[Variations of brain magnetic resonance imaging among manganese-exposed workers].
OBJECTIVE
Variations of the signal intensities in the magnetic resonance (MR) T(1)-weighted image (T(1)WI) of globus pallidus among manganese(Mn)-exposed workers were explored to provide a scientific basis for exposed biomarker of manganese-injured central nervous system (CNS).


METHODS
The brain MR T(1) and T(2) WI in eighteen male asymptomatic Mn-exposed, eight manganism and nine healthy control workers were examined routinely by adopting a 1.5 Tesla signal superconducting system. The SIGP and the signal intensity in frontal white matter (SIFWM) in the same side were determined, then pallidal index (PI) was calculated. Concentration of MnO(2) in workplaces and content of manganese in red blood cell (MnRBC) among workers were respectively determined by flame atomic absorption spectrometer (AAS) and inductively coupled plasma-atomic emission spectrophotometry (ICP-AES). The follow-up investigation in the eight high Mn-exposed workers was made one year later.


RESULTS
The results showed that the median of air MnO(2) in smelting workplace was 0.64 mg/m(3)(0.07 - 5.40 mg/m(3)), which were respective 0.56 mg/m(3)(0.09 - 1.71 mg/m(3)) in power distribution room (low Mn-exposure) and 0.89 mg/m(3) (0.07 - 5.40 mg/m(3)) in furnace (high Mn-exposure). PI in the Mn-exposed and high Mn-exposed workers were both higher than those of the manganism and control workers(116.4 +/- 8.2, 119.0 +/- 7.9, 105.3 +/- 8.4 and 102.2 +/- 1.5, respectively. Mn vs control, t' = 7.146, P = 0.000; Mn vs manganism, t = 3.181, P = 0.004. High Mn-exposure vs control, t' = 7.446, P = 0.000; high Mn-exposure vs manganism, t = 3.763, P = 0.001). The increased signal in T(1)WI of globus pallidus was observed in Mn-exposed workers, especially in high Mn-exposed workers. The content of manganese in red blood cell of Mn-exposed and control workers was significantly higher than those of the manganism workers [(151.6 +/- 40.5) ng/ml, (149.2 +/- 21.3) ng/ml, (154.5 +/- 46.6) ng/ml, (144.4 +/- 14.2) ng/ml, (20.8 +/- 7.4) ng/ml respectively. The difference was significant in statistics. Manganism vs control, t = 20.206, P = 0.000; manganism vs Mn, t' = 13.144, P = 0.000; manganism vs low and high Mn, t' = 12.964, 9.957, respectively, P = 0.000]. Only a decreased median of air MnO(2) in furnace was found one year later (0.89, 0.31 mg/m(3), Z = -2.142, P = 0.032). The difference was significant in statistics.


CONCLUSIONS
Our data suggests that SIGP of MR T(1)WI among workers was obviously increased by manganese-exposure. PI may be taken as the signal of CNS injury which was induced by manganese-exposure.
Guangxi Institute for Occupational Disease Prevention and Treatment, Nanning, China.
Wei-ping
WP
Qin
Xue
X
Fu
Yue-ming
YM
Jiang
Li-ling
LL
Long
Xiang-rong
XR
Li
Hai-bin
HB
Chen
Zhi-bi
ZB
Huang
Wei-jia
WJ
Zhao
Xue-an
XA
Mo
Wei
W
Zheng
D000328:Adult; D000395:Air Pollutants, Occupational / Q000032:analysis*; D016022:Case-Control Studies; D005917:Globus Pallidus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020149:Manganese Poisoning / Q000473:pathology*; D008875:Middle Aged; D016273:Occupational Exposure
D000395:Air Pollutants, Occupational