Thyroid scintigram. Sensitivity with sodium pertechnetate Tc 99m and gamma camera with pinhole collimator

The emerging function and clinical significance of circRNAs in Thyroid Cancer and Autoimmune Thyroid Diseases

Thyroid cancer (TC) is one of the most common malignant tumors, with high morbidity and mortality rates worldwide. The incidence of TC, especially that of papillary thyroid carcinoma (PTC); has increased rapidly in recent decades. Autoimmune thyroid disease (AITD) is closely related to TC and has an estimated prevalence of 5%. Thus, it is becoming increasingly important to identify potential diagnostic biomarkers and therapeutic targets for TC and AITD. Circular RNAs (circRNAs) are a class of non-coding RNAs with covalently bonded circular structures that lack 5'-3' polarity and polyadenylated tails. Several circRNAs play crucial roles in the development of various diseases, including TC and AITD, and could be important new biomarkers and/or targets for the diagnosis and therapy of such disorders. Although there are four subtypes of TC, research on circRNA has largely focused on its connection to PTC. Therefore, this review mainly summarizes the relationships between circRNAs and PTC and AITD, including the molecular mechanisms underlying these relationships. In particular, the functions of “miRNA sponges” and their interactions with proteins and RNA are discussed. The possible targeting of circRNAs for the prevention, diagnosis, and treatment of TC and AITD is also described. CircRNAs could be potential biomarkers of TC and AITD, although validation will be required before they can be implemented in clinical practice.

Thyroid and parathyroid imaging

This article reviews the current roles of imaging in the diagnosis of thyroid and parathyroid disorders, with an emphasis on ultrasound evaluation. Imaging of the thyroid and parathyroid can be performed with nuclear medicine, ultrasound, CT, and MRI. Indications for thyroid and parathyroid imaging studies have recently changed. The availability of experienced endocrine surgeons, as well as the development of accurate laboratory tests, fine-needle aspiration (FNA) biopsy, and high-resolution ultrasound, have dramatically influenced the evaluation of thyroid and parathyroid disease. In patients with thyroid nodular disease, a clinical examination by an experienced clinician with appropriate lab values and palpation-guided FNA is the current diagnostic protocol of choice. Ultrasound evaluation of high-risk patients and ultrasound-guided FNA both augment this protocol when necessary. In patients with diffuse thyroid glandular disease, radionuclide imaging and color Doppler sonography both can be used for evaluation. When preoperative imaging is clinically necessary, sonography or scintigraphy can be used for parathyroid adenoma localization in patients with primary hyperparathyroidism. The recent development of technetium-99m sestamibi as a parathyroid imaging agent has improved the sensitivity of scintigraphy for parathyroid adenoma localization. Ultrasound and radionuclide imaging have also become valuable imaging techniques for parathyroid localization in patients with recurrent or persistent hyperparathyroidism.

Observer variation in the scintigraphic diagnosis of solitary cold thyroid lesions

In order to evaluate the reproducibility of the diagnosis of solitary cold thyroid lesions, two specialists in nuclear medicine and two specialists in endocrinology independently twice read 240 thyroid 99mTc pertechnetate scintigrams. No significant difference or interaction between the results obtained from the right and the left lobe was found. A solitary cold lesion was diagnosed in 100 of the 480 lobes; however, in only 30 did all four observers agree upon the diagnosis. Interobserver variation was determined by pairwise comparison of observers. The observed agreement was between 0.91 and 0.94. After adjusting for expected chance agreement, kappa values between 0.57 and 0.70 were found. Intraobserver variation was smaller than interobserver variation, revealing agreement rates of 0.93-0.96 and kappa values between 0.71 and 0.77. Agreement was related to large lesions, lesions located centrally in the lobe, and ovoid-shaped lesions. Clinicians should be aware to what extent they can rely on the information they use in their decisions. The considerable inconsistency in the evaluation of cold lesions on thyroid scintigrams should be taken into consideration, and calls in question the value of using thyroid scintigrams for deciding whether a patient should be referred for operation or biopsy.