Findings of MIBG cardiac scintigraphy: Dementia with lewy bodies and related dementia

Dementia with Lewy bodies (DLB) is the second most common neurodegenerative form of dementia. The core features of DLB include progressive cognitive decline, parkinsonism, autonomic failure, and sleep disorders. Because the symptoms are similar between DLB and Alzheimer’s disease (AD), it is often difficult to make a definitive diagnosis, in particular, during the early course of the illness. Cardiac ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy is one of the most useful tools for differentiating DLB from AD. DLB patients generally show markedly reduced cardiac MIBG uptake, regardless of the presence of parkinsonism. This finding is consistent with pathological findings of cardiac sympathetic nerve involvement in DLB. However, patients with AD, corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), and vascular dementia (VaD) generally show normal cardiac MIBG uptake. Therefore, MIBG cardiac scintigraphy provides a powerful method for early differentiation of DLB from other forms of dementia, with equal or superior diagnostic capabilities when compared to dopamine transporter imaging or perfusion/metabolic imaging. Recent studies have demonstrated that most subjects with rapid eye movement (REM) sleep behavior disorder (RBD) progressing to DLB or Parkinson’s disease (PD) during long follow-up periods also have abnormal cardiac MIBG uptake. Thus, MIBG cardiac scintigraphy may have the potential to detect prodromal DLB before obvious cognitive and functional changes are observed. This procedure could more accurately identify early dementia and could enhance the development and use of disease-modifying therapies for DLB.