Incidental brain uptake of Gallium-68 DOTATATE positron emission tomography/computed tomography scan in patients with neuroendocrine tumors: a case report and literature review.

Abstract

Background: Neuroendocrine tumors (NETs) often express somatostatin receptors, which makes Gallium-68 DOTATATE positron emission tomography/computed tomography (68Ga-DOTATATE PET/CT) scan an important diagnostic tool. However, incidental brain uptakes on 68Ga-DOTATATE PET/CT scan pose a significant diagnostic challenge, where these uptakes can represent meningiomas or tumor metastasis.

Case description: This case report presents two cases of patients with low-grade NETs that had incidental brain uptake on 68Ga-DOTATATE PET/CT. In the first case, a 48-year-old female with a history of bronchial carcinoid tumor and Cushing's syndrome had incidental uptake near the right skull, which magnetic resonance imaging (MRI) confirmed as a stable meningioma. In the second case, a 65-year-old female with a grade 1 gastric NET had incidental uptake in the right temporal and left occipital lobes; however, follow-up MRI was negative. Given the affinity of meningiomas for somatostatin analogues, such findings can complicate the interpretation of PET/CT results.

Conclusions: Previous studies reported a prevalence of Incidental brain uptake on 68Ga-DOTATATE PET/CT scan between 1.6% to 11%. The prevalence of meningioma was between 1.6% to 9%. In minor cases, the uptake revealed other causes such as varix abnormalities and metastasis. MRI is considered essential for differentiating meningioma from tumor metastasis, although some cases of meningioma can be missed while showing on PET/CT. Incidental brain uptake on 68Ga-DOTATATE PET/CT scan, while usually suggestive of meningioma, requires follow-up with MRI to confirm the diagnosis and prevent unwarranted aggressive treatments. Awareness of the diagnostic challenges is crucial for the appropriate management of patients with NETs.