Assessment of brain iron and neuronal integrity in patients with Parkinson's disease using novel MRI contrasts.

Full Abstract

Postmortem demonstration of increased iron in the substantia nigra (SN) is a well-appreciated finding in Parkinson's disease (PD). Iron facilitates generation of free radicals, which are thought to play a role in dopamine neuronal loss. To date, however, magnetic resonance imaging (MRI) has failed to show significant in vivo differences in SN iron levels in subjects with PD versus control subjects. This finding may be due to the limitations in tissue contrasts achievable with conventional T(1)- and T(2)-weighted MRI sequences that have been used. With the recent development of novel rotating frame transverse (T(2rho)) and longitudinal (T(1rho)) relaxation MRI methods that appear to be sensitive to iron and neuronal loss, respectively, we embarked on a study of 8 individuals with PD (Hoehn & Yahr, Stage II) and 8 age-matched control subjects. Using these techniques with a 4T MRI magnet, we assessed iron deposits and neuronal integrity in the SN. First, T(2rho) MRI, which is reflective of iron-related dynamic dephasing mechanisms (e.g., chemical exchange and diffusion in the locally different magnetic susceptibilities), demonstrated a statistically significant difference between the PD and control group, while routine T(2) MRI did not. Second, T(1rho) measurements, which appear to reflect upon neuronal count, indicated neuronal loss in the SN in PD. We show here that sub-millimeter resolution T(1rho) and T(2rho) MRI relaxation methods can provide a noninvasive measure of iron content as well as evidence of neuronal loss in the midbrain of patients with PD.

Author information

Author/s: Michaeli, Shalom (S); Oz, Gülin (G); Sorce, Dennis J (DJ); Garwood, Michael (M); Ugurbil, Kamil (K); Majestic, Stacy (S); Tuite, Paul (P);

Affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA. shalom(-atsign-)cmrr.umn.edu

Grants: CA92004 (Agency:NCI NIH HHS) ; EB 00422 (Agency:NIBIB NIH HHS) ; NS 40801 (Agency:NINDS NIH HHS) ; RR08079 (Agency:NCRR NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Movement disorders : official journal of the Movement Disorder Society (Mov Disord), published in United States. (Language: eng)

Reference: 2007-Feb; vol 22 (issue 3) : pp 334-40

Dates: Created 2007/03/06; Completed 2007/05/01; Revised 2007/12/03;

PMID: 17149719, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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