Comparison of different methods for the estimation of aortic pulse wave velocity from 4D flow cardiovascular magnetic resonance

Abstract

BackgroundArterial pulse wave velocity (PWV) is associated with increased mortality in aging and disease. Several studies have shown the accuracy of applanation tonometry carotid-femoral PWV (Cf-PWV) and the relevance of evaluating central aorta stiffness using 2D cardiovascular magnetic resonance (CMR) to estimate PWV, and aortic distensibility-derived PWV through the theoretical Bramwell-Hill model (BH-PWV). Our aim was to compare various methods of aortic PWV (aoPWV) estimation from 4D flow CMR, in terms of associations with age, Cf-PWV, BH-PWV and left ventricular (LV) mass-to-volume ratio while evaluating inter-observer reproducibility and robustness to temporal resolution.MethodsWe studied 47 healthy subjects (49.5 ± 18 years) who underwent Cf-PWV and CMR including aortic 4D flow CMR as well as 2D cine SSFP for BH-PWV and LV mass-to-volume ratio estimation. The aorta was semi-automatically segmented from 4D flow data, and mean velocity waveforms were estimated in 25 planes perpendicular to the aortic centerline. 4D flow CMR aoPWV was calculated: using velocity curves at two locations, namely ascending aorta (AAo) and distal descending aorta (DAo) aorta (S1, 2D-like strategy), or using all velocity curves along the entire aortic centreline (3D-like strategies) with iterative transit time (TT) estimates (S2) or a plane fitting of velocity curves systolic upslope (S3). For S1 and S2, TT was calculated using three approaches: cross-correlation (TTc), wavelets (TTw) and Fourier transforms (TTf). Intra-class correlation coefficients (ICC) and Bland-Altman biases (BA) were used to evaluate inter-observer reproducibility and effect of lower temporal resolution.Results4D flow CMR aoPWV estimates were significantly (p < 0.05) correlated to the CMR-independent Cf-PWV, BH-PWV, age and LV mass-to-volume ratio, with the strongest correlations for the 3D-like strategy using wavelets TT (S2-TTw) (R = 0.62, 0.65, 0.77 and 0.52, respectively, all p < 0.001). S2-TTw was also highly reproducible (ICC = 0.99, BA = 0.09 m/s) and robust to lower temporal resolution (ICC = 0.97, BA = 0.15 m/s).ConclusionsReproducible 4D flow CMR aoPWV estimates can be obtained using full 3D aortic coverage. Such 4D flow CMR stiffness measures were significantly associated with Cf-PWV, BH-PWV, age and LV mass-to-volume ratio, with a slight superiority of the 3D strategy using wavelets transit time (S2-TTw).

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

“…This implies that MUSA may be a more reliable technique to calculate cPWV from OS PC‐MRI measured velocities. TTF method has been used extensively to quantify transit time of velocity waveforms with high temporal resolution obtained from ultrasound 19,26,50 . However, recent studies have reported that other transit‐time quantification algorithms could be more reliable when dealing with relatively lower temporal resolutions in PC‐MRI–based PWV measurements 29,37,51 .…”

“…TTF method has been used extensively to quantify transit time of velocity waveforms with high temporal resolution obtained from ultrasound. 19,26,50 However, recent studies have reported that other transit-time quantification algorithms could be more reliable when dealing with relatively lower temporal resolutions in PC-MRI-based PWV measurements. 29,37,51 Also, it has been suggested that choosing the best algorithms might depend on the velocity waveform characteristics that are known to be different in various regions of vasculatures.…”

Quantitative magnetic resonance imaging measures of three‐dimensional aortic morphology in healthy aging and hypertension

“…This ultimately enhances the signal to noise ratio in the resulting aortic images but might limit the usefulness in patients with counterindication to contrast agents. However, one might note that our segmentation technique was shown to be robust to low image quality, as it was able to reliably segment four‐dimensional flow MRI‐derived aortic angiograms, 36,37 which are known to have lower signal‐to‐noise ratio than conventional anatomical images. Our MRI data were acquired from three different sites using different field strengths (1.5 T and 3 T) and sequences (SPGR and SSFP).…”

Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging

“…Recently, it was also shown that the estimation of aoPWV with 4D flow MRI can be obtained and reproduced using a full 3D coverage in the human aortic arch. The results were compared and significantly associated with standard PWV acquisition [ 127 ]. Four-dimensional PC MRI was also used to determine PWV and wall shear stress in the aortic arch at the same time [ 128 ].…”