Acoustic Backscatter Features Associated with Production of Tissue Homogenate using Pulsed Cavitational Ultrasound Therapy

The use of a spatial variability criterion for acoustic backscatter is investigated as a potential method to assess lesion morphology and size in pulsed cavitational ultrasound therapy (PCUT). Backscatter signals were recorded during varied acoustic exposures that produced lesions in which tissue homogenate was either present or absent. Spatial variability was quantified by tracking changes in cross‐correlation sequences of A‐lines received during each exposure. Distributions of mean spatial variability are observed to be significantly higher for mechanically homogenized lesions than for those in which no homogenate is observed. A threshold spatial variability criterion is defined based on these distributions and is shown to be highly correlated (> 95%) with damage morphology. Furthermore, backscatter associated with the formation of homogenized lesions is characteristically observed to migrate away from the transducer during insonation. The magnitude of this backscatter shift is related to the axial dimension of the resultant lesion.