Incidental Finding of Squamous Cell Carcinoma on a 68Ga-DOTATATE PET Scan

Neuroendocrine tumors (NETs) are a relatively rare entity; however, the incidence and prevalence of these tumors are increasing, likely attributed to improved diagnostic accuracy. The diagnosis of suspected NETs is facilitated by clinical symptoms, laboratory test abnormalities such as elevated chromogranin-A, and other diagnostic modalities such as the use of computed tomography scans, magnetic resonance imaging scans, positron emission tomography (PET) scans, and biopsy. The expression of high levels of somatostatin receptors in NETs enables the use of a specialized PET scan using the radiolabeled somatostatin analogues 68Ga-DOTATATE. The sensitivity and specificity of 68Ga-DOTATATE PET is very high for the diagnosis of NETs, but the specificity decreases especially with no clear symptoms and with only borderline elevated tumor markers. We present a case of a suspected NET, which was initially diagnosed as a metastatic NET by virtue of a positive 68Ga-DOTATATE PET scan; however, on biopsy it was revealed to be a squamous cell carcinoma originating from the head and neck.

Development of hematologic toxicity with sequential treatment of Y90 followed by PRRT in five patients at single institution with metastatic neuroendocrine patients.

81 Background: In metastatic neuroendocrine tumors (NET) peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues (Lu-177-DOTATATE) and selective intra-arterial radio-therapy (SIRT) with Y-90-microspheres are increasingly used promising treatment options. Rarely patients have been treated with sequential use of both treatment modalities . Severe adverse effects are rare and mainly concern hematologic changes and development of prolonged cytopenias . There is no data about possible cumulative side effects particularly regarding hematologic toxicity in the case of sequential use of both treatments. Methods: 5 Patients with hepatic metastasized NET treated both with SIRT and PRRT during 2010 - 2019 were included. Average time interval between treatment of y90 and PRRT was 2.5 years. All of them were treated with y90 before PRRT. Average treatment with Y90 was 3 doses. Results: In the follow up Platelets (159 to 89), leukocytes (7.5 to 3.7) and hemoglobin (13 to 11.6 ) decreased significantly, LFTs, bilirubin and creatinine did not change significantly. No severe toxicity (Grade 3 or 4) was experienced. 80 % of the patients showed decreasing blood counts after the therapies and was prolonged for average of 9 months. Conclusions: In metastatic neuroendocrine tumors (NET) sequential treatment with peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin analogues (Lu-177-DOTATATE) after selective intra-arterial radio-therapy (SIRT) with Y-90-microspheres is possible and well tolerated except for hematological toxicity.

State of the Art and Recent Developments of Radiopharmaceuticals for Pancreatic Neuroendocrine Tumors Imaging

Background: Neuroendocrine Tumors (NETs) are relatively rare tumors, mainly originating from the digestive system, that tend to grow slowly and are often diagnosed when metastasised. Surgery is the sole curative option but is feasible only in a minority of patients. Among them, pancreatic neuroendocrine tumors (pancreatic NETs or pNETs) account for less than 5% of all pancreatic tumors. Viable therapeutic options include medical treatments such as biotherapies and more recently Peptide Receptor Radionuclide Therapies (PRRT) with radiolabeled somatostatin analogues. Molecular imaging, with main reference to PET/CT, has a major role in patients with pNETs. Objective: The overexpression of specific membrane receptors, as well as the ability of cells to take up amine precursors in NET, have been exploited for the development of specific targeting imaging agents. Methods: SPECT/CT and PET/CT with specific isotopes such as [68Ga]-1,4,7,10-tetra-azacyclododecane- N,N’,N’’,N’’’-tetra-acetic acid (DOTA)-somatostatin analogs, [18F]-FDG and [18F]-fluorodopa have been clinically explored. Results: To overcome the limitations of SSTR imaging, interesting improvements are connected with the availability of new radiotracers, activating with different mechanisms compared to somatostatin analogues, such as glucagon-like peptide 1 receptor (GLP-1 R) agonists or antagonists. Conclusion: This paper shows an overview of the RPs used so far in the imaging of pNETs with insight on potential new radiopharmaceuticals currently under clinical evaluation.

SPECT/CT with radiolabeled somatostatin analogues in the evaluation of systemic granulomatous infections

Objective: To evaluate SPECT/CT with radiolabeled somatostatin analogues (RSAs) in systemic granulomatous infections in comparison with gallium-67 (67Ga) citrate scintigraphy. Materials and Methods: We studied 28 patients with active systemic granulomatous infections, including tuberculosis, paracoccidioidomycosis, pneumocystosis, cryptococcosis, aspergillosis, leishmaniasis, infectious vasculitis, and an unspecified opportunistic infection. Of the 28 patients, 23 had started specific treatment before the study outset. All patients underwent whole-body SPECT/CT imaging: 7 after injection of 99mTc-EDDA-HYNIC-TOC, and 21 after injection of 111In-DTPA-octreotide. All patients also underwent 67Ga citrate imaging, except for one patient who died before the 67Ga was available. Results: In 20 of the 27 patients who underwent imaging with both tracers, 27 sites of active disease were detected by 67Ga citrate imaging and by SPECT/CT with an RSA. Both tracers had negative results in the other 7 patients. RSA uptake was visually lower than 67Ga uptake in 11 of the 20 patients with positive images and similar to 67Ga uptake in the other 9 patients. The only patient who did not undergo 67Ga scintigraphy underwent 99mTc-EDDA-HYNIC-TOC SPECT/CT-guided biopsy of a lung cavity with focal RSA uptake, which turned to be positive for aspergillosis. Conclusion: SPECT/CT with 99mTc-EDDA-HYNIC-TOC or 111In-DTPA-octreotide seems to be a good alternative to 67Ga citrate imaging for the evaluation of patients with systemic granulomatous disease.