A new sensor technology for 2D ultrasound-guided needle tracking.

2D Ultrasound (US) is becoming the preferred modality for image-guided interventions due to its low cost and portability. However, the main limitation is the limited visibility of surgical tools. We present a new sensor technology that can easily be embedded on needles that are used for US-guided interventions.

MRI-3D ultrasound-X-ray image fusion with electromagnetic tracking for transendocardial therapeutic injections: in-vitro validation and in-vivo feasibility.

Myocardial infarction (MI) is one of the leading causes of death in the world. Small animal studies have shown that stem-cell therapy offers dramatic functional improvement post-MI. An endomyocardial catheter injection approach to therapeutic agent delivery has been proposed to improve efficacy through increased cell retention.

A method for measuring the accuracy of multi-modal image fusion system for catheter-based cardiac interventions using a novel motion enabled targeting phantom.

Targeted stem cell therapy offers great potential for the repair of infarcted cardiac tissue following heart attack. Safe delivery of stem-cells via catheter based interventions remains a challenge. A multi-modal image fusion approach has been considered for safe targeting of myocardial infarct border zones.

Real-time 3D ultrasound guided interventional system for cardiac stem cell therapy with motion compensation.

This paper describes a clinically translatable interventional guidance platform to improve the accuracy and precision of stem cell injections into a beating heart. The proposed platform overlays live position of an injection catheter onto a fusion of a pre-procedural MR roadmap with real-time 3D transesophageal echocardiography (TEE). Electromagnetic (EM) tracking is used to initialize the fusion.

A non-disruptive technology for robust 3D tool tracking for ultrasound-guided interventions.

In the past decade ultrasound (US) has become the preferred modality for a number of interventional procedures, offering excellent soft tissue visualization. The main limitation however is limited visualization of surgical tools. A new method is proposed for robust 3D tracking and US image enhancement of surgical tools under US guidance.

Brachytherapy seed reconstruction with joint-encoded C-arm single-axis rotation and motion compensation.

C-arm fluoroscopy images are frequently used for qualitative assessment of prostate brachytherapy. Three-dimensional seed reconstruction from C-arm images is necessary for intraoperative dosimetry and quantitative assessment. Seed reconstruction requires accurately known C-arm poses.

Fast and accurate calibration of an X-ray imager to an electromagnetic tracking system for interventional cardiac procedures.

Cardiovascular disease affects millions of Americans each year. Interventional guidance systems are being developed as treatment options for some of the more delicate procedures, including targeted stem cell therapy. As advanced systems for such types of interventional guidance are being developed, electromagnetic (EM) tracking is coming in demand to perform navigation.

Dynamic intraoperative dosimetry for prostate brachytherapy using a nonisocentric C-arm.

Purpose: To evaluate a prototypical system of dynamic intraoperative dosimetry for prostate brachytherapy using registered ultrasound and fluoroscopy (RUF) with a nonisocentric C-arm (GE OEC, Salt Lake City, UT) and to compare intraoperative dosimetry of RUF as well as ultrasound-based seed localization (USD) with Day 0 CT dosimetry.

Methods: Seed positions were independently determined using RUF and USD. RUF uses a radio-opaque fiducial for registration to ultrasound and 3-dimensional reconstruction of seeds relative to prostate using nonisocentric C-arm fluoroscopy.

REDMAPS: reduced-dimensionality matching for prostate brachytherapy seed reconstruction.

The success of prostate brachytherapy critically depends on delivering adequate dose to the prostate gland. Intraoperative localization of the implanted seeds provides potential for dose evaluation and optimization during therapy. A reduced-dimensionality matching algorithm for prostate brachytherapy seed reconstruction (REDMAPS) that uses multiple X-ray fluoroscopy images obtained from different poses is proposed.

Prostate brachytherapy seed reconstruction with Gaussian blurring and optimal coverage cost.

Intraoperative dosimetry in prostate brachytherapy requires localization of the implanted radioactive seeds. A tomosynthesis-based seed reconstruction method is proposed. A three-dimensional volume is reconstructed from Gaussian-blurred projection images and candidate seed locations are computed from the reconstructed volume.

