⁶⁸Ga-DOTATATE PET to Characterize Lesions in the Neuroaxis

Aim : The differentiation of paragangliomas, schwannomas, meningiomas, and other neuroaxis tumors in the head and neck remains difficult when conventional MRI is inconclusive. This study assesses the utility of Ga-68-DOTATATE PET/CT as an adjunct to hone the diagnosis.Patients and Methods : This retrospective study considered 70 neuroaxis lesions in 52 patients with Ga-68-DOTATATE PET/CT examinations; 22 lesions (31%) had pathologic confirmation. Lesions were grouped based on pathological diagnosis and best radiologic diagnosis when pathology was not available. Wilcoxon rank sum tests were used to test for differences in SUVmax among paragangliomas, schwannomas, and meningiomas. Receiver operator characteristic curves were constructed.Results : Paragangliomas had a significantly greater Ga-68-DOTATATE uptake (median SUVmax, 62; interquartile range [IQR], 89) than nonparagangliomas. Schwannomas had near-zero Ga-68-DOTATATE uptake (median SUVmax, 2; IQR, 1). Intermediate Ga-68-DOTATATE uptake was seen for meningiomas (median SUVmax, 19; IQR, 6) and other neuroaxis lesions (median SUVmax, 7; IQR, 9). Receiver operator characteristic analysis demonstrated an area under the curve of 0.87 for paragangliomas versus all other lesions and 0.97 for schwannomas versus all other lesions.Conclusions : Marked Ga-68-DOTATATE uptake (>50 SUVmax) favors a diagnosis of paraganglioma, although paragangliomas exhibit a wide variability of uptake. Low to moderate level Ga-68-DOTATATE uptake is nonspecific and may represent diverse pathophysiology including paraganglioma, meningioma, and other neuroaxis tumors but essentially excludes schwannomas, which exhibited virtually no uptake.