CT-derived perivascular adipose tissue attenuation in bicuspid aortic valve: insights into perivalvular and ascending aortic remodeling

Background

Bicuspid aortic valve (BAV) is associated with progressive valvular degeneration and ascending aortic dilatation. Recent studies suggest that inflammatory mechanisms may contribute to this process; however, noninvasive imaging markers that reflect these alterations remain limited. Computed tomography (CT)–derived perivascular adipose tissue attenuation (PVAT) has been associated with the degree of inflammation in other arterial territories. We hypothesized that CT-derived PVAT attenuation could provide novel insights into inflammatory changes around the aortic valve and ascending aorta in BAV.

Purpose

To evaluate CT-derived PVAT attenuation at the perivalvular level and along the ascending aorta in patients with BAV.

Methods

In this retrospective study, 142 patients undergoing CTA were included: 70 BAV with aortic stenosis (AS), 26 BAV with aortic regurgitation (AR) and dilated ascending aorta, and 46 controls. PVAT was assessed using a semiautomated software adapted from coronary PVAT analysis. PVAT was defined as adipose tissue extending 3 mm radially from the aortic valve and 5 mm from the ascending aorta. Attenuation was quantified by calculating CT attenuation of voxels within −190 to −30 Hounsfield units (HU), and mean and maximal PVAT values were recorded and compared across groups.

Results

At the perivalvular level, mean PVAT was higher in BAV than controls (−65.2 vs −71.4 HU, p<0.001). Mean PVAT increased stepwise from controls (−71.4 HU) to BAV with AS (−67.7 HU) and was highest in BAV with AR and dilated aorta (−59.5 HU, p<0.05). Maximal PVAT showed also similar significant differences with a more pronounced gradient (−58.6 HU, −53.4 HU, and −43.4 HU, respectively; p<0.001, Figure1).

Along the ascending aorta, mean PVAT were comparable between controls (−74.2 HU) and BAV with AS (−74.2 HU; p=0.579), whereas BAV with AR and dilated aorta demonstrated higher attenuation (−66.8 HU) compared with both controls (p=0.001) and BAV with AS (p=0.003). A similar pattern was observed for maximal PVAT (−62.7 HU in controls, −60.1 HU in BAV with AS, and −48.7 HU in BAV with AR and dilation; p<0.001 for comparisons involving the dilated group). PVAT along the ascending aorta demonstrated a significant distance-dependent and nonlinear pattern (p<0.001), with the highest values observed proximally and progressive decline distally (Figure2).

Conclusion

PVAT attenuation is elevated in patients with BAV, particularly at the perivalvular level and in those with AR and dilated ascending aorta. Along the ascending aorta, attenuation is highest proximally and decreases distally. These findings suggest that higher PVAT attenuation in BAV may reflect regional inflammatory changes associated with perivalvular and aortic remodeling and support further investigation of PVAT attenuation as a potential noninvasive imaging marker in BAV.Figure 1.PVAT in BAV and ControlsFigure 2.PVAT by Distance