68Ga-DOTATATE and 18F-FDG PET/CT in Paraganglioma and Pheochromocytoma: utility, patterns and heterogeneity

Abstract

BackgroundPheochromocytomas (PCC) and paragangliomas (PGL) are neuroendocrine tumours arising from pluripotent neural crest stem cells and are associated with neurons of the autonomic nervous system. PCCs/PGLs are often hereditary and multifocal, and their biologic behaviour and metabolic activity vary making imaging of these tumours challenging. The imaging gold standard has been I-123 MIBG complemented by CT or MRI. PGLs being neuroendocrine tumours express somatostatin receptors enabling imaging with Ga-68 DOTA-coupled peptides such as DOTATATE. Imaging with F-18 FDG also provides additional information regarding metabolic activity and biologic aggressiveness of these tumours, or, in some situations, reflecting metabolic reprogramming of these tumours. We report our experience using both Ga-68 DOTATATE and F-18 FDG PET/CT imaging in patients with PGLs and PCCs.MethodsThis was a retrospective review of 23 patients with proven PGL/PCC who underwent both DOTATATE and FDG PET/CT. Seven patients also had I-123 MIBG SPECT/CT and 1 patient had I-124 MIBG PET/CT. Lesional intensity and patterns of uptake were analysed.ResultsDOTATATE and FDG were positive at most sites of disease (96.2 % vs 91.4 %), although uptake intensity was significantly higher on DOTATATE with a median SUV of 21 compared to 12.5 for FDG (p < 0.001). SUVmax on F-18 FDG was significantly higher (p < 0.001) in clinically aggressive cases. I-123/I-124 MIBG detected fewer lesions (30.4 %).ConclusionOverall, Ga-68 DOTATATE PET/CT detected similar number but has significantly greater lesion-to-background contrast compared to F-18 FDG PET/CT. Combined with high specificity, patient convenience and relatively low cost, DOTATATE PET/CT should be considered the ideal first line investigation for imaging PGL/PCC. Depending on DOTATATE findings and the clinical question, FDG and MIBG remain useful and, in selected cases, may provide more accurate staging, disease characterisation and guide treatment choices.

Role of DOTATATE‐PET/CT in preoperative assessment of phaeochromocytoma and paragangliomas

“…Recent studies have reported high sensitivity using DOTATATE‐PET/CT for head and neck PGLs, especially tumours associated with SDHD mutations . This imaging modality is now recommended as the primary investigation for PGLs due to its high sensitivity and higher greater lesion to background contrast compared to FDG‐PET . However, as DOTATATE uptake is present in the normal adrenal glands, the sensitivity of Somatostatin receptor imaging (SRI) during primary assessment has not yet been established.…”

“…12 This imaging modality is now recommended as the primary investigation for PGLs due to its high sensitivity and higher greater lesion to background contrast compared to FDG-PET. 13 However, as DOTATATE uptake is present in the normal adrenal glands, the sensitivity of Somatostatin receptor imaging (SRI) during primary assessment has not yet been established. With the expansion of theranostics and growing availability of Lutetium-177 (Lutate) peptide receptor radionuclide therapy (PRRT), a positive DOTATATE scan may provide guidance for treatment decisions.…”

Complementary role of MRI and positron emission tomography in diagnosing cerebral abscess in a patient with metastatic paraganglioma

“…Our experience also suggests utility for paragangliomas, 2 and it has been shown to be more sensitive than metaiodobenzylguanidine (MIBG) imaging, especially in patients with germline SDHB mutations. There is a greater reliance on imaging when clinical assessment is confounded by such factors, and our case illustrates the value of a multi-modality approach.…”

“…GaTate-PET/CT targets masses expressing somatostatin receptors and is widely used for evaluating neuroendocrine tumours. Our experience also suggests utility for paragangliomas, 2 and it has been shown to be more sensitive than metaiodobenzylguanidine (MIBG) imaging, especially in patients with germline SDHB mutations. 3 The lack of GaTate uptake in the intracranial mass made a paraganglioma metastasis unlikely given high uptake at other known sites of disease.…”

Theranostics of Neuroendocrine Tumors

“…However, PRRT is highly recommended in patients with metastatic or inoperable NETs and positive expression of SSTR2 [11,22,23,24,25]. Although PRRT with radiolabeled somatostatin analogs is most commonly used for patients with WHO grade 1 and grade 2 gastrointestinal and bronchial NETs, patients with pheochromocytoma, paraganglioma, neuroblastoma, and medullary thyroid carcinoma may also benefit from the treatment [26,27,28,29]. …”