework

Eung-Joo Lee, William Plishker, Xinyang Liu, Timothy Kane, Shuvra Bhattacharyya, Raj Shekhar

Proceedings Volume 10951, 109511T (2019) https://doi.org/10.1117/12.2512994

KEYWORDS: Image segmentation, Laparoscopy, Binary data, Video, Neural networks, Magnetic resonance imaging, Data modeling, Instrument modeling, Robotics, Image processing

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Proceedings Article | 8 March 2019 Presentation + Paper

Magnetically anchored pan-tilt stereoscopic robot with optical-inertial stabilization for minimally invasive surgery

Mojtaba Karimi, Saeed Shiry Ghidary, Raj Shekhar, Timothy Kane, Reza Monfaredi

Proceedings Volume 10951, 109511E (2019) https://doi.org/10.1117/12.2513019

KEYWORDS: Cameras, Surgery, Sensors, Video, Telecommunications, Robotics, Stereoscopic cameras, Control systems, Imaging systems

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SPIE Journal Paper | 10 October 2016

Laparoscopic stereoscopic augmented reality: toward a clinically viable electromagnetic tracking solution

Xinyang Liu, Sukryool Kang, William Plishker, George Zaki, Timothy Kane, Raj Shekhar

JMI, Vol. 3, Issue 04, 045001, (October 2016) https://doi.org/10.1117/12.10.1117/1.JMI.3.4.045001

KEYWORDS: Laparoscopy, Sensors, Calibration, Visualization, Ultrasonography, Video, Electromagnetism, Imaging systems, Optical tracking, Cameras

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Proceedings Article | 18 March 2016 Paper

Accurate tracking of tumor volume change during radiotherapy by CT-CBCT registration with intensity correction

Seyoun Park, Adam Robinson, Harry Quon, Ana Kiess, Colette Shen, John Wong, William Plishker, Raj Shekhar, Junghoon Lee

Proceedings Volume 9786, 97860P (2016) https://doi.org/10.1117/12.2217047

KEYWORDS: Image registration, Image segmentation, Radiotherapy, Computed tomography, Image processing algorithms and systems, Graphics processing units, Tumors, Neck

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Proceedings Article | 20 March 2015 Paper

Deformable registration of CT and cone-beam CT by local CBCT intensity correction

Seyoun Park, William Plishker, Raj Shekhar, Harry Quon, John Wong, Junghoon Lee

Proceedings Volume 9413, 941333 (2015) https://doi.org/10.1117/12.2082485

KEYWORDS: Image registration, Computed tomography, Optical flow, Tissues, Cancer, Radiotherapy, Image-guided intervention, Surgery, Medical imaging, Radiation oncology

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Proceedings Article | 18 March 2015 Paper

Application of single-image camera calibration for ultrasound augmented laparoscopic visualization

Xinyang Liu, He Su, Sukryool Kang, Timothy Kane, Raj Shekhar

Proceedings Volume 9415, 94151T (2015) https://doi.org/10.1117/12.2082194

KEYWORDS: Calibration, Cameras, Laparoscopy, Distortion, Visualization, Optical tracking, Corner detection, Ultrasonography, Imaging systems, Autoregressive models

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Proceedings Article | 12 March 2014 Paper

Stereoscopic augmented reality using ultrasound volume rendering for laparoscopic surgery in children

Jihun Oh, Xin Kang, Emmanuel Wilson, Craig Peters, Timothy Kane, Raj Shekhar

Proceedings Volume 9036, 90360Y (2014) https://doi.org/10.1117/12.2043929

KEYWORDS: Ultrasonography, Laparoscopy, Visualization, Transducers, Video, Surgery, Imaging systems, Calibration, Volume rendering, 3D image processing

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Proceedings Article | 12 March 2010 Paper

Parallel image registration with a thin client interface

Ganesh Saiprasad, Yi-Jung Lo, William Plishker, Peng Lei, Tabassum Ahmad, Raj Shekhar

Proceedings Volume 7628, 76280V (2010) https://doi.org/10.1117/12.844457

KEYWORDS: Image registration, Computed tomography, Rigid registration, Image restoration, Positron emission tomography, Magnetic resonance imaging, Image processing, Image fusion, Tumors, Neuroimaging

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Proceedings Article | 21 March 2007 Paper

Development of continuous CT-guided minimally invasive surgery

Raj Shekhar, Omkar Dandekar, Steven Kavic, Ivan George, Reuben Mezrich, Adrian Park

Proceedings Volume 6509, 65090D (2007) https://doi.org/10.1117/12.708783

KEYWORDS: Surgery, Laparoscopy, Computed tomography, Image registration, Visualization, X-ray computed tomography, 3D image processing, 3D visualizations, Optical tracking, Scanners

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Proceedings Article | 21 March 2007 Paper

