The significance of incidental brain uptake on 68Ga-DOTATATE PET-CT in neuroendocrine tumour patients.

Objective: Radiolabelled somatostatin analogues detect neuroendocrine tumours (NETs), but may reveal other tumour types. We examined the prevalence of possible meningioma in patients with known or suspected NETs imaged with Ga-DOTATATE PET-computed tomography (CT) on the basis of central nervous system uptake and compared with findings on magnetic resonance and contrast-enhanced CT imaging.

Methods: Retrospective imaging reports from 313 patients who had undergone Ga-DOTATATE PET imaging for primary or repeat NET staging were searched to identify suspected meningiomas on PET. Images were then compared with findings on subsequent complementary MRI or contrast-enhanced CT scanning (performed within mean±112 days of PET-CT) if available.

Results: Of 313 patients, 22 had regions of uptake suggestive of meningioma. MRI was available for 12 patients and contrast-enhanced CT was available for one patient. Of these, one patient with known von Hippel-Lindau syndrome had probable cerebellar NET metastasis. Six patient scans indicated lesions consistent with PET. Two of these reported initially did not comment on meningioma. No obvious lesion was found in the remaining six patients; however, five showed a possible correlation to venous structures. The mean maximum standardized uptake value±SEM for lesions in all 21 probable meningioma patients was 4.90±0.45.

Conclusion: Ga-DOTATATE is a sensitive marker of probable meningioma and may identify small lesions not reported on subsequent MRI. Lesions clearly observed on PET were identified on review in half of patients where complementary MR or CT imaging was available. Haemangioblastoma and metastatic NETs may have focal peripheral uptake similar to meningioma on Ga-DOTATATE PET and should be considered in the differential.