A General Linear Relaxometry Model of R-1 Using Imaging Data

作者：Callaghan Martina F^*; Helms Gunther; Lutti Antoine; Mohammadi Siawoosh; Weiskopf Nikolaus

来源：Magnetic Resonance in Medicine, 2015, 73(3): 1309-1314.

DOI：10.1002/mrm.25210

• R-1
• T-1
• PD
• PD*
• MT
• R-2*
• T-2*
• longitudinal relaxation
• transverse relaxation
• magnetization transfer
• quantitative
• 3T
• water content
• relaxometry

PurposeThe longitudinal relaxation rate (R-1) measured in vivo depends on the local microstructural properties of the tissue, such as macromolecular, iron, and water content. Here, we use whole brain multiparametric in vivo data and a general linear relaxometry model to describe the dependence of R-1 on these components. We explore a) the validity of having a single fixed set of model coefficients for the whole brain and b) the stability of the model coefficients in a large cohort.
MethodsMaps of magnetization transfer (MT) and effective transverse relaxation rate (R-2*) were used as surrogates for macromolecular and iron content, respectively. Spatial variations in these parameters reflected variations in underlying tissue microstructure. A linear model was applied to the whole brain, including gray/white matter and deep brain structures, to determine the global model coefficients. Synthetic R-1 values were then calculated using these coefficients and compared with the measured R-1 maps.
ResultsThe model's validity was demonstrated by correspondence between the synthetic and measured R-1 values and by high stability of the model coefficients across a large cohort.
ConclusionA single set of global coefficients can be used to relate R-1, MT, and R-2* across the whole brain. Our population study demonstrates the robustness and stability of the model. Magn Reson Med, 2014.

• 出版日期2015-3