title: Carotid artery dissection on non-contrast CT: does color improve the diagnostic confidence?
abstract: OBJECTIVE
  The purpose of this work was to evaluate if the use of color maps, instead of conventional grayscale images, would improve the observer's diagnostic confidence in the non-contrast CT evaluation of internal carotid artery dissection (ICAD).
  
  
  METHODS
  One hundred patients (61 men, 39 women; mean age, 51 years; range, 25-78 years), 40 with and 60 without ICAD, underwent non-contrast CT and were included in this the retrospective study. In this study, three groups of patients were considered: patients with MR confirmation of ICAD, n=40; patients with MR confirmation of ICAD absence, n=20; patients who underwent CT of the carotid arteries because of atherosclerotic disease, n=40. Four blinded observers with different levels of expertise (expert, intermediate A, intermediate B and trainee) analyzed the non-contrast CT datasets using a cross model (one case grayscale and the following case using the color scale). The presence of ICAD was scored on a 5-point scale in order to assess the observer's diagnostic confidence. After 3 months the four observers evaluated the same datasets by using the same cross-model for the alternate readings (one case color scale and the following case using the grayscale). Statistical analysis included receiver operating characteristics (ROC) curve analysis, the Cohen weighted test and sensitivity, specificity, PPV, NPV, accuracy, LR+ and LR-.
  
  
  RESULTS
  The ROC curve analysis showed that, for all observers, the use of color scale resulted in an improved diagnostic confidence with AUC values increasing from 0.896 to 0.936, 0.823 to 0.849, 0.84 to 0.909 and 0.749 to 0.861 for expert, intermediate A, intermediate B and trainee observers, respectively. The increase in diagnostic confidence (between the AUC areas) was statistically significant (p=0.036) for the trainee. Accuracy as well as sensitivity, specificity, PPV, NPV, LR+ and LR- were improved using the color scale.
  
  
  CONCLUSIONS
  Our study suggests that the use of a color scale instead the conventional grayscale improves the diagnostic confidence, accuracy and inter-observer agreement of the readers, in particular of junior ones, in the diagnosis of ICAD on non-contrast CT.
authors.affiliation: Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari - Polo di Monserrato, s.s. 554 Monserrato, Cagliari 09045, Italy. Electronic address: lucasaba@tiscali.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Saba
authors.affiliation: Department of Radiology, Azienda Ospedaliero Brotzu (A.O.B.), di Cagliari, Cagliari 09100, Italy.
authors.forename: Giovanni Maria
authors.initials: GM
authors.lastname: Argiolas
authors.affiliation: Department of Radiology, New York University School of Medicine, New York, USA; Department of Neurology and Psychiatry, Sapienza University of Rome, Italy.
authors.forename: Eytan
authors.initials: E
authors.lastname: Raz
authors.affiliation: Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari - Polo di Monserrato, s.s. 554 Monserrato, Cagliari 09045, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Sannia
authors.affiliation: Diagnostic and Monitoring Division, AtheroPointTM LLC, Roseville, CA, USA; Electrical Engineering Department (Aff.), Idaho State University, ID, USA.
authors.forename: Jasjit S
authors.initials: JS
authors.lastname: Suri
authors.affiliation: Department of Radiology, Azienda Ospedaliero Brotzu (A.O.B.), di Cagliari, Cagliari 09100, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Siotto
authors.affiliation: Department of Vascular Surgery, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari - Polo di Monserrato, s.s. 554 Monserrato, Cagliari 09045, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Sanfilippo
authors.affiliation: Department of Vascular Surgery, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari - Polo di Monserrato, s.s. 554 Monserrato, Cagliari 09045, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Montisci
authors.affiliation: Department of Radiology, Azienda Ospedaliero Universitaria (A.O.U.), di Cagliari - Polo di Monserrato, s.s. 554 Monserrato, Cagliari 09045, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Piga
authors.affiliation: Department of Radiology, Neuroradiology Division, University of Virginia, Box 800170, Charlottesville, VA, 22908, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Wintermark
mesh_terms: D000328:Adult; D000368:Aged; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D020215:Carotid Artery, Internal, Dissection / Q000000981:diagnostic imaging*; D003116:Color; D003287:Contrast Media; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012372:ROC Curve; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media
keywords: CT; Carotid; Dissection