The Experts below are selected from a list of 1704 Experts worldwide ranked by ideXlab platform
Sandy Napel - One of the best experts on this subject based on the ideXlab platform.
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Virtual Endoscopy using perspective volume rendered three dimensional sonographic data technique and clinical applications
American Journal of Roentgenology, 1999Co-Authors: Esther L Yuh, R B Jeffrey, Robyn L Birdwell, Bertha Chen, Sandy NapelAbstract:OBJECTIVE: We present a technique for obtaining three-dimensional external and Virtual Endoscopy views of organs using perspective volume-rendered gray-scale and Doppler sonographic data, and we explore potential clinical applications in the carotid artery, the female pelvis, and the bladder. CONCLUSION: Using the proposed methods, radiologists will find it possible to create Virtual Endoscopy and external perspective views using sonographic data. The technique works well for revealing the interior of fluid-filled structures and cavities. However, expected improvements in computer performance and integration with existing sonographic equipment will be necessary for the technique to become practical in the clinical environment.
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Automated flight path planning for Virtual Endoscopy
Medical physics, 1998Co-Authors: David S. Paik, Geoffrey D Rubin, Christopher F. Beaulieu, R. Brooke Jeffrey, Sandy NapelAbstract:In this paper, a novel technique for rapid and automatic computation of flight paths for guiding Virtual endoscopic exploration of three-dimensional medical images is described. While manually planning flight paths is a tedious and time consuming task, our algorithm is automated and fast. Our method for positioning the Virtual camera is based on the medial axis transform but is much more computationally efficient. By iteratively correcting a path toward the medial axis, the necessity of evaluating simple point criteria during morphological thinning is eliminated. The Virtual camera is also oriented in a stable viewing direction, avoiding sudden twists and turns. We tested our algorithm on volumetric data sets of eight colons, one aorta and one bronchial tree. The algorithm computed the flight paths in several minutes per volume on an inexpensive workstation with minimal computation time added for multiple paths through branching structures (10%–13% per extra path). The results of our algorithm are smooth, centralized paths that aid in the task of navigation in Virtual endoscopic exploration of three-dimensional medicalimages.
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Virtual Endoscopy of the paranasal sinuses using perspective volume rendered helical sinus computed tomography
Laryngoscope, 1997Co-Authors: Sapideh Gilani, Alexander Norbash, Helmut Ringl, Geoffrey D Rubin, Sandy Napel, David J TerrisAbstract:Our goal was to use three-dimensional information obtained from helical computed tomographic (CT) data to explore and evaluate the nasal cavity, nasopharynx, and paranasal sinuses by simulated Virtual Endoscopy (VE). This was done by utilizing a new image reconstruction method known as perspective volume rendering (PVR). Thin-section helical CT of the nasal cavity, nasopharynx, and paranasal sinuses was performed on a conventional CT scanner. The data were transferred to a workstation to create views similar to those seen with Endoscopy. Additional views not normally accessible by conventional Endoscopy were generated. Key perspectives were selected, and a video flight model was choreographed and synthesized through the nasal cavity and sinuses based on the CT data. VE allows evaluation of the nasal cavity, nasopharynx, and paranasal sinuses with appreciation of the relationships of these spatially complex structures. In addition, this technique allows structural visualization with unconventional angles, perspectives, and locations not conventionally accessible. Although biopsies, cultures, and lavages routinely done with Endoscopy cannot be performed with VE, this technique holds promise for improving the diagnostic evaluation of the nasal cavity, the nasopharynx, and the paranasal sinuses. The unconventional visual perspectives and very low morbidity may complement many applications of simple diagnostic Endoscopy.
I Ahmad - One of the best experts on this subject based on the ideXlab platform.
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enhancing airway assessment of patients with head and neck pathology using Virtual Endoscopy
Indian Journal of Anaesthesia, 2017Co-Authors: I Ahmad, Oliver Keane, Sarah MuldoonAbstract:Studies have demonstrated that poor assessment and planning contribute to airway complications and that current airway assessment strategies have a poor diagnostic accuracy in predicting difficult intubation in the general population. Patients with head and neck pathology are at higher risk for difficulties during airway management and are more likely to need emergency surgical access. Therefore, thorough assessment of this group of patients is mandatory. The addition of Virtual Endoscopy (VE) to clinical history and computerised tomography imaging has been shown to improve diagnostic accuracy for supraglottic, glottic and infraglottic lesions and has a positive influence in formulating a more cautious and thorough airway management strategy in this high-risk group of patients. This article reviews whether VE can enhance airway assessment in patients with head and neck pathology and help reduce airway complications.
