Abstract
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Objectives AADC is an enzyme for the synthesis of dopamine from L-dopa. AADC deficiency is caused by congenital anomaly. Taiwanese carry a high prevalence of AADC deficiency due to the mutation IVS6+4 A→T and patients(pts) usually die at 5-6 y/o. The diagnosis remains a great challenge. Brain MRI is of limited use. The pts usually have low HVA and 5-HIAA, and increased L-dopa and 3-O-methyldopa in CSF. We tried to use 18F-FDOPA PET and 99mTc-TRODAT-1 SPECT for the diagnosis, evaluation and maybe selection of pts for gene therapy.
Methods FDOPA PET: After 100 mg of carbidopa was given orally for 60 mins, the pts were injected with 200 MBq of 18F-FDOPA and wait for 90 mins for PET/CT scan. TRODAT-1 SPECT: the pts were injected with 280 MBq of 99mTc-TRODAT-1 and wait for 4 hrs for brain SPECT.
Results Nine pts (5M:4F; 0.5-2.3 y/o) were collected for study. All 9 pts showed total absence of FDOPA uptake in the striatum, which confirms the diagnosis. In 99mTc-TRODAT-1 SPECT, 4 showed symmetrical uptake in both basal ganglia. This indicates intact presynaptic dopaminergic neural terminals. Five others showed asymmetrical uptake.
Conclusions From this study, 18F-FDOPA PET can be used for the confirmation of pts suspecious of AADC deficiency. No study on the role of 99mTc-TRODAT-1 SPECT has been reported yet. The pathogenic mechanism of asymmetrical uptake remains to be clarified. Gene therapy has been planned in our institute. For better prognosis, the pts with symmetrical TRODAT-1 uptake may be better candidates for gene therapy.
- © 2009 by Society of Nuclear Medicine