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.

Broadband (550–1350 nm) diffuse optical characterization of thyroid chromophores

“…In literature, various optical techniques have been explored to diagnose thyroid related pathologies, such as diffuse optical spectroscopy 5 , 6 , diffuse correlation spectroscopy 5 , static and time-resolved fluorescence spectroscopy 7 , 8 , optical biopsy using Raman spectroscopy 9 , 10 , Fourier transform infrared spectroscopy 11 , optical coherence tomography 12 , elastic light-scattering spectroscopy 13 and two-photon excited fluorescence spectroscopy 14 . Among these techniques, diffuse optical approaches are non-invasive in nature and have the capability to investigate both chemical and functional properties of the organ.…”

Time-resolved fluorescence spectroscopy for clinical diagnosis of actinic cheilitis

“…They have already been used for melanoma [20], basal cell carcinoma [21], in situ oral carcinoma [22] and skin photoaging [23]. Small fiber dimension allows to use them also for non-invasive inspection in hollow core organs as colon [24], thyroid [25], or vascular systems [26,27]. The satisfactory sensitivity and specificity values achieved for discrimination of diseased tissue have promoted the use of these systems to assist medical doctor during surgeries, such as in the case of the brain [28] and oral cancer [22].…”

The use of fluorescence lifetime technology in benign and malignant thyroid tissues

“…Brandao et al ., 26 performed fluorescence lifetime measurements on healthy, benign and malignant thyroid surgical specimens. Fresh thyroid specimens were excited at 285–300 nm light, and fluorescent emission peaks were observed at 340 nm and 450 nm.…”