The reliability of first harmonic Fourier phase analysis fitting to simulated time–activity curves

The accuracy of the phase value and closeness of curve fitting from Fourier first harmonic analysis is assessed in a range of simulated time-activity curves, of varying amplitude and noise characteristics at three heart rates, over the full and reduced R-R intervals. The accuracy of the phase value is not impaired by reducing the period to that of optimal fitting, whereas the closeness of fitting is improved, particularly at resting heart rates. The reliability of first harmonic Fourier analysis may be improved by reducing the period to which fitting is undertaken to the dynamic part of the time-activity curve.