Karin Shmueli1, Peter van Gelderen1, Brian Yao1, Jacco A. de Zwart1, Masaki Fukunaga1, Jeff H. Duyn1
1Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
Interpretation of phase images is confounded by the dependence of the contrast on the tissue orientation relative to the main magnetic field (B0). To mitigate this, inverse Fourier methods have been proposed to reconstruct the underlying tissue magnetic susceptibility from the phase data. To evaluate this approach, we assessed the similarity of susceptibility maps calculated from phase images of human brain sections acquired at 0 and 90 relative to B0. The phase contrast was often reversed by rotation whereas the susceptibility maps were mostly unaffected. This demonstrates that the susceptibility calculation overcomes the strong orientation dependence of the phase contrast.