@article {Foroughi2008, title = {Localization of pelvic anatomical coordinate system using US/atlas registration for total hip replacement}, journal = {Medical image computing and computer-assisted intervention (MICCAI)}, volume = {11}, number = {Pt 2}, year = {2008}, pages = {871{\textendash}879}, publisher = {Johns Hopkins University, Baltimore, MD, USA pezhman@cs jhu edu}, abstract = {

In Total Hip Replacement (THR) procedures, misalignment of the acetabular component can lead to dislocation, impingement For the successful alignment of acetabular component, precise estimation of pelvic anatomical coordinate system is necessary Conventional navigation systems use CT scan or fluoroscopy, or involve implanted bone fiducials or invasive probing of bony landmarks to locate the anatomical coordinate In this paper, an ultrasound-based approach is proposed that exploits prior knowledge about the anatomy of the pelvis in the form of a 3D surface atlas Tracked ultrasound images are utilized to extract sample points from the surface of the pelvis A generic coordinate system in the specific patient is localized by registering these points to a statistical atlas of the pelvis in which a canonical anatomical coordinate system had been defined This technique has been evaluated using simulation, dry bone, and cadaver experiments, was able to localize the anatomical coordinate system with the accuracy of about 1 degree

}, keywords = {Algorithms, Arthroplasty, Automated, Computer-Assisted, Hip, Hip Joint, Humans, Image Enhancement, Image Interpretation, Imaging, methods, Pattern Recognition, Pelvic Bones, Replacement, Reproducibility of Results, Sensitivity, Specificity, Subtraction Technique, Surgery, surgery/ultrasonography, Three-Dimensional, Ultrasonography}, author = {Pezhman Foroughi and Danny Y Song and Gouthami Chintalapani and Russell H. Taylor and Gabor Fichtinger} } @article {Fichtinger2008b, title = {Robotic assistance for ultrasound-guided prostate brachytherapy}, journal = {Medical Image Analysis}, volume = {12}, number = {5}, year = {2008}, month = {06/2008}, pages = {535}, publisher = {Queen{\textquoteright}s University; 25 Union Street;725 Goodwin Hall; Kingston; ON; Canada gabor@cs queensu ca}, abstract = {

We present a robotically assisted prostate brachytherapy system, test results in training phantoms, Phase-I clinical trials The system consists of a transrectal ultrasound (TRUS), a spatially co-registered robot,fully integrated with an FDA-approved commercial treatment planning system The salient feature of the system is a small parallel robot affixed to the mounting posts of the template The robot replaces the template interchangeably,using the same coordinate system Established clinical hardware,workflow, calibration remain intact In all phantom experiments,we recorded the first insertion attempt without adjustment All clinically relevant locations in the prostate were reached Non-parallel needle trajectories were achieved The pre-insertion transverse, rotational errors (measured with a Polaris optical tracker relative to the template{\textquoteright}s coordinate frame) were 0 25 mm (STD=0 17 mm), 0 75 degrees (STD=0 37 degrees) In phantoms,needle tip placement errors measured in TRUS were 1 04 mm (STD=0 50mm) A Phase-I clinical feasibility, safety trial has been successfully completed with the system We encountered needle tip positioning errors of a magnitude greater than 4mm in only 2 of 179 robotically guided needles,in contrast to manual template guidance where errors of this magnitude are much more common Further clinical trials are necessary to determine whether the apparent benefits of the robotic assistant will lead to improvements in clinical efficacy, outcomes

}, keywords = {Brachytherapy, Computer-Assisted, Equipment Design, Equipment Failure Analysis, Humans, instrumentation, instrumentation/methods, Interventional, Male, Prostatic Neoplasms, Radiotherapy, radiotherapy/ultrasonography, Robotics, Ultrasonography}, doi = {10 1016/j media 2008 06 002}, url = {http://dx doi org/10 1016/j media 2008 06 002}, author = {Gabor Fichtinger and Jonathan Fiene and Christopher Kennedy and Gernot Kronreif and Iulian Iordachita and Danny Y Song and E. Clif Burdette and Peter Kazanzides} } @conference {Karim-Aghaloo2008, title = {Towards detecting surgical clips in 3D ultrasound for target localization in radiation therapy: a study on tissue phantoms}, booktitle = {International Conference of the IEEE Engineering in Medicine and Biology Society}, volume = {2008}, year = {2008}, pages = {5282{\textendash}5285}, publisher = {Department of Electrical, Computer Engineering, Queens University, Kingston, ON K7L3N6, Canada}, organization = {Department of Electrical, Computer Engineering, Queens University, Kingston, ON K7L3N6, Canada}, abstract = {

