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Autoimmune thyroid diseases (AITD) are a heterogeneous group of disorders. They include, in particular, Graves' disease and Hashimoto's thyroiditis with a wide range of different functional status ranging from subclinical biochemical abnormalities to severe hyperthyroidism or severe hypothyroidism respectively. Furthermore, other conditions more frequently infectious or drug related can cause an immune reaction in the thyroid tissue. In AITDs, positron emission tomography/computed tomography (PET/CT) does not play a primary role for disease diagnosis or management, but accidental findings can occur in both symptomatic and asymptomatic patients, and they should be recognized and well interpreted. A comprehensive literature search of the PubMed databases was conducted to identify papers (systematic review, prospective and retrospective study, case report) evaluating the role of PET/CT in thyroid autoimmune diseases. Thyroid diffuse uptake of 18F-fluoro-2-deoxy-2-d-glucose ([18F]FDG) has been shown to be frequently associated with AITDs, but also with immune-induced thyroid disorders related to SARS-CoV-2 or immunotherapy, while malignant lesions more often have a focal aspect. Other radiopharmaceuticals as [68Ga]-DOTA-peptides, [68Ga]-fibroblast activation protein inhibitors (FAPIs) and [68Ga]-prostate specific membrane antigen ([68Ga]-PSMA) showed similar findings. In conclusion, PET/CT scan in AITDs does not play a primary role in the diagnosis, but the occasional finding of a thyroid uptake must always be described in the report and possibly investigated for a better patient's management.

Background: Surgery is the elective treatment for cervical relapse from differentiated thyroid cancer (DTC) but it is technically challenging, with risk of failure and morbidity. We explored the feasibility and the efficacy of radioguided occult lesion localization (ROLL) with intratumoral 99mTc radiolabeled human albumin macroaggregates ([99mTc]MAA) injection in this setting., Methods: Fifteen patients who underwent ROLL by ultrasonography (US)-guided intratumoral injection of [99mTc]MAA between December 2013 and October 2016 for DTC recurrence were considered for this study. A hand-held gamma-probe was employed for intrasurgical lesion detection. Mini-invasive ROLL-guided excision for soft tissue recurrence and ROLL-assisted modified radical neck dissection for lymph-node metastases were performed respectively., Results: DTC recurrence was located in loco-regional lymph-nodes (N.=8 patients) and in thyroid bed (N.=7 patients). A total of 27 lesions was identified and injected before surgery. On a total of 124 lesions resected, histology showed 38 DTC metastases. In particular, 26 out of 27 lesions injected with [99mTc]MAA were correctly detected intra-operatively and resected without surgical complications. Ten patients received subsequent radioactive iodine (RAI) treatment to verify the complete recurrence resection. At a median follow-up of 16 months patients were classified in complete response (N.=4), biochemical incomplete response (N.=3), indeterminate response (N.=1) with no evidence of structural disease. The remaining 7 patients were classified as structural incomplete response for cervical persistent disease (N.=2), for cervical recurrence (N.=2) and for both cervical and lung metastases progression (N.=3)., Conclusions: ROLL is a simple and safe procedure in the surgical management of DTC loco-regional relapse.

The 2013/59 EURATOM directive defines all nuclear medicine applications for therapeutic purpose as a form of radiotherapy and underlines the need of both justification and optimization of these procedures, including radioactive iodine therapy (RAIT) with [131I] for metastatic differentiated thyroid cancer (DTC). In metastatic DTC, optimal activity to be administered to achieve the best response rate with limited toxicity is still a matter of debate and international guidelines do not provide univocal recommendations on the preferable use of empiric versus a dosimetry-based approach in these patients. The purpose of this literature review is to describe the possible limits of dosimetry in RAIT planning according to methodological aspects, tumoral heterogeneity and to report clinical data on the impact on patients' outcome of different approaches. Due to the lack of standardized dosimetry protocols and clinical data assessing the superiority of a dosimetry-based vs an empiric approach in these patients, there is a need of standardisation and prospective, properly conducted studies to validate and to assess the best approach.

Introduction: Interventional oncology locoregional therapies are validated treatment modalities for primary and secondary tumors in liver, lung, kidney and bone. At this time, there is no accordance in the choice of imaging modality to assess treatment response. Morphological imaging and RECIST 1.1 criteria based on size variation are limited by several critical points. On the other hand the role of functional imaging, in particular by [18F]-fluorodeoxyglucose ([18F]-FDG) positron emission tomography (PET), in both staging and response evaluation of locoregional treatments remains unclear because of the heterogeneous nature of available data. The aim of this paper was to summarize the available literature illustrating the state of art of metabolic evaluation of response after locoregional therapies in the three major organs of interest: liver, lung and bone., Evidence Acquisition: Medline database was searched for relevant original paper evaluating the role of [18F]-FDG PET in interventional oncology treatment published up to June 2017 excluding case reports., Evidence Synthesis: Finally 41 studies papers evaluating the role of [18F]-FDG PET in both staging and in response evaluation of locoregional treatments focused on liver tumoral lesions (N.=29), on lung lesions (N.=10) and on bone lesions (N.=2) were considered for this review., Conclusions: PET/CT appears to perform well in the assessment of response to interventional therapies compared to conventional imaging, not only in terms of response evaluation but also as a possible prognostic tool. Nevertheless further prospective, homogenous studies are required to confirm these data, in particular for lung and bone lesions.