Virtual scopy is a computerized, non-invasive technique used in simulating views provided by a fiber optic endoscope. Multidetector CT (MDCT) enhances the technique of Virtual scopy, by its z-axis resolution, faster data acquisition and improved 3D-image quality. The common application included Virtual Colonoscopy, Bronchoscopy, Gastroscopy, Angioscopy, Labyrinthoscopy, Thoracoscopy and Stentoscopy. Of the 45 Virtual scopies referred to Radiology Department at INHS Asvini, the single largest application was Virtual Angioscopy followed by Stentoscopy and the smallest was evaluation of larynx, labyrinth, colon and mediastinum accounting for 3 each. Endoscopy data and histopathological diagnosis was available in 17 patients, who underwent Virtual studies of larynx, airway, stomach, mediastinum and colon. MJAFI 2006; 62 : 60-63Key Word : Virtual Endoscopy, Virtual scopy, Internal Volume Rendering injector and CARE Bolus software. In most cases, a detector configuration of 4 x 1 mm, a table feed of 5 mm/rotation at 140 mAs, 120 kV and a gantry rotation time of 500 msec was used, resulting in a slice thickness of 0.5 mm. Processing of Image DataImages from all 45 cases were first interpreted using cine viewing of axial images and secondary MPRs on the main console. Subsequently, volume rendering, 3D scopic views and fly-throughs were generated on a dedicated Leonardo workstation. Virtual scopy images were generated using volume and surface rendering. Four distinct data parameters, i.e. window width, level, opacity and brightness were interactively adjusted, influencing the images generated.For Virtual Colonoscopy, a colon model was created with segmentation of the colon. Guided navigation using a centerline simulated a flight path of the entire colon. With real-time volume rendering at more than 10 frames/sec, interactive navigation of the endoscopic views analysed the colonic lumen. 2-D views corresponding to the navigation viewpoint were available for verification purposes. By turning, zooming, and rotating during the "fly-through" examination of the endoscopic views, the structures were more closely examined. ResultsOf the 45 Virtual scopies performed, the single largest application was Virtual Angioscopy followed by Stentoscopy. The smallest sub-groups were evaluation of larynx, labyrinth, colon and mediastinum accounting for 3 patients each. Endoscopy data and histopathological diagnosis was available in 17 patients, who underwent virtual studies of larynx, airway, stomach, mediastinum and colon. Of the 17 cases, the CT scopy diagnosis matched with Endoscopic/

3D Computed Tomographic Angiography (CTA) is a noninvasive volumetric imaging technique increasingly used for evaluation of vascular system. The introduction of Multidetector CT (MDCT) has increased scanning speed, allowing shorter acquisition time, greater volume coverage and decreased contrast requirement while diminishing respiratory motion artifacts. Thin-slice collimation protocols are routinely used which generate isotropic 3D voxels that improve image quality. The ideal CTA study requires scanning at peak vascular enhancement for optimal opacification of arteries with separation of arteries and veins. MDCT has enabled complete lower extremity inflow and runoff studies with a single injection, as well as thin-section CTA covering the entirety of the Carotid arteries and Circle of Willis. Sixteen row MDCT has increased scanning speed further facilitating the development of novel applications such as coronary CTA. CTA when perfomed with MDCT offers a "one scan - many views" option useful in imaging vascular diseases. CTA has important advantages over conventional angiography, such as reduced risk, diminished time and better patient acceptance. With MDCT, 3D CTA is crossing vessel tortuosity and evaluation of vessel fragility.

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