title: Cardioembolic stroke: dual-energy cardiac CT for differentiation of left atrial appendage thrombus and circulatory stasis.
abstract: OBJECTIVE
  To assess the diagnostic performance of dual-energy cardiac computed tomography (CT) in the detection of left atrial appendage (LAA) thrombi and differentiation between thrombus and circulatory stasis in patients with stroke, by using transesophageal echocardiography (TEE) as the reference standard.
  
  
  METHODS
  The institutional review board approved this study, and patients provided informed consent. Thirty-two patients with stroke who had atrial fibrillation (AF) and either thrombus or the spontaneous echo contrast (SEC) echo pattern at TEE were prospectively enrolled. For the control group, 31 patients who were planning to undergo AF ablation and who had no abnormalities at TEE were enrolled. All patients underwent dual-energy cardiac CT that was not electrocardiographically gated. For quantitative analysis, iodine concentration was measured on CT images. The statistical significance of differences in mean iodine concentration between thrombus and SEC as measured at CT was assessed by using the Student t test.
  
  
  RESULTS
  Among the 63 patients, a total of 13 thrombi and 19 instances of SEC were detected at TEE. Using TEE as the reference standard, the overall sensitivity, specificity, positive predictive value, and negative predictive value of dual-energy cardiac CT in the detection of thrombi and SEC in the LAA were 97% (95% confidence interval [CI]: 82%, 100%), 100% (95% CI: 86%, 100%), 100%, and 97%, respectively. At CT, the mean iodine concentration was 1.23 mg/mL ± 0.34 (standard deviation) for thrombus and 3.61 mg/mL ± 1.01 for SEC (P = .001).
  
  
  CONCLUSIONS
  Dual-energy cardiac CT is a highly sensitive modality for detecting LAA thrombus and for differentiating thrombus from SEC in patients with stroke.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, South Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Hur
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Hye-Jeong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Ji Eun
authors.initials: JE
authors.lastname: Nam
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Hong
authors.forename: Hee Yeong
authors.initials: HY
authors.lastname: Kim
authors.forename: Ji Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Byoung Wook
authors.initials: BW
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020517:Atrial Appendage / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003287:Contrast Media; D003326:Coronary Circulation; D003328:Coronary Thrombosis / Q000150:complications* / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D012307:Risk Factors; D012680:Sensitivity and Specificity; D020521:Stroke / Q000209:etiology*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014283:Triiodobenzoic Acids
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol