A new performance analysis metric for medical ultrasound

The resolution of medical ultrasound systems is usually characterized by the width of the mainlobe, typically the full width at half maximum (FWHM), in beamplots. The FWHM has, however, been shown to sometimes provide misleading information about systems. The concept of "cystic resolution" in which performance is quantified as the size of the void that produces a specified contrast, has been previously introduced to medical ultrasound. We extend the concept and develop a general metric to analyze the 3D broadband performance of arbitrary ultrasound systems. We provide an example of application in which we compare the performance of a conventional system using a 1D array and time delay beamforming of radiofrequency (RF) data to that of a system based on a 2D array that focuses solely via phase rotation of complex I/Q data formed by directly sampling the received RF signal.