Speckle reduction methods in ultrasound pulse-echo imaging

The coherent nature of the ultrasound imaging pulse allows for the possibility of interference effects and the appearance of the speckle artefact which occurs in virtually all medical ultrasound images. Speckle affects RF A-line signals and hence may influence parameters derived from it. The nature of speckle free signals associated with a region of `fully developed´ speckle, as defined by the rough volume model, are examined. Results from computer simulation are provided for: the statistical approaches of angle and frequency compounding; frequency diversity; an adaptive unsharp mask filter, and the (deterministic) approach of zero adjustment processing