Endoleaks after endovascular abdominal aortic aneurysm repair: management strategies according to CT findings.

OBJECTIVE: With increasing use of endovascular techniques for repair of abdominal aortic aneurysms, the prevalence of leakage into excluded aneurysm sacs (endoleaks) as a complication has risen. We will describe and illustrate the imaging findings for endoleaks involving abdominal aortic aneurysms. We will also discuss which types of endoleaks require urgent catheter-based evaluation. CONCLUSION: Radiologists should be familiar with the classification scheme for endoleaks and understand which types of endoleaks require urgent catheter-based evaluation.

Contrast-enhanced ultrasound imaging of atherosclerotic carotid plaque neovascularization: a new surrogate marker of atherosclerosis?

An atherosclerotic plaque requires a nutrient blood supply, which is predominantly derived from arterial vasa vasorum. A variety of factors (environmental and genetic) contribute to the initiation and growth of atherosclerosis within vessel walls. Chemotactic factors, such as tissue ischemic and hypoxic factors, stimulate the release of vascular endothelial growth factor (VEGF) proteins, resulting in vessel wall angiogenesis. These developments often precede the formation of the luminal plaque. In this report, we describe the use of contrast-enhanced carotid ultrasound (CECU) imaging for the detection and quantification of intra-plaque neovascularization. The efficacy of CECU was measured against the neovascular density observed within the tissue specimens obtained at the time of carotid endarterectomy surgery. The objective of this study was to provide a histologic correlation between CECU and carotid artery atherosclerotic plaque neovascularization. Fifteen patients with significant atherosclerotic carotid artery disease received a CECU examination prior to undergoing a carotid endarterectomy (CEA). Two patients received bilateral endarterectomies, resulting in a total of 17 cases. At the time of surgery, carotid plaque samples were surgically removed and stained with specific vascular markers (CD31, CD34, von Willebrand factor, and hemosiderin) designed to identify the presence and degree of neovascularization. The intra-plaque neovascularization recorded on preoperative CECU was correlated with the degree of neovascularization noted in the tissue specimens. The CECU neovascularization was correlated to CD31-stained tissue specimens. This correlation value was 0.68 using Spearman's rank method. When CECU results were correlated with the other histologic markers (CD34, von Willebrand factor, and hemosiderin), a correlation of 0.50 was obtained. In conclusion, contrast-enhanced carotid ultrasound correlated to the presence and degree of intra-plaque neovascularization as determined from histology specimens.

Role of surrogate markers in assessing patients with diabetes mellitus and the metabolic syndrome and in evaluating lipid-lowering therapy.

Diabetes mellitus and the metabolic syndrome (MS) are reaching epidemic proportions in the United States, and cardiovascular disease continues to be the leading cause of death among patients with diabetes. A range of noninvasive screening tools may help reduce the morbidity and mortality of patients with diabetes because of early detection of subclinical cardiovascular disease and active monitoring of the effectiveness of therapy. Surrogate markers of subclinical disease include conventional and contrast-enhanced ultrasound imaging of carotid artery intima-media thickness (c-IMT), 2-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, and brachial artery reactivity testing. Because these noninvasive imaging tools are relatively comfortable and entail relatively low risk to the patient, they are ideal for initial screening and for the repeated imaging that is required for monitoring the effectiveness of therapy. Moreover, when used in large numbers of patients with diabetes, prediabetes, and the MS, these imaging tools may be useful in developing and validating thresholds for the use of lipid-lowering therapy as well as clear therapeutic goals for this population. In addition, contrast-enhanced c-IMT scans now produce real-time images of the vasa vasorum and neovascularization of atherosclerotic plaque, potentially causing a paradigm shift in our view of the genesis of atherosclerosis and affecting treatment options for all populations. Thus, surrogate markers may not only help improve individual patient outcomes, they also may help direct scarce medical resources to maximize medical benefits, improve overall medical care, and minimize costs and untoward side effects.

Emerging, noninvasive surrogate markers of atherosclerosis.

Noninvasive surrogate markers of atherosclerosis allow the physician to identify subclinical disease before the occurrence of adverse cardiovascular events, thereby limiting the need to perform invasive diagnostic procedures. Imaging modalities, such as carotid artery ultrasound, two-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, brachial artery reactivity testing, and epicardial coronary flow reserve measurements, provide information that may improve the predictive value of a person's risk of developing clinically significant atherosclerotic disease. Newer imaging modalities have also emerged to bring insight into the pathophysiology and treatment of atherosclerosis.