@conference {Foroughi2009, title = {Multi-modality fusion of CT and 3D ultrasound and tracked strain images for breast irradiation planning}, booktitle = {SPIE Medical Imaging 2009: Ultrasonic Imaging and Signal Processing}, volume = {7265}, number = {72651B}, year = {2009}, author = {Pezhman Foroughi and Csaba Csoma and Hassan Rivaz and Gabor Fichtinger and Richard Zellars and Gregory D. Hager and Emad Boctor} } @article {Rivaz2008b, title = {Ablation monitoring with elastography: 2D in-vivo and 3D ex-vivo studies}, journal = {Medical image computing and computer-assisted intervention (MICCAI)}, volume = {11}, number = {Pt 2}, year = {2008}, pages = {458{\textendash}466}, publisher = {ERC for Computer Integrated Surgery, Johns Hopkins University, USA rivaz@jhu edu}, abstract = {

The clinical feasibility of 2D elastography methods is hindered by the requirement that the operator avoid out-of-plane motion of the ultrasound image during palpation, and also by the lack of volumetric elastography measurements In this paper, we develop, evaluate a 3D elastography method operating on volumetric data acquired from a 3D probe Our method is based on minimizing a cost function using dynamic programming (DP) The cost function incorporates similarity of echo amplitudes, displacement continuity We present, to the best of our knowledge, the first in-vivo patient studies of monitoring liver ablation with freehand DP elastography The thermal lesion was not discernable in the B-mode image but it was clearly visible in the strain image as well as in validation CT We also present 3D strain images from thermal lesions in ex-vivo ablation Good agreement was observed between strain images, CT, gross pathology

}, keywords = {Carcinoma, Catheter Ablation, Computer-Assisted, Elasticity Imaging Techniques, Feasibility Studies, Hepatectomy, Hepatocellular, Humans, Image Interpretation, Imaging, Liver Neoplasms, methods, Surgery, surgery/ultrasonography, Three-Dimensional, Treatment Outcome}, author = {Hassan Rivaz and Ioana Fleming and Lia Assumpcao and Gabor Fichtinger and Ulrike Hamper and Michael Choti and Gregory D. Hager and Emad Boctor} } @article {Rivaz2008a, title = {Ultrasound elastography: a dynamic programming approach}, journal = {IEEE transactions on medical imaging}, volume = {27}, number = {10}, year = {2008}, month = {Oct}, pages = {1373{\textendash}1377}, publisher = {Engineering Research Center for Computer Integrated Surgery, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA}, abstract = {

This paper introduces a 2-D strain imaging technique based on minimizing a cost function using dynamic programming (DP) The cost function incorporates similarity of echo amplitudes, displacement continuity Since tissue deformations are smooth, the incorporation of the smoothness into the cost function results in reduced decorrelation noise As a result, the method generates high-quality strain images of freehand palpation elastography with up to 10\% compression, showing that the method is more robust to signal decorrelation (caused by scatterer motion in high axial compression, nonaxial motions of the probe) in comparison to the standard correlation techniques The method operates in less than 1 s, is thus also potentially suitable for real time elastography

