title: Accuracy of dual-source computed tomography in quantitative assessment of low density coronary stenosis--a motion phantom study.
abstract: OBJECTIVE
  We assessed the accuracy and reproducibility of non-calcified plaque quantification as simulated by a low-density stenosis in vessel phantoms using diameter and area measures, as well as the influence of vessel size and motion on quantification accuracy in dual-source computed tomography (DSCT).
  
  
  METHODS
  Four phantoms (2, 2.5, 3, and 4 mm in luminal diameter) made from a radiopaque Lucite (126 +/- 23 Hounsfield units, HU) simulating a fixed radiolucent concentric coronary stenosis (7 +/- 2 HU, 50% luminal narrowing) were connected to a cardiac motion simulator. Stenosis quantification was based on area and diameter measurements. All measurements were highly reproducible (all ICC > or =0.95, p < 0.001).
  
  
  RESULTS
  The mean measured degree of stenosis was 38.0 +/- 11.7% for a single diameter measurement, resulting in a mean relative error of 22.0 +/- 18.7%, decreasing with increasing phantom size (31.9 +/- 22.1%; 25.2 +/- 20.9%; 16.3 +/- 12.8%; 14.5 +/- 11.4%; for 2-, 2.5-, 3-, and 4-mm phantoms, respectively; p < 0.0001). Measurement accuracy significantly increased to 13.3 +/- 13.9% by using area measurement (p < 0.0001). The degree of stenosis was not significantly different when comparing a motioned image with an image at rest.
  
  
  CONCLUSIONS
  DSCT enables highly reproducible quantification of low density stenosis, but underestimates the degree of stenosis, especially in small vessels. Area-based measurements reflect the true degree of stenosis with higher accuracy than diameter.
authors.affiliation: Cardiac MR PET CT Program, Massachusetts General Hospital and Harvard Medical School, 165 Charles River Plaza Suite 400, Boston, MA 02114, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Toepker
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Schlett
authors.forename: Thomas
authors.initials: T
authors.lastname: Irlbeck
authors.forename: Amir A
authors.initials: AA
authors.lastname: Mahabadi
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Christiane
authors.initials: C
authors.lastname: Leidecker
authors.forename: Patrick
authors.initials: P
authors.lastname: Donnelly
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D017023:Coronary Angiography / Q000295:instrumentation / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D006801:Humans; D009038:Motion; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*