title: Automatic lumen segmentation in calcified plaques: dual-energy CT versus standard reconstructions in comparison with digital subtraction angiography.
abstract: OBJECTIVE
  Dual-energy CT has the potential to automatically remove calcified plaques from angiographic data sets. The objective of this study is to compare the accuracy of visual grading of stenoses after plaque removal with visual grading in standard reconstructions. Digital subtraction angiography (DSA) was used as a reference standard.
  
  
  METHODS
  Twenty-five patients underwent dual-energy CT (140 kV and 80 mAs; 80 kV and 234 mAs) angiography and DSA. Plaque and bone removal was performed. Twenty-nine calcified stenoses were quantified using standard reconstructions, plaque and bone removal maximum intensity projections after plaque and bone removal, and DSA images, according to the North American Symptomatic Carotid Endarterectomy Trial criteria. The accuracy of the detection of relevant stenoses (> 70%) and occlusions was assessed. Correlation coefficients of the grades of stenoses with DSA were calculated. The influence of vessel enhancement on the accuracy of plaque removal was analyzed.
  
  
  RESULTS
  The average postprocessing time was 45 seconds. After plaque removal, all 25 relevant and four nonrelevant stenoses were correctly detected. Six relevant stenoses were overestimated as complete occlusions. With the standard reconstructions, two nonrelevant stenoses were overestimated as relevant. Correlation coefficients (r(2)) for the grading of stenoses after plaque removal and with standard reconstructions versus DSA were 0.7694 and 0.4329, respectively. Vessel contrast enhancement correlated weakly (r(2) = 0.2072) with the accuracy of plaque removal.
  
  
  CONCLUSIONS
  Dual-energy CT with plaque removal automatically delivers CT luminograms with a high sensitivity for the detection of relevant stenoses and a higher correlation to DSA than standard reconstructions but frequently leads to an overestimation of high-grade stenoses as occlusions. Thus, dual-energy CT plaque and bone removal should be used complementary to standard reconstructions, and not exclusively.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University of Tübingen, Tübingen 72076, Germany. Christoph.thomas@med.uni-tuebingen.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Andreas
authors.initials: A
authors.lastname: Korn
authors.forename: Dominik
authors.initials: D
authors.lastname: Ketelsen
authors.forename: Soeren
authors.initials: S
authors.lastname: Danz
authors.forename: Ilias
authors.initials: I
authors.lastname: Tsifikas
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Ulrike
authors.initials: U
authors.lastname: Ernemann
authors.forename: Martin
authors.initials: M
authors.lastname: Heuschmid
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction / Q000379:methods*; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000601:surgery; D002533:Cerebral Angiography / Q000379:methods*; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted; D012886:Skull / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome