LAUSR

The accumulation of adipose tissue has long been thought of as a risk factor for cardiovascular disease (CVD) [1]. However, the dynamic effects in metabolic homeostasis and pathology are still being discovered [2]. The complexity of factors associated with obesity including adipokines associated with various adipose tissue depots is frequently overlooked [3]. Intuitively, one of these depots, perivascular adipose tissue (PVAT), is likely contributing to the development and/or progression of CVD given its proximity to arterial vasculature. A subset of PVAT that surrounds the coronary arteries, epicardial fat, has been well studied in the development of coronary artery disease [4]. Another subset of PVAT, periaortic adipose tissue has also been implicated in CVD, however, previous studies have limited their investigation to a specific population, unique depots, or a single CVD [5–7]. Herein, the current study describes the quantification of periaortic adipose tissue volume in both the thoracic and abdominal regions in a unique population and correlates this value to specific measures of CVD. Once the study protocol and procedures were approved by the University of Cincinnati Institutional Review Board (IRB#2013-8286), An electronic medical record was queried for patients who obtained non-contrasted computed tomography (CT) scans of their chest and/or abdomen over a 2-year period. These deidentified records were reviewed to verify subjects met inclusion/exclusion criteria which were broad, allowing for a diverse patient population. Inclusion criteria included 18 years of age or older and non-contrasted CT scan of chest and/or abdomen. Exclusion criteria where limited to variables that would compromise the measurement of the periaortic tissue volume including previous aortic surgery, gross anatomical anomalies (including trauma) or the use of contrast as the increased attenuation within the lumen would alter the radiodensity of the surrounding tissue. After appropriate subjects were identified, abdominal and thoracic periaortic adipose tissue volume was quantified in a similar manner as previously conducted [5]. The segment of thoracic aorta that was measured started at the level of the pulmonary artery bifurcation and extended 70 mm inferiorly. The abdominal aortic segment was measured starting at the level of the aortic bifurcation and extended superiorly 40 mm. Adipose tissue was selectively gated using a window width of –195 to –45 Hounsfield units (HU) with a center of –120 HU [5]. The region of interest was encircled with a diameter being 10 mm larger than the anteroposterior aortic diameter and then adipose tissue was selectively gated [6]. The degree of aortic calcification was determined by the volume of hyperattenuation with a minimum of three connected pixels with attenuation over 130 HU [5]. CLINICAL CARDIOLOGY