In spectral Doppler imaging, a high PRF is used independent of the velocity scale. The adjustment is then of the velocity scale. By optimizing the velocity scale independent of the high PRF in an on-going or automated basis, user activation may be avoided and/or interruption to reconfigure for an altered PRF may be avoided. The acquired data may be stored, allowing for past data to be processed again when a new velocity scale or other setting is selected. The resulting spectral Doppler image may continue to display spectra over time without a gap or without premature loss of spectra due to reconfiguring.