Application of a real-time, calculable limiting form of the Renyi entropy for molecular imaging of tumors

Previously, we reported new methods for ultrasound signal characterization using entropy, H_f; a generalized entropy, the Renyi entropy, I_f(r); and a limiting form of Renyi entropy suitable for real-time calculation, I_f,∞. All of these quantities demonstrated significantly more sensitivity to subtle changes in scattering architecture than energy-based methods in certain settings. In this study, the real-time calculable limit of the Renyi entropy, I_f,∞, is applied for the imaging of angiogenic murine neovasculature in a breast cancer xenograft using a targeted contrast agent. It is shown that this approach may be used to reliably detect the accumulation of targeted nanoparticles at five minutes post-injection in this in vivo model.