The objective of this investigation was to compare transthoracic ultrasound (US) determinations of ascending aortic diameters in rats with video microscopy (VM), the current standard for measuring aortic diameters in rats.
The diameter of the ascending aorta was measured in 111 adult Lewis male rats, by VM and US, with a 9 MHz probe, before and after intervention for induction of experimental aneurysm of the ascending aorta.
The Bland-Altman test showed a high degree of agreement between the two methods, with a bias of only 0.23 mm (95 % confidence limits - 0.86 - 0.39 mm). Also, the measurements obtained by US correlated highly (r = 0.83, p < 0.0001) with those obtained by VM. Rat ascending aortic diameters obtained both by VM and US correlated significantly with the weight (r = 0.62 and r = 0.39, respectively), and with the age of the animals (r = 0.74 and r = 0.49, respectively).
This study demonstrates that noninvasive US ascending aortic measurements are a reliable supplement to VM for the development of an ascending aortic aneurysm model, and for monitoring the efficiency of novel therapeutic agents.