Model-based registration for dynamic cardiac perfusion MRI

Purpose: To assess the accuracy of a model-based approach for registration of myocardial dynamic contrast-enhanced (DCE)-MRI corrupted by respiratory motion. Materials and Methods: Ten patients were scanned for myocardial perfusion on 3T or 1.5T scanners, and short- and long-axis slices were acquired. Interframe registration was done using an iterative model-based method in conjunction with a mean square difference metric. The method was tested by comparing the absolute motion before and after registration, as determined from manually registered images. Regional flow indices of myocardium calculated from the manually registered data were compared with those obtained with the model-based registration technique. Results: The mean absolute motion of the heart for the short-axis data sets over all the time frames decreased from 5.3 ± 5.2 mm (3.3 ± 3.1 pixels) to 0.8 ± 1.3 mm (0.5 ± 0.7 pixels) in the vertical direction, and from 3.0 ± 3.7 mm (1.7 ± 2.1 pixels) to 0.9 ± 1.2 mm (0.5 ± 0.7 pixels) in the horizontal direction. A mean absolute improvement of 77% over all the data sets was observed in the estimation of the regional perfusion flow indices of the tissue as compared to those obtained from manual registration. Similar results were obtained with two-chamber-view long-axis data sets. Conclusion: The model-based registration method for DCE cardiac data is comparable to manual registration and offers a unique registration method that reduces errors in the quantification of myocardial perfusion parameters as compared to those obtained from manual registration.