Measuring iron in the brain using quantitative susceptibility mapping and X-ray fluorescence imaging

Abstract

Measuring iron content in the brain has important implications for a number of neurodegenerative diseases. Quantitative susceptibility mapping (QSM), derived from magnetic resonance images, has been used to measure total iron content in vivo and in post mortem brain. In this paper, we show how magnetic susceptibility from QSM correlates with total iron content measured by X-ray fluorescence (XRF) imaging and by inductively coupled plasma mass spectrometry (ICPMS). The relationship between susceptibility and ferritin iron was estimated at 1.10 ± 0.08 ppb susceptibility per μg iron/g wet tissue, similar to that of iron in fixed (frozen/thawed) cadaveric brain and previously published data from unfixed brains. We conclude that magnetic susceptibility can provide a direct and reliable quantitative measurement of iron content and that it can be used clinically at least in regions with high iron content.

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

“…QSM provides a quantitative and local anatomical contrast by estimating magnetic susceptibility sources from their signature on the MRI signal phase (de Rochefort et al, 2008). QSM results have shown agreement with both post-mortem iron measurements (Langkammer et al, 2012;Sun et al, 2015;Zheng et al, 2013) and additional iron-sensitive MRI techniques (Bilgic et al, 2012;Poynton et al, 2015). Furthermore, at ultra high-field strength (B0≥7 Tesla), QSM has demonstrated superb anatomical contrast and superior delineation of GM substructures compared to R2* and conventional iron-sensitive measures (Deistung et al, 2013;Lotfipour et al, 2012).…”

MR Quantitative Susceptibility Imaging for the Evaluation of Iron Loading in the Brains of Patients with -Thalassemia Major

“…[9][10][11] QSM has been successfully applied in multiple sclerosis, Parkinson disease, and so forth. A recent study 14 has also established positive correlation between magnetic susceptibility values measured by use of QSM and iron content measured by x-ray fluorescence imaging and inductively coupled plasma mass spectrometry. In the present study, we quantified the brain iron content in a cohort of patients with ␤-thalassemia major and compared this with healthy age-matched subjects.…”

Contribution of metals to brain MR signal intensity: review articles

“…A hyperintense lesion is present in the globus pallidus (white arrow) on sagittal T1WI due to manganese deposition and a low signal intensity on T2WI [55][56][57][58]. As the correlation between the iron content and T2WI is questionable, T2*-weighted imaging [59], susceptibility-weighted imaging [60], and quantitative susceptibility mapping [61,62] have been tested as methods of estimating the iron content. While the iron content can indeed by estimated more accurately with MRI using these techniques, the paramagnetic effects caused by other elements still affect such measurements.…”