A study is performed to measure the visibility of small surgical clips in 3D ultrasound volumes of a phantom as the first step towards using such clips as fiducial markers in radiation therapy Visibility is calculated as the contrast to noise ratio of the echo from the clip to the background The appearance of a resonance tail is also calculated using a moment analysis Contrast is found to be high, mostly independent of material, size of the clip All clips are visible, but the length of the tail is found to be dependent on clip orientation to the ultrasound beam The consistent visibility of the clips suggests they are suitable as fiducial markers in ultrasound, the dependency of the resonance tail on orientation provides an opportunity to distinguish clips from other specular reflectors

}, keywords = {Computer-Assisted, Equipment Design, Equipment Failure Analysis, Humans, Image Enhancement, Imaging, instrumentation, instrumentation/methods, methods, Phantoms, Radiotherapy, Reproducibility of Results, Sensitivity, Specificity, Surgical Instruments, Three-Dimensional, Ultrasonography}, doi = {10 1109/IEMBS 2008 4650406}, url = {http://dx doi org/10 1109/IEMBS 2008 4650406}, author = {Zahra Karim-Aghaloo and Prasad Shrawane and Purang Abolmaesumi and Gabor Fichtinger and Robert Rohling} } @article {Singh2007a, title = {Patient selection determines the prostate cancer yield of dynamic contrast-enhanced magnetic resonance imaging-guided transrectal biopsies in a closed 3-Tesla scanner}, journal = {British Journal of Urology international}, volume = {101}, number = {2}, year = {2007}, month = {Jan}, pages = {181{\textendash}185}, publisher = {Radiation Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-1642, USA Anurag Singh@RoswellPark org}, abstract = {

OBJECTIVE: To evaluate the cancer yield of transrectal prostate biopsies in a 3-T magnetic resonance imaging (MRI) scanner in patients with elevated prostate specific antigen (PSA) levels, recent negative transrectal ultrasonography (TRUS)-guided prostate biopsies PATIENTS AND METHODS: Between July 2004, November 2005, patients with at least one previous negative prostate biopsy within the previous 12 months had MRI-guided biopsy of the prostate in a 3-T MRI scanner Patients with previous positive biopsies for cancer were excluded Target selection was based on T2-weighted imaging, dynamic contrast-enhanced (DCE) imaging studies RESULTS: Thirteen patients were eligible; their median (range) age was 61 (47-74) years, PSA value 4 90 (1 3-12 3) ng/mL Most patients had one previous negative biopsy (range 1-4) Four patients had a family history of prostate cancer There were 37 distinct targets based on T2-weighted imaging Fifteen of 16 distinct DCE abnormalities were co-localized with a target based on T2-weighted imaging Despite this correlation, only one of 13 patients had a directed biopsy positive for cancer Including systematic biopsies, two of 13 patients had a biopsy positive for prostate cancer One patient had prostate intraepithelial neoplasia, one had atypical glands in the specimen CONCLUSION: The prostate-cancer yield of transrectal biopsies in a 3-T MRI scanner, among patients with recent negative TRUS-guided prostate biopsies, is similar to repeat systematic TRUS-guided biopsy DCE correlates with T2-imaging but does not appear to improve prostate cancer yield in this population

}, keywords = {Aged, Biopsy, blood, Cohort Studies, Contrast Media, diagnosis, Digital Rectal Examination, Humans, Interventional, Magnetic Resonance Imaging, Male, methods, Middle Aged, Needle, pathology, Patient Selection, Predictive Value of Tests, Prostate, Prostate-Specific Antigen, Prostatic Neoplasms, Sensitivity, Specificity, standards, Ultrasonography}, doi = {10 1111/j 1464-410X 2007 07219 x}, url = {http://dx doi org/10 1111/j 1464-410X 2007 07219 x}, author = {Anurag K. Singh and Axel Krieger and Jean-Baptiste Lattouf and Peter Guion and R.L. Grubb III and Paul Albert and Greg Metzger and Karen Ullman and Sharon Smith and Gabor Fichtinger and Iclal Ocak and Peter Choyke and Cynthia Menard and Jonathan Coleman} } @article {Krupa2007, title = {Real-time tissue tracking with B-mode ultrasound using speckle and visual servoing}, journal = {Tenth International Conference on Medical Image Computing and Computer-Assisted Intervention (MICCAI)}, volume = {10}, number = {Pt 2}, year = {2007}, pages = {1{\textendash}8}, publisher = {IRISA - INRIA Rennes, France alexandre krupa@irisa fr}, abstract = {

We present a method for real-time tracking of moving soft tissue with B-mode ultrasound (US) The method makes use of the speckle information contained in the US images to estimate the in-plane, out-of-plane motion of a fixed target relative to the ultrasound scan plane The motion information is then used as closed-loop feedback to a robot which corrects for the target motion The concept is demonstrated for translation motions in an experimental setup consisting of an ultrasound speckle phantom, a robot for simulating tissue motion, and a robot that performs motion stabilization from US images This concept shows promise for US-guided procedures that require real-time motion tracking, compensation

