Brain 18 F-FDG-PET and an optimized cingulate island ratio to differentiate Lewy body dementia and Alzheimer's disease

Identifying Mixed Dementia With Lewy Bodies and Alzheimer Disease Using Multitracer PET Imaging: A Case Study

ABSTRACT

We reported imaging findings with complex signs that were corresponded with both dementia with Lewy bodies (DLB) and Alzheimer disease (AD) in the case of a 78-year-old woman. Initially suspected as DLB due to cognitive and movement issues, diagnostic support included the cingulate island sign on 18 F-FDG PET, positive 131 I-MIBG cardiac scintigraphy, and DAT PET. However, MRI indicated hippocampal atrophy, and 18 F-FDG PET showed hypometabolism in the medial temporal lobe, suggesting the possibility of concomitant AD. Subsequent detection of β-amyloid pathology and tau accumulation in the brain further supported the concurrent presence of AD pathology.

Functional connectivity in Lewy body disease with visual hallucinations

BACKGROUND AND PURPOSE

Visual hallucinations are a common, potentially distressing experience of people with Lewy body disease (LBD). The underlying brain changes giving rise to visual hallucinations are not fully understood, although previous models have posited that alterations in the connectivity between brain regions involved in attention and visual processing are critical.

METHODS

Data from 41 people with LBD and visual hallucinations, 48 with LBD without visual hallucinations and 60 similarly aged healthy comparator participants were used. Connections were investigated between regions in the visual cortex and ventral attention, dorsal attention and default mode networks.

RESULTS

Participants with visual hallucinations had worse cognition and motor function than those without visual hallucinations. In those with visual hallucinations, reduced functional connectivity within the ventral attention network and from the visual to default mode network was found. Connectivity strength between the visual and default mode network correlated with the number of correct responses on a pareidolia task, and connectivity within the ventral attention network with visuospatial performance.

CONCLUSIONS

Our results add to evidence of dysfunctional connectivity in the visual and attentional networks in those with LBD and visual hallucinations.