Neuroimaging of Dementia with Lewy Bodies

Abstract

Dementia with Lewy bodies (DLB) is the second most common form of neurodegenerative dementia following Alzheimer’s disease (AD). Despite the development of consensus diagnostic criteria, differentiating DLB from other types of dementia, such as AD, can be difficult. Several imaging studies are currently underway to differentiate DLB from other types of dementia. Magnetic resonance imaging of DLB shows preservation of the medial temporal lobe structure and predominant atrophy of subcortical structures, including the substantia innominata and dorsal midbrain, compared with AD. Decreased perfusion in the occipital lobe and relatively increased perfusion in the deep gray matter (striatum and thalamus) on single photon emission CT (SPECT) are shown to be characteristic features of DLB. MIBG myocardial scintigraphy provides a higher sensitivity and higher specificity for diagnosing probable DLB from AD than perfusion SPECT. Dopamine transporter imaging, an available technique in Japan since 2014, shows good diagnostic accuracy for DLB. The international consensus criteria for DLB (2005) incorporate abnormal imaging on dopamine transporter as a supportive feature. As idiopathic REM sleep behavior disorder (iRBD) is considered to be a prodromal stage of alpha-synucleinopathies, the above findings are observed in some patients with iRBD. This review summarizes the applications and findings from neuroimaging studies of DLB and iRBD.