Detection of cervical metastatic lymph nodes in papillary thyroid carcinoma by Fourier transform infrared spectroscopy.

BACKGROUND A previous study demonstrated that Fourier transform infrared (FTIR) spectroscopy can distinguish thyroid cancer from benign thyroid lesions. The aim of this study was to explore the use of FTIR for identifying metastatic lymph nodes of papillary thyroid cancer in vitro, and distinguishing between metastatic and non-metastatic tissue. METHODS Some 184 freshly removed cervical lymph nodes were obtained from 22 patients with papillary thyroid cancer undergoing thyroid surgery with lymph node dissection. Samples were measured by FTIR spectroscopy before being processed for histopathological diagnosis. The FTIR spectrum of each sample identified 13 bands from 1000 to 4000 cm(-1) . The peak position, intensity and full width at half maximum of each absorbent band were measured, and the relative intensity ratios were calculated. The FTIR spectra of metastatic lymph nodes were compared with those of non-metastatic nodes, and a linear discriminant analysis was performed based on these data. RESULTS Histopathological examination confirmed 61 metastatic and 123 non-metastatic lymph nodes. The FTIR parameters of metastatic and non-metastatic lymph nodes differed owing to the content or configuration alterations of nucleic acids, proteins, lipids and carbohydrates. The sensitivity for FTIR in diagnosing metastatic lymph nodes was 80·3 per cent, the specificity was 91·9 per cent and the accuracy was 88·0 per cent. CONCLUSION FTIR spectroscopy is a novel technique for detection of metastatic lymph nodes and may prove useful in surgery for papillary thyroid cancer.