Previous single-center or meta-analysis studies analyzed myocardial 123I-metaiodobenzylguanidine (123I-MIBG) scintigraphy in a single image session and demonstrated low sensitivity and high specificity for discriminating Parkinson disease (PD) from atypical Parkinsonian syndromes (APS). This study aimed to assess diagnostic ability of myocardial 123I-MIBG scintigraphy at 2 phases to discriminate PD from APS.
This hospital-based prospective study enrolled 162 PD and 26 APS patients who underwent 2 sequential 123I-MIBG scintigraphy evaluations. Patients were stratified into normal and decreased 123I-MIBG groups according to early and delayed heart-to-mediastinum (H/M) ratios. Patients with PD and normal 123I-MIBG uptake (initial delayed H/M ratio, ≥1.78) were considered scans without evidence of cardiac norepinephrine deficit (SWEND). Early and delayed H/M ratios on the initial and 2-year follow-up scintigraphs were studied. The diagnostic sensitivity and specificity were calculated from these confusion matrices and were analyzed according to receiver-operating characteristic curve analysis. A repeated-measures general linear model was used to investigate differences among groups over time in H/M ratio changes and washout rates.
Follow-up 123I-MIBG scintigraphy analysis had a higher diagnostic sensitivity (89.5%) than the initial imaging (72.2%). The improved sensitivity was associated with a steeper decrease in H/M ratio in the SWEND group than in the APS group.
Follow-up 123I-MIBG scintigraphy can identify cardiac sympathetic denervation and its progression in patients with PD and may be effective in discriminating PD from APS. A later decrease in myocardial 123I-MIBG uptake in the group with SWEND meets the Braak staging threshold hypothesis for synucleinopathy.
From the Departments of *Neurology
†Nuclear Medicine, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Received for publication October 29, 2018; revision accepted October 31, 2018.
Conflicts of interest and sources of funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (NRF-2017R1D1A1B06028086).The funder had no role in study design, data collection and analysis, decision to publish, and manuscript preparation. None declared to all authors.
Author Contributions: J.S.K. designed the study; D.W.R. and J.S.K. prepared the manuscript; D.W.R., J.S.K., J.E.L., Y.S.O., S.W.Y., and K.S.L. collected the data; I.R.Y. performed the image analysis; D.W.R. and J.S.K. analyzed the data; J.S.K., J.E.L., Y.S.O., S.W.Y., I.R.Y., and K.S.L. critically reviewed the manuscript; J.S.K. obtained the study funding. All authors have read and approved the final version of the manuscript.
Correspondence to: Joong-Seok Kim, MD, PhD, Department of Neurology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222, Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea. E-mail: firstname.lastname@example.org.
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