22. European Stroke Conference 209 Vascular imaging Clinical utility of cervical and intracranial CT angiography in etiologic definition of ischemic stroke. J. Oliveira-Filho1, A.D.M. Barros2, L.F. Fonseca3, M.C. Mueller4, L.M.G.B. Ventura5, A.A. Jesus6, C.C. Reis7, M.J. Lordelo8, N.J.S. Barreto-Neto9, I.L.O. Ferreira10, R.D. Fernandes11, P.A.P. Jesus12 Federal University of Bahia, Salvador, BRAZIL1, Federal University of Bahia, Salvador, BRA-ZIL2, Federal University of Bahia, Salvador, BRAZIL3, Federal University of Bahia, Salvador, BRAZIL4, Federal University of Bahia, Salvador, BRAZIL5, Federal University of Bahia, Salvador, BRAZIL6, Federal University of Bahia, Salvador, BRAZIL7, Federal University of Bahia, Salvador, BRAZIL8, Federal University of Bahia, Salvador, BRAZIL9, Federal University of Bahia, Salvador, BRAZIL10, Federal University of Bahia, Salvador, BRA-ZIL11, Federal University of Bahia, Salvador, BRAZIL12 Background: Definition of secondary stroke prevention strategies is important to reduce early stroke recurrence. CT angiography (CTA) has been increasingly used for definition of stroke mechanism, but quantification of its clinical utility is lacking. Our aim was to quantify the following parameters before and after adding CTA to clinical investigation: interrater agreement for etiologic diagnosis; and how frequent was there a change in clinical opinion regarding etiologic diagnosis and anti-thrombotic 394 © 2013 S. Karger AG, Basel Scientific Programme therapy. Methods: Consecutive patients admitted to an outpatient stroke clinic underwent CTA and the de-gree of extracranial and intracranial atherosclerosis was defined by a neuroradiologist who was blinded to clinical information. Two stroke neurologists were given clinical vignettes containing ad-mission symptoms, brain imaging (CT or MRI), cardiac investigation (EKG and echocardiography) and Duplex ultrasound of neck vessels and asked to define the most probable etiologic diagnosis by SSS-TOAST criteria and their choice of antithrombotic therapy. The same questions were asked af-ter presenting the CTA results. Results: Fifty-four patients were recruited, mean age 58 +/- 15 years, 39% male. Inter-rater agree-ment was similar before and after CTA evaluation (k=0.634, 95% CI=0.526-0.742 before; and k=0.507, 95% CI=0.401-0.613 after). Most frequent etiologic diagnosis before CTA was cardioaor-tic embolism followed by small vessel atherosclerosis. After CTA, most frequent etiologic diagnosis was large vessel atherosclerosis. Overall, clinical opinion regarding etiologic diagnosis changed in 30% of cases and antithrombotic treatment choice in 28%. No clinical or demographic predictors of a change in clinical opinion after CTA were identified. Conclusions: After conventional stroke investigation with ancillary tests, CTA changes clinical opin-ion regarding etiology and antithrombotic treatment in almost one-third of patients. A full investiga-tion of head and neck vessels seems to be indicated for all patients with ischemic stroke. 210 Vascular imaging A systematic comparison of different techniques to measure clot length in patients with Acute Ischemic Stroke. A.A. Qazi1, M. Eesa2, E.M. Qazi3, M. Goyal4, A.M. Demchuk5, B.K. Menon6 University of Calgary, Dept of Medicine, Calgary, CANADA1, University of Calgary, Dept of Radiology, Calgary, CANADA2, University of Calgary, Dept of Clinical Neurosciences, Calgary, CANADA3, University of Calgary, Dept of Radiology, Calgary, CANADA4, University of Calgary, Dept of Clinical Neurosciences and Dept of Radiology, Calgary, CANADA5, University of Calgary, Dept of Clinical Neurosciences and Dept of Radiology, Calgary, CANADA6 Introduction: Clot length on CT/CTA has been used to predict recanalization with thrombolytic treatment in patients with acute ischemic stroke (AIS). We compared different techniques of measur-ing clot length on CT/CTA to identify the most reliable method. Methods: 41 patients with M1 MCA occlusions from INTERRSeCT, a prospective imaging based cohort study of AIS patients, were in-cluded in the current study. Hyperdense sign was measured on NCCT (5 mm slice thickness). Clot length was measured on CTA at 3 mm and 24 mm slice thickness in the axial and coronal plane by: 1) measuring the non-visualized segment of M1 MCA and 2) calculating ratio of residual lumen length within M1 MCA segment to length of contralateral patent M1 MCA segment. Two readers analyzed all images independently and were blinded to CTA when reading NCCT. Level of concor-dance between raters for each method was calculated using Cohen’s kappa for categorical variables and Intra-class Correlation Coefficient (ICC type 2, single measure). A method has high inter-rater reliability only if the level of concordance is high. A statistically significant difference (two-sided alpha <0.05) in the raters’ assessment was determined using an Analysis of Variance (ANOVA). OsiriX version 3.5 was used for image analysis; Stata version 12 was used for data analysis. Results: The level of concordance between raters as well as p values for difference in ratings between raters for each method is shown in Table 1. Measuring residual lumen ratio on CTA (3 mm) is the most reliable technique for measuring clot length. Measuring length of hyperdense sign on NCCT is fair-ly reliable. Direct clot length measurements on CTA are only reliable if done on CTA thick (24mm) slices using MIP. Conclusion: Reliability of clot length assessment and therefore its interaction with treatment type in predicting recanalization depends on the type of imaging modality and technique used. CTA still remains the best tool to measure clot length.
Karger_ESC London_2013
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