Diagnóstico de lesões da tireóide pela espectroscopia de absorção no infravermelho por transformada de Fourier-FTIR / Thyroid lesions diagnosis by fourier transformed infrared absorption spectroscopy (FTIR)

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

11/12/2009

RESUMO

Thyroid nodules are a common disorder, with 4-7% of incidence in the Brazilian population. Although the fine needle aspiration (FNA) is an accurate method for thyroid tumors diagnosis, the discrimination between benign and malignant neoplasm is currently not possible in some cases with high incidence of false negative diagnosis, leading to a surgical intervention due to the risk of carcinomas. The aim of this study was to verify if the Fourier Transform infrared spectroscopy (FTIR) can contribute to the diagnosis of thyroid carcinomas and goiters, using samples of tissue and aspirates. Samples of FNA, homogenates and tissues of thyroid nodules with histopathological diagnosis were obtained and prepared for FTIR spectroscopy analysis. The FNA and homogenates samples were measured by -FTIR (between 950 1750 cm-1), at a nominal resolution of 4 cm-1 and 120 scans). Tissue samples were analized directly by ATR-FTIR technique, at a resolution 2 cm-1, with 60 scans in the same region. All spectra were corrected by the baseline and normalized by amides area (1550-1640 cm-1) in order to minimize variations of sample homogeneity. Then, spectra were converted into second derivatives using the Savitzk-Golay algorithm with a 13 points window. The Ward\ s minimum variance algorithm and Euclidean distances among the points were used for cluster analysis. Some FNA samples showed complex spectral pattern. All samples showed some cell pellets and large amount of hormone, represented by the bands of 1545 and 1655 cm-1. Bands in 1409, 1412, 1414, 1578 and 1579 cm-1 were also found, indicating possible presence of sugar, DNA, citric acid or metabolic products. In this study, it was obtained an excellent separation between goiter and malign lesion for the samples of tissues, with 100% of specificity in specific cluster and 67% sensibility and 50 of specificity. In homogenate and FNA samples this sensibility and specificity were lower, because among these samples, it were included many types of thyroid lesions. To obtain a more precise diagnosis for FNA of follicular thyroid the sample size should be increased. The results of this study suggest that FTIR spectroscopy may be useful for discriminate thyroid carcinomas from goiters in tissue samples.

ASSUNTO(S)

biópsia óptica câncer de tireóide espectroscopia ftir ftir spectroscopy thyroid cancer

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