6 research outputs found
Towards 3D ultrasound image based soft tissue tracking: a transrectal ultrasound prostate image alignment system
The emergence of real-time 3D ultrasound (US) makes it possible to consider
image-based tracking of subcutaneous soft tissue targets for computer guided
diagnosis and therapy. We propose a 3D transrectal US based tracking system for
precise prostate biopsy sample localisation. The aim is to improve sample
distribution, to enable targeting of unsampled regions for repeated biopsies,
and to make post-interventional quality controls possible. Since the patient is
not immobilized, since the prostate is mobile and due to the fact that probe
movements are only constrained by the rectum during biopsy acquisition, the
tracking system must be able to estimate rigid transformations that are beyond
the capture range of common image similarity measures. We propose a fast and
robust multi-resolution attribute-vector registration approach that combines
global and local optimization methods to solve this problem. Global
optimization is performed on a probe movement model that reduces the
dimensionality of the search space and thus renders optimization efficient. The
method was tested on 237 prostate volumes acquired from 14 different patients
for 3D to 3D and 3D to orthogonal 2D slices registration. The 3D-3D version of
the algorithm converged correctly in 96.7% of all cases in 6.5s with an
accuracy of 1.41mm (r.m.s.) and 3.84mm (max). The 3D to slices method yielded a
success rate of 88.9% in 2.3s with an accuracy of 1.37mm (r.m.s.) and 4.3mm
(max)
Effective Volumetric Feature Modeling and Coarse Correspondence via Improved 3DSIFT and Spectral Matching
This paper presents a nonrigid coarse correspondence computation algorithm for volumetric images. Our matching algorithm first extracts then correlates image features based on a revised and improved 3DSIFT (I3DSIFT) algorithm. With a scale-related keypoint reorientation and descriptor construction, this feature correlation is less sensitive to image rotation and scaling. Then, we present an improved spectral matching (ISM) algorithm on correlated features to obtain a one-to-one mapping between corresponded features. One can effectively extend this feature correspondence to dense correspondence between volume images. Our algorithm can benefit nonrigid volumetric image registration in many tasks such as motion modeling in medical image analysis and processing
Physics-Based Probabilistic Motion Compensation of Elastically Deformable Objects
A predictive tracking approach and a novel method for visual motion compensation are introduced, which accurately reconstruct and compensate the deformation of the elastic object, even in the case of complete measurement information loss. The core of the methods involves a probabilistic physical model of the object, from which all other mathematical models are systematically derived. Due to flexible adaptation of the models, the balance between their complexity and their accuracy is achieved