Ultrastructural features of collagen in thyroid carcinoma tissue observed by polarization second harmonic generation microscopy

Danielle Tokarz,Virginijus Barzda,Brian C Wilson,Sylvia L Asa,Richard Cisek,Ahmad Golaraei

doi:10.1364/boe.6.003475

Abstract

Changes in collagen ultrastructure between malignant and normal human thyroid tissue were investigated ex vivo using polarization second harmonic generation (SHG) microscopy. The second-order nonlinear optical susceptibility tensor component ratio and the degree of linear polarization (DOLP) of the SHG signal were measured. The ratio values are related to the collagen ultrastructure, while DOLP indicates the relative amount of coherent signal and incoherent scattering of SHG. Increase in ratio values and decrease in DOLP were observed for tumor tissue compared to normal thyroid, indicating higher ultrastructural disorder in tumor collagen.

Highlights

Thyroid cancers are the most common malignancy of the endocrine organs [1] and the incidence rate of differentiated thyroid cancers has increased significantly over the past decade [2]
PIPO second harmonic generation (SHG) microscopy was used to investigate ultrastructural changes in collagen between follicles in non-tumorous thyroid tissue and follicular variant papillary thyroid carcinoma (FVPTC) as well as collagen found in the papillae of classical papillary thyroid carcinoma (cPTC)
Bright field microscopy images of the hematoxylin and eosin (H&E) stained tissue sections are shown in Fig. 1(a), 1(g), 1(m) and the corresponding areas imaged with PIPO SHG microscopy in Fig. 1(b), 1(h), 1(n) are indicated

Summary

Introduction

Thyroid cancers are the most common malignancy of the endocrine organs [1] and the incidence rate of differentiated thyroid cancers has increased significantly over the past decade [2]. Diagnosis of thyroid cancer is confirmed by visualizing stained thyroid tissue with brightfield microscopy. By applying polarization-sensitive measurements, the second-order nonlinear optical susceptibility tensor component ratio, χ(2)ZZZ’/χ(2)ZXX’, and the degree of linear polarization, DOLP, can be measured. These metrics provide additional information on the collagen ultrastructural characteristics that is complementary to the concentration and spatial distribution measures. Polarization-sensitive SHG microscopy has been previously applied to determine differences in normal and malignant breast tissue [8], models of ovarian cancer [9], and non-small cell lung carcinoma [7]. We use polarization-in, polarization-out (PIPO) SHG microscopy to investigate classical papillary thyroid carcinoma (cPTC) and follicular variant papillary thyroid carcinoma (FVPTC)

Methods

Results

Conclusion