title: Dynamic CT angiography after abdominal aortic endovascular aneurysm repair: influence of enhancement patterns and optimal bolus timing on endoleak detection.
abstract: OBJECTIVE
  To determine the time course of enhancement patterns in the aorta and endoleaks at dynamic computed tomographic (CT) angiography as well as their effect on the endoleak detection rate in patients who have undergone abdominal aortic endovascular aneurysm repair (EVAR).
  
  
  METHODS
  This retrospective study was approved by the local ethics committee and compliant with the Declaration of Helsinki. All patients gave written informed consent for the scientific analysis of their data. Seventy-one patients (mean age, 72 years ± 8 [standard deviation]) were retrospectively included after EVAR of the abdominal aorta. All patients underwent dynamic CT angiography with 10 unidirectional scan phases, followed by a venous phase. Endoleaks were detected visually in all scan phases; the magnitude of enhancement was assessed by using region-of-interest measurements in the aorta and the detectable endoleaks. Statistical analysis was performed with the χ(2) test, the paired t test, and analysis of variance with repeated measurements.
  
  
  RESULTS
  The highest mean aortic enhancement was achieved 12 seconds after the bolus-tracking threshold, and the highest mean endoleak enhancement was achieved 22 seconds after the bolus-tracking threshold. In total, 44 endoleaks were detected. The detection rates differed significantly in between the dynamic CT angiography phases (minimum, seven endoleaks at 2 seconds after the bolus-tracking threshold; maximum, 44 endoleaks at 27 seconds after the bolus-tracking threshold; P = .001). The highest detection rate was achieved when the contrast between aortic and endoleak enhancement reached its maximum.
  
  
  CONCLUSIONS
  Dynamic CT angiography revealed that the peak enhancement of endoleaks is significantly different than that of the aorta and that endoleaks may not be adequately evaluated with conventional biphasic CT protocols. The use of dynamic CT angiography is associated with a significantly increased detection rate of endoleaks compared with the detection rates at the time points of conventional biphasic CT.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University of Leipzig-Heart Center, Strümpellstrasse 39, Leipzig, Germany. ukas.lehmkuhl@med.uni-leipzig.de
authors.forename: Lukas
authors.initials: L
authors.lastname: Lehmkuhl
authors.forename: Claudia
authors.initials: C
authors.lastname: Andres
authors.forename: Christian
authors.initials: C
authors.lastname: Lücke
authors.forename: Janine
authors.initials: J
authors.lastname: Hoffmann
authors.forename: Borek
authors.initials: B
authors.lastname: Foldyna
authors.forename: Matthias
authors.initials: M
authors.lastname: Grothoff
authors.forename: Stefan
authors.initials: S
authors.lastname: Nitzsche
authors.forename: Andrej
authors.initials: A
authors.lastname: Schmidt
authors.forename: Matthias
authors.initials: M
authors.lastname: Ulrich
authors.forename: Dierk
authors.initials: D
authors.lastname: Scheinert
authors.forename: Matthias
authors.initials: M
authors.lastname: Gutberlet
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D017544:Aortic Aneurysm, Abdominal / Q000150:complications* / Q000601:surgery*; D003287:Contrast Media / Q000008:administration & dosage; D057867:Endoleak / Q000000981:diagnostic imaging* / Q000209:etiology*; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol