An application of smoothing splines for molecular imaging of tumors using an improved calculation of a limiting form of Renyi entropy

In several investigations of molecular imaging of angiogenic neovasculature using a targeted contrast agent, Renyi entropy (I
_f
(r)) and a limiting form of Renyi entropy (I
_f
,
_∞
) exhibited significantly more sensitivity to subtle changes in scattering architecture than energy-based methods. Many of these studies required the fitting of a cubic spline to backscattered waveforms prior to calculation of entropy (either If(r) or I
_f
,
_∞
)In this study it is shown that the robustness of I
_f
,
_∞
may be improved by using a smoothing spline. Results are presented showing the impact of different smoothing parameters. In addition, if smoothing is preceded by lowpass filtering of the waveforms, further improvements may be obtained.