title: [Virtual colonoscopy using CT and MRI].
abstract: OBJECTIVE
  To evaluate experimentally and in patients the sensitivity and effective dose of virtual electron-beam tomography (EBT) colonoscopy for detecting small colon tumors and to compare the methods and results with virtual colonoscopy using spiral CT and MR imaging in a review of the literature.
  
  
  METHODS
  Six polyps with diameters between 3 and 12 mm were created and randomly placed in resected pig colon. After distension with air, the pig colon was scanned with continuous volume scanning (CVS, 3 mm collimation) and a pitch of 0.4, 0.8 and 1.5. Twenty patients positive for the fecal blood test were examined after rectal CO2 insufflation and i.v. administration of 1 mg glucagon. A 13 s CVS scan was used to cover the entire colon within one breath-hold. 3D volume-rendered fly-throughs were evaluated by two independent radiologists. Effective dose equivalent was estimated using an Alderson phantom equipped with thermoluminescence dosimeters.
  
  
  RESULTS
  In the tumor model, all polyps were detectable at a pitch of 1.5. A further reduction of the pitch ratio did not improve the conspicuity of the polyps. In patient studies, all tumors (n = 4) and polyps (n = 3) were correctly identified on 3D fly-throughs. Two false positive results were obtained. Effective dose equivalent was calculated at 3.2 mSv per scan.
  
  
  CONCLUSIONS
  Our preliminary results indicate that virtual EBT colonoscopy holds promise for fast screening for colon polyps. The best technique for virtual colonoscopy (Spiral CT, EBT, MRI) has not yet been determined and the future role of virtual colonoscopy must still be defined.
authors.affiliation: Institut für Radiologische Diagnostik, Klinikum Grosshadern, Ludwig-Maximilians-Universität München.
authors.forename: J
authors.initials: J
authors.lastname: Scheidler
authors.forename: C
authors.initials: C
authors.lastname: Frank
authors.forename: C
authors.initials: C
authors.lastname: Becker
authors.forename: H
authors.initials: H
authors.lastname: Feist
authors.forename: G
authors.initials: G
authors.lastname: Michalski
authors.forename: M
authors.initials: M
authors.lastname: Schätzl
authors.forename: A
authors.initials: A
authors.lastname: Bäuml
authors.forename: A F
authors.initials: AF
authors.lastname: Heuck
authors.forename: M F
authors.initials: MF
authors.lastname: Reiser
mesh_terms: D003111:Colonic Polyps / Q000175:diagnosis*; D003113:Colonoscopy / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface
vernacular_title: Virtuelle CT- und MRT-Koloskopie.