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the effect of Virtual Endoscopy on diagnostic accuracy and airway management strategies in patients with head and neck pathology a prospective cohort study
Canadian Journal of Anaesthesia-journal Canadien D Anesthesie, 2017Co-Authors: Kariem Elboghdadly, Britta Millhoff, D N Onwochei, I AhmadAbstract:There is growing evidence to suggest a deficiency in anesthesiologists’ diagnosis of airway pathology and subsequent airway management planning, and conventional instruments have not shown increases in safety. Virtual Endoscopy (VE) is a tool that can detail intraluminal anatomical “fly-through” information in a format visually similar to the flexible endoscopic views familiar to anesthesiologists. We aimed to determine the effect of VE on diagnostic accuracy and airway management strategies when compared with conventional tools. Clinical scenarios, along with computerized tomography (CT) imaging, were presented to 20 anesthesiologists, and structured questions were asked regarding diagnosis of airway pathology and airway management strategy. Virtual Endoscopy videos were then provided and the questions were repeated. Following the CT and VE presentations, the anesthesiologists’ responses involving diagnostic accuracy and airway management strategy were compared between the CT and VE techniques. Answers relating to the utility of VE were also sought. Diagnostic accuracy was 54.1% with CT alone and increased to 67.7% when VE was added (P = 0.007). In 48% of cases, the addition of VE to clinical history and CT led to changes in airway management strategy (P < 0.001), and 90.6% of these changes were deemed more cautious (P < 0.001). Virtual Endoscopy improves the accuracy in diagnosis of airway pathology when compared with CT alone. Furthermore, it leads to more conservative and potentially safer airway management strategies in patients with head and neck pathology.
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the effect of Virtual Endoscopy on diagnostic accuracy and airway management strategies in patients with head and neck pathology a prospective cohort study
Canadian Journal of Anaesthesia-journal Canadien D Anesthesie, 2017Co-Authors: Kariem Elboghdadly, Britta Millhoff, D N Onwochei, I AhmadAbstract:Purpose There is growing evidence to suggest a deficiency in anesthesiologists’ diagnosis of airway pathology and subsequent airway management planning, and conventional instruments have not shown increases in safety. Virtual Endoscopy (VE) is a tool that can detail intraluminal anatomical “fly-through” information in a format visually similar to the flexible endoscopic views familiar to anesthesiologists. We aimed to determine the effect of VE on diagnostic accuracy and airway management strategies when compared with conventional tools.
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Virtual Endoscopy a new assessment tool in difficult airway management
Journal of Clinical Anesthesia, 2015Co-Authors: I Ahmad, Britta Millhoff, M John, K Andi, R OakleyAbstract:Abstract Preemptive mapping of the airway is a useful adjunct to conventional clinical assessments when airway management planning for patients with complex head and neck pathology. NasEndoscopy is frequently used for this purpose but is also invasive and poorly tolerated in a subset of patients and, even in expert hands, may not allow complete visualization of the glottis and subglottic structures. We present a novel tool for difficult airway management planning in the form of Virtual Endoscopy by applying free online OsiriX software to head and neck computed tomographic scans to generate a "fly-through" airway reconstruction. To highlight how well Virtual Endoscopy correlates to conventional fibreoscopy, we compare both of these assessment tools in 3 patients with glottic, subglottic, and multilevel airway pathologies. Virtual Endoscopy represents a unique, noninvasive, safe, and accurate airway assessment and educational resource, which warrants further exploration.
Stefan Wolfsberger - One of the best experts on this subject based on the ideXlab platform.
