Background

The heterogeneous composition of substantia nigra (SN), including iron, nigrosome-1 substructure, and myelinated white matter, complicates the interpretation of MRI signals.

Purpose

To investigate R2* and quantitative susceptibility mapping (QSM) in the SN subdivisions of participants with Parkinson disease and healthy control subjects.

Materials and Methods

In this prospective study conducted from November 2018 to November 2019, participants with Parkinson disease and sex-matched healthy control subjects underwent 3-T MRI. R2* and QSM values were measured and compared in the anterior SN and posterior SN at the rostral (superior) and caudal (inferior) levels. Postmortem MRI and histology correlation of midbrain tissues was evaluated to investigate the effect of myelin and iron in the SN on R2* and QSM values.

Results

Forty individuals were evaluated: 20 healthy control subjects (mean age, 61 years ± 3 [standard deviation]; 10 men) and 20 participants with Parkinson disease (mean age, 61 years ± 4; 10 men). The R2* values of participants with Parkinson disease were higher in all subdivisions of the SN compared with R2* values in healthy control subjects (all P < .05). For QSM, no evidence of a difference was found in the rostral posterior SN (healthy control subjects, 54.1 ppb ± 21.0; Parkinson disease, 62.2 ppb ± 19.8; P = .49). The combination of rostral R2* and caudal QSM values resulted in an area under the receiver operating characteristic curve of 0.84. R2* values showed higher correlation with QSM values at the caudal level than at the rostral level within each group (all P < .001). Postmortem investigation demonstrated that R2* and QSM values showed weak correlation in the myelin-rich areas (r = 0.22 and r = 0.36, P < .001) and strong correlation in myelin-scanty areas (r ranged from approximately 0.52 to approximately 0.78, P < .001) in the SN.

Conclusion

Considering the iron and myelin distribution in the substantia nigra subdivisions, the subdivisional analysis of substantia nigra using R2* and quantitative susceptibility mapping might aid in specifically differentiating individuals with Parkinson disease from healthy control subjects.

© RSNA, 2021

Online supplemental material is available for this article.

中文翻译：

---

铁和髓磷脂对黑质磁化率 MRI 的差异影响

背景

黑质 (SN) 的异质成分，包括铁、nigrosome-1 亚结构和有髓鞘白质，使 MRI 信号的解释变得复杂。

目的

研究帕金森病参与者和健康对照受试者的 SN 分区中的 R2* 和定量敏感性图谱 (QSM)。

材料和方法

在这项于 2018 年 11 月至 2019 年 11 月进行的前瞻性研究中，患有帕金森病的参与者和性别匹配的健康对照受试者接受了 3-T MRI。测量并比较前 SN 和后 SN 的吻侧（上）和尾侧（下）水平的 R2* 和 QSM 值。评估中脑组织的死后 MRI 和组织学相关性，以研究 SN 中髓磷脂和铁对 R2* 和 QSM 值的影响。

结果

对 40 名个体进行了评估：20 名健康对照受试者（平均年龄，61 岁±3 [标准差]；10 名男性）和 20 名患有帕金森病的参与者（平均年龄，61 岁±4；10 名男性）。与健康对照受试者的 R2* 值相比，SN 所有细分中帕金森病参与者的 R2* 值均较高（所有P < .05）。对于 QSM，未发现头侧后 SN 存在差异的证据（健康对照受试者，54.1 ppb ± 21.0；帕金森病，62.2 ppb ± 19.8；P = .49）。头端 R2* 和尾端 QSM 值的组合导致受试者工作特征曲线下面积为 0.84。在每组内，R2* 值与尾部水平的 QSM 值的相关性高于与喙部水平的相关性（所有P< .001)。尸检研究表明，R2* 和 QSM 值在髓磷脂丰富区域中表现出弱相关性（r = 0.22 和r = 0.36，P < .001），而在髓磷脂稀少区域中表现出强相关性（r范围从大约 0.52 到大约 0.78，P < .001) 在 SN 中。

结论

考虑到黑质分区中的铁和髓磷脂分布，使用 R2* 和定量磁化率图对黑质进行分区分析可能有助于将帕金森病患者与健康对照受试者进行特异性区分。

© 北美放射学会，2021

本文提供在线补充材料。