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  • 1
    ISSN: 1600-0501
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We developed a head-mounted display (HMD) with integrated computer-generated stereoscopic projection of target structures and integrated it into visit, a specific oral implant planning and navigation software. The HMD is equipped with two miniature computer monitors that project computer-generated graphics stereoscopically into the optical path. Its position is tracked by the navigation system's optical tracker and target structures are displayed in their true position over the operation site. In order to test this system's accuracy and spatial perception of the viewer, five interforaminal implants in three dry human mandibles were planned with visit and executed using the stereoscopic projection through the HMD. The deviation between planned and achieved position of the implants was measured on corresponding computed tomography (CT) scan images recorded post-operatively. The deviation between planned and achieved implant position at the jaw crest was 0.57 ± 0.49 mm measured from the lingual, and 0.58 ± 0.4 mm measured from the buccal cortex. At the tip of the implants the deviation was 0.77 ± 0.63 mm at the lingual and 0.79 ± 0.71 mm at the buccal cortex. The mean angular deviation between planned and executed implant position was 3.55 ± 2.07 degrees. The present in vitro experiment indicates that the concept of preoperative planning and transfer to the operative field by an HMD allows us to achieve an average precision within 1 mm (range up to 3 mm) of the implant position and within 3° deviation for the implant inclination (range up to 10°). Control during the drilling procedure is significantly improved by stereoscopic vision through the HMD resulting in a more accurate inclination of the implants.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0460
    Keywords: Esophageal carcinoma ; Tumor infiltration ; CT staging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The computed tomograms of 74 patients with histologically proven carcinomas of the esophagus, including the esophagogastric junction, were retrospectively evaluated. In 58 patients (78%) the CT findings could be compared with surgical and histologic results. Aortic infiltration was assumed in cases with contiguous contact of aorta and tumor on at least four CT slices (slice thickness: 8 mm) and a transverse “contact-angle” of more than 60 degrees. In this regard CT showed a sensitivity of 86% and a specificity of 92% according to surgery. Tracheo bronchial infiltration was suggested when compression or change of position of these structures was observed (sensitivity of 86%, specificity of 65%). Infiltration of the diaphragm was detected by CT with a sensitivity of 60% and a specificity of 88%. Infiltrations of pleura or pericardium could not be diagnosed by CT in our study. Consequently, CT is a valuable method to show aortic infiltration (negative predictive value, 95%; positive predictive value, 86%) and an infiltration of the tracheobronchial system (negative predictive value, 79%; positive predictive value, 75%) in patients with carcinoma of the esophagus.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 40 (2000), S. 340-342 
    ISSN: 1432-2102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Der Radiologe 40 (2000), S. 1-1 
    ISSN: 1432-2102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-6792
    Keywords: power and coherence probability maps ; mental tasks ; brain morphology ; 3D reconstruction ; volume rendering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A method for the projection of EEG data on the brain surface is proposed. The EEG data are obtained during the performance of mentaltasks and represented as probability maps of power and coherencechanges with respect to the averaged EEG at rest. The morphological data are obtained from 3D reconstructions of the brain by means of serial slices provided by an MRI scanner. Before scanning the positions of the EEG electrodes were marked by dummy electrodes of plexiglass filled with a contrast medium. Changes of power are color-coded and entered at the respective electrode positions, changes of coherence between the respective positions. The applicability of this procedure in the fields of psychology, psychiatry and neurology is discussed.
    Type of Medium: Electronic Resource
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