VCBM 14: Eurographics Workshop on Visual Computing for Biology and Medicine

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/7762

Browse

Browsing VCBM 14: Eurographics Workshop on Visual Computing for Biology and Medicine by Subject "Enhancement"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Deriving Anatomical Context from 4D Ultrasound
    (The Eurographics Association, 2014) Müller, Markus; Helljesen, Linn E. S.; Prevost, Raphael; Viola, Ivan; Nylund, Kim; Gilja, Odd Helge; Navab, Nassir; Wein, Wolfgang; Ivan Viola and Katja Buehler and Timo Ropinski
    Real-time three-dimensional (also known as 4D) ultrasound imaging using matrix array probes has the potential to create large-volume information of entire organs such as the liver without external tracking hardware. This information can in turn be placed into the context of a CT or MRI scan of the same patient. However for such an approach many image processing challenges need to be overcome and sources of error addressed, including reconstruction drift, anatomical deformations, varying appearance of anatomy, and imaging artifacts. In this work, we present a fully automatic system including robust image-based ultrasound tracking, a novel learning-based global initialization of the anatomical context, and joint mono- and multi-modal registration. In an evaluation on 4D US sequences and MRI scans of eight volunteers we achieve automatic reconstruction and registration without any user interaction, assess the registration errors based on physician-defined landmarks, and demonstrate realtime tracking of free-breathing sequences.
  • Thumbnail Image
    Item
    Imaging the Vascular Network of the Human Spleen from Immunostained Serial Sections
    (The Eurographics Association, 2014) Ulrich, Christine; Lobachev, Oleg; Steiniger, Birte; Guthe, Michael; Ivan Viola and Katja Buehler and Timo Ropinski
    The spleen is one of the organs, where the micro-structure and the function on that level are not completely understood. It was for example only recently found that is has an open circulation, which distinguishes it from all other organs. Imaging the complete vascular network from the arteries to open-ended capillaries would greatly facilitate research in this area. The structure of such tissue is best uncovered using immunehistological staining. This can however only be applied to thin tissue sections and larger structures span several slices. Due to the deformation induced when cutting the specimen, standard registration algorithms cannot be used to merge the images into a volume. We propose a specialized matching algorithm to robustly determine corresponding regions in the images. After a rigid alignment of the scans, we use a cubic B-spline to deform and align the images. During this process we minimize the total deformation to produce as accurate results as possible.
  • Thumbnail Image
    Item
    Misalignment Correction in Open Cone-Beam CT
    (The Eurographics Association, 2014) Wieckowski, Adam; Stopp, Fabian; Käseberg, Marc; Keeve, Erwin; Ivan Viola and Katja Buehler and Timo Ropinski
    Cone-beam computed tomography (CBCT) is an established standard for both, medical and industrial volumetric imaging. To compute a 3D volume, multiple 2D x-ray projection images of an object of interest are acquired from different directions. Using the geometric information about the acquisition geometry of each image, the volume is reconstructed. Incorrect geometric information (misalignments) leads to blurring and other artifacts in the resulting reconstruction. The exact acquisition geometry is commonly calculated by the analysis of a scan of a dedicated calibration body (off-line calibration). Such approach requires high repeat accuracy of the scanner mechanics and cannot account for non-systematic deviations. Current methods allowing for misalignment correction without a dedicated phantom, e.g. by iteratively adapting the geometry to minimize the arising artifacts, were developed to work with planar trajectories. It poses a problem for open CBCT systems driving complex trajectories. Therefore, we propose an enhanced method allowing for misalignment correction for general trajectories. We developed a new quality function and a flexible modeling for misalignments. We successfully applied our method to real datasets acquired along planar and non-planar trajectories. The correction with our approach substantially increases the resulting volume quality.
  • Thumbnail Image
    Item
    Personalized X-ray Reconstruction of the Proximal Femur via a New Control Point-based 2D-3D Registration and Residual Complexity Minimization
    (The Eurographics Association, 2014) Yu, Weimin; Zheng, Guoyan; Ivan Viola and Katja Buehler and Timo Ropinski
    In this paper we present a new control point-based 2D-3D registration approach for a deformable registration of a 3D volumetric template to a limited number of 2D calibrated C-arm images and show its application to a personalized X-ray reconstruction of the proximal femur. In our approach, the 2D-3D registration is done with a hierarchical two-stage strategy: the scaled rigid 2D-3D registration stage followed by a regularized deformable b-spline 2D-3D registration stage. In both stages, a set of control points with uniform spacing are placed over the domain of the 3D volumetric template first. The registrations are then driven by computing updated positions of these control points with intensity-based 2D-2D image registrations of C-arm images with the associated digitally reconstructed radiographs (DRRs), which then allows computing the associated registration transformation at each stage. In order to account for intensity nonstationarities and complex spatially-varying intensity distortion in the deformable b-spline 2D-3D registration stage, the intensity-based 2D-2D image registrations at this stage are done based on minimizing the complexity of the residual images between the C-arm images and the associated DRRs. Comprehensive experiments on simulated images, on images of cadaveric femurs and on clinical datasets are designed and conducted to evaluate the performance of the proposed approach. Quantitative and qualitative evaluation results are given, which demonstrate the efficacy of the present approach.