NONLINEAR REFLECTION ULTRASOUND TISSUE CLASSIFICATION

THERE IS EVIDENCE THAT A MEASURE OF THE ULTRASOUND NONLINEAR PARAMETER (B/A) CAN BE A GOOD TISSUE CLASSIFIER. RECENTLY, THE MEDICAL ULTRASOUND COMMUNITY HAS WITNESSED A GREAT DEAL OF EFFORT IN THIS AREA. HOWEVER, TO DATE ALL THE REPORTED TECHNIQUES ARE EITHER SUITABLE ONLY FOR TRANSMISSION MODE OR REQUIRE A MULTITUDE OF ULTRASOUND BEAMSOR FREQUENCIES (OR BOTH). THESE ARE, OF COURSE, SEVERE SHORTCOMINGS AS FAR AS CONVENTIONAL PULSE/ECHO B-MODE ULTRASOUND IS CONCERNED. IT IS PLANNED TO UNDERTAKE A PROGRAM TO DEVELOP A NOVEL SYSTEM THAT (1) OPERATES IN REFLECTION, (2) USES ONLY ONE ULTRASOUND BEAM, AND (3) OPERATES WITH ONLY ONE FREQUENCY. THIS APPROACH IS BASED ON VARIABLE AMPLITUDE EXCITATION. THE ECHO AMPLITUDES WILL BE MEASURED AT A FIXED POINT OF THEA-LINE FOR PROGRESSIVELY INCREASING EXCITATION AMPLITUDES. ANY DEVIATION FROM LINEARITY BETWEEN THE EXCITATION AMPLITUDE AND THE ECHO AMPLITUDE THEN SERVES AS A MEASURE OFTHE INTEGRATED NONLINEARITY BETWEEN THE TRANSDUCER AND THE DEFINED POINT ON THE A-LINE. DURING PHASE I, IT IS PLANNED TO COMPLETE THE INSTRUMENTATION OF A MECHANICALLY SCANNED SYSTEM AND DEMONSTRATE THE FEASIBILITY OF THIS CONCEPT. SPECIAL-PURPOSE IMAGING HARDWARE, BASED ON ELECTRONIC SCANNING, WILL BE DEVELOPED IN PHASE II.