Objective

Magnetic resonance imaging is a non-invasive method that allows the indirect quantification of manganese (Mn) and iron (Fe) accumulation in the brain due to their paramagnetic features. The WELDOX II study aimed to explore the influence of airborne and systemic exposure to Mn and Fe on the brain deposition using the relaxation rates R1 and R2* as biomarkers of metal accumulation in regions of interest in 161 men, including active and former welders.

Material and methods

We obtained data on the relaxation rates R1 and R2* in regions that included structures within the globus pallidus (GP), substantia nigra (SN), and white matter of the frontal lobe (FL) of both hemispheres, as well as Mn in whole blood (MnB), and serum ferritin (SF). The study subjects, all male, included 48 active and 20 former welders, 41 patients with Parkinson's disease (PD), 13 patients with hemochromatosis (HC), and 39 controls. Respirable Mn and Fe were measured during a working shift for welders. Mixed regression models were applied to estimate the effects of MnB and SF on R1 and R2*. Furthermore, we estimated the influence of airborne Mn and Fe on the relaxation rates in active welders.

Results

MnB and SF were significant predictors of R1 but not of R2* in the GP, and were marginally associated with R1 in the SN (SF) and FL (MnB). Being a welder or suffering from PD or HC elicited no additional group effect on R1 or R2* beyond the effects of MnB and SF. In active welders, shift concentrations of respirable Mn > 100 μg/m³ were associated with stronger R1 signals in the GP. In addition to the effects of MnB and SF, the welding technique had no further influence on R1.

Conclusions

MnB and SF were significant predictors of R1 but not of R2*, indicative of metal accumulation, especially in the GP. Also, high airborne Mn concentration was associated with higher R1 signals in this brain region. The negative results obtained for being a welder or for the techniques with higher exposure to ultrafine particles when the blood-borne concentration was included into the models indicate that airborne exposure to Mn may act mainly through MnB.

中文翻译：

---

锰和铁的暴露与弛豫率R1和R2 *的关联-来自WELDOX II研究的磁共振成像结果

客观的

磁共振成像是一种非侵入性方法，由于其顺磁性特征，可以间接量化大脑中锰（Mn）和铁（Fe）的积累。WELDOX II的研究旨在通过使用松弛率R1和R2 *作为161名男性（包括活动焊工和前焊工）感兴趣区域中金属积累的生物标志物，来探讨空气和全身性暴露于Mn和Fe对大脑沉积的影响。

材料与方法

我们获得了包括两个部位的苍白球（GP），黑质（SN）和额叶白质（FL）内的结构以及整个Mn在内的区域的弛豫率R1和R2 *的数据血液（MnB）和血清铁蛋白（SF）。研究对象均为男性，包括48名活跃焊工和20名以前的焊工，41名帕金森病（PD），13名血色素沉着病（HC）和39名对照。在焊接工人的工作班次中测量了可吸入的Mn和Fe。应用混合回归模型来评估MnB和SF对R1和R2 *的影响。此外，我们估算了空气中锰和铁对主动焊机松弛率的影响。

结果

MnB和SF是GP中R1的重要预测因子，而不是R2 *的重要预测因子，在SN（SF）和FL（MnB）中与R1的关联很小。作为焊工或患有PD或HC，除了MnB和SF的影响外，对R1或R2 *不会产生任何其他的基团影响。在主动焊机中，可吸入Mn的转移浓度> 100μg/ m ³与GP中更强的R1信号相关。除了MnB和SF的影响外，焊接技术对R1没有进一步的影响。

结论

MnB和SF是R1的重要预测因子，但不是R2 *的重要预测因子，表明金属积累，特别是在GP中。同样，高浓度的空气中锰与该大脑区域中较高的R1信号有关。当模型中包括血中浓度时，作为焊工或采用更高暴露于超细颗粒的技术所获得的负面结果表明，空气中暴露于Mn可能主要通过MnB起作用。