Quantification of periaortic adipose tissue in contrast-enhanced CT angiography: technical feasibility and methodological considerations.

To examine the feasibility of the quantification of abdominal periaortic fat tissue (PaFT) (tissue within - 45 to - 195 HU) in enhanced CT-angiographies compared to unenhanced CT-scans and identify methodological issues affecting its clinical implementation. Using OsirixMD, PaFT volume and mean HU value were retrospectively measured within a 5 mm periaortic ring in paired unenhanced and enhanced abdominal aortic CT-scans. The correlation between PaFT values was examined in a derivation cohort (n = 101) and linear regression analysis produced correction factors to convert values from enhanced into values from unenhanced CTs. The conversion factors were then applied to enhanced CTs in a different validation cohort (n = 47) and agreement of corrected enhanced values with values from unenhanced scans was evaluated. Correlation between PaFT Volume und Mean HU from enhanced and unenhanced scans was very high (r > 0.99 and r = 0.95, respectively, p < 0.0001 for both). The correction factors for PaFT Volume and Mean HU were 1.1057 and 1.0011. Potential confounding factors (CT-kilovoltage, slice thickness, mean intraluminal contrast density, aortic wall calcification, longitudinal variation of intraluminal contrast density, aortic diameter) showed no significant effect in a multivariate regression analysis (p > 0.05). Bland-Altman analysis of corrected enhanced and unenhanced values showed excellent agreement and Passing-Bablok regression confirmed minimal/no residual bias. PaFT can be quantified in enhanced CT-angiographies very reliably. PaFT Volume scores are very consistently slightly underestimated in enhanced scans by about 10%, while the PaFT Mean HU value remains practically constant and offers distinct methodological advantages. However, a number of methodological issues remain to be addressed.

Congenital subclavian steal syndrome with multiple cerebellar infarctions caused by an atypical circumflex retroesophageal right aortic arch with atretic aberrant left subclavian artery.

A right-sided aortic arch is a rare anomaly with an incidence of 0.1% worldwide and is usually associated with a mirror image of all supra-aortic branches or an aberrant left subclavian artery. The latter is often associated with a Kommerell diverticulum, although it can rarely be hypoplastic or atretic and lead to congenital subclavian steal. In most patients, the situation is well-tolerated. In this report, we present a case of subclavian steal syndrome with multiple cerebellar infarcts in a patient with an atypical right-sided aortic arch and an atretic aberrant left subclavian artery arising from a left-sided descending thoracic aorta.

Retrograde ascending Stanford B aortic dissection complicating a routine infrarenal endovascular aortic reconstruction.

Retrograde ascending aortic dissections usually complicate endovascular reconstructions of Stanford B dissections. Although rare, with an incidence of 1.3% to 6.8%, they are catastrophic, with a high mortality rate of up to 42%. The exact mechanism is not known, but all indications point to a mechanical interaction between the tips of the proximal bare stent and a fragile aortic wall. Practically all reported cases involve dissections of the thoracic aorta. We report a patient with an asymptomatic retrograde ascending aortic dissection that originated at the level of a damaged suprarenal stent during capture tip retrieval during a routine endovascular aneurysm repair to treat an infrarenal aortic aneurysm.