Fusion of CT Angiography (CTA ) With 3D Contrast Enhanced Ultrasound ( CEUS ) as a Method for Follow up After Endovascular Aneurysm Repair (EVR)

Abdominal Aortic Aneurysm (AAA) is a known vascular entity that may be life threatening and requires treatment once it's diameter exceeds 5.5 cm or in any diameter in symptomatic patients.

Known risk factors for developing Abdominal Aortic Aneurysm (AAA) include tabacco consumption, Sex (male predominance), age (above 65 with a history of smoking or age above 75 without a history of smoking ), hypertension, diabetes mellitus and hyperchlesterolemia1 The most common treatment approach nowadays is the endovascular approach, a procedure known as endovascular aortic repair (EVAR). The most common procedure related complication is the expansion of the aneurysm from a "feeding vessel", usually a lumbar or intercostal artery. Another known complication is an endoleak from the stentgraft, through its proximal or distal part/.

Today, accepted EVAR follow up protocol consists of a multiphasic CT angiography (CTA) scan .The initial scan is performed without contrast, the second scan is performed in the arterial phase and a third scan is performed in the late (portal) phase. CTA is performed at one month after the procedure and ultrasound exams there after.

Ultrasonography is a useful method for detection and evaluation of AAA and is recommended as an annual screening tool for patients above 65 with smoking history or above 75 without smoking history. Duplex Ultrasonography has no ionizing radiation and is useful for the dynamic estimation of the aortic width in patients post EVAR. However, the sensitivity of ultrasonography solely for detection of endoleaks in post EVAR patients is not high, mostly due to known inborn limitations of ultrasound including decreased penetration in obese patients , and suboptimal demonstration of retroperitoneal structures due to gas in the intestine.

In recent years, the development of "fusion" applications allow the dual modality merge between ultrasound and CT scans. The dual modality allows the direct comparison of imaging findings in real time. Fusion imaging is used as follow up examinations of known imaging findings on CT that cannot be optimally demonstrated on ultrasonography. Once these findings are followed up by ultrasonography, an substantial amount of radiation can be reduced.