title: Reproducibility of Middle Cerebral Artery Stenosis Measurements by DSA: Comparison of the NASCET and WASID Methods.
abstract: OBJECTIVE
  To evaluate the intra- and inter-observer variability of the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) criteria for the evaluation of middle cerebral artery (MCA) stenosis using digital subtraction angiography (DSA).
  
  
  METHODS
  DSA images of 114 cases with 131 stenotic MCAs were retrospectively analyzed. Two radiologists and a researcher measured the degree of MCA stenosis independently using both NASCET and WASID methods. To determine intra-observer agreement, all the observers reevaluated the degree of MCA stenosis 4 weeks later. The linear relation and coefficient of variation (CV) between the measurements made by the two methods were assessed by correlation coefficient and multi-factor analysis of variance (ANOVA), respectively. Intra- and inter-observer variability of the two methods was evaluated by intraclass correlation coefficient (ICC), Spearman's R value, Pearson correlation coefficient and Bland-Altman plots.
  
  
  RESULTS
  Despite the fact that the degree of MCA stenosis measured by NASCET was lower than measured using the WASID method, there was good linear correlation between the measurements made by the two methods (for the mean measurements of the 3 observers, NASCET% = 0.891 × WASID% - 1.89%; ICC, Spearman's R value and Pearson correlation were 0.874, 0.855, and 0.874, respectively). The CVs of both intra- and inter-observer measurements of MCA stenosis using WASID were significantly lower than that using NASCET confirmed by the multi-factor ANOVA results, which showed only the measurement methods of MCA stenosis had significant effects on the CVs both in intra- and inter-observer measurements (both P values < 0.001). Intra-observer measurements showed good or excellent agreement with respect to WASID and NASCET evaluation (ICC, 0.656 to 0.817 and 0.635 to 0.761, respectively). Good agreement for the WASID evaluation (ICC, 0.592 to 0.628) and for the NASCET evaluation (ICC, 0.529 to 0.568) was observed for inter-observer measurements. Bland-Altman plots demonstrated that the WASID method had better reproducibility and intra-observer agreement than NASCET method for evaluating MCA stenosis.
  
  
  CONCLUSIONS
  Both NASCET and WASID methods have an acceptable level of agreement; however, the WASID method had better reproducibility for the evaluation of MCA stenosis, and thus the WASID method may serve as a standard for measuring the degree of MCA stenosis.
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Luguang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhan
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Ma
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Tian
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Yuanliang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Yinmei
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Shiyue
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Radiology, Changhai Hospital of Shanghai, The Second Military Medical University, No. 168 Changhai Road, Shanghai, 200433, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Lu
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction / Q000379:methods*; D016893:Carotid Stenosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000473:pathology*; D012189:Retrospective Studies