}, keywords = {Algorithms, Computer-Assisted, Elasticity Imaging Techniques, Humans, Image Enhancement, Image Interpretation, Imaging, instrumentation/methods, methods, Numerical Analysis, Phantoms, Sensitivity, Specificity}, doi = {10 1109/TMI 2008 917243}, url = {http://dx doi org/10 1109/TMI 2008 917243}, author = {Hassan Rivaz and Emad Boctor and Pezhman Foroughi and Richard Zellars and Gabor Fichtinger and Gregory D. Hager} } @conference {Rivaz2007, title = {Beam Steering Approach for Speckle Characterization and Out-of-Plane Motion Estimation in Real Tissue}, booktitle = {Procedings IEEE Ultrasonics Symposium}, year = {2007}, month = {10/2007}, pages = {781{\textendash}784}, doi = {10 1109/ULTSYM 2007 200}, author = {Hassan Rivaz and Richard Zellars and Gregory D. Hager and Gabor Fichtinger and Emad Boctor} } @conference {Fichtinger2007, title = {New approaches to calibration and segmentation in interventional ultrasound}, booktitle = {Procedings 4th IEEE International Symposium on Biomedical Imaging: From Nano to Macro ISBI 2007}, year = {2007}, month = {12{\textendash}15 April}, pages = {1060{\textendash}1063}, doi = {10 1109/ISBI 2007 357038}, author = {Gabor Fichtinger and Emad Boctor and Gregory D. Hager} } @conference {Foroughi2007, title = {P6D-2 Ultrasound Bone Segmentation Using Dynamic Programming}, booktitle = {Procedings IEEE Ultrasonics Symposium}, year = {2007}, month = {28{\textendash}31 Oct}, pages = {2523{\textendash}2526}, doi = {10 1109/ULTSYM 2007 635}, author = {Pezhman Foroughi and Emad Boctor and Michael Swartz and Russell H. Taylor and Gabor Fichtinger} } @conference {Rivaz2007a, title = {A robust meshing and calibration approach for sensorless freehand 3D ultrasound}, booktitle = {Medical Imaging 2007: Ultrasonic Imaging and Signal Processing}, volume = {6513}, number = {1}, year = {2007}, pages = {651318}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 712423}, url = {http://link aip org/link/?PSI/6513/651318/1}, author = {Hassan Rivaz and Emad Boctor and Gabor Fichtinger} } @conference {Rivaz2007d, title = {Speckle Characterization And Out-Of-Plane Motion Estimation In Tissue}, booktitle = {Sixth International Conference on the Ultrasonic Measurement and Imaging of Tissue Elasticity}, year = {2007}, author = {Hassan Rivaz and Gregory D. Hager and Richard Zellars and Gabor Fichtinger and Emad Boctor} } @conference {Rivaz2007b, title = {Toward Real-Time 2d Ultrasound Elastography Using Global Optimization Of A Regularized Displacement Field}, booktitle = {Sixth International Conference on the Ultrasonic Measurement and Imaging of Tissue Elasticity}, year = {2007}, author = {Hassan Rivaz and Pezhman Foroughi and Emad Boctor and Richard Zellars and Gabor Fichtinger and Gregory D. Hager} } @conference {Rivaz2007c, title = {Ultrasound Elastography: a Dynamic Programming Approach}, booktitle = {Workshop to the 10th MICCAI Conference}, year = {2007}, author = {Hassan Rivaz and Pezhman Foroughi and Emad Boctor and Richard Zellars and Gabor Fichtinger and Gregory D. Hager} } @article {Boctor2006a, title = {Bootstrapped ultrasound calibration}, journal = {Studies in health technology and informatics}, volume = {119}, year = {2006}, pages = {61{\textendash}66}, publisher = {Engineering Research Center, Johns Hopkins University, USA}, abstract = {

This paper introduces an enhanced (bootstrapped) method for tracked ultrasound probe calibration Prior to calibration, a position sensor is used to track an ultrasound probe in 3D space, while the US image is used to determine calibration target locations within the image From this information, an estimate of the transformation matrix of the scan plane with respect to the position sensor is computed While all prior calibration methods terminate at this phase, we use this initial calibration estimate to bootstrap an additional optimization of the transformation matrix on independent data to yield the minimum reconstruction error on calibration targets The bootstrapped workflow makes use of a closed-form calibration solver, associated sensitivity analysis, allowing for rapid, robust convergence to an optimal calibration matrix Bootstrapping demonstrates superior reconstruction accuracy

}, keywords = {Calibration, Imaging, standards, Three-Dimensional, Ultrasonography, United States}, author = {Emad Boctor and Iulian Iordachita and Michael Choti and Gregory D. Hager and Gabor Fichtinger} } @article {Boctor2006b, title = {Ultrasound monitoring of tissue ablation via deformation model and shape priors}, journal = {Medical image computing and computer-assisted intervention (MICCAI)}, volume = {9}, number = {Pt 2}, year = {2006}, pages = {405{\textendash}412}, abstract = {

