Pallidal Index Measured with Three-Dimensional T1-Weighted Gradient Echo Sequence is a Good Predictor of Manganese Exposure in Welders

Abstract

Purpose: To evaluate which T1-wieghted technique between 3D gradient-echo (FSPGR) and conventional spin-echo (SE) sequence is more sensitive predictor of neurobehavioral dysfunction found in welders with chronic manganese (Mn) acquired at 3 Tesla. Materials and Methods: Forty-three current male welders and 29 age- and gender-matched, nonwelding production workers (control individuals) were recruited to the present study. Each subject underwent neurological examination, blood sample collection, and neurobehavioral tests, in addition to magnetic resonance imaging (MRI) examination. The MRI examinations were performed using a 3.0 Tesla whole-body scanner. T1-weighted axial images were obtained using SE and FSPGR with a 180 inversion recovery prepared pulse, and the corresponding pallidal indices (PI), PI (SE), and PI (FSPGR), were calculated. Results: Both PI (SE) and PI (FSPGR) were well correlated with blood Mn level, but only PI (FSPGR) was significantly correlated with air Mn concentration (P ¼ 0.007). Of the neurobehavioral performance indicators, after controlling for covariates, PI (FSPGR) was significantly associated with cognitive components, such as the digit symbol score, the digit span backward score, the Stroop test score and also with the grooved pegboard (dominant hand) score, whereas PI (SE) was associated only with grooved pegboard (dominant hand) score. Conclusion: PI using a T1-weighted 3D FSPGR sequence shows the best correlation with neurobehavioral performance indicators and is the best measure for detection of blood and airborne Mn concentrations in welders exposed to excessive occupational Mn.