Ultrasound Imaging of the Thoracic and Abdominal Aorta in Mice to Determine Aneurysm Dimensions

Abstract

Contemporary high-resolution ultrasound instruments have sufficient resolution to facilitate the measurement of mouse aortas. These instruments have been widely used to measure aortic dimensions in mouse models of aortic aneurysms. Aortic aneurysms are defined as permanent dilations of the aorta, which occur most frequently in the ascending and abdominal regions. Sequential measurements of aortic dimensions by ultrasound are the principal approach for assessing the development and progression of aortic aneurysms in vivo. Although many reported studies used ultrasound imaging to measure aortic diameters as a primary endpoint, there are confounding factors, such as probe position and cardiac cycle, that may impact the accuracy of data acquisition, analysis, and interpretation. The purpose of this protocol is to provide a practical guide on the use of ultrasound to measure the aortic diameter in a reliable and reproducible manner. This protocol introduces the preparation of mice and instruments, the acquisition of appropriate ultrasound images, and data analysis.

Hypercholesterolemia Accelerates Both the Initiation and Progression of Angiotensin II-induced Abdominal Aortic Aneurysms

“…Luminal diameters of suprarenal aortas were measured using a Vevo 2100 ultrasound imaging system at indicated intervals. 13 Mice were anesthetized with isoflurane and restrained in a supine position. Short-axis scan was performed from the level of left renal artery moving vertically up to the suprarenal region.…”

Inhibition of Angiotensin II Dependent AT1a Receptor Stimulation Attenuates Thoracic Aortic Pathology in Fibrillin-1C1041G/+Mice

“…The approach used in this study also consistently imaged the aorta from the right parasternal view. 18 While this view is optimal for determining dimensions of the ascending aorta, it reduces precision of aortic root measurements. In the present study, there was strenuous adherence to a standardized protocol.…”

“…Ultrasound was performed by standardized protocols that have been as described previously. 17,22 Briefly, mice were anesthetized using inhaled isoflurane (2-3% vol/vol) and maintained at a heart rate of 450-550 beats per minute during image capture to reduce anesthesia exposure and maintain consistent heart rate between animals (Somnosuite, Kent Scientific). The order by which mice were subject to ultrasound was randomized.…”

“…Aortic diameters were measured for a 1 year interval using a standardized ultrasound protocol. 17,18 In accord with current guidelines, the study was performed in both sexes of these mice. These studies demonstrated a strong sexual dimorphism with greater expansion in Fbn1 C1041G/+ males and minimal progressive expansion in Fbn1 C1041G/+ females.…”

Ultrasound Monitoring of Descending Aortic Aneurysms and Dissections in Mice

“…High frequency ultrasonography is a common approach for aortic monitoring in mice. 4 The standard ultrasound approach using a para-sternal view can visualize the aortic root, ascending aorta, and aortic arch, while this approach cannot visualize the descending region due to the presence of lungs and ribs. Therefore, the ability to perform in vivo monitoring of descending aortic diseases in mice has been an impediment.…”