Follow-up on Small Abdominal Aortic Aneurysms Using Three Dimensional Ultrasound: Volume Versus Diameter.

OBJECTIVES: Rupture risk in abdominal aortic aneurysms (AAAs) is assessed using AAA diameter; yet 10% of ruptures occur in a small aneurysm. This underlines the inadequacy of diameter as a standalone parameter. In this prospective follow-up study, ultrasound determined aneurysm diameter was compared with aneurysm volume determined by three dimensional ultrasound (3D-US) in a group of 179 AAAs. DESIGN: This was a prospective cohort study with repeated diameter and volume measurements by 3D-US. MATERIAL AND METHODS: In total, 179 patients with small infrarenal AAAs (diameter 30-55 mm) were enrolled consecutively. At enrolment and at 12 month follow-up, maximum diameter, using dual plane technique, and three dimensional volume were measured. Based on a previous accuracy study, significant change in diameter and volume were defined as an increase exceeding the known range of variability (ROV) of each US technique; ±3.7 mm and ±8.8 mL, respectively. Post-hoc Kaplan-Meier analysis was performed to estimate time to conversion to treatment after the conclusion of the follow-up period between two groups. RESULTS: In total, 125 patients (70%) had an unchanged diameter during follow-up. In this group, 50 patients (40%) had an increasing aortic volume. Forty-five (83%) of the 54 patients with an increasing aortic diameter showed a corresponding volume increase. During a median follow-up of 367 days (364-380 days), a mean increase in diameter of 2.7 mm (±2.6 mm) and a mean increase in volume of 11.6 mL (±9.9 mL) were recorded. In post-hoc analysis, it was found that more AAAs with a stable diameter and a growing volume than AAAs with a stable diameter and volume were undergoing aortic repair during follow-up, based on the maximum diameter. CONCLUSION: In this cohort of small AAAs, 40% of patients with a stable diameter had an increasing volume at 12 month follow-up. From this perspective, 3D-US could have a future supplemental role in AAA surveillance programmes.

Contrast Enhanced Ultrasound can Replace Computed Tomography Angiography for Surveillance After Endovascular Aortic Aneurysm Repair.

OBJECTIVE/BACKGROUND: Surveillance after endovascular aortic aneurysm repair (EVAR) is mandatory and computed tomography angiography (CTA) is considered the standard imaging modality, although patients are exposed to ionizing radiation and nephrotoxic contrast medium. The primary aim of this study was to determine the diagnostic efficacy of duplex ultrasound (DUS) and contrast enhanced ultrasound (CEUS) using CTA as the gold standard. The secondary aim was to determine the clinical consequences of endoleaks missed by DUS and CEUS, or CTA. METHODS: All patients with EVAR for an aorto-iliac aneurysm between 1 August 2011 and 31 October 2014 were prospectively and consecutively enrolled. CEUS was added to the existing surveillance protocol, which included DUS, plain abdominal X-ray, and CTA at 3 and 12 months after stent implantation. RESULTS: In 278 patients, endoleaks were detected in 68, 69, and 46 cases by CTA, CEUS, and DUS, respectively. The sensitivity and specificity of DUS and CEUS were 46% and 93%, and 85% and 95%, respectively. CEUS and CTA were diagnostically equivalent, as opposed to DUS and CTA (p = .002). Endoleaks detected by CTA led to re-intervention in 11 (4%) patients. These endoleaks were also detected by CEUS; however, three out of 11 patients were missed by DUS and underwent re-intervention: limb extension, re-cuff, and attempt to coil lumbar leaks. Endoleaks missed by CEUS or CTA were type II endoleaks without sac expansion. CONCLUSION: In surveillance programs after EVAR a diagnostic CEUS examination may replace CTA.