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Virtual Endoscopy in neurosurgery: A review
Neurosurgery, 2013Co-Authors: Angela Neubauer, Stefan WolfsbergerAbstract:Virtual Endoscopy is the computerized creation of images depicting the inside of patient anatomy reconstructed in a Virtual reality environment. It permits interactive, noninvasive, 3-dimensional visual inspection of anatomical cavities or vessels. This can aid in diagnostics, potentially replacing an actual endoscopic procedure, and help in the preparation of a surgical intervention by bridging the gap between plain 2-dimensional radiologic images and the 3-dimensional depiction of anatomy during actual Endoscopy. If not only the endoscopic vision but also endoscopic handling, including realistic haptic feedback, is simulated, Virtual Endoscopy can be an effective training tool for novice surgeons. In neurosurgery, the main fields of the application of Virtual Endoscopy are third ventriculostomy, endonasal surgery, and the evaluation of pathologies in cerebral blood vessels. Progress in this very active field of research is achieved through cooperation between the technical and the medical communities. While the technology advances and new methods for modeling, reconstruction, and simulation are being developed, clinicians evaluate existing simulators, steer the development of new ones, and explore new fields of application. This review introduces some of the most interesting Virtual reality systems for endoscopic neurosurgery developed in recent years and presents clinical studies conducted either on areas of application or specific systems. In addition, benefits and limitations of single products and simulated neuroEndoscopy in general are pointed out.
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Intra-operative Virtual Endoscopy for image guided endonasal transsphenoidal pituitary surgery.
International journal of computer assisted radiology and surgery, 2009Co-Authors: Florian Schulze, Katja Bühler, André Neubauer, Armin Kanitsar, Leslie Holton, Stefan WolfsbergerAbstract:Purpose Virtual Endoscopy has already proven its benefit for pre-operative planning of endoscopic pituitary surgery. The translation of such a system into the operating room is a logical consequence, but only a few general intra-operative image guided systems providing Virtual endoscopic images have been proposed so far. A discussion of related visualization and interaction problems occurring during sinus and pituitary surgery is still missing.
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advanced Virtual Endoscopy for endoscopic transsphenoidal pituitary surgery
Neurosurgery, 2006Co-Authors: Stefan Wolfsberger, Katja Bühler, André Neubauer, R. Wegenkittl, Thomas Czech, Stephan Gentzsch, Hansgerd Bocherschwarz, Engelbert KnospAbstract:Objective Virtual Endoscopy (vE) is the navigation of a camera through a Virtual anatomical space that is computationally reconstructed from radiological image data. Inside this three-dimensional space, arbitrary movements and adaptations of viewing parameters are possible. Thereby, vE can be used for noninvasive diagnostic purposes and for simulation of surgical tasks. This article describes the development of an advanced system of vE for endoscopic transsphenoidal pituitary surgery and its application to teaching, training, and in the routine clinical setting. Methods The vE system was applied to a series of 35 patients with pituitary pathology (32 adenomas, three Rathke's cleft cysts) operated endoscopically via the transsphenoidal route at the Department of Neurosurgery of the Medical University Vienna between 2004 and 2006. Results The Virtual endoscopic images correlated well with the intraoperative view. For the transsphenoidal approach, vE improved intraoperative orientation by depicting anatomical landmarks and variations. For planning a safe and tailored opening of the sellar floor, transparent visualization of the pituitary adenoma and the normal gland in relation to the internal carotid arteries was useful. Conclusion According to our experience, vE can be a valuable tool for endoscopic transsphenoidal pituitary surgery for training purposes and preoperative planning. For the novice, it can act as a simulator for endoscopic anatomy and for training surgical tasks. For the experienced pituitary surgeon, vE can depict the individual patient's anatomy, and may, therefore, improve intraoperative orientation. By prospectively visualizing unpredictable anatomical variations, vE may increase the safety of this surgical procedure.
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perspective isosurface and direct volume rendering for Virtual Endoscopy applications
IEEE VGTC Conference on Visualization, 2006Co-Authors: Henning Scharsach, Stefan Wolfsberger, André Neubauer, Markus Hadwiger, Katja BühlerAbstract:Virtual Endoscopy has proven to be a very powerful tool in endoscopic surgery. However, most Virtual Endoscopy systems are restricted to rendering isosurfaces or require segmentation in order to visualize additional objects behind occluding tissue. This paper presents a system for real-time perspective direct volume and isosurface rendering, which allows to simultaneously visualize both the interesting tissue and everything that is behind. Large volume data can be viewed seamlessly from inside or outside the volume without any pre-computation or segmentation. Our system uses a novel ray-casting pipeline for GPUs that has been optimized for the requirements of Virtual Endoscopy and also allows easy incorporation of auxiliary geometry, e.g., for displaying parts of the endoscopic device, pointers, or grid lines for orientation purposes. We present three main applications of this system and the underlying ray-casting algorithm. Although our ray-casting approach is of general applicability, we have specifically applied it to Virtual colonoscopy, Virtual angioscopy, and Virtual pituitary surgery.
