Validation of Low Dose Non-contrast CT Scanning and Ultrasound Scanning as a Screening Tool for Abdominal Aortic Aneurysms – A Substudy from the DANCAVAS Trial

Abstract

Objective: Establishing non-contrast-enhanced Computed Tomography (CT), as equal and/or superior to the current abdominal aortic aneurysm (AAA) screening standard e Ultrasound Sonography (US). Material: 538 consecutive attending men to the pilot study of the randomized Danish CardioVascular Screening trial (DANCAVAS trial). Method: Participants underwent non-contrast CT and US examination. Measurements were done outer-to-outer in both transverse and anterior-posterior (AP) axial plane. All were done in systolic phase. Abdominal aortic aneurysms were defined as a maximal infrarenal aortic diameter of 30 mm or more. Sensitivity and specificity were calculated using CT and US as the golden standard, respectively. All measurements were tested for correlation and variance in diameters. Differences in means were tested using the paired t-test. Results: Of the 529 men examined, 30 AAAs were found by CT, giving a prevalence of 5.7%. However, US failed to detect 9 of these, resulting in a sensitivity of 70%. US specificity was 99%. Thus US based AAA prevalence was 4.0%. CT tested against US; sensitivity overall was 87.5% with a specificity of 98.2%. Analysis of paired differences showed no significance between CT and US, with means varying only slightly in both axial measurements. Measurements made in both the AP and transverse plane showed general agreement between the modalities with no tendency to increasing variance with increasing diameters. Conclusions: In a multifaceted screening program for CVD, CT appears superior to US. In addition to detecting the AAA otherwise detectable by US, the CT scanning enables a more thorough evaluation by providing visualization of unknown lesions of the coronary vessels, thoracic aorta and the iliac arteries. In fact, some isolated iliac aneurysms were detected by CT and not US. In addition, the US based prevalence on Fyen (2014) is almost similar to the prevalence of 4.2% detected in the Viborg County (1994e98), and higher than the prevalence of 3.3% detected in the VIVA trial (2008e11) in the Mid region of Denmark Median Arcuate Ligament Syndrome Qasam M. Ghulam , Kim K. Bredahl , Thomas Axelsen , Torben V. . Schroeder , Lisbeth E. Hvolris , Viggo B. Kristiansen , Svend Schulze , Lisbeth G. Jorgensen , Jonas P. Eiberg a,e a Clinic of Vascular Surgery, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark b Department of Radiology, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark c Center for Clinical Education, Center for HR, Region H, Blegdamsvej 9, 2100 Copenhagen, Denmark d Department of Gastro-Surgery, Hvidovre Hospital, Kettegard Alle 30, 2650 Hvidovre, Denmark e University of Copenhagen, Blegdamsvej 9, 2100 Copenhagen, Denmark Abstract The median arcuate ligament syndrome (MALS) is a rare entityThe median arcuate ligament syndrome (MALS) is a rare entity and poorly described in the Danish literature, which makes the exact prevalence difficult to estimate. It is more often among women, typically younger and less cardiovascular stigmatized as compared to the usual patients suffering intestinal ischemia. It is believed that the median arcuate ligament (MAL), being a fibrous structure of the diaphragm, compresses the celiac trunk, causing a stenosis and the characteristic “hook-shape” found on imaging. Whether symptoms originate from malperfusion of the gastrointestinal organs or are caused by compression of sympathetic fibers is not fully elucidated. The syndrome is characterized by chronic abdominal pain, postprandiale pain and weight loss. Moreover, worsening of abdominal pain associated with physical activity and when lying supine is commonly described. Most centers are reluctant to perform percutaneous transluminal angioplasty (PTA), because of the significant risk of stent-fracture and failure, as well as open ligament release and revascularization due to the extensive nature of such a procedure. Within the last decade, laparoscopic approacheswith release of themedian arcuate ligament have shown promising results and few periand postoperative complications. In some cases with insufficient symptom relief after ligament relief, a postoperative PTA can be performed adjunctively without the risk of stent-fracture. Median arcuate ligament syndrome is a rare disease, and should be a diagnosis of