Validation of Ultrasound Determination of Local Pulse Wave Velocity in the Human Ascending Aorta Against MRI Measurements

Abstract

Background

Pulse Wave Velocity (PWV) is a measure of arterial stiffness which predicts cardiovascular risk independently of blood pressure. Local PWV can be measured non-invasively in the ascending aorta of adults by means of Ultrasound (US), using successive recordings of Diameter (D) and the velocity (U) [1].

Aim

To test US measurements of local PWV in the ascending aorta of human adults against MRI measurements of local PWV.

Methods

PWV in the ascending aorta of 8 healthy volunteers (age 22–34y, 3 females) was measured using a Siemens MAGNETOM Aera 1.5T MRI scanner as per standard protocols with cine and phase contrast imaging (sampling frequency 100 samples/cardiac cycle) and D and U were calculated using validated software [2]. US images were recorded using GE Vivid E95 scanner with a 1.5–4.5 MHz phased array transducer. PLAX was used for diameter recordings and A5CH for velocity. Measurements were recorded for 20s during a breath-hold. D and U waveforms were extracted from each imaging modality to calculate PWV using the ln(D)U-loops technique [3].

Results

Average results are summarised in Table 1. The mean difference in PWV between MRI and US was 2.8 ± 0.3%.

Conclusions

PWV measured by US shows excellent agreement with MRI in the ascending aorta of adults. Given US availability, this technique offers an easy, affordable and non-invasive means of determining PWV and mechanical properties of the ascending aorta; thus, providing a tool for screening studies.

Table 1 MRI and US measurements of D, U and PWV. Data are means ± standard deviations (n=8).