MULTIDIRECTIONAL ULTRASONIC BLOOD-FLOW-IMAGING SYSTEM

ULTRASOUND FLOW MEASUREMENT AND PARTICULARLY COLOR FLOW MAPPING (CFM) SYSTEMS PROVIDE A VALUABLE TOOL FOR MEDICAL DIAGNOSIS. THESE TECHNIQUES PRIMARILY EXPLOIT THE DOPPLER EFFECT WHICH, DESPITE ITS GREAT SUCCESS, RESULTS IN TWO FUNDAMENTAL DRAWBACKS: (1) THE INABILITY TO MEASURE NONAXIALFLOW COMPONENTS AND (2) THE INABILITY TO MEASURE HIGH VELOCITIES AT LARGE DEPTHS. THIS PROJECT WILL DEVELOP A SYSTEM THAT (1) PROVIDES THE CAPABILITY FOR MEASURING THE TRANSVERSE COMPONENTS OF FLOW VELOCITY AND (2) CAN MEASURE VERY HIGH VELOCITIES, BOTH WITHHIGH LATERAL RESOLUTION. THE TECHNIQUE USES A NEWLY DEVELOPED MULTIBEAM ACOUSTIC LENS IN WHICH THE SEPARATIONS BETWEEN THE ACOUSTIC FOCI ARE PREDETERMINED BY THE LENS DESIGN. THE ULTRASOUND SIGNALS SCATTERED FROM THESE FOCI ARE CROSS-CORRELATED, RESULTING IN FLOW VELOCITY MEASUREMENT. IN PHASE I, THIS WILL BE DEMONSTRATED BY A SUITABLE DUAL-BEAM ACOUSTIC LENS USING A FLOW PHANTOM. THIS WILL THEN PAVE THE WAY FOR A 3-D VELOCITY VECTOR IMAGING SYSTEM. DURING PHASE II, A THREE-BEAM SYSTEM WILL BE DEVELOPED AND COMBINED WITH CONVENTIONAL DOPPLER FOR A COMPLETE 3-D FLOW VELOCITY VECTOR IMAGING SYSTEM. SUCH A SYSTEM SHOULD ACCURATELY DETECT FLOW DISTURBANCES ARISING FROM, FOR EXAMPLE, ATHEROSCLEROTIC LESIONS.