A rapid approach to monitor ablative therapy through optimizing shape, elasticity parameters is introduced Our motivating clinical application is targeting, intraoperative monitoring of hepatic tumor thermal ablation, but the method translates to the generic problem of encapsulated stiff masses (solid organs, tumors, ablated lesions, etc ) in ultrasound imaging The approach involves the integration of the following components: a biomechanical computational model of the tissue, a correlation approach to estimate/track tissue deformation, and an optimization method to solve the inverse problem, recover the shape parameters in the volume of interest Successful convergence, reliability studies were conducted on simulated data Then ex-vivo studies were performed on 18 ex-vivo bovine liver samples previously ablated under ultrasound monitoring in controlled laboratory environment While B-mode ultrasound does not clearly identify the development of necrotic lesions, the proposed technique can potentially segment the ablation zone The same framework can also yield both partial, full elasticity reconstruction

}, keywords = {Algorithms, Animals, Automated, Biological, Cattle, Computer-Assisted, Elasticity, Hepatectomy, Image Enhancement, Image Interpretation, Imaging, Interventional, Liver, Mechanical, methods, Models, Pattern Recognition, physiology/surgery/ultrasonography, Reproducibility of Results, Sensitivity, Specificity, Statistical, Stress, Subtraction Technique, Surgery, Three-Dimensional, Ultrasonography}, author = {Emad Boctor and Michelle de Oliveira and Michael Choti and Roger Ghanem and Russell H. Taylor and Gregory D. Hager and Gabor Fichtinger} } @conference {Boctor2006, title = {Ultrasound self-calibration}, booktitle = {Medical Imaging 2006: Visualization, Image-Guided Procedures, and Display}, volume = {6141}, number = {1}, year = {2006}, pages = {61412N}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 659594}, url = {http://link aip org/link/?PSI/6141/61412N/1}, author = {Emad Boctor and Iulian Iordachita and Gabor Fichtinger and Gregory D. Hager} } @conference {Rivaz2006, title = {Ultrasound Speckle Detection Using Low Order Moments}, booktitle = {Procedings IEEE Ultrasonics Symposium}, year = {2006}, month = {10/2006}, pages = {2092{\textendash}2095}, doi = {10 1109/ULTSYM 2006 501}, author = {Hassan Rivaz and Emad Boctor and Gabor Fichtinger} } @conference {Kon2005, title = {CIS-UltraCal: an open-source ultrasound calibration toolkit}, booktitle = {Medical Imaging 2005: Ultrasonic Imaging and Signal Processing}, volume = {5750}, number = {1}, year = {2005}, pages = {516-523}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 596929}, url = {http://link aip org/link/?PSI/5750/516/1}, author = {Ryan Kon and Joshua Leven and Kishore Kothapalli and Emad Boctor and Gabor Fichtinger and Gregory D. Hager and Russell H. Taylor} } @article {Boctor2005, title = {Real-time quality control of tracked ultrasound}, journal = {Medical image computing and computer-assisted intervention (MICCAI)}, volume = {8}, number = {Pt 1}, year = {2005}, pages = {621{\textendash}630}, abstract = {

The overwhelming majority of intra-operative hazard situations in tracked ultrasound (US) systems are attributed to failure of registration between tracking, imaging coordinate frames We introduce a novel methodology for eal-time in-vivo quality control of tracked US systems, in order to capture registration failures during the clinical procedure In effect, we dynamically recalibrate the tracked US system for rotation, scale factor, and in-plane position offset up to a scale factor We detect any unexpected change in these parameters through capturing discrepancies in the resulting calibration matrix, thereby assuring quality (accuracy, consistency) of the tracked system No phantom is used for the recalibration We perform the task of quality control in the background, transparently to the clinical user while the subject is being scanned We present the concept, mathematical formulation, and experimental evaluation in-vitro This new method can play an important role in guaranteeing accurate, consistent, and reliable performance of tracked ultrasound

