Method and apparatus for remote tissue identification by statistical modeling and hypothesis testing of echo ultrasound signals

A method for manufacturing a filter which extracts, from a statistically significant sample of the values of signals which represent detected echoes of ultrasound which are scattered from unknown tissue, a signal which is a measure of the likelihood that the accumulated sample was generated by a mathematical model which characterizes a known tissue type, comprising the steps of:

• directing ultrasound energy into a sample of the known tissue;
• detecting values characteristic of echoes of the ultrasound which are scattered from the known tissue;
• accumulating a statistically significant sample of the detected characteristic values;
• calculating, from the accumulated sample, autoregressive parameters which characterize an autoregressive process which models the sample values;
• and
• constructing a Kalman predictive filter which incorporates the determined autoregressive parameters.

Appartus for remote identification of a tissue comprising:

• means for directing ultrasound energy into an unknown tissue;
• means for detecting a characteristic of echoes of the ultrasound which are scattered from the unknown tissue;
• means for accumulating a statistically significant sample of signals which represent values of the detected characteristic;
• a plurality of filter means, each of which function to filter the accumulated sample to extract a signal which is a measure of the likelihood that the accumulated sample was generated by an associated, predetermined mathematical model, wherein each of said mathematical models is associated with a possible tissue type;
• and
• means which apply the signals extracted by the filters, as inputs to a predetermined logical decision function to select the extracted signal which is associated with the model which most likely produced the sample and assign the tissue type associated with the model producing the chosen signal as the identity of the unknown tissue.