@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 {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 {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 {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} } @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} } @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} }