Two dimensional arrays for 3-D ultrasound imaging

Phased array ultrasound transducers have been fabricated in our laboratories at Duke University since 1970. In 1986, we began the development of 2-D arrays with a 20 × 20 element Mills cross array including 64 active channels operating at 1 MHz which produced the first real time 3-D ultrasound images. In our more recent arrays we have progressed to 108 × 108 = 11,664 elements in a series of transducers operating from 2.5 - 10 MHz. These were used in a commercial version of our Duke 3-D system developed by Volumetrics Medical Imaging for cardiac applications. The system scans a 65° 3-D pyramid at up to 60 volumes/sec and features five simultaneous slice images at any desired angle and depth as well as real time 3-D rendering, 3-D pulsed and color flow Doppler. We have also modified this scanner to produce the first real time 3-D rectilinear and curvilinear images using arrays of 256 × 256 = 65,536 elements operating at 5 MHz for vascular and small parts applications. Finally, we have developed catheter 2-D arrays for intra-cardiac 3-D ultrasound including 112 channels in a 2.2 mm lumen (7 French) operating at 5-7 MHz. In animal studies, these transducers have been applied to the guidance of cardiac interventional procedures including RF ablation, ECG mapping, surgical biopsy and atrial septal puncture.