Population based ultrasonographic screening of abdominal aortic aneurysms

Abstract

radiation exposure. Non-contrast CT may be utilized when ultrasound (US) is not suitable and CTA is also useful in pre-procedural planning in delineating the type, size, extent and location of aneurysm as well as branch vessel involvement [7]. MRI is an attractive alternative modality for evaluating AAA as well as other vascular systems [8], but it is not widely available, expensive, and time-consuming and requires higher technical expertise. MRA can be used for pre-procedural planning if CT cannot be performed [7]. US is non-invasive, widely available, portable, cost effective and has no radiation as well has high sensitivity (94-100 %), specificity (98-100 %) and reproducibility [9] in detection of AAA, making it the ideal screening modality for AAA.The benefits of AAA screening using a one-time US have been demonstrated by several large randomized controlled trials in UK, Denmark and Western Australia [1,10]. AAA-related mortality has been shown to decrease by 40 % at 3-5 years [11], and 42-66 % at 13 years [12,13], with an absolute decline in mortality by 1.4 per 1000 men [12]. AAA-mortality at 5-12 years was shown to be 0-2.4 % [5,6], with a 42-52 % decrease of AAA related death in those who attended screening [12,13]. All-cause mortality was also shown to be slightly decreased by 3 % at 11-15 years, possibly due to management of other cardiovascular risk factors [1,12]. The incidence of rupture was also significantly reduced (Hazard ratio of 0.44-0.57) up to 13 years [12,13]. The rate of emergency repair was halved and elective repair doubled upto 13-15 years [12,13]. This robust data led the United States Preventive Services Task Force (USPSTF) to recommend a one-time US AAA screening in male smokers of age 65-75 years. For the same age group, it recommends selective use in male never-smokers and advocates against screening for female never-smokers. No specific recommendation is made for female smokers due to insufficient evidence [1]. In the current issue of Abdominal Aortic Aneurysm (AAA), defined as an infrarenal aortic diameter >3.0 cm is not infrequently seen in the older population, especially in male smokers. The overall prevalence of AAA in men >50 years is 3.9-7.2 % (6-7 % in smokers, 2 % in non-smokers) whereas in women the overall prevalence is 1.0−1.3 % (0.8−2.0 % in smokers, 0.03-0.6 % in non-smokers) [1]. AAA is also associated with a positive family history and thoracic aortic aneurysms [2]. Although AAA is usually asymptomatic, the first presentation may be a rupture, the probability of which increases with size of the aneurysm sac (6.5-11 % for 5-5.9 cm, 1 % for 4-4.9 cm, 0 % for 3.0-3.9 cm) [1,3] and it is three times more common in females at comparable diameters [4]. Rupture has a high mortality rate (75-90 %), with the majority (59-83 %) passing before reaching the hospital and the operative mortality is high as well (40 %) [1]. To avoid the risk of rupture, AAA is electively repaired, either using an endovascular (EVAR) or open approach, when it is >5.5 cm or grows >1.0 cm/ year [5...

Evolving clinical applications of contrast-enhanced ultrasound (CEUS) in the abdominal aorta

“…US can accurately measure an aneurysm's diameter, provided that the probe is properly angled so that the measurements are made on a level perpendicular to the longitudinal axis of the aorta. US can be used as a screening tool for men with a smoking history aged 65 to 74 years in order to exclude the presence of an aneurysm and thus reduce aneurysm-related mortality, even in a community setting (28,(33)(34)(35). US is limited for the evaluation of supra-and infra-renal borders of an AAA and the detection of additional aneurysms affecting the iliac arteries (28).…”