Parametric imaging of rat mammary tumors in vivo for the purposes of tissue characterization

Objective. To estimate the average scatterer properties from ultrasonic backscatter in tissues for evaluating differences between neoplastic and healthy tissues. Methods. Parametric images of 8 retired breeder rats in which spontaneous mammary tumors had developed were created by superimposing color-coded pixels related to the estimated average scatterer properties on conventional gray scale mode images. Results. The images showed a distinct difference between the tumors and surrounding healthy tissues. Analysis of the average scatterer diameters and acoustic concentrations showed a statistically significant difference (P < .05) between estimates inside and outside the tumors for most of the cases. Scatterer sizes inside the tumors were on average 30% larger than scatterer sizes in surrounding normal tissues. A feature analysis plot showed that there was a distinct difference between results obtained inside and outside the tumors. Conclusions. Parametric imaging that uses estimates of scatterer properties in tissues may lead to detection and characterization (diagnosis) of diseased tissues on conventional sonographic scanning systems.