title: Dynamic CT angiography after abdominal aortic endovascular aneurysm repair: differences in contrast agent dynamics in the aorta and endoleaks--preliminary results.
abstract: OBJECTIVE
  To assess differences in aortic and endoleak enhancement in patients after endovascular aneurysm repair (EVAR) with dynamic computed tomography (CT) angiography.
  
  
  METHODS
  Twenty-one consecutive patients (mean age, 74.5 y ± 6; range, 61-88 y) with endoleaks after EVAR of the abdominal aorta were examined on a second-generation dual-source CT unit with 10 unidirectional scan phases (temporal resolution, 5 s; 80 kV; 120 reference-mAs; z-axis field of view, 283 mm), followed by a venous scan phase. Enhancement was assessed in aorta and endoleaks for all phases by density measurements. The diagnostic reliability of endoleak detection was assessed on a five-point confidence scale.
  
  
  RESULTS
  In total, 26 endoleaks (type I, n = 1; type II, n = 25) were detected. The highest detection rate was found in phase 5 (22 s after threshold; P < .01 vs other dynamic phases). Mean peak aortic enhancement (560 HU ± 96) was present in an early arterial phase (phase 3, 12 s after threshold), whereas the mean peak endoleak enhancement (398 HU ± 174) for type II endoleaks was present later, in phase 4 (17 s after threshold). Despite perceived high diagnostic confidence in phases 1 and 2 (ie, typical arterial phase of biphasic CT protocol), only 23% and 62% of endoleaks were detected, respectively, whereas peak diagnostic confidence (phases 4 and 5) corresponded well with the maximum endoleak detection rate but decreased significantly in later phases (ie, 6-10).
  
  
  CONCLUSIONS
  Preliminary dynamic CT angiography results in post-EVAR follow-up revealed notably different peaks of endoleak and aortic enhancement, which are not covered sufficiently by conventional biphasic CT protocols. Phase 5 demonstrated the highest type II endoleak detection rate, with high diagnostic confidence.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University of Leipzig Heart Center, Leipzig, Germany. lukas.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: Borek
authors.initials: B
authors.lastname: Foldyna
authors.forename: Matthias
authors.initials: M
authors.lastname: Grothoff
authors.forename: Dierk
authors.initials: D
authors.lastname: Scheinert
authors.forename: Stefan
authors.initials: S
authors.lastname: Nitzsche
authors.forename: Matthias
authors.initials: M
authors.lastname: Gutberlet
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000601:surgery*; D001027:Aortography / Q000379:methods*; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D016009:Chi-Square Distribution; D003287:Contrast Media; D057867:Endoleak / Q000000981:diagnostic imaging* / Q000209:etiology; D057510:Endovascular Procedures / Q000009:adverse effects*; D005260:Female; D005858:Germany; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media