The Effect of Spatial and Temporal Resolution of Cine Phase Contrast MRI on Wall Shear Stress and Oscillatory Shear Index Assessment

Abstract

IntroductionWall shear stress (WSS) and oscillatory shear index (OSI) are associated with atherosclerotic disease. Both parameters are derived from blood velocities, which can be measured with phase-contrast MRI (PC-MRI). Limitations in spatiotemporal resolution of PC-MRI are known to affect these measurements. Our aim was to investigate the effect of spatiotemporal resolution using a carotid artery phantom.MethodsA carotid artery phantom was connected to a flow set-up supplying pulsatile flow. MRI measurement planes were placed at the common carotid artery (CCA) and internal carotid artery (ICA). Two-dimensional PC-MRI measurements were performed with thirty different spatiotemporal resolution settings. The MRI flow measurement was validated with ultrasound probe measurements. Mean flow, peak flow, flow waveform, WSS and OSI were compared for these spatiotemporal resolutions using regression analysis. The slopes of the regression lines were reported in %/mm and %/100ms. The distribution of low and high WSS and OSI was compared between different spatiotemporal resolutions.ResultsThe mean PC-MRI CCA flow (2.5±0.2mL/s) agreed with the ultrasound probe measurements (2.7±0.02mL/s). Mean flow (mL/s) depended only on spatial resolution (CCA:-13%/mm, ICA:-49%/mm). Peak flow (mL/s) depended on both spatial (CCA:-13%/mm, ICA:-17%/mm) and temporal resolution (CCA:-19%/100ms, ICA:-24%/100ms). Mean WSS (Pa) was in inverse relationship only with spatial resolution (CCA:-19%/mm, ICA:-33%/mm). OSI was dependent on spatial resolution for CCA (-26%/mm) and temporal resolution for ICA (-16%/100ms). The regions of low and high WSS and OSI matched for most of the spatiotemporal resolutions (CCA:30/30, ICA:28/30 cases for WSS; CCA:23/30, ICA:29/30 cases for OSI).ConclusionWe show that both mean flow and mean WSS are independent of temporal resolution. Peak flow and OSI are dependent on both spatial and temporal resolution. However, the magnitude of mean and peak flow, WSS and OSI, and the spatial distribution of OSI and WSS did not exhibit a strong dependency on spatiotemporal resolution.

Wall shear stress estimation in the aorta: Impact of wall motion, spatiotemporal resolution, and phase noise

“…This partially agrees with findings made by Cibis et al, 15 who reported on a dependence of OSI on temporal resolution. This partially agrees with findings made by Cibis et al, 15 who reported on a dependence of OSI on temporal resolution.…”

“…The latter has already been studied in related works, 13,15,19 although the extent of uncertainties induced by acquisition parameters compared to those induced by imprecise wall tracking had not been reported yet. Equally, we evaluated the influence of spatiotemporal resolution and phase noise in synthetic datasets using the identical implementation to estimate shear stress parameters.…”

“…10,[15][16][17][18] However, the resulting surface mesh only represents an approximation of the vessel wall location, as it lacks the dynamics through the cardiac cycle. Here, a method widely adopted is to segment the vessel of interest based on the timeaveraged phase contrast magnetic resonance angiography (PC-MRA) image volume.…”

“…13,15,19,20 Particularly, a thorough study by Petersson et al 19 using synthetic data found that image-based WSS estimates are impacted by velocity encoding, velocity resolution, and spatial resolution to a considerable extent. 13,15,19,20 Particularly, a thorough study by Petersson et al 19 using synthetic data found that image-based WSS estimates are impacted by velocity encoding, velocity resolution, and spatial resolution to a considerable extent.…”

4D flow imaging with UNFOLD in a reduced FOV

“…However, 2DRF pulse durations of about 3.5 ms reduced the temporal resolution compared with conventional 1‐dimensional (1D) slab‐selective RF pulses (1DRF, such as SINC) . The temporal resolution is, however, critical for correct peak flow quantification . Furthermore, the reduced FOV (rFOV) needs to be oversampled in both phase‐encoding directions (i.e., rFOV > FOX), to prevent static spatial aliasing, which prolongs the scan time.…”