P2E-2 Acoustic Radiation Force Impulse Imaging of Excised Human Prostates

We present initial results in acoustic radiation force impulse (ARFI) imaging of excised human prostates. Prostates were obtained from four patients undergoing prostatectomy for prostate cancer. All men had positive biopsy prior to surgery and had consented to allowing elastographic imaging of the excised tissue. The prostates were obtained immediately after surgery and immersed and scanned in an isotonic saline bath at room temperature. Scanning was performed with a Siemens Antares scanner using a VF10-5 linear array. Tissue displacement was induced with pushing pulses of 30 mus duration at 6.67 MHz and an Isppa of < 1 kW/cm². Pushing beams were focused at 2 cm with an F/# of 3.5. RF data were collected and processed off-line using cross correlation methods to obtain displacement estimates. Low-resolution displacement images were obtained in near-real time (~3 seconds/frame) to guide image acquisition. The saved RF data were later processed to produce displacement images with improved SNR. Prostates were scanned free-hand, looking for interesting b-mode or ARFI targets. Peak displacements in healthy tissue were in the range of 6-12 mum. Cancerous lesions were stiffer and showed smaller displacements