John F Pallanch - One of the best experts on this subject based on the ideXlab platform.
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mapping the frontal sinus ostia using Virtual Endoscopy
Laryngoscope, 2012Co-Authors: Amy C Dearking, John F PallanchAbstract:Objectives/Hypothesis: To determine the relative location of the frontal sinus opening to other frontal cells using Virtual Endoscopy; and to assess whether the relative location of the frontal sinus ostium can be predicted. Study Design: Retrospective analysis of high-resolution computed tomography scans from 50 adult patients without frontal sinus disease or previous sinus surgery. Methods: Using Virtual Endoscopy software, 100 frontal recesses were mapped for the presence and relative position of the frontal sinus ostium to the following cells: agger nasi (ANC); frontal bullar; frontal types 1, 2, and 3; supraorbital ethmoid; suprabullar; and intersinus septal cells. Results: ANC and frontal type 3 cells were present in 92% and 45% of frontal recesses, respectively. All other cell types had a prevalence of ≤25%. Fifty percent of recesses had two rows of ostia anterior to posterior (AP), and the frontal opening was anterior in 52%. When there were three rows of cells AP (39%), the frontal opening was in the center in 64% of cases. Thirty-five percent of recesses had two rows of ostia medial to lateral (ML), and the frontal opening was medial 80% of the time. When there were three rows of openings ML (45%), the frontal opening was in the center 56% of the time. Conclusions: The frontal sinus recess is variable and complex. Virtual Endoscopy can be used to analyze the frontal recess and assist in presurgical planning. Although there is variability in the ostial configuration present in the frontal recess, the probable position of the frontal sinus ostium can be predicted. Laryngoscope, 2012
Geoffrey D Rubin - One of the best experts on this subject based on the ideXlab platform.
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Automated flight path planning for Virtual Endoscopy
Medical physics, 1998Co-Authors: David S. Paik, Geoffrey D Rubin, Christopher F. Beaulieu, R. Brooke Jeffrey, Sandy NapelAbstract:In this paper, a novel technique for rapid and automatic computation of flight paths for guiding Virtual endoscopic exploration of three-dimensional medical images is described. While manually planning flight paths is a tedious and time consuming task, our algorithm is automated and fast. Our method for positioning the Virtual camera is based on the medial axis transform but is much more computationally efficient. By iteratively correcting a path toward the medial axis, the necessity of evaluating simple point criteria during morphological thinning is eliminated. The Virtual camera is also oriented in a stable viewing direction, avoiding sudden twists and turns. We tested our algorithm on volumetric data sets of eight colons, one aorta and one bronchial tree. The algorithm computed the flight paths in several minutes per volume on an inexpensive workstation with minimal computation time added for multiple paths through branching structures (10%–13% per extra path). The results of our algorithm are smooth, centralized paths that aid in the task of navigation in Virtual endoscopic exploration of three-dimensional medicalimages.
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Virtual Endoscopy of the paranasal sinuses using perspective volume rendered helical sinus computed tomography
Laryngoscope, 1997Co-Authors: Sapideh Gilani, Alexander Norbash, Helmut Ringl, Geoffrey D Rubin, Sandy Napel, David J TerrisAbstract:Our goal was to use three-dimensional information obtained from helical computed tomographic (CT) data to explore and evaluate the nasal cavity, nasopharynx, and paranasal sinuses by simulated Virtual Endoscopy (VE). This was done by utilizing a new image reconstruction method known as perspective volume rendering (PVR). Thin-section helical CT of the nasal cavity, nasopharynx, and paranasal sinuses was performed on a conventional CT scanner. The data were transferred to a workstation to create views similar to those seen with Endoscopy. Additional views not normally accessible by conventional Endoscopy were generated. Key perspectives were selected, and a video flight model was choreographed and synthesized through the nasal cavity and sinuses based on the CT data. VE allows evaluation of the nasal cavity, nasopharynx, and paranasal sinuses with appreciation of the relationships of these spatially complex structures. In addition, this technique allows structural visualization with unconventional angles, perspectives, and locations not conventionally accessible. Although biopsies, cultures, and lavages routinely done with Endoscopy cannot be performed with VE, this technique holds promise for improving the diagnostic evaluation of the nasal cavity, the nasopharynx, and the paranasal sinuses. The unconventional visual perspectives and very low morbidity may complement many applications of simple diagnostic Endoscopy.