PET guidance for liver radiofrequency ablation: an evaluation

Peng Lei, Omkar Dandekar, Faaiza Mahmoud, David Widlus, Patrick Malloy, Raj Shekhar

Proceedings Volume 6509, 650918 (2007) https://doi.org/10.1117/12.709683

KEYWORDS: Image registration, Positron emission tomography, Computed tomography, Liver, Radiofrequency ablation, Image fusion, Tumors, Scanners, Algorithm development, Tissues

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Proceedings Article | 21 March 2007 Paper

Automatic prostate localization using elastic registration of planning CT and daily 3D ultrasound images

Jianzhou Wu, Omkar Dandekar, Vivek Walimbe, Warren D'Souza, Raj Shekhar

Proceedings Volume 6509, 650913 (2007) https://doi.org/10.1117/12.711598

KEYWORDS: Ultrasonography, Prostate, Image registration, Computed tomography, 3D image processing, Radiotherapy, Automatic alignment, 3D acquisition, Image filtering, X-ray computed tomography

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Proceedings Article | 19 March 2007 Paper

A statistical approach to high-quality CT reconstruction at low radiation doses for real-time guidance and navigation

Avanti Shetye, Raj Shekhar

Proceedings Volume 6510, 65105U (2007) https://doi.org/10.1117/12.710107

KEYWORDS: X-ray computed tomography, Image quality, Reconstruction algorithms, CT reconstruction, Computed tomography, Visualization, Metals, X-rays, Scanners, Detection and tracking algorithms

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Proceedings Article | 16 March 2006 Paper

A scalable beamforming architecture for real-time 3D ultrasonic imaging using nonuniform sampling

Omkar Dandekar, Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 6147, 61470M (2006) https://doi.org/10.1117/12.653714

KEYWORDS: Nonuniform sampling, Ultrasonography, Point spread functions, 3D image processing, Transducers, 3D acquisition, Phased arrays, Apodization, Image resolution, Field programmable gate arrays

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Proceedings Article | 16 March 2006 Paper

Fully automatic segmentation of left ventricular myocardium in real-time three-dimensional echocardiography

Vivek Walimbe, Vladimir Zagrodsky, Raj Shekhar

Proceedings Volume 6144, 61444H (2006) https://doi.org/10.1117/12.654050

KEYWORDS: Image segmentation, 3D image processing, 3D modeling, Image processing algorithms and systems, Echocardiography, Image registration, 3D acquisition, Algorithm development, Image restoration, Medical imaging

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Purpose: We report a deformable model (DM)-based fully automatic segmentation of the left ventricular (LV) myocardium (endocardium + epicardium) in real-time three-dimensional (3D) echocardiography. Methods: Initialization of the DM is performed through automated mutual information-based registration of the image to be segmented with a 3D template (image + corresponding endo-epicardial wiremesh). The initialized endocardial and epicardial wiremesh templates are then simultaneously refined iteratively under the joint influence of mesh-derived internal forces, image-derived external (gradient vector flow-based) forces, and endo-epicardium mesh-interaction forces. Incorporation of adaptive mesh-interaction forces into the DM refinement, a novelty of the current work, ensures appropriate relative endo-epicardial orientation during simultaneous refinement. Repeating for the entire cardiac sequence provides the segmented myocardium for all phases. Preliminary comparison is presented between automatic and expert-defined myocardial segmentation for five subjects imaged in clinical settings using a Philips SONOS 7500 scanner. Results: Root mean square (rms) radial distance error between the algorithm-determined and expert-traced endocardial and epicardial contours in six predetermined planar views was 3.86 ± 0.72 mm and 4.0 ± 0.63 mm in end-diastole, 3.9 ± 0.51 mm and 4.04 ± 0.65 mm in systole, respectively. Mean absolute error between average myocardial thickness calculated using automatic and expert-defined contours was 1.64 ± 0.56 mm (apical), 1.3 ± 0.58 mm (mid) and 1.46 ± 0.45 mm (basal). The absolute difference in ejection fraction calculated using our algorithm and by the expert using the TomTec software was 7.2 ± 0.84 %. Conclusion: We demonstrate successful segmentation of LV myocardium, which allows clinically important LV structure and function (e.g. wall thickness, LV volume and ejection fraction) to be tracked over the entire cardiac cycle.

