title: Endovascular thoracic aortic aneurysm repair: evaluating the utility of intravascular ultrasound measurements.
abstract: OBJECTIVE
  To compare intravascular ultrasound (IVUS) and computed tomography (CT) measurements of aortic diameter for the determination of stent-graft sizes used in thoracic endovascular aneurysm repair (TEVAR).
  
  
  METHODS
  A retrospective review was conducted of 71 IVUS measurements performed in 33 patients (17 men; mean age 69 years) undergoing endovascular repair for thoracic aortic aneurysm (TAA). For comparison, an inanimate model of the aortic arch and the great vessels was created; 5 independent operators took multiple blinded IVUS measurements. Measurement accuracy is presented as the mean and coefficient of variance in percent.
  
  
  RESULTS
  In 47 (66%) of the 71 clinical measurements, IVUS yielded a value that was larger than the CT scan measurement; in 8 (11%), the difference was at least 5 mm. In the model, CT centerline measurements were accurate within a mean 0.3 mm (0.6%) of the actual diameter; IVUS measurements were accurate within a mean 1.4 mm (2.8%). Centerline IVUS measurements increased the accuracy to within 0.8 mm (1.8%) of the actual diameter.
  
  
  CONCLUSIONS
  IVUS measurements of the thoracic aorta were larger than CT measurements 66% of the time. However, there are 2 concerns with IVUS: off-center measurements distort the image and tangential measurements on a curve do not reflect a true centerline diameter. Thus, off-center IVUS measurements or those taken in the tortuous portion of the aorta may not be as accurate as centerline CT measurements.
authors.affiliation: Department of Vascular Surgery, University of Tennessee School of Medicine, Memphis, TN 38120, USA. jfernandezmd@cvsclinic.com
authors.forename: Joss D
authors.initials: JD
authors.lastname: Fernandez
authors.forename: Sean
authors.initials: S
authors.lastname: Donovan
authors.forename: H Edward
authors.initials: HE
authors.lastname: Garrett
authors.forename: Suzanne
authors.initials: S
authors.lastname: Burgar
mesh_terms: D000368:Aged; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging; D017545:Aortic Aneurysm, Thoracic / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D019047:Phantoms, Imaging; D011183:Postoperative Complications; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D018084:Ultrasonography, Interventional