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Contrast ultrasound imaging: the best method to detect type II endoleak during endovascular aneurysm repair follow-up.

OBJECTIVES
Type II endoleak is the most common complication after endovascular aneurysm repair and require close surveillance. Hence, the need to validate new techniques as alternative to helical CT-scan, the reference standard. The aim of this study is to evaluate the efficacy of Cadence Contrast Pulse Sequencing ultrasound technique with second generation contrast agents in detecting endoleaks, and to compare the results with data obtained from CTA.


METHODS
30 patients with endovascular stent grafts, during their regular follow-up consisting in serial CT and ultrasound exams performed at discharge, at one and six months and at one year thereafter, previous informed consent, were enrolled in a prospectic double blind study design in order to compare triphasic helical CT-scan to another adjunctive ultrasound investigation (Cadence CPS technique with Sono Vue). No more than 15 days occurred between the two examinations. In the study were evaluated only data obtained from the comparison of the two concomitant investigations, independently from the follow-up. Variables analysed were changes in the maximum diameter of the aneurysmal sac, presence and type of endoleak, if detected. In the case of disagreement between the two diagnostic tools angiography was performed.


RESULTS
One patient dropped out because of violation of the study protocol (a stroke occurred in the time interval between the two investigations). Both exams visualised patency and proper graft placement in all the remaining patients. Aneurysmal diameters with both investigations overlapped (r(s):0.98). In 21 patients no endoleak was detected with a significant aneurysmal sac shrinkage (P<0.001). In seven patients both methods confirmed presence of endoleak. Ultrasonography detected all type of endoleaks, while CT-scan was uncertain in one. Moreover, in one patient CT-angiography showed an increased aneurysmal diameter without other evidence, while a contrast ultrasound investigation disclosed a type II low-flow endoleak, confirmed by angiography.


CONCLUSIONS
The Cadence Contrast Pulse Sequencing with echo contrast agent is an ultrasound technique that substantially improves the ultrasound diagnostic reliability.