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La valutazione della risposta al trattamento con inibitori della tirosin-chinasi in pazienti con carcinoma tiroideo è argomento ampiamente dibattuto; negli ultimi anni la PET/CT sta dimostrando il suo ruolo fondamentale, in quanto la risposta metabolica al trattamento è spesso più precoce di quella morfologica, soprattutto in caso di utilizzo di farmaci citostatici. Questa rassegna ha lo scopo di riassumere le evidenze scientifiche sull’argomento.

Purpose: Medullary thyroid carcinoma (MTC) originates from thyroid parafollicular C-cells and represents <5% of all thyroid cancers. Serum Calcitonin (CTn) is considered the most sensitive marker of persistent or recurrent disease and is measured in association to CEA. According to the American Thyroid Association (ATA) guidelines, following initial surgery when CTn level remains below 150 pg/mL, follow-up may rely on repeated serum marker determinations and on neck ultrasonography (US). When CTn level exceeds 150 pg/ml, additional imaging is required. In this review, we provide an overview of available imaging tools to monitor MTC course and propose an effective imaging strategy for MTC patients according to their clinical situation. Methods: A literature search focusing on available imaging tools to monitor MTC provided the currently available information for this review. Recent evidence-based reports and reviews were considered as priority over older evidence. Results: For MTC patients with detectable CTn levels and disease recurrence, PET/CT imaging with 18F-DOPA or 68Ga-DOTA-peptides present the best sensitivity for lesion detection. 18F FDG PET/CT represents a prognostic tool and is useful in case of aggressive disease. Neck ultrasound, chest CT scan and MRI of the liver and of the axial skeleton represent complementary techniques. Beyond the diagnostic accuracy, the clinical impact of imaging is variable according to different disease settings and tumor marker levels. Finally, other applications of imaging such as response to focal and systemic treatments and new promising PET tracers should be further investigated. Conclusion: The role of imaging in MTC patients improved, especially with the use of 18F-DOPA PET/CT that provides high quality diagnostic images. However, the impact on therapeutic management should be further evaluated in the different disease settings and in proper prospective trials.

Purpose: Aim of our study was to search for variables associated with worse outcomes in patients treated with radioactive iodine (RAI) for hyperthyroidism by a dosimetric-based approach. Methods: Four hundred twenty-four patients with hyperthyroidism related to Toxic Multinodular Goiter (TMG; n= 213), Grave’s disease (GD; n= 150) and toxic adenoma (TA; n= 61) treated with RAI between 2000 and 2018 and with at least 12 months follow-up were retrospectively evaluated. Association between outcomes (response vs. no response) at 6 and 12 months and baseline TSH values, anti-thyroid drugs (ATD) duration and posology, RAI absorbed dose and dimensional reduction of target mass at ultrasound was evaluated by Mann–Whitney test. Risk factors for response vs. no-response were analysed by binary logistic regression model. Results: Overall response rate was 78.7 and 83% at 6 and 12 months, respectively. Both at 6 and 12 months higher TSH baseline values (p< 0.001), lower ATD duration (p= 0.004 and p= 0.043), lower ATD posology (p= 0.014 and p= 0.005), and lower dose to target (DT) (327 vs. 373 Gy, p= 0.003) were associated to response. Longer ATD duration and higher ATD posology were independent risk factors for no response at 6 and 12 months in GD and TMG, with no response at 6 months in TA subgroups. Conclusions: Low TSH levels, longer duration and higher posology of ATD were associated with worse response to RAI. These data confirm that RAI therapy should be considered earlier in patients’ management to allow better outcome and avoid ATD toxicity.

Prostate-specific membrane antigen (PSMA) is a transmembrane enzyme also known as folate hydrolase 1 highly expressed by prostate cancer (PCa) cells. However, PSMA overexpression by tumor-associated neovasculature of a variety of solid tumors, including glioblastoma (GBM), has also been proven. This clinical case reports about a 67-year-old man with a history of PCa who underwent radical surgery for GBM and performed a 68Ga-PSMA-11 PET/CT to restage PCa. PET imaging showed PSMA uptake in GBM residual disease after surgery. This finding suggests a possible role of PSMA inhibitors as diagnostic and therapeutic agents in patients affected by GBM.

We present a rare case of a 42-year-old man with a long history of von Hippel–Lindau disease that was scanned with 68Ga-DOTA-TOC PET/CT for suspicion of disease relapse. 68Ga-DOTA-TOC imaging demonstrated increased DOTA-TOC uptake in pancreas tail and intramedullary and extramedullary spinal hemangioblastomas, only some of which have already been highlighted at MRI examination. This case illustrates the significant role the 68Ga-labeled somatostatin receptor analogs PET/CT in the management of the von Hippel–Lindau disease.