Cingulate island sign

Case contributed by Timothy Boles
Diagnosis almost certain


Cognitive decline and visual hallucinations.

Patient Data

Age: 80
Gender: Male
Nuclear medicine

FDG PET/CT demonstrating the cingulate island sign in a patient with a diagnosis of dementia with Lewy bodies. 

There is decreased uptake in the bilateral parietal and occipital lobes. Uptake is preserved in the posterior cingulate with surrounding hypometabolism which creates the appearance of an island of increased uptake - otherwise known as the cingulate island sign (arrow).

Case Discussion

Dementia with Lewy bodies (DLB) is one of the most common types of degenerative dementia, secondary to Alzheimer disease (AD). Clinically, DLB is characterized by progressive dementia, parkinsonism, fluctuating cognition, recurrent complex visual eye hallucinations and rapid eye movement sleep behavior disorder.

Several biomarkers are used clinically in the differential diagnosis of DLB. The cingulate island sign is a supportive biomarker in discriminating DLB from AD according to the diagnostic criteria and refers to the relative preservation of posterior cingulate cortex metabolism, in relation to the parietal and occipital lobes.

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