X-ray image guided angioplasty is a minimally invasive procedure that involves the insertion of a catheter into a
blood vessel to remove blockages to blood flow. There are several issues associated with conventional angioplasty
which cause risks for the patient (damage to blood vessels, dislodging plaques, etc.) and difficulties for the
clinician (X-ray exposure, fatigue, etc.). Autonomous or semi-autonomous robot-assisted catheter insertion is a
solution that can reduce these problems substantially. To perform autonomous catheter insertion, closed-loop
position control of the distal tip of the catheter is required during insertion. Therefore accurate real-time position
feedback is needed for this purpose. We have developed a real-time image processing algorithm for catheter tip
position tracking which has an acceptable performance but is sensitive to X-ray image artifacts caused by bones
and dense tissues. A magnetic tracking system (MTS) is another modality that has also been used for catheter
tip position tracking, but it is sensitive to external electromagnetic interferences and ferromagnetic material.
Combining the measurement data provided by both imaging and magnetic sensors can compensate for the
deficiencies of each and can also improve the robustness of catheter tip position tracking. We have developed a
Kalman filter based sensor fusion scheme to overcome deficiencies of both of these methods and create a reliable
real-time tracking of a catheter tip. Experiments have been performed by inserting a guide catheter into a model
of the vasculature. The method has been tested in presence of occlusion in the images and also electromagnetic
interference.
KEYWORDS: Ultrasonography, 3D image processing, Heart, Visualization, 3D visualizations, Human-machine interfaces, 3D acquisition, Haptic technology, Image processing, 3D modeling
There are commercial products which provide 3D rendered volumes, reconstructed from electro-anatomical mapping
and/or pre-operative CT/MR images of a patient's heart with tools for highlighting target locations for
cardiac ablation applications. However, it is not possible to update the three-dimensional (3D) volume intraoperatively
to provide the interventional cardiologist with more up-to-date feedback at each instant of time. In
this paper, we describe the system we have developed for real-time three-dimensional stereo visualization for
cardiac ablation. A 4D ultrasound probe is used to acquire and update a 3D image volume. A magnetic tracking
device is used to track the distal part of the ablation catheter in real time and a master-slave robot-assisted system
is developed for actuation of a steerable catheter. Three-dimensional ultrasound image volumes go through some
processing to make the heart tissue and the catheter more visible. The rendered volume is shown in a virtual
environment. The catheter can also be added as a virtual tool to this environment to achieve a higher update
rate on the catheter's position. The ultrasound probe is also equipped with an EM tracker which is used for
online registration of the ultrasound images and the catheter tracking data. The whole augmented reality scene
can be shown stereoscopically to enhance depth perception for the user. We have used transthoracic echocardiography
(TTE) instead of the conventional transoesophageal (TEE) or intracardiac (ICE) echocardiogram. A
beating heart model has been used to perform the experiments. This method can be used both for diagnostic
and therapeutic applications as well as training interventional cardiologists.
Patch clamping is used in electrophysiology to study single or multiple ion channels in cells. Multiple micropipettes
are used as electrodes to collect data from several cells. Placement of these electrodes is a time consuming
and complicated task due to the lack of depth perception, limited view through the microscope lens and the
possibility of collisions between micro-pipettes. To aid in this process, a computer-assisted approach is developed
using image processing techniques applied to images obtained through the microscope. Image processing
algorithms are applied to perform autofocusing, relative depth estimation, distance estimation and tracking of
the micro-pipettes in the images without making any major changes in the existing patch clamp equipment. An
autofocusing algorithm with a micrometer precision is developed and the relative depth estimation is performed
based on autofocusing. A micro-pipette tip detection algorithm is developed which can be used to initialize or
reset the tracking algorithm and to calibrate the system by registering the relative image and micro-manipulator
coordinates. An image-based tracking algorithm is also developed to track a micro-pipette tip in real time.
The real-time tracking data is then used for visual servoing the micro-pipette tips and updating the calibration
information.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.