Volume and iron content in basal ganglia and thalamus

Abstract

Magnetic resonance imaging (MRI) studies have highlighted the possibility to investigate brain iron content in vivo. In this study, we combined T2* relaxometry and automatic segmentation of basal ganglia based on T1-weighted images in healthy subjects, with the aim of characterizing age related changes in volume and iron-related relaxivity values (R2*) of these structures. Thirty healthy subjects underwent MR imaging at 3 Tesla. Mean R2* values and volumes were calculated for the selected subcortical structures (pallidum, putamen, thalamus and caudate nucleus). Our results showed a correlation between R2* values and iron concentration as calculated from published post-mortem data. Furthermore, we observed a shrinkage/iron increase with a different pattern in the anatomical regions selected in this work, suggesting that the age-related changes on these MR parameters are specific to the subcortical structure considered. In particular, the putamen demonstrated a decrease of volume and an increase of iron level, with the posterior region of this structure appearing more disposed to iron deposition. Our work suggests that combining volumetry and iron estimation in MRI permits to investigate in vivo neurophysiological and neuropathological changes of basal ganglia.

High-resolution characterisation of the aging brain using simultaneous quantitative susceptibility mapping (QSM) and R2* measurements at 7 T

“…In contrast, the GP result with QSM, whilst rich in iron in absolute terms, did not demonstrate an age-related increase. The high R2* values for the GP (independent of age) in contrast to thalamus, caudate and putamen are consistent with previous in vivo R2* reports and post-mortem correlations with iron concentration (Gelman et al, 1999;Langkammer et al, 2010;Péran et al, 2009;Yao et al, 2009). Furthermore, agerelated increase in R2* have been reported previously in the GP in some studies (Callaghan et al, 2014;Draganski et al, 2011).…”

“…To date, the T2* transverse relaxation time, or its inverse rate, R2* (=1/T2*), has been routinely utilised as a surrogate marker to assess brain iron deposition with both in vivo (Gelman et al, 1999;Péran et al, 2009;Yao et al, 2009) and post mortem data (Langkammer et al, 2010), demonstrating a linear relationship between R2* and iron concentration in deep grey matter (GM). R2*, however, is known to be a composite measure sensitive to T2/diffusion effects and magnetic field inhomogeneities.…”

Longitudinal profile of iron accumulation in good‐grade subarachnoid hemorrhage

“…The location of iron accumulation was further associated with microstructural axonal damage. Recently, several studies reported a linear relationship between transverse magnetic resonance relaxation rates and iron content in healthy subjects and postmortem tissue, indicating that R2* imaging is a good surrogate for detecting cerebral iron accumulations 25, 26, 27. By a rater‐driven approach, T2*‐weighted imaging of SAH patients in their chronic stage allowed to identify signal alterations within the subarachnoid space even years after the onset 28, 29, 30.…”

The Corticospinal Tract in Huntington's Disease

“…T 2 *-Weighted Images Processing T 2 *-weighted volumes were post processed according to previously published methods Peran et al 2009). Briefly, the 6 T 2 *-weighted volumes were averaged to generate a mean T 2 *-weighted volume.…”