Optical spectroscopy characteristics can differentiate benign and malignant renal tissues: a potentially useful modality

Abstract

Purpose: Promising results of optical signals have been reported in the literature for the diagnosis of Barrett's esophagus, oral cavity lesions, brain tumor margins, cervical intraepithelial neoplasia, skin cancer and bladder cancer. The potential usefulness of these techniques in renal tissues and neoplasms has not been described to date. This initial study examined the feasibility of using fluorescence and diffuse reflectance spectroscopy to differentiate between malignant and benign renal tissues.

Materials and methods: An ex vivo study was conducted to identify optical characteristics of various renal tissue types. Pathologically confirmed benign and malignant renal samples were obtained from nephrectomy specimens from patients undergoing radical nephrectomy. Fluorescence and diffuse reflectance spectra were measured from benign and malignant renal tissues.

Results: All renal tissues, malignant or benign, contain 2 primary emission peaks-a strong one at approximately 285 nm excitation, approximately 340 nm emission (Peak A), and a weak one at approximately 340 nm excitation, approximately 460 nm emission (Peak B). Peak A of normal renal tissue typically locates at the shorter excitation wavelength region than that of malignant tissue. The intensity of Peak B from benign tissues tends to be greater than that from malignant renal tissues. Diffuse reflectance intensities from malignant renal tissues between 600 and 800 nm are markedly greater than those from normal renal tissue. Empirical discrimination algorithms developed based on selected fluorescence and diffuse reflectance spectral characteristics yields accurate differentiation between benign and malignant renal tissues.

Conclusions: Highly accurate differentiation between normal human renal tissues and renal cell cancers is feasible using combined fluorescence and diffuse reflectance spectroscopy in an ex vivo setting. If successful in future clinical studies, optical spectroscopy could aid in margin detection and tissue discrimination while performing nephron sparing surgery.