NE-AUA 2006 Annual Meeting, September 28 - 30, 2006, The Westin Hotel & Rhode Island Convention Center Providence, Rhode Island
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A Novel Optical Non-Ivasive Method to Differentiate Normal Prostate Epithelium from Prostate Cancer: An Ex Vivo Study
O. A'Amar, PhD, J. Brahmbhatt, BA, F. Chaves, MD, B. Tiernobb, PhD, S. Arya, MD, A. De las Morenas, MD, L. Liou, MD, PhD, I. Bigio, PhD. 
Boston University School of Medicine and Department of Engineering, Boston, MA

Introduction and Objective: Prostate cancer is both multifocal and not reliably detectable by any current imaging modality. The current standard is transurethral guided random biopsy of the prostate but the negative predictive value can be low due to sampling error. In addition, the actual biopsy cancer volume and grade may not correlate with the radical prostatectomy specimen. There is a need for a portable method to guide prostate biopsies and map the prostate more accurately. This would allow greater confidence in both a negative biopsy as well as allow targeted diagnosis. Elastic Scattering Spectroscopy (ESS) utilized the scattering properties of light from a tissue surface to create a profile. This profile can be used to identify tissue pathology in-situ and in real time, without the need for excision and conventional histopathology. We investigated the use of ESS in distinguishing between normal and pathological prostate tissue.
Methods: We obtained IRB approval and utilized ESS on 9 freshly-excised radical prostatectomy specimens. The measurement probe consists of a small source and detector fibers that are separated by 350 μm. The pulsed xenon-arc lamp source provided light within the wavelength range of 350 to 850 nm and the detector can sense light scatter to a depth of 400 microns. Within one hour of resection, the specimens were step sectioned and ESS measurements were taken with the correlated prostate area excised for standard histopathological processing. All measurements were taken in the presence of ambient illumination with background subtraction, and calibrated against a spectrally flat-diffuse reflector. The readings were then correlated to the histological analysis.
Results: We obtained normalized ESS spectra for 58 tissue sites on 9 prostate glands for which we have corresponding histopathology reports. 42 were of benign prostatic tissue, 8 were of inflammatory prostate tissue, 6 were of prostatic adenocarcinoma, and 2 were of high-grade prostatic intra-epithelial neoplasia (PIN). Clear differences between the diagnostic categories are visible “by inspection” of each spectra. Some of the distinguishing spectral features are consistent with an increase in the size distribution of the scattering centers for malignant conditions such as nuclei, organelles, and cytoplasm. Figure 1 shows that when the spectra were averaged within each category, two wavelength peaks of 500 and 625 had flat spectral slopes for both benign and inflammatory tissue. However, PIN had a negative slope while cancer had a positive slope.
Conclusions: ESS appears to be a promising technology to distinguish between normal and neoplastic prostatic epithelium. It allows the delineation at the cellular level via an optical methodology that is both real-time and portable. Since the tissues were all non-perfused (ex vivo), in vivo work will need to be performed before clinical utilization.


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