Abstract
BackgroundCarotid-femoral pulse wave velocity (cf-PWV) and aortic PWV measured using MRI (MRI-PWV) show good correlation, but with a significant and consistent bias across studies. The aim of the current study was to evaluate whether the differences between cf.-PWV and MRI-PWV can be accounted for by inaccuracies of currently used distance measurements.MethodsOne hundred fourteen study participants were recruited into one of 4 groups: Type 2 diabetes melltus (T2DM) with cardiovascular disease (CVD) (n = 23), T2DM without CVD (n = 41), CVD without T2DM (n = 25) and a control group (n = 25). All participants underwent cf.-PWV, cardiac MRI and whole body MR angiography(WB-MRA). 90 study participants also underwent aortic PWV using MRI. cf.-PWVEXT was performed using a SphygmoCor device (Atcor Medical, West Ryde, Australia). The true intra-arterial pathlength was measured using the WB-MRA and then used to recalculate the cf.-PWVEXT to give a cf.-PWVMRA.ResultsDistance measurements were significantly lower on WB-MRA than on external tape measure (mean diff = −85.4 ± 54.0 mm,p < 0.001). MRI-PWV was significantly lower than cf.-PWVEXT (MRI-PWV = 8.1 ± 2.9 vs. cf.-PWVEXT = 10.9 ± 2.7 ms−1,p < 0.001). When cf.-PWV was recalculated using the inter-arterial distance from WB-MRA, this difference was significantly reduced but not lost (MRI-PWV = 8.1 ± 2.9 ms−1 vs. cf.-PWVMRA 9.1 ± 2.1 ms−1, mean diff = −0.96 ± 2.52 ms−1,p = 0.001). Recalculation of the PWV increased correlation with age and pulse pressure.ConclusionDifferences in cf.-PWV and MRI PWV can be predominantly but not entirely explained by inaccuracies introduced by the use of simple surface measurements to represent the convoluted arterial path between the carotid and femoral arteries.
Highlights
Carotid-femoral pulse wave velocity and aortic PWV measured using Magnetic Resonance Imaging (MRI) (MRI-PWV) show good correlation, but with a significant and consistent bias across studies
Recruitment criteria, strategy and study protocol have been described in detail previously [10, 11], but in summary, subjects were recruited and categorised into 4 groups based on their history of type 2 diabetes and cardiovascular disease (CVD) as follows: Group 1: Type 2 diabetes mellitus (T2DM) with a prior clinical diagnosis of cardiovascular disease that included coronary artery disease (CAD), cerebrovascular disease and/or lower extremity arterial disease (LEAD); Group 2: Type 2 diabetes mellitus with no clinical evidence of cardiovascular disease; Group 3: Absence of diabetes mellitus with clinical evidence of CAD, cerebrovascular disease and/or LEAD; Group 4: Healthy controls, with no biochemical evidence of diabetes mellitus and no clinical evidence of cardiovascular disease
Cf.PWVEXT was significantly higher than the recalculated cf.-PWVMRA
Summary
Carotid-femoral pulse wave velocity (cf-PWV) and aortic PWV measured using MRI (MRI-PWV) show good correlation, but with a significant and consistent bias across studies. Arteriosclerosis is the process of arterial stiffening that has significant pathophysiological implications and is strongly associated with cardiovascular events [1] It is predominantly a product of age and pulse pressure, reflecting the effects of repetitive strain on the elastic fibers of the arterial wall [2]. The two techniques correlate well with each other, but with a significant and consistent bias between the two techniques across studies with cf.-PWV consistently being approximately 1.6–1.7 ms−1 higher than MRI-PWV [5, 6] This is consistent with observations of 1.9 ms−1 difference between the aortic pulse wave velocity measured invasively and the cf-PWV, this previous study used a direct carotid-femoral measurement which is known to overestimate distance travelled and PWV by approximately 25% [7]. The muscular and elastic properties of the aorta and its branch vessels is known to change throughout their length which in turn affects their stiffness and by extension PWV [6, 9]
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