Imaging Modalities for Manganese Toxicity

Abstract

Rapidly advancing imaging technology has been essential to the study of manganese (Mn) toxicity in vivo. Over the past few decades, imaging techniques have been effectively utilized as markers of Mn exposure and to investigate the biological effects of Mn neurotoxicity. This chapter will review several of the imaging modalities that have made an impact in Mn neurotoxicity research. The scope of this chapter will include discussions of magnetic resonance imaging (MRI), including magnetic resonance spectroscopy (MRS), diffusion weighted imaging (DWI), and functional MRI (fMRI), as well as positron emission tomography (PET), single photon emission computed tomography (SPECT), and X-ray fluorescence imaging. For each modality, the basic principle of the imaging technique will be briefly described to facilitate proper data interpretation and understanding of limitations. This will be followed by a discussion on the main research findings using that modality, and how they have shaped our understanding of Mn toxicity.

Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection

“…More importantly, the pharmacokinetic washout rates of nanoparticle agents are slow, often taking more than 24 h for adequate clearance. This raises major concerns regarding toxicity, especially for agents that contain Gd 3+ or Mn 2+ ions, or iron-based particles other than iron oxides, each of which has shown longer-term toxic effects (24, 25). Furthermore, the current contrast agents that are approved by the Food and Drug Administration for pharmacokinetics studies already satisfy clinical needs, which provides little motivation to invest efforts to create new T 1 MRI contrast agents for pharmacokinetics studies.…”

Pre-cleaning of hair is not beneficial in LA-ICP-MS studies of chronic metal exposure

“…Chronic exposure to toxic elements is a serious health concern [1,2], but population-wide monitoring of individual exposures is costly and logistically challenging-particularly for common sampling mediums of blood and urine [3,4]. Hair samples provide a useful screening tool for assessing metal exposure because collection of hair is quick and non-invasive, modern technologies can make assessment affordable, and the highly stable matrix of hair requires only basic storage conditions [3,[5][6][7][8].…”

Association of MRI T1 relaxation time with neuropsychological test performance in manganese- exposed welders

“…Few studies to date have examined whether and how neuropsychological impairments are associated with Mn deposition in several specific regions of interest (ROI) in the human brain (Schneider et al, 2006; 2013; 2015). T1-weighted magnetic resonance imaging (MRI) has been suggested as a non-invasive tool to reflect increased brain Mn levels due to Mn exposure both in humans (Dydak and Criswell, 2015, Eriksson et al, 1992, Nelson et al, 1993, Newland et al, 1989) and non-human primates (Burton and Guilarte, 2009, Dorman et al, 2006, Guilarte, 2013, Schneider, Williams, 2015). The MRI signal intensity increases due to the Mn ion's paramagnetic properties, which creates a shortening of the T1 relaxation time (Dydak and Criswell, 2015).…”

“…T1-weighted magnetic resonance imaging (MRI) has been suggested as a non-invasive tool to reflect increased brain Mn levels due to Mn exposure both in humans (Dydak and Criswell, 2015, Eriksson et al, 1992, Nelson et al, 1993, Newland et al, 1989) and non-human primates (Burton and Guilarte, 2009, Dorman et al, 2006, Guilarte, 2013, Schneider, Williams, 2015). The MRI signal intensity increases due to the Mn ion's paramagnetic properties, which creates a shortening of the T1 relaxation time (Dydak and Criswell, 2015). Mn exposure has been found to lower the T1 relaxation time in the brain, primarily in the basal ganglia; with visible MRI signal changes in the globus pallidus (Criswell et al, 2012, Kim et al, 1999).…”