Increase in signal intensities on T1-weighted magnetic resonance images in asymptomatic manganese-exposed workers.
OBJECTIVE
To clarify the clinical significance of increased signal intensities on T1 weighted magnetic resonance imaging (MRI) we performed a large-scale epidemiological study on asymptomatic manganese (Mn)-exposed workers with its focus on MRI.


METHODS
We randomly selected 121 male workers out of a total of 750 workers including Mn-exposed, non-exposed manual, and non-exposed clerical workers in the factories. We studied environmental and biological monitoring, neurological examination, and MRI.


RESULTS
The proportion of workers with increased signal intensities among the exposed, the non-exposed manual workers, and the non-exposed clerical workers was 46.1%, 18.8%, and 0%, respectively. Especially, 73.5% of the welders showed increased signal intensities. In no subject, were clinical signs of manganism observed. The pallidal index correlated with blood Mn concentration.


CONCLUSIONS
Increase in signal intensities on the T1-weighted image reflect recent exposure to Mn, but not necessarily manganism. At which increase of signal intensity, the progression of manganism from Mn exposure occurs, remains to be solved.
Kim
Y
Y
Department of Occupational and Environmental Medicine, Ulsan University Hospital, Dong-ku, South Korea. yanghokm@nuri.net
Kim
K S
KS
Yang
J S
JS
Park
I J
IJ
Kim
E
E
Jin
Y
Y
Kwon
K R
KR
Chang
K H
KH
Kim
J W
JW
Park
S H
SH
Lim
H S
HS
Cheong
H K
HK
Shin
Y C
YC
Park
J
J
Moon
Y
Y
D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D007723:Korea; D008279:Magnetic Resonance Imaging; D008297:Male; D008345:Manganese / Q000097:blood*; D020149:Manganese Poisoning / Q000209:etiology / Q000473:pathology*; D016273:Occupational Exposure / Q000009:adverse effects*; D015398:Signal Transduction / Q000187:drug effects*; D011795:Surveys and Questionnaires
D008345:Manganese