Assessment of relative brain iron concentrations using T2‐weighted and T2*‐weighted MRI at 3 Tesla

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Abstract
In this paper a new method is presented for the relative assessment of brain iron concentrations based on the evaluation of T2 and T2* -weighted images. A multiecho sequence is employed for rapid measurement of T2 and T2*, enabling calculation of the line broadening effect ( T2′). Several groups have failed to show a correlation between T2 and brain iron content. However, quantification of T2′, and the associated relaxation rate R2′, may provide a more specific relative measure of brain iron concentration. This may find application in the study of brain diseases, which cause associated changes in brain iron levels. A new method of field inhomogeneity correction is presented that allows the separation of global and local field inhomogeneities, leading to more accurate T2* measurements and hence, T2′ values. The combination of T2*, and T2-weighted MRI methods enables the differentiation of Parlkinson's disease patients from normal age-matched controls based on differences in iron content within the substantia nigra.