title: Magnetic susceptibility in the deep layers of the primary motor cortex in Amyotrophic Lateral Sclerosis.
abstract: Amyotrophic Lateral Sclerosis (ALS) is a progressive neurological disorder that entails degeneration of both upper and lower motor neurons. The primary motor cortex (M1) in patients with upper motor neuron (UMN) impairment is pronouncedly hypointense in Magnetic Resonance (MR) T2* contrast. In the present study, 3D gradient-recalled multi-echo sequences were used on a 7 Tesla MR system to acquire T2*-weighted images targeting M1 at high spatial resolution. MR raw data were used for Quantitative Susceptibility Mapping (QSM). Measures of magnetic susceptibility correlated with the expected concentration of non-heme iron in different regions of the cerebral cortex in healthy subjects. In ALS patients, significant increases in magnetic susceptibility co-localized with the T2* hypointensity observed in the middle and deep layers of M1. The magnetic susceptibility, hence iron concentration, of the deep cortical layers of patients' M1 subregions corresponding to Penfield's areas of the hand and foot in both hemispheres significantly correlated with the clinical scores of UMN impairment of the corresponding limbs. QSM therefore reflects the presence of iron deposits related to neuroinflammatory reaction and cortical microgliosis, and might prove useful in estimating M1 iron concentration, as a possible radiological sign of severe UMN burden in ALS patients.
authors.affiliation: Imago7 Research Foundation, Pisa, Italy; Laboratory of Medical Physics and Biotechnologies for Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Costagli
authors.affiliation: Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Donatelli
authors.affiliation: Laboratory of Medical Physics and Biotechnologies for Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Biagi
authors.affiliation: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Caldarazzo Ienco
authors.affiliation: Neurology Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Siciliano
authors.affiliation: Imago7 Research Foundation, Pisa, Italy; Laboratory of Medical Physics and Biotechnologies for Magnetic Resonance, IRCCS Stella Maris, Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Tosetti
authors.affiliation: Imago7 Research Foundation, Pisa, Italy; Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cosottini
mesh_terms: D000368:Aged; D000690:Amyotrophic Lateral Sclerosis / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D007501:Iron / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009044:Motor Cortex / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology
chemical_list: D007501:Iron