}, keywords = {Algorithms, Computer Systems, Computer-Assisted, Health Care, Humans, Image Enhancement, Image Interpretation, Interventional, methods, Quality Assurance, Quality Control, Reproducibility of Results, Sensitivity, Specificity, Surgery, Ultrasonography, User-Computer Interface}, author = {Emad Boctor and Iulian Iordachita and Gabor Fichtinger and Gregory D. Hager} } @conference {DeOliveira2005a, title = {Robot-assisted 3D strain imaging for monitoring thermal ablation of liver}, booktitle = {Annual congress of the Society of American Gastrointestinal Endoscopic Surgeons}, year = {2005}, pages = {240-241}, author = {Michelle de Oliveira and Emad Boctor and Michael Awad and Russell H. Taylor and Gabor Fichtinger and Michael Choti} } @conference {Boctor2005b, title = {Ultrasound Self-Calibration and Real-Time Quality Control for Interventions}, booktitle = {IEEE International Ultrasonics Symposium}, year = {2005}, author = {Emad Boctor and Iulian Iordachita and Gabor Fichtinger and Gregory D. Hager} } @conference {Boctor2004a, title = {CISUS: an integrated 3D ultrasound system for IGT using a modular tracking API}, booktitle = {Medical Imaging 2004: Visualization, Image-Guided Procedures, and Display}, volume = {5367}, number = {1}, year = {2004}, pages = {247-256}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 537776}, url = {http://link aip org/link/?PSI/5367/247/1}, author = {Emad Boctor and Anand Viswanathan and Steve Pieper and Michael Choti and Russell H. Taylor and Ron Kikinis and Gabor Fichtinger}, editor = {Robert L. Galloway, Jr.} } @conference {Boctor2004f, title = {Development of a Robotically-Assisted 3-D Ultrasound System for Radiofrequency Ablation of Liver Tumors}, booktitle = {6th World Congress of the Hepato-Pancreato-Biliary Association (IHPBA)}, year = {2004}, author = {Emad Boctor and Michael Awad and Gabor Fichtinger and Russell H. Taylor and Michael Choti} } @conference {Boctor2004c, title = {A dual-armed robotic system for intraoperative ultrasound guided hepatic ablative therapy: a prospective study}, booktitle = {Procedings IEEE International Conference on Robotics and Automation ICRA {\textquoteright}04}, volume = {3}, year = {2004}, month = {Apr 26{\textendash}May 1,}, pages = {2517{\textendash}2522}, doi = {10 1109/ROBOT 2004 1307440}, author = {Emad Boctor and Gregory Fischer and Michael Choti and Gabor Fichtinger and Russell H. Taylor} } @article {Viswanathan2004, title = {Immediate Ultrasound Calibration from Three Poses and Minimal Image Processing}, journal = {Proceedings in Lecture Notes in Computer Science Medical Image Computing and Computer-Assisted Intervention (MICCAI)}, volume = {3217}, year = {2004}, pages = {446-454}, author = {Anand Viswanathan and Emad Boctor and Russell H. Taylor and Gregory D. Hager and Gabor Fichtinger} } @conference {Boctor2004, title = {A novel closed form solution for ultrasound calibration}, booktitle = {Procedings IEEE International Symposium on Biomedical Imaging: Nano to Macro}, year = {2004}, month = {15{\textendash}18 April}, pages = {527{\textendash}530}, doi = {10 1109/ISBI 2004 1398591}, author = {Emad Boctor and Anand Viswanathan and Michael Choti and Russell H. Taylor and Gabor Fichtinger and Gregory D. Hager} } @article {Boctor2004b, title = {Robotic Strain Imaging for Monitoring Thermal Ablation of Liver Tumors}, journal = {Proceedings in Lecture Notes in Computer Science}, volume = {3217}, year = {2004}, pages = {81-88}, author = {Emad Boctor and Gabor Fichtinger and Ambert Yeung and Michael Awad and Russell H. Taylor and Michael Choti} } @conference {Boctor2004e, title = {Robotically assisted ablative treatment guided by freehand 3D ultrasound}, booktitle = {Conference of Computer Assisted Radiology and Surgery (CARS)}, year = {2004}, pages = {503-508}, author = {Emad Boctor and Robert Webster and Michael Choti and Russell H. Taylor and Gabor Fichtinger} } @article {Boctor2004d, title = {Virtual remote center of motion control for needle placement robots}, journal = {Journal of Computer Assisted Surgery}, volume = {9 (5)}, year = {2004}, pages = {175-183}, author = {Emad Boctor and Robert Webster and Herve Mathieu and Allison Okamura and Gabor Fichtinger} } @conference {Boctor2003, title = {Rapid calibration method for registration and 3D tracking of ultrasound images using spatial localizer}, booktitle = {Medical Imaging 2003: Ultrasonic Imaging and Signal Processing}, volume = {5035}, number = {1}, year = {2003}, pages = {521-532}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 479953}, url = {http://link aip org/link/?PSI/5035/521/1}, author = {Emad Boctor and Ameet K. Jain and Michael Choti and Russell H. Taylor and Gabor Fichtinger} } @conference {Boctor2003c, title = {Robotically assisted intraoperative ultrasound with application to ablative therapy of liver cancer}, booktitle = {Medical Imaging 2003: Visualization, Image-Guided Procedures, and Display}, volume = {5029}, number = {1}, year = {2003}, pages = {281-291}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 480338}, url = {http://link aip org/link/?PSI/5029/281/1}, author = {Emad Boctor and Russell H. Taylor and Gabor Fichtinger and Michael Choti}, editor = {Robert L. Galloway, Jr.} } @conference {Boctor2003a, title = {Tracked 3D ultrasound in radio-frequency liver ablation}, booktitle = {Medical Imaging 2003: Ultrasonic Imaging and Signal Processing}, volume = {5035}, number = {1}, year = {2003}, pages = {174-182}, publisher = {SPIE}, organization = {SPIE}, doi = {10 1117/12 479952}, url = {http://link aip org/link/?PSI/5035/174/1}, author = {Emad Boctor and Gabor Fichtinger and Russell H. Taylor and Michael Choti}, editor = {William F. Walker and Michael F. Insana} } @article {Boctor2003b, title = {Virtual remote center of motion control for needle placement robots}, journal = {Journal of Computer Aided Surgery}, volume = {9}, number = {5}, year = {2003}, pages = {175{\textendash}183}, abstract = {

