Introduction There is increasing evidence that imaging with [123I]FP-CIT SPECT is helpful in differentiating dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) but it is not known how well the scan performs in differentiating DLB from frontotemporal dementia (FTD).
Method We compared the striatal dopamine transporter (DAT) binding in FTD (n=12), DLB (n=10) and AD (n=9) by visually rating the caudate and putamen on [123I]FP-CIT SPECT scans.
Results The majority (9/10) of DLB cases had an abnormal scan and a significant reduction of uptake of DAT binding in the putamen and the caudate. A third (4/12) of the FTD cases also had an abnormal scan and a significant reduction in uptake in the putamen and the caudate. In contrast, only one out of nine AD cases had an abnormal scan. Significant differences were found when comparisons were made between the groups for visual analysis of the entire scan (p=0.001) and the four regions of interest (p=0.001 – 0.013). In contrast to the AD group (specificity of scan 89%), the specificity of [123I]FP-CIT SPECT scans was reduced in the FTD group to 67%. Three quarters of the study population had at least one extrapyramidal motor sign (EPMS), with bradykinesia being the most common EPMS in both FTD (83%) and DLB (70%).
Conclusions This study highlights to clinicians that a positive (abnormal) [123I]FP-CIT SPECT scan, even in a patient with an EPMS, does not exclude the diagnosis of FTD and emphasises the importance of a comprehensive clinical evaluation and a detailed cognitive assessment.
- Frontotemporal dementia
- dementia with Lewy bodies
- [123I]FP-CIT SPECT
- frontotemporal lobar degeneration
- dopamine transporter
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Funding Dr Morgan received research support from GE Healthcare (free FP-CIT ligands for FTD cases).
Competing interests Dr Walker has received consultancy and speaker fees and research support from GE Healthcare, consultancy fees from Bayer Healthcare and Novartis, and research support from Lundbeck. Professor Booij, Professor Costa and Dr Kemp have received consultancy and speaker fees and research support payments from GE Healthcare. This work was supported by GE Healthcare Ligand order number: DAT-08-02.
Ethics approval Ethics approval provided by the Essex 1 Research Ethics Committee. Patients signed consent forms approved by an Ethics Committee and the Caldicott Guardian approval was sought for data sharing.
Provenance and peer review Not commissioned; externally peer reviewed.