Initial Versus Follow-up Sequential Myocardial 123I-MIBG Scintigraphy to Discriminate Parkinson Disease From Atypical Parkinsonian Syndromes

Purpose 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. Patients and Methods 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. Results 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. Conclusions 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. 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: neuronet@catholic.ac.kr. Supplemental digital content is available for this article. Direct URL citation appears in the printed text and is provided in the HTML and PDF versions of this article on the journal's Web site (www.nuclearmed.com). Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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