REDUCED-DIMENSIONALITY MATCHING FOR 3-D RECONSTRUCTION OF PROSTATE BRACHYTHERAPY IMPLANTS FROM INCOMPLETE DATA.

X-ray fluoroscopy is widely used for intra-operative dosimetry in prostate brachytherapy. Three-dimensional locations of the implanted radioactive seeds can be calculated from multiple X-ray images upon resolving the correspondence of seeds. This is usually modeled as an assignment problem that is NP-hard.

Optimal matching for prostate brachytherapy seed localization with dimension reduction.

In prostate brachytherapy, x-ray fluoroscopy has been used for intra-operative dosimetry to provide qualitative assessment of implant quality. More recent developments have made possible 3D localization of the implanted radioactive seeds. This is usually modeled as an assignment problem and solved by resolving the correspondence of seeds.

CTREC: C-arm Tracking and Reconstruction using Elliptic Curves.

C-arm fluoroscopy is ubiquitous in contemporary surgery, but it lacks the ability to accurately reconstruct three-dimensional information, attributable to the difficulty in obtaining the pose of X-ray images in 3D space. We propose a unified mathematical framework to address the issues of intra-operative pose estimation, correspondence and reconstruction, using simple elliptic curves. In contrast to other fiducial-based tracking methods, our method uses a single ellipse to constrain 5 out of 6 degrees of freedom of C-arm pose, along with randomly distributed unknown points in the imaging volume (either naturally present or induced by randomly placed beads or other markers in the image space) from two images/views to completely recover the C-arm pose.

TOMOSYNTHESIS-BASED RADIOACTIVE SEED LOCALIZATION IN PROSTATE BRACHYTHERAPY USING MODIFIED DISTANCE MAP IMAGES.

We have developed a tomosynthesis-based radioactive seed localization method for prostate brachytherapy. In contrast to the projection image-based matching approach, our method does not involve explicit segmentation of seeds and can recover hidden seeds. Modified distance map images are computed from a limited number of x-ray projection images, and are backprojected to reconstuct a 3-D volume of interest.

Prostate implant reconstruction with discrete tomography.

We developed a discrete tomography method for prostate implant reconstructions using only a limited number of X-ray projection images. A 3D voxel volume is reconstructed by back-projection and using distance maps generated from the projection images. The true seed locations are extracted from the voxel volume while false positive seeds are eliminated using a novel optimal geometry coverage model.

Toward optimal matching for 3D reconstruction of brachytherapy seeds.

X-ray C-arm fluoroscopy is a natural choice for intra-operative seed localization in prostate brachytherapy. Resolving the correspondence of seeds in the projection images can be modeled as an assignment problem that is NP-hard. Our approach rests on the practical observation that the optimal solution has almost zero cost if the pose of the C-arm is known accurately.

C-arm tracking and reconstruction without an external tracker.

For quantitative C-arm fluoroscopy, we have developed a unified mathematical framework to tackle the issues of intra-operative calibration, pose estimation, correspondence and reconstruction, without the use of optical/electromagnetic trackers or precision-made fiducial fixtures. Our method uses randomly distributed unknown points in the imaging volume, either naturally present or induced by randomly sticking beads or other simple markers in the image pace. After these points are segmented, a high dimensional non-linear optimization computes all unknown parameters for calibration, C-arm pose, correspondence and reconstruction.

C-arm calibration--is it really necessary?

C-arm fluoroscopy is modelled as a perspective projection, the parameters of which are estimated through a calibration procedure. It has been universally accepted that precise intra-procedural calibration is a prerequisite for accurate quantitative C-arm fluoroscopy guidance. Calibration, however, significantly adds to system complexity, which is a major impediment to clinical practice.

Matching and reconstruction of brachytherapy seeds using the Hungarian algorithm (MARSHAL).

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.

FTRAC--a robust fluoroscope tracking fiducial.

C-arm fluoroscopy is ubiquitous in contemporary surgery, but it lacks the ability to accurately reconstruct three-dimensional (3D) information. A major obstacle in fluoroscopic reconstruction is discerning the pose of the x-ray image, in 3D space. Optical/magnetic trackers tend to be prohibitively expensive, intrusive and cumbersome in many applications.