Transrectal ultrasound assessment of murine aorta and iliac arteries

Recent research in arterial aneurysm formation has focused on animal model development. Mice are an. ideal experimental organism due to their short li fe cycle, prolific progeny, and extensively studied genome. Most experiment s require the sacrifice of the mice to observe and assess any morphological changes. Noninvasive or minimally invasive imaging is limited due to the r elatively small size of the structures. The development of such a technique , therefore, is especially useful for allowing repeated measurement without sacrificing the mice. We introduce a novel technique of imaging and measur ing the aorta, the aorta/inferior vena cava complex, and the right and the left common iliac artery/vein complex by the use of an intravascular ultras ound catheter, The catheter is inserted through the anus and rectum and int o the sigmoid and left colon, where the aorta can be observed to fluctuate at approximately 500 beats/min. The aortic bifurcation can also be observed . The diameters of the aorta and the inferior vena cava were measured first with the transrectal ultrasound technique and then with direct visualizati on upon laparotomy for 10 mice. This revealed a percentage error between 13 .7 and 14.2% for this novel technique. Fifteen more sets of vessel measurem ents were also made with 8 male and 7 female mice. The results demonstrated a correlation between vessel size and body weight in male but not female m ice and suggested an intersex difference in vessel growth rate. We conclude that transrectal ultrasound is a useful tool in imaging and measuring the murine aorta and its bifurcation, (C) 2000 Academic Press.