Biomedical Research

Colorectal carcinoma is the second most common malignancy in the United States after skin cancer. However, early detection of colorectal carcinoma is far more difficult than it is in the case of skin cancer. GRI's primary focus is on the development of an endoscopic imaging device to help improve this situation. The sensor is a high-frequency (~70 MHz), broadband ultrasound microsystem designed to image cellular structure/tissue along the esophageal and gastrointestinal (GI) tracts. The radial resolution of the imager is ~9 µm. The primary images are acquired in a conical volume that extends ~1 mm to 3 mm in depth. The region of depth coverage can be split into several sample intervals to increase the range of depths. Within the observed volume, cells and tissue structure are imaged layer-by-layer, and an incisionless biopsy is effectively performed. The size of the sample volume is determined primarily by current read-out integrated circuit technology; with increasing time this volume will increase. The current system design is more than adequate for several key endoscopic functions. These include: 1) the the availability of a patient friendly, pre-cancer/post-cancer diagnostic for severe gastroesophageal reflux disease (Barrett's esophagus) Currently invasive “needle” biopsies are in use, but the new sensor permits painless, incisionless biopsies to be made, 2) the imaging of pre-cancerous dysplastic mucosa, polyps, and adenomas in the colon, 3) real-time grading of dysplasia, 4) immediate viewing of cellular structure in tumors (e.g., squamous cell carcinoma and adenocarcinoma, benign growths), 5) guidance for directing fine-needle aspiration biopsies to regions that pose the greatest threat.

The current work was preceded by tests that demonstrated the overall viability of the project. The scans shown below were part of an initial investigation aimed at determining the sensitivity of a 105 MHz ultrasound system. [See Q.Q. Zhang ; F.T. Djuth ; Q.F. Zhou ; K.K. Shung (2004), High performance piezoelectric films for high frequency MEMS ultrasonic transducers, IEEE Ultrasonics Symposium, DOI: 10.1109/ULTSYM.2004.1418215.]