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

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Wall 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.

Methods: A 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.

Results: The 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).

Conclusion: We 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.

No MeSH data available.


Related in: MedlinePlus

a) Flow waveforms at different spatial(sr) and temporal(tr) resolutions. Dashed lines show the PC-MRI measurements and the red line shows the ultrasound probe measurement. Spatial resolution varied between 0.2mm and 1 mm and the temporal resolution varied between 9.1 ms and 142.9 ms. b) Ultrasound probe vs. PC-MRI flow measurements.
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pone.0163316.g002: a) Flow waveforms at different spatial(sr) and temporal(tr) resolutions. Dashed lines show the PC-MRI measurements and the red line shows the ultrasound probe measurement. Spatial resolution varied between 0.2mm and 1 mm and the temporal resolution varied between 9.1 ms and 142.9 ms. b) Ultrasound probe vs. PC-MRI flow measurements.

Mentions: Flow waveforms obtained from PC-MRI measurements at the highest and the lowest spatial and temporal resolutions are shown in Fig 2a. The red line shows the flow waveform based on the ultrasound probe measurement. At the highest spatial resolution (0.2 mm) and the highest temporal resolution (24.4 ms, black dashed line), the shape of the flow waveform was similar to the one measured by the ultrasound probe. At the lowest spatial resolution (1.0 mm) and the highest temporal resolution (9.1 ms, light blue dashed line), the shape of the flow waveform was still captured although peak flow was underestimated (7.8 mL/s). At lowest temporal resolution (142.9 ms, red and orange dashed lines), the peak flow was shifted backward in the cardiac cycle and underestimated. The ultrasound probe measurements were plotted against the PC-MRI measured flows in Fig 2b which shows underestimation of flow at higher flows in all cases except for the measurement at the highest spatial and temporal resolution.


The Effect of Spatial and Temporal Resolution of Cine Phase Contrast MRI on Wall Shear Stress and Oscillatory Shear Index Assessment
a) Flow waveforms at different spatial(sr) and temporal(tr) resolutions. Dashed lines show the PC-MRI measurements and the red line shows the ultrasound probe measurement. Spatial resolution varied between 0.2mm and 1 mm and the temporal resolution varied between 9.1 ms and 142.9 ms. b) Ultrasound probe vs. PC-MRI flow measurements.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036833&req=5

pone.0163316.g002: a) Flow waveforms at different spatial(sr) and temporal(tr) resolutions. Dashed lines show the PC-MRI measurements and the red line shows the ultrasound probe measurement. Spatial resolution varied between 0.2mm and 1 mm and the temporal resolution varied between 9.1 ms and 142.9 ms. b) Ultrasound probe vs. PC-MRI flow measurements.
Mentions: Flow waveforms obtained from PC-MRI measurements at the highest and the lowest spatial and temporal resolutions are shown in Fig 2a. The red line shows the flow waveform based on the ultrasound probe measurement. At the highest spatial resolution (0.2 mm) and the highest temporal resolution (24.4 ms, black dashed line), the shape of the flow waveform was similar to the one measured by the ultrasound probe. At the lowest spatial resolution (1.0 mm) and the highest temporal resolution (9.1 ms, light blue dashed line), the shape of the flow waveform was still captured although peak flow was underestimated (7.8 mL/s). At lowest temporal resolution (142.9 ms, red and orange dashed lines), the peak flow was shifted backward in the cardiac cycle and underestimated. The ultrasound probe measurements were plotted against the PC-MRI measured flows in Fig 2b which shows underestimation of flow at higher flows in all cases except for the measurement at the highest spatial and temporal resolution.

View Article: PubMed Central - PubMed

ABSTRACT

Introduction: Wall 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.

Methods: A 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.

Results: The 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).

Conclusion: We 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.

No MeSH data available.


Related in: MedlinePlus