title: Residual Thromboembolic Material in Cerebral Arteries after Endovascular Stroke Therapy Can Be Identified by Dual-Energy CT.
abstract: OBJECTIVE
  Dual-energy CT features the opportunity to differentiate among up to 3 different materials because the absorption of x-rays depends on the applied tube voltage and the atomic number of the material. For example, it is possible to distinguish between blood-brain barrier disruption and an intracerebral hemorrhage following treatment for a stroke. The aim of this study was to evaluate whether dual-energy CT is capable of distinguishing intra-arterial contrast agent from residually clotted vessels immediately after endovascular stroke therapy.
  
  
  METHODS
  Sixteen patients (9 women, 7 men; mean age, 63.6 ± 13.09 years) were examined. Measurements were made on the postinterventional dual-energy CT virtual noncontrast, iodine map, and "weighted" brain window (weighted dual-energy) series. Postinterventional conventional angiography was used as the criterion standard method.
  
  
  RESULTS
  A residual clot was found in 10 patients. On the virtual noncontrast series, the Hounsfield attenuation of the clotted arteries was higher than that in the corresponding perfused contralateral arteries (53.72 ± 9.42 HU versus 41.64 ± 7.87 HU; P < .05). The latter had higher absorption values on the weighted dual-energy series than on the virtual noncontrast series (49.37 ± 7.44 HU versus 41.64 ± 7.87 HU; P < .05). The sensitivity for the detection of a residual clot was 90%; the specificity was 83.3%, and the accuracy was 87.5%. Interrater agreement was good (κ = 0.733).
  
  
  CONCLUSIONS
  Dual-energy CT may be valuable in the detection of clot persistence or early re-thrombosis without the necessity of additional contrast administration. However, its relevance for the prediction of outcomes remains to be determined in further studies.
authors.affiliation: From the Departments of Neuroradiology (A.E.G., E.R.G.) astrid.grams@googlemail.com astrid.grams@i-med.ac.at.
authors.forename: A E
authors.initials: AE
authors.lastname: Grams
authors.affiliation: Neurology (M.K., J.W., M.S.).
authors.forename: M
authors.initials: M
authors.lastname: Knoflach
authors.affiliation: Radiology (R.R., B.G.), Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Rehwald
authors.affiliation: Neurology (M.K., J.W., M.S.).
authors.forename: J
authors.initials: J
authors.lastname: Willeit
authors.affiliation: Neurology (M.K., J.W., M.S.).
authors.forename: M
authors.initials: M
authors.lastname: Sojer
authors.affiliation: From the Departments of Neuroradiology (A.E.G., E.R.G.).
authors.forename: E R
authors.initials: ER
authors.lastname: Gizewski
authors.affiliation: Radiology (R.R., B.G.), Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: B
authors.initials: B
authors.lastname: Glodny
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000000981:diagnostic imaging; D057510:Endovascular Procedures; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000473:pathology / Q000628:therapy*; D020767:Intracranial Thrombosis / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015641:Radiography, Interventional / Q000379:methods*; D020521:Stroke / Q000000981:diagnostic imaging / Q000628:therapy*; D014057:Tomography, X-Ray Computed / Q000379:methods*