Kieran O'Brien1,
Gunnar Krueger2, 3, Franois Lazeyras1, Rolf
Gruetter, 14, Alexis Roche2, 5
1CIBM,
University of Geneva, Geneva, Switzerland; 2Advanced Clinical
Imaging Technology, Siemens Healthcare IM S AW, Lausanne, Switzerland; 3CIBM,
Ecole Polytechnique Fdrale de Lausanne & University of Lausanne,
Lausanne, Switzerland; 4CIBM, cole Polytechnique Fdrale de
Lausanne, Lausanne, Switzerland; 5CIBM, CHUV, Lausanne,
Switzerland
MP2RAGE provides a self-bias corrected image by taking the image ratio of two image volumes; however due to the inherent numerical instability of a ratio calculation, this causes the signal to diverge when low and the noise in the ratio image to be amplified. To remove the numerical instability we modified the image ratio calculation with a tunable parameter, gamma, that can be optimized for individual data sets to suppress noise without affecting voxels with signal. When applied to MP2RAGE scans, the ratio results in customary T1w images.