Proceedings Article | 10 March 2006 Paper

Elastic registration using 3D ChainMail: application to virtual colonoscopy

Carlos Castro-Pareja, Barry Daly, Raj Shekhar

Proceedings Volume 6144, 61442Y (2006) https://doi.org/10.1117/12.653644

KEYWORDS: Image registration, 3D modeling, Virtual colonoscopy, Optimization (mathematics), Computed tomography, Image resolution, Colon, Colorectal cancer, Medical imaging, 3D applications

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Proceedings Article | 15 February 2006 Paper

A cubic interpolation pipeline for fast computation of 3D deformation fields modeled using B-splines

Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 6063, 606301 (2006) https://doi.org/10.1117/12.650801

KEYWORDS: 3D image processing, Image registration, Clocks, 3D modeling, Image processing, Field programmable gate arrays, Medical imaging, Computing systems, Surgery, Control systems

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Proceedings Article | 15 February 2006 Paper

A hardware-accelerated approach to computing multiple image similarity measures from joint histogram

Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 6063, 60630N (2006) https://doi.org/10.1117/12.643206

KEYWORDS: Image registration, Iris, Image restoration, Image processing, Surgery, Field programmable gate arrays, Computed tomography, Magnetic resonance imaging, Positron emission tomography, Optimization (mathematics)

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Proceedings Article | 29 April 2005 Paper

Adaptive reduction of intensity levels in 3D images for mutual information-based registration

Carlos Castro-Pareja, Raj Shekhar

Proceedings Volume 5747, (2005) https://doi.org/10.1117/12.595499

KEYWORDS: Image registration, Magnetic resonance imaging, Detection and tracking algorithms, Positron emission tomography, Quantization, Computed tomography, Rigid registration, 3D image processing, Image processing algorithms and systems, Image segmentation

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Proceedings Article | 25 February 2005 Paper

FPGA-based real-time anisotropic diffusion filtering of 3D ultrasound images

Carlos Castro-Pareja, Omkar Dandekar, Raj Shekhar

Proceedings Volume 5671, (2005) https://doi.org/10.1117/12.586198

KEYWORDS: 3D image processing, Anisotropic diffusion, Anisotropic filtering, Ultrasonography, Gaussian filters, Image filtering, Diffusion, Clocks, Image processing, 3D acquisition

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Proceedings Article | 18 May 2004 Paper

FPGA-based acceleration of mutual information calculation for real-time 3D image registration

Carlos Castro-Pareja, Jogikal Jagadeesh, Raj Shekhar

Proceedings Volume 5297, (2004) https://doi.org/10.1117/12.525412

KEYWORDS: Image registration, Field programmable gate arrays, Image fusion, Image processing, Medical imaging, 3D image processing, Computer architecture, Photovoltaics, Clocks, Diagnostics

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Proceedings Article | 12 May 2004 Paper

Elastic registration of 3D whole body CT and PET images by quaternion-based interpolation of multiple piecewise linear rigid-body registrations

Vivek Walimbe, Vladimir Zagrodsky, Shanker Raja, Bohdan Bybel, Mangesh Kanvinde, Raj Shekhar

Proceedings Volume 5370, (2004) https://doi.org/10.1117/12.535501

KEYWORDS: Image registration, Computed tomography, Positron emission tomography, 3D image processing, Image segmentation, Algorithm development, Affine motion model, Tumors, Visualization, 3D modeling

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Proceedings Article | 9 May 2002 Paper

Segmentation of 830- and 1310-nm LASIK corneal optical coherence tomography images

Yan Li, Raj Shekhar, David Huang

Proceedings Volume 4684, (2002) https://doi.org/10.1117/12.467123

KEYWORDS: Optical coherence tomography, Image segmentation, Cornea, Interfaces, LASIK, Eye, Ultrasonics, Image processing, Ultrasonography, Surgery

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Proceedings Article | 3 July 2001 Paper

Multifunction extension of simplex optimization method for mutual information-based registration of ultrasound volumes

Vladimir Zagrodsky, Raj Shekhar, J. Fredrick Cornhill

Proceedings Volume 4322, (2001) https://doi.org/10.1117/12.431124

KEYWORDS: Ultrasonography, Image registration, Quantization, 3D acquisition, Optimization (mathematics), Speckle, 3D image processing, Data conversion, MATLAB, 3D scanning

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Proceedings Article | 6 June 2000 Paper

Mutual information-based registration of cardiac ultrasound volumes

Vladimir Zagrodsky, Raj Shekhar, J. Fredrick Cornhill

Proceedings Volume 3979, (2000) https://doi.org/10.1117/12.387674

KEYWORDS: Ultrasonography, Image registration, 3D acquisition, 3D image processing, Echocardiography, Heart, Speckle, Signal to noise ratio, Data conversion, Electrocardiography

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Proceedings Article | 20 May 1999 Paper

Quantification of coronary arterial plaque volume using 3D reconstructions formed by fusing intravascular ultrasound and biplane angiography

Jon Klingensmith, David Vince, Raj Shekhar, Barry Kuban, E. Tuzcu, J. Fredrick Cornhill

Proceedings Volume 3660, (1999) https://doi.org/10.1117/12.349604

KEYWORDS: Intravascular ultrasound, Image segmentation, Angiography, 3D modeling, Transducers, Arteries, Calibration, 3D image processing, Tissues, Visualization

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Showing 5 of 27 publications

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