Automatic Non-rigid Temporal Alignment of IVUS Sequences

Clinical studies on atherosclerosis regression/progression performed by intravascular ultrasound analysis require the alignment of pullbacks of the same patient before and after clinical interventions, In this paper, a methodology for the automatic alignment of IVUS sequences based on the dynamic time warping technique is proposed. The method is adapted to the specific IVUS alignment task by applying the non-rigid alignment technique to multidimensional morphological signals, and by introducing a sliding window approach together with a regularization term. To show the effectiveness of our method, an extensive validation is performed both on synthetic data and in-vivo IVUS sequences. The proposed method is robust to stent deployment and post dilation surgery and reaches an alignment error of approximately 0.7 mm for in-vivo data, which is comparable to the inter-observer variability.