Aims and objectives
The study is part of a larger research project aimed at investigating the long-term effects of environmental exposure to manganese (Mn)  through morphological and functional MR imaging.
As the globus pallidus (GP) is reported to be the target tissue for brain Mn deposition,
causing abnormal MR signal decay ,
the GP relaxation times,
and particularly T1,
may represent non-invasive biomarkers to be used for further analysis,
given that a good accuracy and reproducibility of the in-vivo...
Methods and materials
A homogeneous spherical phantom filled with a paramagnetic solution (NiSO 4 ) and 10 healthy subjects were scanned with a 3T MAGNETOM Skyra system (Siemens Healthcare,
Germany) and a 64-channel head coil,
using the same acquisition protocol which is detailed in Table 1. TABLE 1: ACQUISITION PARAMETERS WB VIBE VIBE B1 MAP GRAPPATINI 3D MPRAGE FOV (mm) 230*230 230*230 230*230 230*216 230*230 VOXEL SIZE (mm) 1.8*1.8*3 1.8*1.8*3 1.8*1.8*7.5 1.2*1.2*4 0.9*0.9*0.9 TR (ms) /TE(ms)...
The GP spatial variability summary is reported in Table 2,
where each column refers to a distribution of 20 ROIs measurements (left and right GP ROIs from 10 subjects).
The median over the 10 subjects was 4.50% for T1 and 12.36% for T2.
uniformity was much better: in the ‘phantom-GP’,
it exhibited 0.96% for T1 and 0.37% for T2.
The phantom global uniformity was 3.93% for T1 and 1.89% for T2. TABLE 2: GLOBUS PALLIDUS RELAXATION TIMES UNIFORMITY * PATIENT GP 'PHANTOM' GP T1 CV (%)...
the phantom uniformity is higher than what is seen in vivo,
even for the estimated global uniformity.
Given the homogeneous distribution in phantom scans,
a large part of the inhomogeneity seems to stem from the tissue microstructure.
Another technical influence,
particularly for T2 evaluations,
could be partial volume effects due to the 2D nature of the T2 acquisition; this will be further investigated.
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 Lucchini R,
Zoni S et al.
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JS et al (1999) Increase in signal intensities on T1 weighted magnetic resonance images in asymptomatic manganese-exposed workers.
Neurotoxicology 20:901-907  Hilbert T,
Weiland E et al (2018) Accelerated T 2 mapping combining parallel MRI and model-based reconstruction:...