Objective: To determine whether routine implementation of cardiac 123I-MIBG scintigraphy improves the diagnostic performance of the Movement Disorder Society (MDS) “clinically probable Parkinson’s disease (PD)” criteria and to identify an appropriate cutoff value for olfactory testing within the supportive criteria framework.

Background: The MDS clinical diagnostic criteria for PD include olfactory impairment and reduced cardiac 123I-MIBG uptake as supportive criteria. Although previous validation studies demonstrated the overall utility of these criteria, it remains unclear whether routine implementation of cardiac 123I-MIBG scintigraphy improves diagnostic performance and how different cutoff values for olfactory testing affect the criteria.

Method: In this multicenter study, 453 patients with parkinsonism (PD, n=317; non-PD, n=136) underwent olfactory testing using the Odor Stick Identification Test for Japanese (OSIT-J) and cardiac 123I-MIBG scintigraphy. The final clinical diagnosis by attending neurologists served as the reference standard. Diagnostic performance of the MDS “clinically probable PD” category was evaluated, and subgroup analyses assessed the influence of olfactory testing and 123I-MIBG scintigraphy.

Results: Using the cutoff value of OSIT-J <8 (corresponding to the 5th percentile of healthy controls) reported in the validation study, the specificity of olfactory testing did not reach the required threshold of 80%. In contrast, cardiac 123I-MIBG scintigraphy demonstrated specificity ≥80%. When olfactory impairment was defined as anosmia (OSIT-J ≤2), satisfying the ≥80% specificity requirement, the sensitivity and specificity of the MDS criteria were 95.0% and 84.6%, respectively. Diagnostic performance using 123I-MIBG scintigraphy alone was comparable to that obtained with the combined use of both tests. However, exclusion of 123I-MIBG scintigraphy slightly worsened the negative likelihood ratio.

Conclusion: Defining olfactory impairment as anosmia (OSIT-J ≤2) appears appropriate for use as a supportive criterion within the MDS framework. Although the combined use of olfactory testing and cardiac 123I-MIBG scintigraphy did not clearly improve overall diagnostic performance, 123I-MIBG scintigraphy may contribute to improving the ability to exclude PD.

« Back to 2026 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/re-evaluating-olfactory-testing-and-cardiac-123i-mibg-scintigraphy-in-the-mds-clinical-diagnostic-criteria-for-parkinsons-disease/