Keywords:
CNS, Neuroradiology brain, MR, Imaging sequences, Normal variants, Experimental investigations
Authors:
Y. Xing, S. Abdul, R. Dineen, D. Auer; Nottingham/UK
DOI:
10.1594/ecr2018/C-3031
Aims and objectives
Neuromelanin (NM) is a dark pigmented granule preferentially found in catecholaminergic neurons,
such as the substantia nigra (SN) and locus coeruleus (LC).
NM acts as a scavenger that removes excess of potentially toxic substances.
Given this capacity,
NM may be neuroprotective [2] but when released from degenerating neurons may also induce immune-based pathogenic mechanisms and trigger neurodegeneration [3,4].
Parkinson’s disease (PD) has been hypothesised to result from accelerated aging due to exacerbation of oxidative stress in the SN in addition to environmental toxins in which NM plays an essential and catalytic role [5].
Across the human lifespan,
previous histological studies found NM in human SN at around the age of 2-3 years with accumulation but the change over age was inconsistent [6-11].
The preclinical evidence based on animal studies is very limited since NM is hardly expressed in non-primate brains [12].
Using NM-sensitive MRI,
an early in vivo MRI study suggested a non-linear age-effect for the human LC [13].
However,
in vivo charactersiation of the physiological changes of NM-related signal in the SN and its subregions during brain development and age-related degeneration are lacking.
This study aims to investigate the age-related NM signal variation in the SN as well as other physiological factors using optimised neuromelanin-sensitive MRI in a comprehensive lifespan sample.