Multiphasic time-resolved CT angiography in patients after endovascular aortic aneurysm repair provides dynamic information at a similar radiation dose as standard triphasic protocols and shows high sensitivity for endoleak detection and classification.
To assess the feasibility and diagnostic performance of time-resolved computed tomographic (CT) angiography in the detection and classification of endoleaks after endovascular aortic aneurysm repair (EVAR) in high-risk patients.
Materials and Methods
The study was approved by our ethics committee. Written informed consent was obtained from all participating patients. Fifty-four patients (42 male and 12 female patients; mean age, 70.9 years ± 9.3 [standard deviation]) with either thoracic (n = 8) or abdominal (n = 46) aortic aneurysms treated with a stent-graft were prospectively included. The patients were examined with a time-resolved CT angiographic protocol consisting of 12 low-dose phases (80 kVp; 120 mAs [effective]; scan range, 27 cm), with 60 mL of iomeprol. Patients with abdominal aneurysm repair also underwent contrast material–enhanced (CE) ultrasonography (US). The time delay between contrast enhancement within the stent lumen and the endoleak was measured. Effective radiation dose was calculated from the scanner protocols. Measures of diagnostic performance for the detection of endoleaks were calculated for time-resolved CT angiography, with CE US serving as the reference standard.
All time-resolved CT angiographic data sets were diagnostic. Mean effective radiation dose was 14.6 mSv. Four thoracic and 19 abdominal endoleaks were identified by using time-resolved CT angiography. Seventeen of 19 abdominal endoleaks were confirmed with CE US. This rate resulted in a sensitivity of 94%, a specificity of 93%, a positive predictive value of 89%, and a negative predictive value of 96% for time-resolved CT angiography after abdominal EVAR. Type I endoleaks showed significantly earlier mean peak contrast enhancement (0.28 second ± 0.83) compared with that for type II endoleaks (9.17 seconds ± 3.59, P < .0001).
Time-resolved CT angiography with 12 low-dose phases is feasible for patients after thoracic and abdominal EVAR. The protocol approximates the radiation dose of standard triphasic protocols. Its dynamic information differentiates types of endoleaks and shows high diagnostic performance.
© RSNA, 2012
- 1 . Endovascular stent grafting versus open surgical operation in patients with infrarenal aortic aneurysms: a propensity score-adjusted analysis. Circulation 2002;106(7):782–787. Crossref, Medline, Google Scholar
- 2 . Endovascular repair of abdominal aortic aneurysm. N Engl J Med 2008;358(5):494–501. Crossref, Medline, Google Scholar
- 3 . Endoleaks after endovascular abdominal aortic aneurysm repair: detection with dual-energy dual-source CT. Radiology 2008;249(2):682–691. Link, Google Scholar
- 4 . Emergency endovascular repair for ruptured abdominal aortic aneurysms: feasibility and comparison of early results with conventional open repair. Eur J Vasc Endovasc Surg 2005;30(6):632–639. Crossref, Medline, Google Scholar
- 5 . Endoleakage after endovascular treatment of abdominal aortic aneurysms: diagnosis, significance and treatment. Eur Radiol 2006;16(12):2849–2857. Crossref, Medline, Google Scholar
- 6 . Endoleaks after endovascular repair of aortic aneurysm: are they predictable?— initial results. Radiology 2001;218(2):477–480. Link, Google Scholar
- 7 . Endovascular treatment of thoracic aortic diseases: follow-up and complications with multi-detector computed tomography angiography. Eur J Radiol 2008;65(3):365–376. Crossref, Medline, Google Scholar
- 8 . Time-resolved MR angiography for the classification of endoleaks after endovascular aneurysm repair. J Magn Reson Imaging 2008;27(3):500–503. Crossref, Medline, Google Scholar
- 9 . Endovascular repair of abdominal aortic aneurysms: CTA evaluation of contraindications. Abdom Imaging 2006;31(6):722–731. Crossref, Medline, Google Scholar
- 10 . Thoracic CT findings following endovascular stent-graft treatment for thoracic aortic aneurysm. J Endovasc Ther 2007;14(3):333–341. Crossref, Medline, Google Scholar
- 11 . CT angiography of the aorta [in German]. Radiologe 2007;47(11):982–992. Crossref, Medline, Google Scholar
- 12 . Abdominal aortic aneurysm: can the arterial phase at CT evaluation after endovascular repair be eliminated to reduce radiation dose? Radiology 2006;241(3):908–914. Link, Google Scholar
- 13 . Use of CT angiography to classify endoleaks after endovascular repair of abdominal aortic aneurysms. J Vasc Interv Radiol 2005;16(5):663–667. Crossref, Medline, Google Scholar
- 14 . Imaging of endoleaks after endovascular aneurysm repair (EVAR) with contrast-enhanced ultrasound (CEUS): a pictorial comparison with CTA. Clin Hemorheol Microcirc 2009;41(3):151–168. Crossref, Medline, Google Scholar
- 15 . Report EUR 16262. Brussels, Belgium: European Commission, 1999. Google Scholar
- 16 . Image quality of virtual noncontrast images derived from dual-energy CT angiography after endovascular aneurysm repair. J Vasc Interv Radiol 2010;21(3):315–321. Crossref, Medline, Google Scholar
- 17 . Material differentiation by dual energy CT: initial experience. Eur Radiol 2007;17(6):1510–1517. Crossref, Medline, Google Scholar
- 18 . Abdominal aorta: evaluation with dual-source dual-energy multidetector CT after endovascular repair of aneurysms—initial observations. Radiology 2008;249(2):692–700. Link, Google Scholar
- 19 . Initial experience characterizing a type I endoleak from velocity profiles using time-resolved three-dimensional phase-contrast MRI. J Vasc Surg 2009;49(6):1580–1584. Crossref, Medline, Google Scholar
- 20 . Time-resolved computed tomography imaging of the aorta: a feasibility study. J Thorac Imaging 2010;25(2):161–167. Crossref, Medline, Google Scholar
- 21 . Aneurysm sac pressure after EVAR: the role of endoleak. Eur J Vasc Endovasc Surg 2007;34(4):432–441; discussion 442–443. Crossref, Medline, Google Scholar
- 22 . Type II endoleaks: when is intervention indicated and what is the index of suspicion for types I or III? J Endovasc Ther 2009;16(suppl 1):I106–I118. Medline, Google Scholar
- 23 Significance of endotension, endoleak, and aneurysm pulsatility after endovascular repair. J Vasc Surg 2003;37(4):842–846. Crossref, Medline, Google Scholar
- 24 . SVS practice guidelines for the care of patients with an abdominal aortic aneurysm: executive summary. J Vasc Surg 2009;50(4):880–896. Crossref, Medline, Google Scholar
- 25 . Color duplex ultrasound and contrast-enhanced ultrasound in comparison to MS-CT in the detection of endoleak following endovascular aneurysm repair. Clin Hemorheol Microcirc 2008;39(1-4):121–132. Crossref, Medline, Google Scholar
- 26 . Prospective comparative analysis of colour-Doppler ultrasound, contrast-enhanced ultrasound, computed tomography and magnetic resonance in detecting endoleak after endovascular abdominal aortic aneurysm repair. Eur J Vasc Endovasc Surg 2011;41(2):186–192. Crossref, Medline, Google Scholar
Article HistoryReceived June 16, 2011; revision requested July 26; final revision received December 16; accepted December 29; final version accepted January 20, 2012.
Published online: June 2012
Published in print: June 2012