Douglas C. B. Redd

Raman Spectroscopic Characterization of Human Breast Tissues: Implications for Breast Cancer Diagnosis

Development and application of laser-based diagnostic and therapeutic procedures have been hindered by the current technical inadequacies in tissue diagnosis and characterization. It is now possible to apply the techniques of Raman spectroscopy to achieve rapid, noninvasive, and nondestructive differentiation of diseased from normal tissues. Normal and diseased breast tissues were examined by Raman spectroscopy. The Raman spectra obtained contain features that are attributable to various amounts of carotenoids and lipids. A small contribution from a heme-type signal was detected in some samples of clinically abnormal yet histopathologically benign breast tissue, while a much stronger heme-type signal was detected in most of the breast cancers. Raman spectra of diseased breast tissue (benign and malignant) also show markedly diminished to absent contributions from lipids and reduced contributions from carotenoids. This laser-based spectroscopic modality is readily adaptable to reflected light microscopy and optical fiber techniques, making it potentially useful as an aid in real-time diagnosis, and may thus find application in the fields of histopathology and interventional radiology.

Detection of Silicone in Lymph Node Biopsy Specimens by Near-Infrared Raman Spectroscopy

Near-infrared Raman spectroscopy with a 782-nm cw laser was used to examine lymph node biopsy specimens from women with ruptured breast implants containing silicone gel. For reduction of fluorescence and sample radiation damage, a low-power (30 mW) Ti: sapphire laser, single-stage spectrograph, and CCD detector were employed. Silicone Raman features were clearly visible in lymph node tissue of patients with leaking implants, and the spectra were easily distinguished from those of normal lymph node tissue. The technique has promise for medical diagnostic purposes, and may be amenable to in vivo analysis with adaptation to a fiber-optic probe.

Young Investigator Award Raman Spectroscopy of Human Atherosclerotic Plaque: Implications for Laser Angioplasty

Raman spectroscopy is a specialized technique that permits highly specific identification of specimens, in contrast to fluorescence spectroscopy with which analysis of arterial tissues generates spectra that are broad and featureless, with little difference seen between normal artery and atheroma. Various plaque types and the contributions of different arterial fluorophores were studied to determine if Raman spectroscopy could function as a potential guidance modality for laser angioplasty. Arterial specimens obtained at atherectomy and post mortem were studied in air and while immersed in blood. One hundred fifty-six Raman spectra were collected from arterial specimens and chromatographic samples of collagen, elastin, cholesterol, beta-carotene, and L-tryptophan. Analysis showed both fatty and fibrous atherosclerotic plaques to have characteristic spectral peaks at 1,002, 1,154, and 1,516 cm-1, while the Raman spectrum of normal vessel was featureless. Spectral peaks of beta-carotene were nearly identical to those of fatty plaque. The arterial fluorophores collagen, elastin, cholesterol, and L-tryptophan were non-contributory. The Raman spectrum of fatty plaque immersed in a blood field was also detectable, suggesting that this technique may be useful for in vivo plaque recognition.

Near-IR Fourier transform Raman spectroscopy in surgery and medicine: detection of renal stones and bladder cancer

Tissue diagnosis and characterization are critically important to the development and applications of laser-based therapeutic procedures in urology (viz., laser lithotripsy and bladder cancer treatment). Recently, we demonstrated for the first time that the new technique of near-infrared laser excited Fourier transform (FT)-Raman spectroscopy can readily differentiate various types of renal stones and bladder cancer from normal kidney/bladder tissues. It has thus become possible to develop an FT-Raman-based fiberoptic sensor for clinical use in laser lithotripsy and bladder cancer treatment. The future development of such a diagnostic modality will allow a surgeon/physician to take real-time Raman spectra of urinary calculi or cancerous tissue via a flexible fiberoptic probe.