}, keywords = {Algorithms, Artificial Intelligence, Computer Systems, Computer-Assisted, Equipment Design, Equipment Failure Analysis, Image Enhancement, Image Interpretation, Imaging, instrumentation/methods, Interventional, methods, Pilot Projects, Reproducibility of Results, Robotics, Sensitivity, Specificity, Surgery, Three-Dimensional, Ultrasonography, User-Computer Interface}, author = {Alexandre Krupa and Gabor Fichtinger and Gregory D. Hager} } @article {Fichtinger2007c, title = {Robotic assistance for ultrasound guided prostate brachytherapy}, journal = {Medical Image Computing and Computer-Assisted Intervention (MICCAI)}, volume = {4791}, year = {2007}, pages = {119{\textendash}127}, publisher = {The Johns Hopkins University, Baltimore, Maryland, USA gabor@cs jhu edu}, abstract = {

We present a robotically assisted prostate brachytherapy system, test results in training phantoms The system consists of a transrectal ultrasound (TRUS), a spatially co-registered robot integrated with an FDA-approved commercial treatment planning system The salient feature of the system is a small parallel robot affixed to the mounting posts of the template The robot replaces the template interchangeably, uses the same coordinate system Established clinical hardware, workflow, calibration are left intact In these experiments, we recorded the first insertion attempt without adjustment All clinically relevant locations were reached Non-parallel needle trajectories were achieved The pre-insertion transverse, rotational errors (measured with Polaris optical tracker relative to the template{\textquoteright}s coordinate frame) were 0 25mm (STD = 0 17mm), 0 75 degrees (STD = 0 37 degrees) The needle tip placement errors measured in TRUS were 1 04mm (STD = 0 50mm) The system is in Phase-I clinical feasibility, safety trials, under Institutional Review Board approval

}, keywords = {Brachytherapy, Computer-Assisted, Equipment Design, Equipment Failure Analysis, Humans, instrumentation/methods, Interventional, Male, Prostatic Neoplasms, Radiotherapy, Radiotherapy Planning, radiotherapy/ultrasonography, Robotics, Ultrasonography}, author = {Gabor Fichtinger and Jonathan Fiene and Christopher Kennedy and Gernot Kronreif and Iulian Iordachita and Danny Y Song and E. Clif Burdette and Peter Kazanzides} } @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} } @article {Jain2005e, title = {Matching and reconstruction of brachytherapy seeds using the Hungarian algorithm (MARSHAL)}, journal = {Journal of Medical Physics}, volume = {32}, number = {11}, year = {2005}, month = {Nov}, pages = {3475{\textendash}3492}, abstract = {

Intraoperative dosimetric quality assurance in prostate brachytherapy critically depends on discerning the three-dimensional (3D) locations of implanted seeds The ability to reconstruct the implanted seeds intraoperatively will allow us to make immediate provisions for dosimetric deviations from the optimal implant plan A method for seed reconstruction from segmented C-arm fluoroscopy images is proposed The 3D coordinates of the implanted seeds can be calculated upon resolving the correspondence of seeds in multiple x-ray images We formalize seed-matching as a combinatorial optimization problem, which has salient features: (a) extensively studied solutions by the computer science community; (b) proof for the nonexistence of any polynomial time exact algorithm;, (c) a practical pseudo-polynomial algorithm that mostly runs in O(N3) time using any number of images We prove that two images are insufficient to correctly match the seeds, while a third image renders the matching problem to be of nonpolynomial complexity We utilize the special structure of the problem, propose a pseudopolynomial time algorithm Using three presegmented images, matching, reconstruction of brachytherapy seeds using the Hungarian algorithm achieved complete matching in simulation experiments;, 98 5\% in phantom experiments 3D reconstruction error for correctly matched seeds has a mean of 0 63 mm, and 0 9 mm for incorrectly matched seeds The maximum seed reconstruction error in each implant was typically around 1 32 mm Both on synthetic data, in phantom experiments, matching rate, reconstruction error achieved using presegmented images was found to be sufficient for prostate brachytherapy The algorithm is extendable to deal with arbitrary number of images without any loss in speed or accuracy The algorithm is sufficiently generic to provide a practical solution to any correspondence problem, across different imaging modalities, features

}, keywords = {Algorithms, Automated, Brachytherapy, Calibration, Computer Simulation, Computer-Assisted, Humans, Image Interpretation, Imaging, Male, methods, Models, Numerical Analysis, Pattern Recognition, Phantoms, Prostatic Neoplasms, Radiographic Image Enhancement, Radiographic Image Interpretation, Radiometry, Radiotherapy, Radiotherapy Dosage, Radiotherapy Planning, Reproducibility of Results, Statistical, Theoretical, Three-Dimensional, Time Factors, Ultrasonography}, author = {Ameet K. Jain and Yu Zhou and Tabish Mustufa and E. Clif Burdette and Gregory Chirikjian and Gabor Fichtinger} } @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} }