Dementia with Lewy bodies and Alzheimer's disease: Differential diagnosis by cardiac sympathetic innervation MIBG imaging

Dementia with Lewy bodies (DLB) is the second most common cause of degenerative dementia after Alzheimer's disease (AD). At present, pre-mortem diagnosis of DLB can only be made clinically using the International Consensus Criteria. However, an accurate differential diagnosis between these diseases could improve the therapeutic handling of patients with DLB, due to their supersensitivity to neuroleptic treatment and the difficult treatment of their psychotic symptoms. Objective. To assess the utility of cardiac MIBG imaging as diagnostic study for DLB, to help in the differential diagnosis with AD. Material and methods. Cardiac MIBG imaging was performed in 11 patients with clinical criteria of probable DLB (7 males, mean age 77 years [range 62-89 years], mean MMSE 17 [range 11-28], and in 9 patients with clinical criteria of probable AD (3 males, mean age 79 years [range 61-87 years], mean MMSE 17 [range 4-25]). Planar anterior images of the thorax were acquired at 15 minutes, (early study) and 4 hours (late study) after tracer injection. Myocardial MIBG activity was quantified by means of a heart-to-mediastinum ratio (HMR). A HMR > 1.8 was considered normal. Results. Respect AD patients, patients with DLB showed decreased HMR in the early study (1.34 ± 0.27 [range 1.03-1.98] vs. 1.84 ± 0.22 [range 1.53-2.15], p < 0.001) and in the late study (1.22 ± 0.23 [range 0.95-1.75] vs. 1.73 ± 0.08 [range 1.59-1.89], p < 0.0001). Conclusions. Cardiac MIBG imaging could be a useful tool for differential diagnosis between DLB and AD.