Comparison of cerebral technetium-99m-ethyl cysteinate dimer perfusion in patients with dementia with Lewy bodies and Parkinson's disease dementia.

Objective: Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are closely related neurodegenerative conditions within the Lewy body spectrum. The relationship between DLB and PDD remains debated, with ongoing discussion about whether they are distinct diseases or different manifestations of the same disorder. This study aimed to identify differences in cerebral perfusion patterns between DLB and PDD patients.
Methods: Single-photon emission computed tomography (SPECT) ethyl cysteinate dimer (ECD) imaging was performed on patients diagnosed with DLB ( n  = 46) and PDD ( n  = 30). The data were acquired by two SPECT/computed tomography systems from two affiliated centers and were retrospectively recruited under the local ethics approval. Relative tracer uptake levels were calculated across 47 automatically determined regions of interest and 240 subregions. A two-sided Welch's t -test was employed to evaluate mean perfusion differences, with results further confirmed through a voxel-wise t -test mapping. The Benjamini-Hochberg procedure was used to adjust P -values for multiple comparisons.
Results: The greatest difference in perfusion was in the left associative visual cortex in planes 34 and 36 and the right primary visual cortex in plane 34, with lower mean perfusion observed in PDD patients than those with DLB ( P  = 0.005).
Conclusion: No statistically significant differences in ECD perfusion were found between DLB and PDD patients. The greatest difference was in the visual cortices, where PDD patients suffered a greater loss of perfusion.
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