Improving the follow up after EVAR by using ultrasound image fusion of CEUS and MS-CT

To evaluate whether the image fusion with contrast enhanced ultrasound (CEUS) and CT affects the diagnosis of endoleaks in unclear cases.

35 patients with follow-up examinations after endovascular aneurysm repair (EVAR) were included in this retrospective study. Mean patient age was 73 years (range 54-83 y). B-scan, colour doppler and CEUS (1.2 ml SonoVue®, Bracco Imaging Germany) were performed in all patients by an experienced examiner using two different high-end ultrasound system (Siemens ACUSON S2000™, Siemens Healthcare, Erlangen, Germany or Logic E9, GE Healthcare, Milwaukee,WI, USA) with a multifrequency curved array transducer. The examiner was initially blinded to the CT results. Additional image fusion with CT-angiography (CTA) was then performed. The ultrasound examinations were later read by two blinded unbiased investigators with more than five years of clinical ultrasound in consensus.

All patients were examined using all diagnostic ultrasound tools of the study. The results show that image fusion is easy and convenient to perform. Conventional ultrasound examination with B-scan and colour Doppler examination detected one Type I and one Type II endoleak, contrast enhanced ultrasound detected one Type I and three Type II endoleaks after EVAR whereas CTA depicted one Type I and two Type II endoleaks. Ultrasound image fusion with CT-angiography confirmed one Type I and three Type II endoleaks.

In comparison to conventional ultrasound and CTA the use of CEUS improved the visualization and classification of endoleaks. CEUS shows even small blood flow which can be depicted due to the real time imaging of endoleaks. In unclear cases additional ultrasound image fusion with CEUS and CT angiography improves the visualisation of small endoleaks and this may cause a change in the follow-up interval. CEUS is a good alternative to CT in the detection and follow-up of endoleaks, especially in patients with contraindications to CT contrast agents due to allergies or renal failure, enabling reduced additional costs and exposure to radiation.