Association between aortic stiffness, carotid vessel wall thickness and stenosis severity in peripheral arterial occlusive disease: a comprehensive MRI study

Summary Aortic pulse wave velocity sampled in the descending aorta is associated with maximal stenosis severity, visually scored on CE-MRA in patients with PAOD whereas stenosis severity is correlated to a lesser extent with carotid vessel wall. Background


Background
In atherosclerosis, arterial wall thickening and stiffening precede luminal narrowing. MRI is well-validated for imaging vessel wall thickness (VWT) and stiffness expressed in pulse wave velocity (PWV, defined as the propagation speed of the pressure or flow wave through the aorta). Contrast-enhanced MR angiography (CE-MRA) has evolved into a reliable tool for stenosis detection in peripheral arterial occlusive disease (PAOD). The purpose of this study was to use a comprehensive 3T MRI-approach for comparing stenosis severity on CE-MRA with VWT, sampled in the common carotid artery, and PWV, sampled in the descending aorta.
Four transverse images of the common carotid artery were obtained by multi-slice 2D dual inversion recovery black-blood (DIR) fast gradient-echo ( Figure 1B) with spectral selective fat suppression. A flexible 2-element surface coil was used and positioned on the neck. Inner and outer lumen contours were manually determined ( Figure 1C), defining measurement of mean vessel wall area (VWA) per slice.
PWV was assessed for the descending aorta by applying two one-directional through-plane velocity-encoded MRI acquisitions, planned perpendicular to the aorta and transecting the proximal and abdominal descending aorta, respectively ( Figure 1D). PWV was obtained from systolic wave propagation analysis based on the transittime method ( Figure 1E).
PWV was compared with carotid VWA indexed for body surface area and maximal stenosis severity class detected with CE-MRA.

Results
Mean Fontaine class was 2.3±0.6. Maximal stenosis class per patient presented on CE-MRA was as follows: 2 patients without stenosis (class 1), 1 patient with class 2, 2 patients with class 3, 9 patients with class 4 and 28 patients with class 5. PWV in the descending aorta was well-correlated with maximal stenosis class (Spearman correlation 0.63 (p<0.001), Figure 2A). Carotid VWA and PWV (Pearson correlation 0.48 (p=0.002), Figure  Figure 1 (A) Coronal contrast-enhanced MR angiographic maximum intensity projection images of 67-year-old man presenting with bilateral claudication and significant stenosis in the left external iliac artery (short arrow) and an occlusion in the right superficial femoral artery (long arrow); (B) Sagittal black-blood image of the carotid bifurcation presenting positioning of carotid vessel wall sampling in the common carotid artery (C); (D) Sagittal image of the aorta presenting positioning of two one-directional through-plane velocity-encoded MRI acquisitions at the proximal and abdominal descending aorta. Pulse Wave Velocity is determined from wave propagation analysis between measurement sites (E). http://www.jcmr-online.com/content/14/S1/P132 2B) and carotid VWA and maximal stenosis class (Spearman correlation 0.43 (p=0.005), Figure 2C) were correlated to a lesser extent.

Conclusions
PWV in the descending aorta is associated with maximal stenosis severity, visually scored on CE-MRA in patients with PAOD whereas stenosis severity is correlated to a lesser extent with carotid vessel wall.

Funding
None.