PET and PET/CT imaging in thyroid and adrenal diseases: an update

Lutathera® Orphans: State of the Art and Future Application of Radioligand Therapy with 177Lu-DOTATATE

Lutathera® is the first EMA- and FDA-approved radiopharmaceutical for radioligand therapy (RLT). Currently, on the legacy of the NETTER1 trial, only adult patients with progressive unresectable somatostatin receptor (SSTR) positive gastroenteropancreatic (GEP) neuroendocrine neoplasms (NET) can be treated with Lutathera®. Conversely, patients with SSTR-positive disease arising from outside the gastroenteric region do not currently have access to Lutathera® treatment despite several papers in the literature reporting the effectiveness and safety of RLT in these settings. Moreover, patients with well-differentiated G3 GEP-NET are also still “Lutathera orphans”, and retreatment with RLT in patients with disease relapse is currently not approved. The aim of this critical review is to summarize current literature evidence assessing the role of Lutathera® outside the approved indications. Moreover, ongoing clinical trials evaluating new possible applications of Lutathera® will be considered and discussed to provide an updated picture of future investigations.

Performance of 18F-FDG PET/CT in Selecting Thyroid Nodules with Indeterminate Fine-Needle Aspiration Cytology for Surgery. A Systematic Review and a Meta-Analysis

Thyroid nodules with indeterminate fine-needle aspiration cytology (FNA) represent a major challenge in clinical practice. We conducted a systematic review and meta-analysis evaluating the ability of hybrid imaging using fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) to appropriately select these nodules for surgery. PubMed, CENTRAL, Scopus, and Web of Science were searched until July 2019. Original articles reporting data on the performance of ¹⁸F-FDG PET/CT in thyroid nodules with indeterminate FNA were included. Summary operating points including 95% confidence interval values (95% CI) were estimated using a random-effects model. Out of 786 retrieved papers, eight studies evaluating 104 malignant and 327 benign thyroid nodules were included. The pooled positive and negative likelihood ratios (LR+ and LR-) and diagnostic odds ratio (DOR) of ¹⁸F-FDG PET/CT were 1.7 (95% CI: 1.4-2.0), 0.4 (95% CI: 0.2-0.7), and 3.5 (95% CI: 1.7-7.1), respectively. No heterogeneity was found for LR+ and DOR. In patients with thyroid nodules with indeterminate FNA, ¹⁸F-FDG PET/CT has a moderate ability to correctly discriminate malignant from benign lesions and could represent a reliable option to reduce unnecessary diagnostic surgeries. However, further studies using standardized criteria for interpretation are needed to confirm the reproducibility of these findings.

Increased F-FDG Uptake in Bilateral Gynecomastia Secondary to Feminizing Adrenal Tumor: A Rare Case Report and Review of Literature

A 21 year old male who presented with painful enlargement of both the breasts and a hyperestrogenic state, was found to harbor a heterogeneous mass arising from the right adrenal on contrast enhanced Computed Tomography abdomen. The mass was hypermetabolic with no regional, nodal or distant metastases on Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography /Computed Tomography examination. Notably, substantial tracer uptake was seen in bilateral gynecomastia. The patient underwent a right adrenalectomy with the histopathology report confirming adrenocortical carcinoma. This case demonstrates utility of FDG PET/CT in adrenocortical carcinoma. However, when interpreting FDG PET/CT as a staging tool in oncological male patients, one should consider gynecomastia as a possible cause for increased FDG uptake in the breast as it may lead to a false positive interpretation.

Surgical treatment of potentially primary malignant adrenal tumors: an unresolved issue

Although the great majority of incidentalomas are adrenocortical adenomas, a number of them, depending on the size and radiological characteristics of the lesions, will turn out to be carcinomas. These tumors may present as suspicious on initial evaluation and potentially malignant or malignant on histology. Adrenocortical carcinoma is a rare and aggressive malignancy with evolving diagnostic and therapeutic approaches. Laparoscopic surgery has become the gold standard for surgery of benign adrenal tumors. Despite the extensive experience gained in laparoscopic adrenalectomy, controversy still remains in the management of adrenal tumors with high suspicion or evidence of malignancy. The aim of this review is to update the existing information regarding the diagnostic approach and surgical management of suspicious and potentially malignant primary adrenal tumors.The interpretation of radiologic characteristics is a cornerstone in pre-operative assessment of large adrenal masses, since open surgery remains the preferred procedure when malignancy is suspected in large tumors with possible local invasion. Despite the improvement of imaging techniques, they lack sufficient accuracy to exclude primary malignancy in tumors from 4 cm to 10 cm in size. An initial laparoscopic approach can be used in this group of patients, but early conversion to open technique is mandatory if curative resection cannot be performed. Adrenal tumors >10 cm of malignant potential should be treated by the open approach from the start. Solitary adrenal metastasis from another primary malignancy is usually amenable to laparoscopic surgery. Patients with suspected adrenal cancer should be referred to tertiary centers that perform laparoscopic and open adrenal surgery with minimal morbidity and mortality.