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Value of 123I-MIBG radioactivity in the differential diagnosis of DLB from AD
M Yoshita1, J Taki, K Yokoyama
1Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan. myoshita@ucdavis.edu
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.
Insights
Cardiac iodine-123 metaiodobenzylguanidine (123I-MIBG) scintigraphy accurately distinguishes dementia with Lewy bodies (DLB) from Alzheimer disease (AD). This diagnostic tool is effective even in DLB patients without parkinsonism, showing high sensitivity and specificity.
Area of Science:
- Neurology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Dementia with Lewy bodies (DLB) diagnosis can be challenging, especially when parkinsonism is absent.
- Accurate antemortem diagnosis of DLB without parkinsonism is crucial for appropriate patient management.
Purpose of the Study:
- To assess the diagnostic reliability of cardiac iodine-123 metaiodobenzylguanidine ((123)I-MIBG) radioactivity in differentiating DLB from Alzheimer disease (AD).
- To determine if (123)I-MIBG scintigraphy can distinguish DLB from AD irrespective of the presence or absence of parkinsonism.
Main Methods:
- Myocardial (123)I-MIBG scintigraphy was performed on 37 DLB patients (7 without parkinsonism, 30 with parkinsonism), 42 AD patients, and 10 healthy controls.
- Cardiac sympathetic denervation was evaluated by measuring the heart-to-mediastinum uptake ratio (H/M ratio) and washout rate (WR).
Main Results:
- Both DLB groups showed significantly decreased H/M ratios and increased WR compared to AD and control groups.
- No significant differences in H/M ratio or WR were observed between AD and control groups.
- The delayed H/M ratio demonstrated 100% sensitivity, 100% specificity, and 100% positive predictive value in discriminating DLB from AD at a cutoff of 1.68.
Conclusions:
- Dementia with Lewy bodies is associated with cardiac sympathetic denervation.
- (123)I-MIBG myocardial scintigraphy is a highly sensitive and specific imaging tool for differentiating DLB from AD, even in the absence of parkinsonian symptoms.
