The purpose of the proposed project is to develop and test a rectal near infrared (NIR) scanning polarization imaging unit and an inverse image reconstruction algorithm to map the internal structure of a prostate, and detect and three-dimensionally (3D) locate the cancerous sites. The proposed rectal scanning imaging technique may be used for noninvasive prostate cancer screening. The research will be carried out by a joint research team consisting of optical imaging scientists in Dr. Wang's group at City College of New York, inverse image reconstruction experts in Prof. Xu's group at Fairfield University, and urologists in Dr. Eastham's group at Memorial Sloan- Kettering Cancer Center. The National Disease Research Interchange (NDRI) will supply cancerous and normal prostate tissue samples for the proposed research.

Prostate cancer has a high incidence and mortality rate for men. In year 2005, nearly 230,000 new prostate cancer cases were diagnosed, and about 30,000 deaths were caused by prostate cancers in the United States. Physicians routinely use two examinations to screen men for prostate cancer: the prostate specific antigen (PSA) blood test and a digital rectal examination (DRE). An abnormal DRE and an elevated PSA level are both possible indicators of the disease; however, neither test alone nor in combination can provide a definitive diagnosis of prostate cancer. If either test is abnormal, physicians will suggest have biopsy to make diagnosis. In the biopsy, physicians can see the prostate using a transrectal ultrasound (TRUS) probe, and precisely place biopsy needles to remove tissue from several different spots in the gland. Since the ultrasound imaging has poor contrast between cancerous and normal prostate tissues, and needle biopsy is invasive and may cause damage to prostate, it is highly desirable to develop a better diagnosis method which is more accurate, of higher spatial resolution, and non- or less invasive for prostate cancers detection.

The proposed rectal NIR scanning polarization imaging unit and inverse image reconstruction technique for prostate cancer screening is based on the recently observed absorption difference of cancerous and normal prostate tissues at the fingerprint absorption peaks of water. In our imaging approach, a set of 2D images of prostate will be recorded at the fingerprint absorption peak wavelengths using a rectal NIR scanning imaging unit by scanning a polarized illumination beam at different areas of a prostate through rectum, and recording backscattering light images with a NIR CCD camera. An inverse image reconstruction algorithm will be then used to produce a 3D image of the interior of the prostate using the recorded 2D images. The existence and location of cancerous tissue will be determined from the reconstructed 3D image. All of the optical imaging measurements will be performed using multiple wavelengths at both on-and-off the fingerprint absorption peaks to obtain a reliable estimation of the background. The resulting images, obtained by subtracting off-peak images from the corresponding on-peak images, will have less scattering background and higher contrast between cancerous and normal tissue. The results of rectal NIR scanning polarization imaging will be compared with the ultrasound imaging and biopsy examination to evaluate the positive prediction value and diagnosis role of the rectal optical imaging for prostate cancer screening and detection.

Our preliminary results on NIR scanning imaging measurements and inverse imaging reconstructions have demonstrated the ability of the proposed technique to distinguish cancerous and normal prostate tissue, and detect and three-dimensionally locate cancerous sites in prostate. The proposed technique is a promising less invasive approach for detecting prostate cancer regions without removing tissues. The other notable advantages of the proposed technique are safety, accuracy, low cost, and ease of operation.

The proposed research will impact the current techniques for prostate cancer screening and detection because it may result in a noninvasive optical imaging approach for three-dimensionally locating cancerous sites in prostate, may introduce a new criteria/indicator for prostate cancer screening in addition to the conventional PSA, DRE, and TRUS results, and will enhance the accuracy of diagnosing prostate cancers.