Appropriate assessment method of 123 I-MIBG myocardial scintigraphy for the diagnosis of Lewy body diseases and idiopath
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Appropriate assessment method of 123I‑MIBG myocardial scintigraphy for the diagnosis of Lewy body diseases and idiopathic REM sleep behavior disorder Kazuto Tsukita1,2,3,4 · Naoko Tachibana2,3 · Toshiaki Hamano1,5 Received: 3 April 2020 / Revised: 9 June 2020 / Accepted: 10 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Background In 123I-metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy, the early heart-to-mediastinum (H/M) ratio is considered to reflect the density of the cardiac sympathetic nerve endings, washout rate (WR) is an indicator of the cardiac sympathetic tone, and the delayed H/M ratio reflects both. The Delayed H/M ratio is usually used to support the diagnosis of Lewy body diseases (LBDs) and idiopathic REM sleep behavior disorder (iRBD); however, which values should be used have not been specified. Here, we hypothesized that the combination of these values is appropriate for the diagnostic purpose. Methods In this single-center retrospective cohort study, we recruited 106 patients with LBDs or iRBD and 33 patients without those diseases, of whom we reviewed the 123I-MIBG myocardial scintigraphy results. Results Sensitivity/specificity to diagnose LBDs and iRBD were 0.77/0.94 for the early H/M ratio (≤ 2.0), 0.82/0.94 for the delayed H/M ratio (≤ 2.0), and 0.89/0.91 for WR (≥ 23.0). When patients were considered positive if at least either the early H/M ratio or WR was abnormal, the sensitivity significantly increased to 0.97, whereas the specificity remained similar at 0.91. Furthermore, our subgroup analyses revealed that WR enhancement preceded H/M ratio reduction, but, in patients with a severely reduced early H/M ratio, paradoxically normal WR could be observed. Conclusion We propose the highly sensitive, combined early H/M ratio and WR assessments for 123I-MIBG myocardial scintigraphy. The temporal precedence of cardiac sympathetic dysfunction over denervation and the floor effect in 123I-MIBG uptake may underlie the sensitivity improvement. Keywords 123I-MIBG myocardial scintigraphy · Lewy body diseases · Idiopathic REM sleep behavior disorder
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00415-020-09992-0) contains supplementary material, which is available to authorized users. * Kazuto Tsukita [email protected]‑u.ac.jp 1
Department of Neurology and Center for Sleep‑Related Disorders, Kansai Electric Power Hospital, 2‑1‑7, Fukushima, Osaka 553‑0003, Japan
2
Center for Sleep‑Related Disorders, Kansai Electric Power Hospital, Osaka, Japan
3
Division of Sleep Medicine, Kansai Electric Power Medical Research Institute, Osaka, Japan
4
Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
5
Division of Clinical Neurology, Kansai Electric Power Medical Research Institute, Osaka, Japan
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