title: Fluorescence lifetime of normal, benign, and malignant thyroid tissues.
abstract: Fine-needle aspiration cytology is the standard technique to diagnose thyroid pathologies. However, this method results in a high percentage of inconclusive and false negatives. The use of time-resolved fluorescence techniques to detect biochemical composition and tissue structure alterations could help to develop a portable, minimally invasive, and nondestructive method to assist during surgical procedures. This study aimed to use fluorescence lifetimes to differentiate healthy and benign tissues from malignant thyroid tissue. The thyroid tissue was excited at 298-300 nm and the fluorescence decay registered at 340 and 450 nm. We observed fluorescence lifetimes at 340 nm emission of 0.80 ± 0.26 and 3.94 ± 0.47 ns for healthy tissue; 0.90 ± 0.24 and 4.05 ± 0.46 ns for benign lesions; and 1.21 ± 0.14 and 4.63 ± 0.25 ns for malignant lesions. For 450 nm emissions, we obtain lifetimes of 0.25 ± 0.18 and 3.99 ± 0.39 ns and for healthy tissue, 0.24 ± 0.17 and 4.20 ± 0.48 ns for benign lesions, 0.33 ± 0.32 and 4.55 ± 0.55 ns for malignant lesions. Employing analysis of variance, we differentiate malignant lesions from benign and healthy tissues. In addition, we use quadratic discriminant analysis to distinguish malignant from benign and healthy tissues with an accuracy of 76.1%, sensitivity of 74.7%, and specificity of 83.3%. These results indicate that time-resolved fluorescence can assist medical evaluation of thyroid pathologies during surgeries.
authors.affiliation: Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física. Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Mariana
authors.initials: M
authors.lastname: Brandao
authors.affiliation: Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmo, Otorrino e Cirurgia de Cabeça e Pescoço, Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Iwakura
authors.affiliation: Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmo, Otorrino e Cirurgia de Cabeça e Pescoço, Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Fagne
authors.initials: F
authors.lastname: Basilio
authors.affiliation: Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física. Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Kaique
authors.initials: K
authors.lastname: Haleplian
authors.affiliation: Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física. Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Amando
authors.initials: A
authors.lastname: Ito
authors.affiliation: Universidade de São Paulo, Faculdade de Medicina de Ribeirão Preto, Departamento de Oftalmo, Otorrino e Cirurgia de Cabeça e Pescoço, Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Luiz Carlos Conti
authors.initials: LC
authors.lastname: de Freitas
authors.affiliation: Universidade de São Paulo, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Departamento de Física. Avenue Bandeirantes 3900, Ribeirão Preto, São Paulo 14040-901, Brazil.
authors.forename: Luciano
authors.initials: L
authors.lastname: Bachmann
mesh_terms: D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D061848:Optical Imaging / Q000379:methods*; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013961:Thyroid Gland / Q000737:chemistry*; D013964:Thyroid Neoplasms / Q000737:chemistry*