Ex vivo magnetic resonance imaging in South African manganese mine workers.
BACKGROUND
Manganese (Mn) exposure is associated with increased T1-weighted magnetic resonance imaging (MRI) signal in the basal ganglia. T1 signal intensity has been correlated with occupational Mn exposure but not with clinical symptomatology or neuropathology.


OBJECTIVE
This study investigated predictors of ex vivo T1 MRI basal ganglia signal intensity in neuropathologic tissue obtained from deceased South African mine workers.


METHODS
A 3.0 T MRI was performed on ex vivo brain tissue obtained from 19 Mn mine workers and 10 race- and sex-matched mine workers of other commodities. Basal ganglia regions of interest were identified for each subject with T1-weighted intensity indices generated for each region. In a pathology subset, regional T1 indices were compared to neuronal and glial cell density and tissue metal concentrations.


RESULTS
Intensity indices were higher in Mn mine workers than non-Mn mine workers for the globus pallidus, caudate, anterior putamen, and posterior putamen with the highest values in subjects with the longest cumulative Mn exposure. Intensity indices were inversely correlated with the neuronal cell density in the caudate (p=0.040) and putamen (p=0.050). Tissue Mn concentrations were similar in Mn and non-Mn mine workers. Tissue iron (Fe) concentration trended lower across all regions in Mn mine workers.


CONCLUSIONS
Mn mine workers demonstrated elevated basal ganglia T1 indices when compared to non-Mn mine workers. Predictors of ex vivo T1 MRI signal intensity in Mn mine workers include duration of Mn exposure and neuronal density.
Department of Neurology, Washington University School of Medicine, 660 South Euclid Ave., Box 8111, St. Louis, MO 63110, USA. Electronic address: criswells@neuro.wustl.edu.
Susan R
SR
Criswell
School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews Rd, Parktown 2193, South Africa.
Gill
G
Nelson
Department of Pathology, University of Washington, UW Medicine Pathology, Box 357470, Seattle, WA 98195-7470, USA.
Luis F
LF
Gonzalez-Cuyar
Program in Physical Therapy, Washington University School of Medicine, 4444 Forest Park Ave., Suite 1101, Box 8502, St. Louis, MO 63108, USA.
John
J
Huang
Department of Radiology, Washington University School of Medicine, 660 South Euclid Ave., Box 8131, St. Louis, MO 63110, USA.
Joshua S
JS
Shimony
Department of Family Medicine and Public Health, UC San Diego School of Medicine, 9500 Gilman Drive-0628, La Jolla, CA 92093-0628, USA.
Harvey
H
Checkoway
Department of Environmental and Occupational Health Sciences, University of Washington, School of Public Health Box 357234, Seattle, WA 98195-7234, USA.
Christopher D
CD
Simpson
Department of Environmental and Occupational Health Sciences, University of Washington, School of Public Health Box 357234, Seattle, WA 98195-7234, USA.
Russell
R
Dills
Department of Environmental and Occupational Health Sciences, University of Washington, School of Public Health Box 357234, Seattle, WA 98195-7234, USA.
Noah S
NS
Seixas
Department of Neurology, Washington University School of Medicine, 660 South Euclid Ave., Box 8111, St. Louis, MO 63110, USA; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 27 St Andrews Rd, Parktown 2193, South Africa.
Brad A
BA
Racette
D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D001479:Basal Ganglia / Q000378:metabolism / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D020149:Manganese Poisoning / Q000453:epidemiology / Q000473:pathology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008875:Middle Aged; D000067572:Miners; D013019:South Africa / Q000453:epidemiology; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D005904:Glial Fibrillary Acidic Protein; D008869:Microtubule-Associated Proteins; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C489788:MAP2 protein, human
Ex vivo; MRI; Manganese; Miners