Neuroimaging changes have been much less studied in dementia with Lewy bodies (DLB) compared to Alzheimer’s disease (AD) and Parkinson’s disease (PD). Imaging changes in DLB may be important in regard to assisting with clinical differential diagnosis, understanding neurobiological changes associated with core clinical features and determining whether DLB can be separated as a disease entity from closely related disorders such as AD and PD. We have undertaken MRI, blood flow (Tc-HMPAO) SPECT and FP-CIT (dopamine transporter) SPECT studies in patients with DLB, AD, PD and age-matched controls. Like AD, DLB is associated with generalized atrophy and ventricular enlargement on MRI but relative preservation of the temporal lobe and hippocampus compared with AD. On blood flow SPECT, DLB is characterized by greater parieto-occipital hypoperfusion compared with AD. These changes may underpin visuospatial deficits and visual hallucinations which are both characteristic features of DLB. Using dopamine transporter (FP-CIT) SPECT, DLB is associated with reductions in the caudate and, in particular, putamen compared to AD and controls. Dopaminergic SPECT shows particular promise in assisting in the differential diagnosis of DLB from AD, with visual scan analysis showing sensitivity of around 80% and specificity of over 90%. In conclusion, DLB is associated with relative preservation of the hippocampus and temporal lobe on MRI, parieto-occipital hypoperfusion on blood flow SPECT and dopamine transporter loss using FP-CIT SPECT. These changes help explain key clinical features of DLB, show promise in terms of improving differential diagnosis and show that DLB appears distinct from both AD and PD.
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