Mutual information based 3D registration of rat brain MRI time-series

A mutual information (MI) based registration method is introduced to align the rat brain tissues in MRI time-series, which is critical to the MRI tracer method for quantitative analysis of brain extracellular space (ECS). Specially, two works have been done to address the specific properties of contrast-enhanced MR time-series. First, the use of MI as similarity metric is validated by analyzing its robustness to local intensity variation caused by contrast enhancement. Second, an interactive segmentation method is incorporated into registration framework to extract the brain tissue in reference image. The resultant segmentation is used in MI computing to avoid the adverse effect of surrounding deformed tissue. Several experiments are conducted to evaluate the registration method qualitatively and quantitatively. The experimental results show that the proposed method has a high degree of accuracy and reliability, and is adequate to the task of 3D registration of rat brain MRI time-series.