Giorgia Milotta1, Nadège Corbin1,2, Antoine Lutti3, Siawoosh Mohammadi4,5, and Martina Callaghan1
1Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, 2Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS/University Bordeaux, Bordeaux, France, 3Laboratory for Research in Neuroimaging, Department for Clinical Neuroscience, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, 4Department of Systems Neurosciences, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 5Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
1Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom, 2Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536, CNRS/University Bordeaux, Bordeaux, France, 3Laboratory for Research in Neuroimaging, Department for Clinical Neuroscience, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, 4Department of Systems Neurosciences, University Medical Center Hamburg-Eppendorf, Hamburg, Germany, 5Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
R2*
and T1 estimates depended not only on myelin-water fraction and
residency time, but also on the transmit field efficiency and the specifics of
the estimation. The assumption of a single compartment impacts both measures
leading to observable variance in simulation and in vivo.
Figure 2
– R2*(A) and T1 (B) estimates as function of residency
time (range 100-500ms) and fMW (range 2-20%) with fixed B1eff=100%.
R2* increases as fMW increases due to higher contribution
of the myelin-water compartment (short T2*) in the two-compartment
model. Similarly, a decrease in T1 is observed with increasing fMW
due to higher contribution of the myelin compartment (short T1). C)
Quantification of R2* and T1 variations as a function of
residency time and myelin water fraction.
Figure 3
– A) T1 dependence on B1eff for different residency times
(columns) and the three analysed strategies (rows). ESTATICS shows greater T1
variation for low residency time =100ms, whereas per contrast shows high T1
variation for long residency time = 500ms. B) T1 variation as
function of B1eff for different residency times.