Assessing the Stability of Aortic Aneurysms with Pulse Wave Imaging

Abstract

Purpose:To assess whether the stability of murine aortic aneurysms is associated with the homogeneity of pulse wave propagation within the saccular wall. Materials and Methods:All animal procedures were approved by the institutional Animal Care and Use Committee. Apolipoprotein E and tissue inhibitor of metalloproteinases-1 knockout mice (n = 26) were infused with angiotensin II by using subcutaneously implanted osmotic pumps, with an additional control mouse used for histologic examination (n = 1). Pulse wave imaging (PWI) was performed just before infusion and 15 days after infusion by using 40-MHz ultrasonography at 8000 frames per second (with electrocardiographic gating). Aneurysm appearance on B-mode images was monitored every 2-3 days for 30 days. On the basis of B-mode images obtained after 30 days, aneurysms were deemed to have been unstable if they had ruptured; otherwise, they were deemed stable. Statistical significance was assessed by using two-tailed t tests. Results:In normal aortas, the pulse waves propagated at relatively constant velocities (mean 6 standard deviation, 2.8 m/sec 6 0.9). Fifteen days after infusion, all mice had developed aneurysms, with significant (P , .001/12) changes in maximum anterior-posterior diameter (increase of 54.9% 6 2.5) and pulse wave velocity (PWV) (decrease of 1.3 m/ sec 6 0.8). While there was no significant difference in these parameters (P = .45 for diameter and P = .55 for PWV) between stable aneurysms (n = 12) and unstable aneurysms (n = 14), the standard deviation of the highresolution PWV was significantly higher (P , .001/12) in unstable aneurysms (5.7 m/sec 6 1.6) than in stable ones (3.2 m/sec 6 0.9). Conclusion:High-resolution PWI was used to measure the local homogeneity of pulse wave propagation within the saccular wall, which is lower in unstable aneurysms than in stable ones. Hence, if proven to add additional information beyond size and appearance in human studies, PWI could potentially be used to assess the stability of aneurysms by providing information that is complementary to the anatomic data obtained with conventional B-mode imaging.q RSNA, 2016

Cardiac and respiratory-gated volumetric murine ultrasound

“…The results described here are consistent with previous reports showing an increase in vessel stiffness due to the degradation of elastin and increased collagen turnover [39,32]. This increase in vessel stiffness was also supported by previous reports demonstrating reductions in pulse-wave velocities along the aneurysmal wall [40–42]. Previous work using 2D M-mode ultrasound suggested that aneurysm formation typically decreased the Green-Lagrange circumferential strain from around 15% to 3% [32].…”

Shear wave elasticity imaging for residual endoleak and thrombus characterisation after endoleak embolisation following endovascular aneurysm repair: a canine animal study

“…Contrast-enhanced ultrasound is very sensitive to detect endoleak after EVAR and can be a good alternative [ 23 ]. Other ultrasound elasticity techniques such as pulse wave imaging or strain analysis were previously reported in preclinical and clinical studies to assess the wall stiffness of abdominal aortic aneurysms [ 24 , 25 ]. Only one study reported its feasibility in the context of EVAR follow-up [ 26 ].…”

Assessment of arterial stiffness in periodontitis using a novel pulse wave imaging methodology

“…Similar observations were made in a cohort of patients with history of abdominal aortic aneurysm and hypertension, in whom the shape of the waveform was substantially distorted in the most severe cases (Li et al., ). While the clinical impact of the observed 0.09 reduction in the determination coefficient between periodontitis and periodontal health remains speculative, recently published experimental evidence in a murine model demonstrated a less homogeneous propagation in the pulse wave ( R 2 ) in unstable versus stable aortic aneurysms, despite similar PWV values between the groups (Nandlall & Konofagou, ).…”