18F-DOPA

Several radiopharmaceuticals have been developed to investigate brain and neuroendocrine tumors by means of PET/CT, to overcome the intrinsic limits of 18F-FDG in these clinical settings. 18F-DOPA is a useful tracer, due to a low rate of physiological distribution in normal brain structures of white and gray matter and its affinity for somatic neuroendocrine tumors. Similar to other amino acid tracers, 18F-DOPA PET/CT is helpful in diagnosis of patients with suspected low-grade brain tumor recurrence, because of low signal ratio in normal brain white and gray matter, in particular in comparison to 18F-FDG PET/CT. MRI is the gold standard of diagnosis but 18F-DOPA PET/CT is adjuvant to diagnosis. PET/MRI with 18F-DOPA or other amino acid tracers will play a prevalent role in brain tumor imaging. Another field of application of 18F-DOPA can be the evaluation of substantia nigra metabolism since the dopamine uptake is reduced in Parkinson’s disease. Neuroendocrine tumors may also show uptake of 18F-DOPA: in this field, 18F-DOPA PET/CT can be a valid tool in the assessment of primitive tumor or secondary lesions. In recurrent medullary thyroid carcinoma, this diagnostic tool has an important prognostic value in predicting disease progression and mortality rate. However, in other neuroendocrine tumors, PET/CT imaging should be performed with analogues of somatostatin tracers.