An ideal observer approach to mechanical limits in b-mode ultrasound imaging

In medical applications, the amplitude of ultrasonic pulses is often constrained by mechanical considerations summarized by a mechanical index. We apply the ideal observer approach in a simulation environment to evaluating the role of mechanical index limits on task performance in b-mode ultrasonic imaging. We simulate a linear array operating at 15 MHz and 60% fractional bandwidth, and consider three tasks related to breast sonography at a depth of 4 cm. The ideal observer suggests that there are gains in performance--and hence the quantity of diagnostic information--as the limit on mechanical index is raised. However these gains are almost completely erased after computation of a standard b-mode envelope.