Paul Crow

Raman spectroscopy for identification of epithelial cancers

There is a real need for improvements in cancer detection. Significant problems are encountered when utilising the gold standard of excisional biopsy combined with histopathology. This can include missed lesions, perforation and high levels of inter- and intra-observer discrepancies. The clinical requirements for an objective, non-invasive real time probe for accurate and repeatable measurement of tissue pathological state are overwhelming. This study has evaluated the potential for Raman spectroscopy to achieve this goal. The technique measures the molecular specific inelastic scattering of laser light within tissue, thus enabling the analysis of biochemical changes that precede and accompany disease processes. Initial work has been carried out to optimise a commercially available Raman microspectrometer for tissue measurements; to target potential malignancies with a clinical need for diagnostic improvements (oesophagus. colon, breast, andd prostate) and to build and test spectral libraries and prediction algorithms for tissue types and pathologies. This study has followed rigorous sample collection protocols and histopathological analysis using a board of expert pathologists. Only the data from samples with full agreement of a homogeneous pathology have been used to construct a training data set of Raman spectra. Measurements of tissue specimens from the full spectrum of different pathological groups found in each tissue have been made. Diagnostic predictive models have been constructed and optimised using multivariate analysis techniques. They have been tested using cross-validation or leave-one-out and demonstrated high levels of discrimination between pathology groups (greater than 90% sensitivity and specificity for all tissues). However larger sample numbers are required for further evaluation. The discussions outline the likely work required for successful implementation of in vivo Raman detection of early malignancies.

The use of Raman spectroscopy to differentiate between different prostatic adenocarcinoma cell lines.

Raman spectroscopy (RS) is an optical technique that provides an objective method of pathological diagnosis based on the molecular composition of tissue. Studies have shown that the technique can accurately identify and grade prostatic adenocarcinoma (CaP) in vitro. This study aimed to determine whether RS was able to differentiate between CaP cell lines of varying degrees of biological aggressiveness. Raman spectra were measured from two well-differentiated, androgen-sensitive cell lines (LNCaP and PCa 2b) and two poorly differentiated, androgen-insensitive cell lines (DU145 and PC 3). Principal component analysis was used to study the molecular differences that exist between cell lines and, in conjunction with linear discriminant analysis, was applied to 200 spectra to construct a diagnostic algorithm capable of differentiating between the different cell lines. The algorithm was able to identify the cell line of each individual cell with an overall sensitivity of 98% and a specificity of 99%. The results further demonstrate the ability of RS to differentiate between CaP samples of varying biological aggressiveness. RS shows promise for application in the diagnosis and grading of CaP in clinical practise as well as providing molecular information on CaP samples in a research setting.

The use of Raman spectroscopy to identify and grade prostatic adenocarcinoma in vitro.

Raman spectroscopy is an optical technique, which provides a measure of the molecular composition of tissue. Raman spectra were recorded in vitro from both benign and malignant prostate biopsies, and used to construct a diagnostic algorithm. The algorithm was able to correctly identify each pathological group studied with an overall accuracy of 89%. The technique shows promise as a method for objectively grading prostate cancer.

The use of Raman spectroscopy to identify and characterize transitional cell carcinoma in vitro

To determine whether Raman spectroscopy can be used to differentiate between normal, inflammatory and malignant bladder pathologies in vitro, and secondly if it can used to grade and stage transitional cell carcinoma (TCC).

Optical diagnostics in urology: current applications and future prospects

Optical diagnostic techniques have the potential to improve on traditional methods in various ways. Some techniques objectively analyse the data generated, and therefore show potential in reducing the variation in reporting. Other techniques show potential for real-time application via minimally invasive routes. This would preclude the absolute need for tissue removal and provide the medical practitioner with the information required to immediately proceed to definitive treatment. This concept has been widely termed ‘the optical biopsy’, although some authors think this an unhelpful term, as biopsy implies tissue removal. The ‘holy grail’ in optical diagnostics has been to develop a technique capable of reliably detecting malignant change at a stage early enough to allow local ablative treatment and avoid more extensive surgery.

Urological applications of Raman spectroscopy for improved malignant diagnostics

The incidence of both prostate and bladder cancer is high; prostate cancer being the most frequently diagnosed non-cutaneous cancer affecting Western men. At present the gold standard for diagnosis of pathologies within the bladder and the prostate gland is by means of histological examination of biopsies. This is a subjective means of examining tissue and has an element of both inter and intra-observer variability. A large number of specimens have been collected and analysed using both a NIR-Raman spectrometer and histopathology with H&E staining. Multivariate spectral prediction models have been constructed and tested. An evaluation of misclassification cost models and the use of cancer staging data to train the models has been made.