Advanced virtual endoscopic pituitary surgery Neubauer, A.; Wolfsberger, S.; Forster, M.-T. ...
IEEE transactions on visualization and computer graphics,
09/2005, Letnik:
11, Številka:
5
Journal Article
Recenzirano
Endoscopy has recently been introduced to endonasal transsphenoidal pituitary surgery as a minimally invasive procedure for the removal of various kinds of pituitary tumors. To reduce morbidity and ...mortality with this new technique, the surgeon must be well-trained and well-prepared. Virtual endoscopy can be beneficial as a tool for training, preoperative planning, and intraoperative support. This paper introduces STEPS, a virtual endoscopy system designed to aid surgeons in getting acquainted with the endoscopic view of the anatomy, the handling of instruments, the transsphenoidal approach, and challenges associated with the procedure. STEPS also assists experienced surgeons in planning a real endoscopic intervention by getting familiar with the individual patient anatomy, identifying landmarks, planning the approach, and deciding upon the ideal target position of the actual surgical activity. The application provides interactive visualization, navigation, and perception aids and the possibility of simulating the procedure, including haptic feedback and simulation of surgical instruments.
Surface models of tube trees Felkel, P.; Wegenkittl, R.; Buhler, K.
Proceedings Computer Graphics International, 2004,
2004
Conference Proceeding
This paper describes a new method for generating surfaces of branching tubular structures with given center-lines and radii. As the centerlines are not straight lines, the cross-sections are not ...parallel and well-known algorithms for surface tiling from parallel cross-sections cannot be used. Nonparallel cross-sections can be tiled by means of the maximal-disc interpolation method; special methods for branching-structures modeling by means of convolution surfaces produce excellent results, but these methods are more complex than our approach. The proposed method tiles nonparallel circular cross-sections and constructs a topologically-correct surface mesh. The method is not artifact-free, but it is fast and simple. The surface mesh serves as a data representation of a vessel tree suitable for real-time virtual reality operation planning and operation support within a medical application. Proposed method extracts a "classical" polygonal representation, which can be used in common surface-oriented graphic accelerators
Nonlinear virtual colon unfolding Vilanova Bartroli, A.V.; Wegenkittl, R.; Konig, A. ...
Proceedings Visualization, 2001. VIS '01,
2001
Conference Proceeding
The majority of virtual endoscopy techniques tries to simulate a real endoscopy. A real endoscopy does not always give the optimal information due to the physical limitations it is subject to. In ...this paper, we deal with the unfolding of the surface of the colon as a possible visualization technique for diagnosis and polyp detection. A new two-step technique is presented which deals with the problems of double appearance of polyps and nonuniform sampling that other colon unfolding techniques suffer from. In the first step, a distance map from a central path induces nonlinear rays for unambiguous parameterization of the surface. The second step compensates for locally varying distortions of the unfolded surface. A technique similar to magnification fields in information visualization is hereby applied. The technique produces a single view of a complete, virtually dissected colon.
Virtual endoscopy (vE) allows simulated three-dimensional (3-D) visualisation of anatomical structures by computerised reconstruction of radiological images. The aim of this study was to evaluate the ...feasibility of vE and its potential benefits for endoscopic transsphenoidal pituitary surgery. vE was realised using a commercially available ray-casting software plugin of a picture archiving and communications system (PACS). For this study, the vE system was enhanced with volume segmentation, transparency and cutting tools. The data for vE were derived from high resolution computed tomography (CT) scans of 22 patients with pituitary pathology (20 pituitary adenomas, 2 Rathke's cleft cysts) preoperatively. Anatomic structures were identified on vE images and compared with the intraoperative endoscopic views. The simulated 3-D vE images were found to be comparable to the intraoperative endoscopic anatomy in terms of distortion and angle of view. vE was found to be particularly useful for the preoperative depiction of 1) the nasal anatomy and its variations for choosing the side of the approach, 2) the sphenoid sinus septae and chambers for improved intraoperative orientation, 3) the transparent 3-D simulated visualisation of the pituitary gland, tumour and adjacent anatomic structures in relation to the sphenoid sinus landmarks for planning the opening of the sellar floor. We conclude that vE harbours the potential to become a valuable tool in endoscopic pituitary surgery for training purposes and preoperative planning. Furthermore, vE may add to the safety of interventions in case of anatomic variations.
