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Updated: Dec 10, 2025
Functional Neuroimaging Using Ultrasonic Blood-brain Barrier Disruption and Manganese-enhanced MRI
Published on: July 12, 2012
Whole-brain R1 predicts manganese exposure and biological effects in welders
David A Edmondson1,2,3, Chien-Lin Yeh1,2, Sébastien Hélie4
1School of Health Sciences, Purdue University, 550 Stadium Dr., Hampton Hall of Civil Engineering, West Lafayette, IN, 47907, USA.
Abstract:
Manganese (Mn) is a neurotoxicant that, due to its paramagnetic property, also functions as a magnetic resonance imaging (MRI) T1 contrast agent. Previous studies in Mn toxicity have shown that Mn accumulates in the brain, which may lead to parkinsonian symptoms. In this article, we trained support vector machines (SVM) using whole-brain R1 (R1 = 1/T1) maps from 57 welders and 32 controls to classify subjects based on their air Mn concentration ([Mn]Air), Mn brain accumulation (ExMnBrain), gross motor dysfunction (UPDRS), thalamic GABA concentration (GABAThal), and total years welding. R1 was highly predictive of [Mn]Air above a threshold of 0.20 mg/m3 with an accuracy of 88.8% and recall of 88.9%. R1 was also predictive of subjects with GABAThal having less than or equal to 2.6 mM with an accuracy of 82% and recall of 78.9%. Finally, we used an SVM to predict age as a method of verifying that the results could be attributed to Mn exposure. We found that R1 was predictive of age below 48 years of age with accuracies ranging between 75 and 82% with recall between 94.7% and 76.9% but was not predictive above 48 years of age. Together, this suggests that lower levels of exposure (< 0.20 mg/m3 and < 18 years of welding on the job) do not produce discernable signatures, whereas higher air exposures and subjects with more total years welding produce signatures in the brain that are readily identifiable using SVM.
Insights
Manganese (Mn) brain accumulation, detected by MRI R1 maps, accurately predicts high air Mn concentration and years welding. Lower exposures show no clear brain signature.
Area of Science:
- Neuroscience
- Radiology
- Occupational Health
Background:
- Manganese (Mn) is a neurotoxicant and a paramagnetic substance used as an MRI T1 contrast agent.
- Mn accumulation in the brain is linked to neurological disorders, including parkinsonian symptoms.
Purpose of the Study:
- To investigate the relationship between manganese exposure, brain manganese accumulation, and neurological indicators using machine learning.
- To determine if MRI R1 maps can identify individuals with higher manganese exposure and associated neurological changes.
Main Methods:
- Support vector machines (SVM) were trained using whole-brain R1 maps from 57 welders and 32 controls.
- Classification was based on air Mn concentration ([Mn]Air), brain Mn accumulation (ExMnBrain), motor dysfunction (UPDRS), and thalamic GABA concentration (GABAThal).
- SVM was also used to predict age to validate results against Mn exposure.
Main Results:
- R1 maps accurately predicted air Mn concentration above 0.20 mg/m³ (88.8% accuracy, 88.9% recall).
- R1 predicted lower thalamic GABA concentrations (≤ 2.6 mM) with 82% accuracy and 78.9% recall.
- R1 predicted age below 48 years (75-82% accuracy) but not above, suggesting Mn-specific signatures are linked to cumulative exposure.
Conclusions:
- Higher manganese air exposures and longer welding durations result in identifiable brain signatures detectable by SVM using R1 maps.
- Lower levels of manganese exposure (< 0.20 mg/m³ and < 18 years welding) do not produce discernible brain signatures.
- MRI R1 mapping combined with SVM is a promising tool for assessing occupational manganese exposure and its neurological impact.
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