OBJECTIVE: We present an algorithm that enables percutaneous needle-placement procedures to be performed with unencoded, unregistered, minimally calibrated robots while removing the constraint of placing the needle tip on a mechanically enforced Remote Center of Motion (RCM) MATERIALS AND METHODS: The algorithm requires only online tracking of the surgical tool, a five-degree-of-freedom (5-DOF) robot comprising three prismatic DOF, two rotational DOF An incremental adaptive motion control cycle guides the needle to the insertion point, also orients it to align with the target-entry-point line The robot executes RCM motion without having a physically constrained fulcrum point RESULTS: The proof-of-concept prototype system achieved 0 78 mm translation accuracy, 1 4 degrees rotational accuracy (this is within the tracker accuracy) within 17 iterative steps (0 5-1 s) CONCLUSION: This research enables robotic assistant systems for image-guided percutaneous procedures to be prototyped/constructed more quickly, less expensively than has been previously possible Since the clinical utility of such systems is clear, has been demonstrated in the literature, our work may help promote widespread clinical adoption of this technology by lowering system cost, complexity

}, keywords = {Algorithms, Computer-Assisted, Equipment Design, Imaging, instrumentation, Needles, Robotics, Surgery, Three-Dimensional}, doi = {10 1080/10929080500097661}, url = {http://dx doi org/10 1080/10929080500097661}, author = {Emad Boctor and Robert Webster and Herve Mathieu and Allison Okamura and Gabor Fichtinger} }