[DaT-SCAN SPECT in the differential diagnosis of dementia with Lewy bodies and Alzheimer's disease].

INTRODUCTION Dementia with Lewy bodies (DLB) is one of the main differential diagnosis of Alzheimer's disease (AD). In DLB there is 40-70% loss of striatal dopamine and the loss of dopaminergic cell is accompanied by loss of the dopamine transporter. The loss of dopaminergic neurons in DLB can be confirmed in vivo with I-FP-CIT (DaT-SCAN), a pre-synaptic dopamine transporter marker. There are no changes in DaT-scan in AD compared with controls. AIM. The use of DaT-SCAN for the differential diagnosis between AD and DLB. CASE REPORTS We use the DaT-SCAN to study the nigrostriatal pathway in 6 patients with dementia and moderate parkinsonism. The Mini-Mental Test and the Unified Parkinson's Disease Rating Scale, motor part only (UPDRS), were performed. A SPECT scan was carried out 3 to 4 hours after administration of 185 MBq FP-CIT (ioflupane) a dopaminergic presynaptic ligand. With occipital cortex used as a radioactivity uptake reference, ratios for the caudate nucleus and the anterior and posterior putamen of both hemispheres were calculated. All scans were also rated by a simple visual method. All patients had dementia with moderate fluctuations in cognitive function, parkinsonian syndrome and hallucinations. DaT-SCAN was normal in 2 patients and pathological in 4. CONCLUSION The sensitivity and specificity of the DLB criteria vary markedly. FP-CIT SPECT may be a new tool in the differential diagnosis between DLB and AD.