Meloni A, Zymeski H, Pepe A, Lombardi M, Wood JC. Robust estimation of pulse wave transit time using group delay.
J Magn Reson Imaging 2013;
39:550-8. [PMID:
24123545 DOI:
10.1002/jmri.24207]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Accepted: 04/12/2013] [Indexed: 01/21/2023] Open
Abstract
PURPOSE
To evaluate the efficiency of a novel transit time (Δt) estimation method from cardiovascular magnetic resonance flow curves.
MATERIALS AND METHODS
Flow curves were estimated from phase contrast images of 30 patients. Our method (TT-GD: transit time group delay) operates in the frequency domain and models the ascending aortic waveform as an input passing through a discrete-component "filter," producing the observed descending aortic waveform. The GD of the filter represents the average time delay (Δt) across individual frequency bands of the input. This method was compared with two previously described time-domain methods: TT-point using the half-maximum of the curves and TT-wave using cross-correlation. High temporal resolution flow images were studied at multiple downsampling rates to study the impact of differences in temporal resolution.
RESULTS
Mean Δts obtained with the three methods were comparable. The TT-GD method was the most robust to reduced temporal resolution. While the TT-GD and the TT-wave produced comparable results for velocity and flow waveforms, the TT-point resulted in significant shorter Δts when calculated from velocity waveforms (difference: 1.8±2.7 msec; coefficient of variability: 8.7%). The TT-GD method was the most reproducible, with an intraobserver variability of 3.4% and an interobserver variability of 3.7%.
CONCLUSION
Compared to the traditional TT-point and TT-wave methods, the TT-GD approach was more robust to the choice of temporal resolution, waveform type, and observer.
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