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Removal of intrinsic brain tumors is a delicate process, where a high degree of specificity is required to remove all of the tumor tissue without damaging healthy brain. The accuracy of this process can be greatly enhanced by intraoperative guidance. Optical biopsies using Raman spectroscopy are a minimally invasive and lower-cost alternative to current guidance methods. A miniature Raman probe for performing optical biopsies of human brain tissue is presented. The probe allows sampling inside a conventional stereotactic brain biopsy system: a needle of length 200 mm and inner diameter of 1.8 mm. By employing a miniature standoff Raman design, the probe removes the need for any additional components to be inserted into the brain. Additionally, the probe achieves a very low internal silica background while maintaining good collection of Raman signal. To illustrate this, the probe is compared with a Raman probe that uses a pair of optical fibers for collection. The miniature stand-off Raman probe is shown to collect a comparable number of Raman scattered photons, but the Raman signal to background ratio is improved by a factor of five at Raman shifts below ∼500 cm-1. The probe's suitability for use on tissue is demonstrated by discriminating between different types of healthy porcine brain tissue. [ABSTRACT FROM AUTHOR]

Raman spectroscopy has shown considerable promise as a medical diagnostic tool. The technique is safe for use in vivo and is capable of rapid, objective assessment of neoplastic and inflammatory tissue enabling early diagnosis and targeted treatment. We review potential applications of Raman spectroscopy in the oesophagus, colon and breast where this new technology has the potential to revolutionise patient care. [ABSTRACT FROM AUTHOR]

The application of semi-supervised methodology to improve the classification performance of a Raman spectroscopic probe for the diagnosis of oesophageal cancer is described. It is well known that gold standard histopathology diagnosis can be highly subjective, particularly for diseases which have several stages, such as cancer. A ‘consensus’ pathology decision can be obtained to ensure a robust gold standard by obtaining a diagnosis from several experts and samples are then only included in standard classification models if they have been assigned the same pathology by all experts. This can result in a significant number of samples that are excluded from the analysis as no consensus was reached. In this work semi-supervised methodology was used to extend Principal Component Analysis followed by Linear Discriminant Analysis (PCA-LDA) to incorporate samples without consensus pathology when discriminating between benign and oesophageal cancer specimens measured using a Raman endoscopic probe ex vivo. We demonstrate that a fully semi-supervised approach improved sensitivity and specificity from 73% and 78% (PCA-LDA) to 78% and 84% (semi-supervised) for discriminating between intestinal metaplasia and dysplasia and from 44% and 66% (PCA-LDA) to 63% and 72% (semi-supervised) when discriminating between intestinal metaplasia and low grade dysplasia. [ABSTRACT FROM AUTHOR]

There are distinct challenges implicit to the development of minimally invasive endoscopic surgery for the eradication of early neoplasia in Barrett's oesophagus. Endoscopic resection and ablation of high-grade dysplasia and mucosal cancer offer alternative therapeutic options to those unsuitable or unwilling to contemplate radical surgical excision. It may also become the treatment of choice in the future. Technological developments enable the instantaneous and non-invasive diagnosis of microscopic tissue abnormalities in vivo. This is made possible by improving the level of information that can be obtained from the tissue. As well as the two-dimensional surface morphology image, which the traditional endoscope can view, we have used new techniques to enable structure at depth, using Optical Coherence Tomography, to be imaged in high resolution. Other advances, using Raman spectroscopy, enable the early endoscopic detection of biochemical and molecular changes in tissue that precede any changes in morphology, thus enabling earlier diagnosis of tissue abnormalities. This King James IV lecture details our recent work, to develop advanced imaging for the diagnosis of malignancy and pre-malignancy. After detection endoscopic photodynamic therapy and endoscopic mucosal resection can provide eradication of mucosal neoplasia. Following photodynamic therapy there was complete eradication of all high-grade dysplasia and intramucosal carcinoma in 40 of 42 patients with a maximum endoscopic follow-up period of 72 months. Following endoscopic resection of 95 patients, the mean survival for intramucosal adenocarcinoma and high-grade dysplasia was 40.6 and 60.8 months respectively. [ABSTRACT FROM AUTHOR]

Epithelial cancers, including those of the skin and cervix, are the most common type of cancers in humans. Many recent studies have attempted to use Raman spectroscopy to diagnose these cancers. In this paper, Raman spectral markers related to the temporal and spatial effects of cervical and skin cancers are examined through four separate but related studies. Results from a clinical cervix study show that previous disease has a significant effect on the Raman signatures of the cervix, which allow for near 100% classification for discriminating previous disease versus a true normal. A Raman microspectroscopy study showed that Raman can detect changes due to adjacent regions of dysplasia or HPV that cannot be detected histologically, while a clinical skin study showed that Raman spectra may be detecting malignancy associated changes in tissues surrounding nonmelanoma skin cancers. Finally, results of an organotypic raft culture study provided support for both the skin and the in vitro cervix results. These studies add to the growing body of evidence that optical spectroscopy, in this case Raman spectral markers, can be used to detect subtle temporal and spatial effects in tissue near cancerous sites that go otherwise undetected by conventional histology. [ABSTRACT FROM AUTHOR]