This paper deals with vessel exploration based on computed tomography angiography. Large image sequences of the lower extremities are investigated in a clinical environment. Two different approaches ...for peripheral vessel diagnosis dealing with stenosis and calcification detection are introduced. The paper presents an automated vessel-tracking tool for curved planar reformation. An interactive segmentation tool for bone removal is proposed.
The display of iso-surfaces in medical data sets is an important visualization technique used by radiologists for the diagnosis of volumetric density data sets. The demands put by radiologists on ...such a display technique are interactivity, multiple stacked transparent surfaces and cutting planes that allow an interactive clipping of the surfaces. This paper presents a Java based, platform independent implementation of a very fast surface rendering algorithm which combines the advantages of explicit surface representation, splatting, and shear-warp projection to fulfill all these requirements. The algorithm is implemented within the context of J-Vision, an application for viewing and diagnosing medical images which is currently in use at various hospitals.
Virtual endoscopy presents the cross-sectional acquired 3D-data of a computer tomograph as an endoluminal view. The common approach for the visualization of a virtual endoscopy is surface rendering, ...yielding images close to a real endoscopy. If external structures are of interest, volume rendering techniques have to be used. These methods do not display the exact shape of the inner lumen very well. For certain applications, e.g. operation planning of a transbronchial biopsy, both the shape of the inner lumen as well as outer structures like blood vessels and the tumor have to be delineated. A method is described, that allows a quick and easy hybrid visualization using overlays of different visualization methods like different surfaces or volume renderings with different transfer functions in real time on a low-end PC. To achieve real time frame rates, image based rendering techniques have been used.
Traditional volume visualization techniques may provide incomplete clinical information needed for applications in medical visualization. In the area of vascular visualization important features such ...as the lumen of a diseased vessel segment may not be visible. Curved planar reformation (CPR) has proven to be an acceptable practical solution. Existing CPR techniques, however, still have diagnostically relevant limitations. In this paper, we introduce two advances methods for efficient vessel visualization, based on the concept of CPR. Both methods benefit from relaxation of spatial coherence in favor of improved feature perception. We present a new technique to visualize the interior of a vessel in a single image. A vessel is resampled along a spiral around its central axis. The helical spiral depicts the vessel volume. Furthermore, a method to display an entire vascular tree without mutually occluding vessels is presented. Minimal rotations at the bifurcations avoid occlusions. For each viewing direction the entire vessel structure is visible.
The watershed algorithm belongs to classical algorithms in mathematical morphology. Lotufo et al.1 published a principle of the watershed computation by means of an iterative forest transform (IFT), ...which computes a shortest path forest from given markers. The algorithm itself was described for a 2D case (image) without a detailed discussion of its computation and memory demands for real datasets.
As IFT cleverly solves the problem of plateaus and as it gives precise results when thin objects have to be segmented, it is obvious to use this algorithm for 3D datasets taking in mind the minimizing of a higher memory consumption for the 3D case without loosing low asymptotical time complexity of O(m+C)(and also the real computation speed). The main goal of this paper is an implementation of the IFT algorithm with a priority queue with buckets and careful tuning of this implementation to reach as minimal memory consumption as possible.
The paper presents five possible modifications and methods of implementation of the IFT algorithm. All presented implementations keep the time complexity of the standard priority queue with buckets but the best one minimizes the costly memory allocation and needs only 19–45% of memory for typical 3D medical imaging datasets.
Memory saving was reached by an IFT algorithm simplification, which stores more elements in temporary structures but these elements are simpler and thus need less memory.The best presented modification allows segmentation of large 3D medical datasets (up to 512 × 512 × 680 voxels) with 12‐ or 16‐bits per voxel on currently available PC based workstations.
We describe the results of the literature review focused on the peripheral vessel segmentation in 3D medical datasets, acquired by computer tomography angiography (CTA) of the human leg. The ...fundamental aim of such a segmentation task is a robust method for the detection of main vessels in the leg that simultaneously preserves the vessel calcification (the sediment is called plaque) and allows localization of vessel narrowings (called stenoses). This segmentation has to be free from artifacts, i.e., without false detections of stenoses and without false omitting of any stenotic part. The paper collects seven methods applicable for vessel segmentation.
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