Introduction Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration. Methods Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT. Conclusion These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Introduction : During the COVID-19 pandemic thyroid gland alteration/dysfunction has been emerged as a possible endocrine complication. The present review is focused on inflammatory and autoimmune thyroid complications triggered by SARS-CoV-2 infection by searching through databases like MEDLINE and Scopus up to April 2021. Areas covered : Beside the occurrence of ‘non-thyroidal illness’ in severe clinical conditions, alterations of thyroid function and structure may occur during COVID-19 as a consequence of either direct or indirect effects of SARS-CoV-2 infection on the gland. On the one hand, SARS-CoV-2 uses ACE2 as a receptor to infect the host cells and ACE2 is highly expressed by follicular thyroid cells. On the other hand, COVID-19 is associated with a systemic inflammatory and immune response, involving Th1/Th17/Th2 lymphocytes and proinflammatory cytokines, which resembles the immune activation that occurs in immune-mediated thyroid diseases. COVID-19-related thyroid disorders include destructive thyroiditis and onset or relapse of autoimmune thyroid disorders, leading to a broad spectrum of thyroid dysfunction ranging from thyrotoxicosis to hypothyroidism, that may worsen COVID-19 clinical course and affect prognosis. Expert opinion : Physicians should be aware of the possible occurrence of thyroid dysfunction during and after SARS-CoV-2 infection. Further longitudinal studies are warranted to evaluate potential long-term sequelae.

Purpose Currently, there is an increasing interest regarding the impact of COVID-19 on the thyroid function. As several recent reports have described the onset of thyroid dysfunction in patients diagnosed with COVID-19, we performed a systematic review to assess the prevalence of thyroid dysfunction in patients with COVID-19 as this information could be clinically relevant for the management of these patients. Methods A comprehensive computer literature search using PubMed/Medline and Cochrane databases was performed until November 14, 2020 to search original articles evaluating thyroid dysfunction in COVID-19 patients. Information about thyroid dysfunction assessed by thyroid function test was retrieved by the eligible articles. Qualitative analysis (systematic review) only was performed whether a significant heterogeneity of data was detected. Results Seven studies including 1237 patients with COVID-19 were included. A significant heterogeneity across the studies was found. Most COVID-19 patients were euthyroid with TSH levels in the normal range (from 44 to 94% of the COVID-19 patients assessed in the included studies). The prevalence of thyroid dysfunction in COVID-19 patients (defined as abnormal thyroid function tests) largely varies among the included studies between 13 and 64% of COVID-19 patients as well as clinical presentation. A positive correlation between thyroid dysfunction and clinical severity of COVID-19 was reported. Conclusion Literature data show that thyroid dysfunction is present in a significant percentage of patients with COVID-19. Assessment of thyroid function may be considered in symptomatic COVID-19 patients to have a baseline before introducing thyroid-interfering drugs and those requiring high-intensity care. Further, well-designed studies are needed to better elucidate the impact of COVID-19 on thyroid function and inform thyroid function testing and thyroid dysfunction management in COVID-19 patients.

Parathyroid imaging is essential for the detection and localization of hyperfunctioning parathyroid tissue in patients with primary hyperparathyroidism (phPT). Surgical treatment of phPT mainly consists of minimally invasive parathyroidectomy (MiP), as a single adenoma represents the most common cause of this endocrine disorder. Successful surgery requires an experienced surgeon and relies on the correct preoperative detection and localization of hyperfunctioning parathyroid glands. failure to preoperatively identify the culprit parathyroid gland by imaging may entail a more invasive surgical approach, including bilateral open neck exploration, with higher morbidity compared to minimally invasive parathyroidectomy. Parathyroid imaging may be also useful before surgery in case of secondary hyperparathyroidism (shPT) or hereditary disorders (MeN 1, 2, 4) as it enables correct localization of typically located parathyroid glands, detection of ectopic as well as supernumerary glands. it is now accepted by most surgeons experienced in parathyroid surgery that preoperative imaging plays a key role in their patients' management. recently, the european association of Nuclear Medicine (eaNM) issued an updated version of its guidelines on parathyroid imaging. its aim is to precise the role and the advantages and drawbacks of the various imaging modalities proposed or well established in the preoperative imaging strategy. it also aims to favor high performance in indicating, performing, and interpreting those examinations. The objective of the present article is to offer a summary of those recent eaNM guidelines and their originality among other guidelines in this domain issued by societies of nuclear medicine physicians or other disciplines.

Molecular imaging plays an important role in the evaluation and management of different thyroid cancer histotypes. The existing risk stratification models can be refined, by incorporation of tumor-specific molecular markers that have theranostic power, to optimize patient-specific (individualized) treatment decisions. Molecular imaging with varying radioisotopes of iodine (i.e., 131I, 123I, 124I) is an indispensable component of dynamic and theragnostic risk stratification of differentiated carcinoma (DTC) while [18F]F-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) helps in addressing disease aggressiveness, detects distant metastases, and risk-stratifies patients with radioiodine-refractory DTC, poorly differentiated and anaplastic thyroid cancers. For medullary thyroid cancer (MTC), a neuroendocrine tumor derived from thyroid C-cells, [18F]F-dihydroxyphenylalanine (6-[18F]FDOPA) PET/CT and/or [18F]FDG PET/CT can be used dependent on serum markers levels and kinetics. In addition to radioiodine therapy for DTC, some theragnostic approaches are promising for metastatic MTC as well. Moreover, new redifferentiation strategies are now available to restore uptake in radioiodine-refractory DTC while new theragnostic approaches showed promising preliminary results for advanced and aggressive forms of follicular-cell derived thyroid cancers (i.e., peptide receptor radiotherapy). In order to help clinicians put the role of molecular imaging into perspective, the appropriate role and emerging opportunities for molecular imaging and theragnostics in thyroid cancer are discussed in our present review.