Abstract 2959: Diagnosis of Right-to-Left Shunt in Intracranial Vertebral Artery by Transcranial Color Flow Imaging

Abstract

Objective: Right-to-Left shunt (RLS) detection by Transcranial Doppler is useful for diagnosis of paradoxical embolism. However, we sometimes could not monitor MCA due to insufficient temporal bone window, especially in old patients. Other insonation windows such as transorbital and suboccipital window (basilar artery) are using recently, whereas the ability to detect of intracranial arteries from these windows was not so high. We evaluated usefulness of RLS detection in intracranial vertebral artery (VA) from suboccipital approach that could be measured in almost patients. Methods: We evaluated RLS using transcranial color flow imaging (TC-CFI) in patients with ischemic stroke or transient ischemic attack who could be detected middle cerebral artery (MCA) from temporal bone window and intracranial VA from suboccipital window by TC-CFI. We monitored microembolic signal (MES) at ipsilateral MCA and VA (not hypoplastic side) for 90seconds after injection of 9ml saline agitated with 1ml of air in the right antecubital vein. The procedure was performed three times in each artery with and without Valsalva maneuver. The presence of MES was classified according to Spencer Logarithmic Scale (SLS) criteria. Results: Fifty two patients (46 male, mean age of 64.1±14.3) were included. Twelve patients were positive of MES (23.1%). VA comparison to MCA showed 10 true positive, 40 true negative, 0 false positive and 2 false negative cases (sensitivity 83.3%, specificity 100%, positive predictive value 100%, negative predictive value 95.2% and accuracy 96.2%). In 12 patients with MES, 22 of 36 examinations in MCA were positive of MES (SLS grade I was 20 examinations and grade II was 2 examinations), on the other hand, 20 of 36 examinations in VA were positive (SLS grade I was 20 examinations). The positive ratio of 36 examinations in 12 patients did not show significant difference statistically between MCA and VA. Conclusion: The evaluation of RLS in intracranial VA using TC-CFI from suboccipital window has equal diagnostic ability to MCA, and is useful for the patients with insufficient temporal bone window.