Susceptibility Contrast in High Field MRI of Human Brain as a Function of Tissue Iron Content

By B. Yao, Tie-Qiang Li, P. Gelderen, K. Shmueli, J. D. Zwart, Jeff H. Duyn. NeuroImage, 2008

321 citations recorded by the source corpus.

Magnetic susceptibility provides an important contrast mechanism for MRI. Increasingly, susceptibility-based contrast is being exploited to investigate brain tissue microstructure and to detect abnormal levels of brain iron as these have been implicated in a variety of neuro-degenerative diseases. However, it remains unclear to what extent magnetic susceptibility-related contrast at high field relates to actual brain iron concentrations. In this study, we performed susceptibility weighted imaging as a function of field strength on healthy brains in vivo and post-mortem brain tissues at 1.5T, 3T and 7T. Iron histology was performed on the tissue samples for comparison. The calculated susceptibility-related parameters R2* and signal frequency shift in four iron-rich regions (putamen, globus pallidus, caudate, and thalamus) showed an almost linear dependence (r=0.90 for R2*; r=0.83 for phase, p<0.01) on field strength, suggesting that potential ferritin saturation effects are not relevant to susceptibility-weighted contrast for field strengths up to 7T. The R2* dependence on the putative (literature-based) iron concentration was 0.048 Hz/Tesla/ppm. The histological data from brain samples confirmed the linear dependence of R2* on field strength and showed a slope against iron concentration of 0.0099 Hz/Tesla/ppm dry-weight, which is equivalent to 0.05 Hz/Tesla/ppm wet-weight and closely matched the calculated value in vivo. These results confirm the validity of using susceptibility-weighted contrast as an indicator of iron content in iron-rich brain regions. The absence of saturation effects opens the way to exploit the benefits of MRI at high field strengths for the detection of iron distributions with high sensitivity and resolution.

Subfields: Radiology, Nuclear Medicine and Imaging

View Paper: https://www.semanticscholar.org/paper/c9a5e44f5e6a4f73ae8112393b0e8034417c0df0

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In Radiology, Nuclear Medicine and Imaging

Citations in the corpus

Myelin and iron concentration in the human brain: A quantitative study of MRI contrast (2014, background): “Recently themain focus has shifted to susceptibility weighted imaging (Duyn, 2010; Li et al., 2011; Yao et al., 2009) and thence to quantitative susceptibility mapping (QSM), which is better able to visualize the iron distribution in brain tissue (Langkammer et al.”
Quantitative imaging of intrinsic magnetic tissue properties using MRI signal phase: An approach to in vivo brain iron metabolism? (2011, result): “This finding is in agreement with recent results by Yao et al. (2009), who suppressed external contributions by fitting 2D polynomials on a slice-by-slice basis to unwrapped phase data.”
Toward in vivo histology: A comparison of quantitative susceptibility mapping (QSM) with magnitude-, phase-, and R2⁎-imaging at ultra-high magnetic field strength (2013, unknown): “R2⁎ values of selected structures (head of caudate nucleus, putamen, globus pallidus, thalamus) are in good agreement with literature values (Peters et al., 2007; Yao et al., 2009).”