P317: Whole-brain pattern of iron-aware tissue magnetostaticsin amyotrophic lateral sclerosis

The aim of the study was to determine the whole-brain landscape ofmagnetostatic alterations in amyotrophic lateral sclerosis (ALS) withthe new iron-sensitive MRI contrast, namely quantitative susceptibil-ity mapping (QSM). N = 28 patients with classic (Charcot) ALSwithout dementia (age = 61  10 y.o., disease dura-tion = 18  12 months, ALSFRS-R = 38  6) and N = 39tightly-matched controls (age = 61  11 y.o.) were recruited. AllMRI measurements were performed in a Siemens Verio 3T scanner.Susceptibility-weighted MRI signals were reconstructed, post-processed and analysed using state-of-the-art quantitative methods(Acosta-Cabronero et al. J Neurosci 2016; 36:364). QSM identifiedin vivo evidence for metal (almost certainly iron) accumulation in ALSin the primary motor cortex, corticospinal tract, posterior corpusstriatum, mesencephalic nuclei and lateral prefrontal cortex (PFC).Notably the results suggest pathological accumulation in the primarymotor cortex and globus pallidus, which could be contributing to atoxic insult; whereas increased susceptibility effects in the putamen,substantia nigra and red nucleus appear to be common to a range ofdegenerative states, as we have previously observed them inAlzheimer’s (putamen only, Acosta-Cabronero et al. Plos One2013; 8:e81093) and in normal aging (Acosta-Cabronero et al.2016). The primary motor and corticospinal changes appear unique toALS in contrast to the disorders thus far examined with QSM and,obviously, are strongly coherent with the known degeneration of thisdisease. The lateral PFC abnormality is intriguing and possibly pointsto a bridge between ALS and the comorbid risk of frontotemporaldementia—a hypothesis that warrants further investigation