Department of Neurology and Center for Sleep-Related Disorders, Kansai Electric Power Hospital, 2-1-7, Fukushima, Osaka, 553-0003, Japan.
Center for Sleep-Related Disorders, Kansai Electric Power Hospital, Osaka, Japan.
J Neurol. 2020 Nov;267(11):3248-3257. doi: 10.1007/s00415-020-09992-0. Epub 2020 Jun 16.
In I-metaiodobenzylguanidine (I-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.
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 I-MIBG myocardial scintigraphy 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.
We propose the highly sensitive, combined early H/M ratio and WR assessments for I-MIBG myocardial scintigraphy. The temporal precedence of cardiac sympathetic dysfunction over denervation and the floor effect in I-MIBG uptake may underlie the sensitivity improvement.
在碘代间位苄胍（I-MIBG）心肌闪烁显像中，早期心脏与纵隔（H/M）比值被认为反映了心脏交感神经末梢的密度，洗脱率（WR）是心脏交感神经张力的指标，而延迟 H/M 比值反映了两者。延迟 H/M 比值通常用于支持路易体病（LBD）和特发性 REM 睡眠行为障碍（iRBD）的诊断；然而，尚未指定应使用哪些值。在这里，我们假设这些值的组合适合诊断目的。
在这项单中心回顾性队列研究中，我们招募了 106 例 LBD 或 iRBD 患者和 33 例无这些疾病的患者，对这些患者的 I-MIBG 心肌闪烁显像结果进行了回顾性分析。
早期 H/M 比值（≤2.0）、延迟 H/M 比值（≤2.0）和 WR（≥23.0）对诊断 LBD 和 iRBD 的灵敏度/特异性分别为 0.77/0.94、0.82/0.94 和 0.89/0.91。如果至少早期 H/M 比值或 WR 异常，则将患者视为阳性，此时灵敏度显著提高至 0.97，而特异性仍保持在 0.91。此外，我们的亚组分析表明，WR 增强先于 H/M 比值降低，但在早期 H/M 比值严重降低的患者中，也可能观察到 WR 正常的反常现象。
我们提出了对 I-MIBG 心肌闪烁显像进行高度敏感的早期 H/M 比值和 WR 联合评估。WR 对心脏交感神经功能障碍的检测敏感性高于去神经支配，I-MIBG 摄取的地板效应可能是提高敏感性的基础。
