Required temporal resolution for accurate thoracic aortic pulse wave velocity measurements by phase-contrast magnetic resonance imaging and comparison with clinical standard applanation tonometry

Abstract

BackgroundPulse wave velocity (PWV) is a biomarker for arterial stiffness, clinically assessed by applanation tonometry (AT). Increased use of phase-contrast cardiac magnetic resonance (CMR) imaging allows for PWV assessment with minor routine protocol additions. The aims were to investigate the acquired temporal resolution needed for accurate and precise measurements of CMR-PWV, and develop a tool for CMR-PWV measurements.MethodsComputer phantoms were generated for PWV = 2–20 m/s based on human CMR-PWV data. The PWV measurements were performed in 13 healthy young subjects and 13 patients at risk for cardiovascular disease. The CMR-PWV was measured by through-plane phase-contrast CMR in the ascending aorta and at the diaphragm level. Centre-line aortic distance was determined between flow planes. The AT-PWV was assessed within 2 h after CMR. Three observers (CMR experience: 15, 4, and <1 year) determined CMR-PWV. The developed tool was based on the flow-curve foot transit time for PWV quantification.ResultsComputer phantoms showed bias 0.27 ± 0.32 m/s for a temporal resolution of at least 30 ms. Intraobserver variability for CMR-PWV were: 0 ± 0.03 m/s (15 years), -0.04 ± 0.33 m/s (4 years), and -0.02 ± 0.30 m/s (<1 year). Interobserver variability for CMR-PWV was below 0.02 ± 0.38 m/s. The AT-PWV overestimated CMR-PWV by 1.1 ± 0.7 m/s in healthy young subjects and 1.6 ± 2.7 m/s in patients.ConclusionsAn acquired temporal resolution of at least 30 ms should be used to obtain accurate and precise thoracic aortic phase-contrast CMR-PWV. A new freely available research tool was used to measure PWV in healthy young subjects and in patients, showing low intra- and interobserver variability also for less experienced CMR observers.

Assessment of carotid stiffness by measuring carotid pulse wave velocity using a single‐slice oblique‐sagittal phase‐contrast MRI

“…However, it has been shown in a recent numerical phantom study that with 25 ms temporal resolution, the TTF algorithm can detect ~13 to 135 ms of transit-time delay with less than 5% median error. 77 In our measurements, the transit time between the reference and the averaged velocity waveforms was more than 10 ms, except for the axial locations very close to the carotid bifurcation ( Figure 1F). Given the temporal resolution of the sequence that we used (12 ms) and robustness of cPWV calculations to the exclusion of relatively large region around the carotid bifurcation ( Figure 6), we expect the temporal resolution to have a small impact on the accuracy of the calculated cPWV values.…”

Proximal aortic stiffening in Turner patients may be present before dilation can be detected: a segmental functional MRI study

“…At the time our data acquisition started, transverse images and detection of the foot-of-the-curve time shift was the major proposed method, a transit-time method focussing at the early systolic part of the curve in an attempt to avoid the effect of wave reflection, which, especially in a stiffer aorta, is important. It was used as early as 1993 by Mohiaddin et al [ 48 ] and more recently, by means of computer phantoms, Dorniak et al calculated the minimal required temporal resolution of 30 ms (35 image frames at a heartrate of 60 bpm) for accurate and precise quantitative flow data for CMR-PWV over the range 2–20 m/s in the thoracic aorta [ 49 ]. Newer methods involve complex wavelet cross spectrum analysis [ 50 ], which equally have the advantage of being robust at lower temporal resolution.…”

The association between resting‐state functional magnetic resonance imaging and aortic pulse‐wave velocity in healthy adults

“…PWV was calculated using the time‐to‐foot approach (Dorniak et al, ), implemented through the freely available software Segment CMR (Medviso, publicly available at http://segment.heiberg.se) (Heiberg et al, ). Specifically, aortic PWV was calculated as x / t (expressed in m/s), where x is the aortic path length between the arch and abdominal aorta, and t is the time delay between the arrival of the foot of the pulse wave at these locations.…”