Four-dimensional non-rigid cardiac motion estimation

Electrocardiogram-gated cardiac CT reconstruction methods have been developed to reduce motion artifacts; however, projection data used in reconstruction are limited to those within gating time windows, resulting in large image noise. Motion compensated image reconstruction is capable of fully utilizing all projection data if a motion vector field is known. In this work, we propose a non-rigid four-dimensional image-based motion estimation method which uses a nested conjugated gradient method to minimize a cost function. The proposed method is implemented on GPU using CUDA, and its performance was verified with patient data.