Elastic Moduli of Thyroid Tissues under Compression

Abstract

The aim of this study was to evaluate the elastic moduli of thyroid tissues under uniaxial compression and to establish the biomechanical fundamentals for accurate interpretation of thyroid elastograms. A total of 67 thyroid samples (24 samples of normal thyroid tissue, 2 samples of thyroid tissue with chronic thyroiditis, 12 samples of adenomatous goiter lesions and 7 samples of follicular adenoma, 19 samples of papillary adenocarcinoma (PAC) and 3 samples of follicular adenocarcinoma (FAC)) obtained from 36 patients who had received thyroid surgery were subjected to biomechanical testing within three hours after surgical resection at precompression strains of 5%, 10% and 20% and applied strains of 1%, 2%, 5% and 10% of sample height. As a result, the mean values of elastic moduli for benign thyroid lesions at all examined precompression levels were significantly higher than those for normal thyroid tissue measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, benign thyroid nodule samples were 1.7 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 2.4 times. Stiffness of PAC samples was significantly higher than those for normal thyroid tissue and benign thyroid tumors measured at the same load (p<0.01). At low precompression (5%) and compression (1-2%) levels, PAC samples were 5.0 times harder than normal thyroid tissue. At high precompression (20%) and compression (10%) levels, this difference increased to 17.7 times. In contrast, samples of FAC were much softer than PAC (p<0.05) and were comparable in stiffness to normal thyroid tissues. The significant differences in the stiffness between normal thyroid tissue and thyroid tumors may provide useful information for accurate interpretation of thyroid elastograms.

Ultrasound Thyroid Elastography Using Carotid Artery Pulsation

“…This is consistent with the measurements of elasticity moduli of excised thyroid tissues using a mechanical device. 5 For the remaining nodule that was diagnosed as a benign fibrotic nodule, the TSI was 29.4, indicating that the fibrosis contributed to increasing the stiffness. Nodules with a large amount of fibrosis could result in a false-positive diagnosis of papillary carcinoma on the basis of elastography.…”

“…The TSI of the superior nodule was 41.2, which was much higher than the 16.6 for the inferior nodule. Because papillary carcinoma tends to be stiffer than benign nodules, 5,19 one may suspect that the superior hard nodule has a higher probability of papillary carcinoma than the inferior soft nodule. The histologic examination ( Figure 7, c and d) reveals that the superior nodule does have papillary carcinoma, whereas the inferior nodule is a benign colloid nodule.…”

“…In this study, the TSI was computed from a region with the lowest strain (stiffest region) inside a thyroid nodule and then correlated with the histopathologic diagnosis. Because papillary carcinoma is known to be stiffer than other thyroid tissues, 5,19 the TSI from the stiff part of the thyroid may be useful in detecting papillary carcinoma. The size of the region used for computing TSI was 2 × 2 mm.…”

“…4 Finger palpation, searching for abnormally stiff tissues, has been one of the primary tools for detecting thyroid nodules. Lyshchik et al 5 measured stiffness (elastic modulus) of excised thyroid tissues from 36 patients who had undergone thyroidectomy. They found that papillary car-cinoma, the most prevalent thyroid cancer (81% of all thyroid cancer cases 1 ), is stiffer than normal thyroid tissue and benign thyroid lesions, which indicates that thyroid tissue stiffness may be used for differential diagnosis of thyroid nodules.…”

Biocompatible Tissue Scaffold Compliance Promotes Salivary Gland Morphogenesis and Differentiation

“…S1B), while the 19.66 kPa gels have an elastic moduli similar to reported moduli for many salivarygland-derived and other glandular cancers, respectively. [55][56][57] To assay whether branching morphogenesis of embryonic salivary glands can be impacted by the stiffness of the external environment, standard E13 SMG organ explants were adapted to culture on the surfaces of the PA gels having elastic moduli of 0.48, 3.24, and 19.66 kPa with covalently attached fibronectin. Brightfield images of organ explants cultured on these gels were captured every 24 h for up to 96 h. When the E13 embryonic mSMG organ explants were cultured on PA gels for 96 h, they continued to undergo branching morphogenesis on the 0.48 and 3.24 kPa gels with numerous, well-defined buds detected at 72 and 96 h, similar to the branching pattern of glands grown in vivo (Fig.…”