Abstract: An ultrasonic imaging system capable of transmitting and receiving ultrasound over a wide frequency range, i.e., 500 KHz-300 MHz. Ultrasound may be transmitted from a single transducer array at multiple frequencies simultaneously or sequentially via separate, acoustically isolated transducer elements, each having a unique resonant frequency. Signal-to-noise ratio may be enhanced through use of multiple piezoelectric layer transmit transducer elements and single piezoelectric layer receive transducer elements, both on a single transducer array. Aspect ratios approaching unity for transducer elements of the array may be obtained, which can be used to reduce grating lobes. Sparsely populated transducer arrays are included in the imaging system. Methods of ultrasound imaging and ultrasound therapy obtainable with the present imaging system are included in the invention.

Abstract: The physiology of the heart is analyzed by measuring a series of cardiac cycles using a biomagnetometer or other device capable of detecting cardiac cycles, classifying the cardiac cycles into groups according to the degree of correlation with a template cardiac cycle for the group, and associating the cardiac cycles of the groups with an origin location within the subject. The classifying operation preferably includes selecting a template cardiac cycle against which other previously ungrouped cardiac cycles are to be correlated, performing a correlation analysis of all previously ungrouped cardiac cycles with the template cardiac cycle, and associating with the template cardiac cycle all previously ungrouped cardiac cycles having at least a preselected degree of correlation, to form a group.