Imaging modalities for endoleak surveillance

Abstract

As the global population ages, the issue of abdominal aortic aneurysm continues to grow. With the evolution of new devices and refined operative technique, aneurysm treatment via endovascular aortic repair is becoming increasingly favourable. This, however, is not without drawbacks, where regular surveillance is paramount to long-term success and detection of post-procedure complications. Of these complications, endoleak is the most notable and poses the greatest risk of potential future aortic rupture. The purpose of this review paper is to discuss the armada of imaging modalities used in the detection and evaluation of endoleak and their varying usefulness. Plain abdominal X-ray is a cost-effective tool in detecting gross graft abnormalities such as stent migration or deformity (kinking or fracture). Though it may raise suspicion for endoleak, X-ray does not allow accurate classification of endoleak type when used alone. Duplex ultrasonography quantifies both aortic anatomy and real time flow dynamics. Most screening programmes are conducted using two-dimensional ultrasound. Unfortunately, observer and equipment variability may lead to surveillance discrepancies-but reduced when utilising a dedicated vascular sonography laboratory. Contrast enhanced ultrasonography is a promising alternative to computed tomography, though still is emerging. Computed tomography angiography certainly has disadvantages (ionising radiation, contrast-nephropathy, limited differentiation of endoleak type)-however, it provides near-real surgical dimensions and highlights graft complications and concomitant disease (such as neighbouring infection). With widespread availability and short scan time, it certainly remains valuable in surveillance. Magnetic resonance angiography has a similar sensitivity to computed tomography (minus the radiation), however is plagued by movement and metal artefact. Other novel modalities in endoleak surveillance include fourdimensional ultrasound, multiplanar intra-operative probes, nuclear medicine and wall stress analysis.

Ultrasound Coded‐Excitation Imaging for Endoleak Detection After Complex Endovascular Aortic Repair

“…2,3 Complex aortic aneurysms with pathologies extending into the descending aorta might additionally require a thoracic/ fenestrated endovascular aortic repair combination (T/FEVAR). 5 Endoleaks are a common complication in endovascular aortic repair (EVAR) [6][7][8][9] and often result in re-intervention. 10 Therefore, such procedures require long-term surveillance to ensure patient safety.…”

“…[11][12][13] However, issues such as the cumulative radiation dose, contrast agent use in impaired renal function, limited differentiation of endoleak type as well as high costs are relevant limitations to consider for its use in clinical practice. 9,14,15 Subsequently, the use of other imaging modalities such as contrast-enhanced ultrasonography (CEUS) 14,16 or regular color duplex sonography (DUS) 17 have been investigated repeatedly for the follow-up of FEVAR procedures. Both techniques have already proven to be reliable in endoleak surveillance programs after EVAR.…”

“…Endoleaks are a common complication in endovascular aortic repair (EVAR) 6–9 and often result in re‐intervention 10 . Therefore, such procedures require long‐term surveillance to ensure patient safety.…”

EVAR Follow-Up with Ultrasound Superb Microvascular Imaging (SMI) Compared to CEUS and CT Angiography for Detection of Type II Endoleak

“…MR offers the advantages of no radiation exposure, less or no renal toxicity of contrast agents, and information about flow direction. Nevertheless, it has three main setbacks: classic MRI contraindications, magnetic susceptibility artifacts, and radiofrequency shielding effects [ 23 , 27 ]. Studies that have compared MR with CT imaging have demonstrated that MRI had a higher sensitivity to detect type II endoleaks.…”

Endovaskuläre Aortenreparatur bei Endoleaks

“…der bildgebenden Modalität unterscheiden sich die Leitlinien: So wird bei den amerikanischen Guidelines der Ultraschall (US) mit Ausnahme der ersten Nachuntersuchung gleichwertig zur CTA gewertet, während die europäischen Leitlinien sogar den US vorrangig empfehlen, vor allem für die jährlichen Verlaufskontrollen, während die CTA nur bei den Kontrollen alle 5 Jahre zum Einsatz kommen soll. In diesem Bereich kann insbesondere der kontrastmittelverstärkte Ultraschall punkten, der bei deutlich niedrigeren Kosten eine höhere Sensitivität zur Detektion von Endoleaks als die CTA aufweist, insbesondere bei Typ-II-Endoleaks [ 18 , 22 , 50 , 56 ].…”