Direct measurement of the longitudinal relaxation time T1 provides objective and 
quantitative diagnostic information. However, current T1 mapping methods are 
generally time consuming without the aid of fast imaging. This study used a 
model-based compressed sensing method for fast cardiac T1 mapping in small 
animals. Based on the physics of magnetization recovery, the aliasing artifact 
associated with under-sampling was removed by exploiting the sparsity of the 
signals in the T1 recovery direction. Simulation study was performed to evaluate 
the reconstruction accuracy under various experimental conditions. Several 
approaches that accounted for phase variations were compared for optimized 
reconstruction in the phantom study. In vivo validation was performed on a 
cardiac manganese-enhanced MRI study using mice. Accurate reconstruction of the 
under-sampled images and the resulting T1 maps were achieved in both simulation 
and MRI studies on phantom and in vivo mice. These results suggest that the 
current compressed sensing method allows fast (<80 s) T1 mapping of the mouse 
heart at high spatial resolution (234×469 μm2).