Antony Bertrand-Grenier
University of Quebec at Trois-Rivières, Canada
Title: Feasibility of shear wave elasticity imaging to detect endoleak and evaluate thrombus organization after endovascular repair of an abdominal aortic aneurysm
Biography
Biography: Antony Bertrand-Grenier
Abstract
Purpose: To investigate the feasibility of shear wave elasticity imaging (SWI) for detection of endoleaks and characterization of abdominal aortic aneurysms (AAAs) healing after endovascular aneurysm repair (EVAR), using a combination of duplex ultrasound (DUS) and CT-scan as the reference standard.
Methods: Endoleaks areas were detected on SWI by 2 readers and compared with DUS and CT in 30 patients. Elasticity values of endoleaks and thrombus were calculated and compared. The analysis included: a) Correlation between thrombus elasticity and AAA diameter and volume and their variation over time and b) Correlation between endoleak and fresh thrombus areas and aneurysm diameter and volume.
Results: Endoleaks were present in 6 patients. SWI, DUS, and CT respectively detected 6(100%), 3(50%) and 5(83%) of these endoleaks. SWI detected 3 endoleaks not seen on DUS and one not seen on CT. SWI reported from 6 to 8 false positives (specificity of 62% to 71%). Elasticity moduli in endoleaks and thrombi regions were estimated at 0.06kilopascal (kPa) and 22.3kPa, respectively (P<0.001). Thrombus elasticity of AAA with and without endoleaks were not significantly different (P=0.792). No significant correlations were found between thrombus elasticity moduli and AAA diameter and volume and their variation over time. No significant correlation was found between the proportion of fresh thrombus (less rigid and non-organized thrombi; 3-19kPa) and growth of AAA in diameter and volume.
Conclusion: This clinical study evaluated SWI as a biomarker of endoleak and thrombus stiffness in 30 patients with AAA after EVAR. AAAs were evaluated and correlated with SWI, DUS, and CT-scan. SWI provides real-time mechanical information on AAA sac content that is complementary to B-mode and DUS assessments. Our results suggest that not only SWI may help to detect endoleak but it may also detect aneurysm likely to grow by identifying the amount of fresh thrombus that is likely to be associated with post-EVAR aneurysm enlargement.
Clinical Relevance: SWI has the potential to identify endoleaks and to detect aneurysms that are likely to grow after EVAR. As both techniques are implemented on the same imaging modality, SWI may be combined with DUS in post-EVAR surveillance of endoleak. SWI could reduce costs, exposure to ionizing radiation and nephrotoxic contrast agents associated with CT-scan follow-up.