Clare Fowler

Raman spectroscopy of parathyroid tissue pathology.

Primary hyperparathyroidism (HPT) in 80% of patients is due to a solitary parathyroid adenoma, while in 20% multigland pathology exists, usually hyperplasia [Scott-Coombes, Surgery, 21(12):309–312, 2003]. Despite recent advances in minimally invasive parathyroidectomy, better preoperative localisation techniques and intraoperative parathyroid hormone (PTH) monitoring, a 4% failure rate [Grant CS, Thompson G, Farley D, Arch Surg, 140:47–479, 2005] persists making accurate differentiation between adenomas and hyperplasia of prime importance. We investigated the ability of Raman spectroscopy to accurately differentiate between parathyroid adenomas and hyperplasia. Raman spectra were measured at defined points on the parathyroid tissue sections using a bench-top microscopy system. Multivariate analysis of the spectra was carried out to construct a diagnostic algorithm correlating spectral results with the histopathological diagnosis. A total of 698 spectra were analysed. Principal-component (PCA)-fed linear discriminant analysis (LDA) used to construct a diagnostic algorithm. Detection sensitivity for parathyroid adenomas was 95% and hyperplasia was 93%. These preliminary results indicate that Raman spectroscopy is potentially an excellent tool to differentiate between parathyroid adenomas and hyperplasia.

FTIR of touch imprint cytology: A novel tissue diagnostic technique

Fourier transform infrared spectroscopic (FTIR) interrogation of biological tissues in real time has largely been a challenging proposition because of the strong absorption of mid-infrared light in water filled tissues. To enable sampling of tissues they must be sectioned and dried, which has time and resource implications. FTIR of touch imprint cytology (TIC) has been proposed to circumvent this problem. TIC is a well known histopathological method of rapidly analysing biological tissues. In this article we demonstrate the ability of FTIR of TIC to provide detailed spectra which can be used to differentiate various tissue pathologies. FTIR spectral profiles of TIC of lymph node and thyroid tissues differ visually when compared with TIC spectra of parathyroid tissue. The lymph node showed strong lipid spectral peaks at 1166cm(-1) and 1380cm(-1) including a very strong carbonyl-ester band at 1748cm(-1), and a strong methylene bending band (scissoring, at 1464cm(-1)). Smaller intensity protein peaks at 1547cm(-1) and 1659cm(-1) were also seen. The thyroid spectra, in addition to evident strong protein peaks at 1547cm(-1) and 1659cm(-1), also demonstrated possible nucleic acid signals at 1079cm(-1) and 1244cm(-1). The C-OH peak at 1037cm(-1) was attributed to carbohydrate signals. Parathyroid adenoma showed a marginal shift to lower wavenumbers with decreased amide I and II peak intensities when compared to hyperplasia. Nucleic acid peak positions at 1079cm(-1) and 1244cm(-1) were of higher intensity in adenomas compared to hyperplastic glands possibly demonstrating an increase in cell proliferation and growth. This study demonstrates the feasibility of cytoimprint FTIR for the intraoperative diagnosis of tissue during surgical neck exploration for the management of hyperparathyroidism. There is potential for the application of the technique in sentinel lymph node biopsy diagnosis and tumour margin evaluation.

Role of Fourier transform infrared spectroscopy (FTIR) in the diagnosis of parathyroid pathology

BACKGROUND With the advent of minimally invasive parathyroid surgery (MIPS) accurate pathological diagnosis to differentiate parathyroid adenomas from hyperplasia has become difficult for the pathologist. This is because now single glands are excised, guided by better preoperative localisation scans, while for an accurate pathological diagnosis, at least a two-gland biopsy is required. Ultimately, an accurate pathological diagnosis to establish the aetiology is essential for the management of hyperparathyroidism. To resolve this issue we evaluated the ability of FTIR to accurately differentiate between parathyroid adenoma and hyperplasia using their biochemical signatures. METHODS Samples of diseased glands were collected intraoperatively from consenting patients over a 1-year period. Sixteen glands were analysed - eight hyperplasias and eight adenomas. Samples were analysed using an infrared spectroscope and reflected the biochemical nature of the sample tissue. Spectra collected were subjected to both empirical and multivariate analytical techniques. RESULTS Empirical analysis highlighted differences in spectral protein peaks, with possibly additional subtle differences in nucleic acid spectra between the pathologies. A multivariate statistical predictive model demonstrated the sensitivity of FTIR for adenomas to be 93% and hyperplasia 93%, (88% on cross validation testing). CONCLUSIONS Thus, infrared spectroscopy is potentially an excellent tool to differentiate the two pathologies and could be a useful adjunct to the pathological diagnosis of single glands.

Benefits of introduction of Oncotype DX® testing

INTRODUCTION Decisions regarding adjuvant chemotherapy in women with oestrogen receptor positive, human epidermal growth factor receptor 2 negative, node negative, early invasive breast cancer are unclear. The Recurrence Score® (RS) from Oncotype DX® (ODX) testing guides decisions based on individual cancer genomics. The aim of this study was to evaluate the impact of introducing ODX results on adjuvant treatment decisions and its potential economic benefits. METHODS Patients offered the test were identified from the ODX requesting system. Information on reasons behind chemotherapy treatment decisions were collected from clinical letters and the pathology system. The Nottingham prognostic index (NPI) scores were calculated for each individual patient. RESULTS A total of 101 patients were identified as having undergone ODX testing over 21 months. The median age was 57 years (range: 41‐72 years), the median NPI was 3.70 (range: 3.40‐5.26) and the median RS was 17 (range: 0‐59). NPI did not predict the risk category. All of the patients in the high risk group, 35.1% in the intermediate risk group and 5.4% in the low risk group received chemotherapy. The majority of low risk patients who received chemotherapy made a decision prior to the ODX result. CONCLUSIONS In our unit, RS aided our decision making regarding adjuvant chemotherapy. Patients with a higher RS were more likely to receive chemotherapy. If NPI had been used alone, more women would have been offered chemotherapy. Good communication with patients prior to testing is important to ensure it is cost effective.