Neuroimaging in Manganese-Induced Parkinsonism

Over the last 20 years, the impact of imaging on the clinical sciences has been immense. Tremendous progress has been made in medical imaging of the human body since the invention of computed tomography (CT) and magnetic resonance imaging (MRI). Neuroimaging of patients with metal neurotoxicity can be divided into two types: morphological neuroimaging (anatomy-based imaging) including CT and MRI; and functional neuroimaging (physiology-based imaging) such as magnetic resonance spectroscopy (MRS), single-photon emission computed tomography (SPECT), positron emission tomography (PET), diffusion tensor imaging (DTI), and functional MRI (fMRI). Neuroimaging is undergoing a shift from morphological to functional imaging as new technologies are introduced and technical problems associated with the local production of radioisotopes are solved (Lang, 2000; Walker et al., 2004). MRI, PET, and SPECT have been used for 10 years or more to evaluate workers exposed to manganese (Mn), and to examine the neurological consequences of such exposure. Very recently, functional neuroimaging modalities such as fMRI, MRS, and DTI have been applied to this end. The objectives of this chapter are (1) to review the use of neuroimaging in Mn-induced parkinsonism, and (2) to discuss recent developments in the functional neuroimaging in Mn-induced parkinsonism.