Which technique utilizes FFT (Fast Fourier Transform) for signal analysis with time on the x-axis?

The technique that utilizes Fast Fourier Transform (FFT) for signal analysis, with time plotted on the x-axis, is spectral analysis. In vascular ultrasound, spectral analysis is employed to assess the characteristics of blood flow in vessels by converting time-domain signals into frequency-domain information.

FFT allows the decomposition of complex Doppler signals into their frequency components, providing clear visualization of flow velocities over time. This is particularly important in diagnosing vascular conditions since it enables the assessment of flow patterns, presence of turbulence, and identification of stenosis within the vessel.

Pulsed Doppler and continuous wave (CW) Doppler do involve measurements of blood flow velocities, but they do not specifically use FFT for signal analysis or provide a time-dependent frequency spectrum. Similarly, while color Doppler provides qualitative information about flow direction and relative velocity, it predominantly represents blood flow through color overlays rather than detailed frequency analysis provided by spectral techniques. Spectral analysis distinguishes itself by offering time-based displays of frequency components, making it essential for clinicians in interpreting hemodynamic information.