In gray scale imaging, the most widely used clinical ultrasound modality, only the amplitudes of ultrasound echo signals are detected and displayed as dots on the monitor. However, the emergence of a new class of computer-controlled ultrasound scanning machines represents an outstanding opportunity to implement novel parametric imaging modes that should significantly compliment conventional scanning paradigms. Our goals are to implement and test scatterer size, integrated backscatter and attenuation imaging modes on a clinical scanner. The scanner is also being equipped with various elastography imaging, which will enable these data also to be included. Parametric images will be constructed by applying data reduction techniques that incorporate echo data from a reference phantom to account for imaging system and transducer dependencies of echo data. Scatterer size images will be constructed by applying least squares data reduction routines to fit spectral data to a model, where a free parameter represents the scatterer size. Integrated backscatter is considered the best representation of the scattered energy from a region, where corrections for attenuation and system dependencies on echo data are applied. New attenuation images and region of interest attenuation calculations will be incorporated that also apply reference phantom methods. Means for prerecording reference phantom information into the scanner memory will be evaluated, which would provide absolute internally calibrated ultrasound image data. Although images of scatterer size, integrated backscatter, and tissue strain have been previously reported, they have been plagued by the presence of noise artifacts especially for image data that are generated using echo signal spectra. We propose to improve the SNR of parametric images by spatially compounding parametric images obtained using RF data acquired at different insonification angles of the ultrasound beam. Angular compounding of the parametric images allows multiple, independent estimations of spectral parameters from each image voxel. In addition, angular compounding provides a means of improving images of axial tissue strain (elastograms) obtained by weighted angular compounding. The work is primarily directed towards ultrasound breast tissue imaging, where a research scanner being acquired by the Departments of Medical Physics and Radiology is being sited. Preliminary data will be generated for this application.
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