Prostate Imaging by Vibro-Acoustography

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Although trans-rectal ultrasound (TRUS) is widely used for prostate imaging, there are drawbacks to this technique. Ultrasound imaging inherently produces speckle, which is the snowy pattern that results from random interference of echoes from tissue scatterers. This artifact reduces image contrast and hampers detection of lesions. Moreover, TRUS is not capable of distinguishing between soft and hard lesions. Tissue stiffness is known to be associated with pathology. Another shortcoming of conventional TRUS in prostate imaging is its limitations in imaging prostate brachytherapy seeds. This issue is important when permanent prostate brachytherapy is performed under TRUS guidance. Metallic brachytherapy seeds are often missed in an ultrasound image and consequently radiation dosage calculation cannot be done with confidence in the operative setting. We have developed a novel imaging modality, referred to as Vibro-acoustography, which incorporates many improvements over TRUS, i.e., it is noninvasive, speckle free, sensitive to tissue stiffness, and capable of imaging brachytherapy seeds at any orientation. Active extramural funded research programs to develop a superficial vibro-acoustic probe for general diagnostic imaging, and to investigate applications of vibro-acoustography in breast cancer have provided a strong impetus and background for the development of a trans-rectal vibro-acoustic (TRVA) probe. In this research, we plan to further develop and test this technique for prostate imaging applications. A prostate-specific TRVA probe will be designed and constructed in conjunction with the General Electric medical imaging group. The performance of TRVA for detecting prostate lesions in human subjects will be tested and compared to TRUS imaging. The ability of TRVA to guide minimally invasive prostate therapies and procedures including prostate brachytherapy and cyrotherapy will be evaluated and compared with the performance of ultrasound imaging. The potential for TRVA to map areas of the prostate which have experienced complete cryoablation following cryotherapy versus areas which may have been undertreated also exists. Such imaging capability has significant implications and translation potential towards providing a means of intraoperative quality assurance for this treatment modality. Successful completion of this project should provide a new class of imaging tools for prostate imaging and increase our abilities to detect and treat prostate cancer.