title: 4-D Imaging in cerebrovascular disorders by using 320-slice CT: feasibility and preliminary clinical experience.
abstract: OBJECTIVE
  The authors report study protocols and initial clinical experience in assessing patients with acute and chronic cerebrovascular disorders using the recently introduced technique of volume computed tomography (VCT).
  
  
  METHODS
  Thirteen patients with presumptive cerebrovascular insufficiency underwent VCT using a 320-slice scanner (detector width, 160 mm), including time-resolved whole-brain perfusion and cerebral angiography (four-dimensional computed tomographic angiography [CTA] and computed tomographic perfusion [CTP]). Unenhanced cranial CT (cCT) and helical cervicocranial CT (three-dimensional CTA) were added according to clinical requirements. Study protocols are presented, and image quality, data management, and radiation exposure issues are discussed.
  
  
  RESULTS
  In 12 of 13 patients, the procedure was performed successfully on admission; in the other patient, the study was aborted for clinical reasons and repeated. Total scan time amounted to about 5 minutes, and data reconstruction times were up to 10 minutes. About 9000 primary images were generated, partially in the enhanced Digital Imaging and Communications in Medicine format, thus requiring new data postprocessing and management strategies. Image artifacts restricted the use of single-rotation cCT and incremental VCT (three-dimensional CTA). Overall exposure figures (computed tomographic dose index and dose-length product) were increased by 65% on average when three-dimensional CTA was added to volume cCT and four-dimensional CTA and CTP (5.0 mSv and 2178 mGy . cm, respectively).
  
  
  CONCLUSIONS
  Preliminary clinical experience indicates that whole-brain four-dimensional CTA and CTP is a robust technique that provides relevant clinical information with respect to whole-brain perfusion as well as cerebral hemodynamics. The exposure benefit of deriving time-resolved perfusion and vessel images from one source data set is compromised when adding three-dimensional CTA to the protocol. Other acquisition techniques specific to VCT, such as single-rotation cCT and incremental three-dimensional CTA, suffer from restrictions in terms of image quality at present.
authors.affiliation: Department of Neuroradiology, Charité, University Medicine Berlin, Berlin, Germany. randolf.klingebiel@charite.de
authors.forename: Randolf
authors.initials: R
authors.lastname: Klingebiel
authors.forename: Eberhard
authors.initials: E
authors.lastname: Siebert
authors.forename: Susanne
authors.initials: S
authors.lastname: Diekmann
authors.forename: Edzard
authors.initials: E
authors.lastname: Wiener
authors.forename: Florian
authors.initials: F
authors.lastname: Masuhr
authors.forename: Moritz
authors.initials: M
authors.lastname: Wagner
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Bauknecht
authors.forename: Marc
authors.initials: M
authors.lastname: Dewey
authors.forename: G
authors.initials: G
authors.lastname: Bohner
mesh_terms: D000465:Algorithms; D002533:Cerebral Angiography / Q000379:methods*; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*