Value of 123I-MIBG radioactivity in the differential diagnosis of DLB from AD.
OBJECTIVE
To evaluate the diagnostic reliability of cardiac iodine-123 metaiodobenzylguanidine ((123)I-MIBG) radioactivity in discriminating dementia with Lewy bodies (DLB) from Alzheimer disease (AD) regardless of parkinsonism.


BACKGROUND
The diagnosis of DLB may be confounded by the absence of parkinsonism. This highlights the need to improve the accuracy of antemortem diagnosis of DLB without parkinsonism.


METHODS
Cardiac sympathetic denervation was examined using myocardial (123)I-MIBG scintigraphy in 37 patients with DLB, 42 patients with AD, and 10 normal elderly controls. The DLB patients consisted of seven patients without parkinsonism (DLB/P-) and 30 patients with parkinsonism (DLB/P+) at the time of the study.


RESULTS
The heart-to-mediastinum uptake ratio (H/M ratio) of myocardial MIBG uptake was decreased in both the DLB groups vs the AD group (p < 0.0001) and control group (p < 0.0001). The washout rate (WR) was higher in the DLB group than in the control group (p < 0.0001) and AD group (p < 0.0001). No differences were found between the AD and control groups or between the DLB/P+ and DLB/P- groups in either the early or delayed H/M ratio or WR. In discriminating between DLB and AD, regardless of parkinsonism, the delayed H/M ratio had a sensitivity of 100%, a specificity of 100%, and a positive predictive value of 100% at a cutoff value of 1.68.


CONCLUSIONS
Our results indicate that dementia with Lewy bodies results in cardiac sympathetic denervation and that iodine-123 metaiodobenzylguanidine myocardial scintigraphy is a sensitive tool for discriminating dementia with Lewy bodies from Alzheimer disease even in patients without parkinsonism.
Yoshita
M
M
Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan. myoshita@ucdavis.edu
Taki
J
J
Yokoyama
K
K
Noguchi-Shinohara
M
M
Matsumoto
Y
Y
Nakajima
K
K
Yamada
M
M
D019797:3-Iodobenzylguanidine; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015986:Confounding Factors, Epidemiologic; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D020961:Lewy Body Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine