Recent studies on the statistics of the envelope of the ultrasound echo signal from a random scattering medium suggest that the statistical moments of the signal may carry quantitative information about the scattering microstructure. A mathematical model for the backscattered signal is developed borrowing from linear systems theory and assuming narrow bandwidth conditions. Several microstructures, including sponges of different pore size as well as pig liver, human breast tissue, and human skeletal muscle, are probed experimentally with multiple bandwidth pulses with center frequency matched to the transducer center frequency. Variations of the second normalized intensity moment with the cell volume are considered and exploited experimentally for structure characterization. The concept of effective cell volume and its relationship to the system point spread function is established. The influence of the imaging system point spread function on the statistical moments is considered. To estimate an effective scatterer number and scatterer number density for every sample, higher order and fractional moments are calculated and fitted to theoretical Non- Rayleigh distributions: K, Generalized K, and Rice. Information on interscatterer spacing is obtained from the autocorrelation of the second normalized intensity moment. To analyze the sample structure, phantoms were created from histology sections and the same experimental and analysis procedures were followed. The concept of effective cell surface and its relationship to the system point spread function is established. The experimental results indicate that non-Rayleigh statistical analysis of speckle prove to be useful in characterizing both normal, and abnormal tissue.
Library of Congress Subject Headings
Ultrasonics in medicine; Laser speckle; Laser beams--Scattering; Tissues--Analysis; Histology
Department, Program, or Center
Chester F. Carlson Center for Imaging Science (COS)
Helguera, Maria, "Non-Rayleigh ultrasonic characterization of tissue scattering microstructure via a multibandwidth probing technique" (1999). Thesis. Rochester Institute of Technology. Accessed from
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