title: Optimization of shaded surface display for CT angiography.
abstract: OBJECTIVE
  The authors performed this study to determine the optimum threshold for performing computed tomographic (CT) angiography with shaded surface display (SSD).
  
  
  METHODS
  A dedicated phantom was developed with an 8-mm luminal diameter. Each of 19 vessels had stenoses ranging from 0% to 93.8%. Five blinded, experienced reviewers separately measured each vessel by using SSD with display thresholds of 50, 100, 150, and 200 HU.
  
  
  RESULTS
  For vessel diameters of 2 mm and larger, the best threshold value was 100 HU. This yielded measurements within 2% of the actual diameter and produced no false occlusions. For vessels 1 mm in diameter, the best threshold remained 100 HU, but this threshold was significantly less accurate than the standard (P = .0001) and produced two false occlusions in 15 vessels. For vessels 0.5 mm in diameter, the best threshold was 50 HU, although this still produced measurements significantly less accurate than the gold standard (P = .036) and one false occlusion in 15 vessels.
  
  
  CONCLUSIONS
  CT angiography with SSD and an optimized threshold value is a useful technique in vessels 1 mm and larger.
authors.affiliation: College of Medicine, Penn State University, Hershey, PA 17033, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Addis
authors.forename: K D
authors.initials: KD
authors.lastname: Hopper
authors.forename: T A
authors.initials: TA
authors.lastname: Iyriboz
authors.forename: C J
authors.initials: CJ
authors.lastname: Kasales
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: S W
authors.initials: SW
authors.lastname: Wise
mesh_terms: D000792:Angiography / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014652:Vascular Diseases / Q000000981:diagnostic imaging