Interpolation of Temporal Image Sequences by Optical Flow Based Registration

Modern tomographic imaging devices enable the acquisition of temporal image sequences. In our project, we study cine MRI sequences of patients with myocardial infarction. Because the sequences are acquired with different temporal resolutions, a temporal interpolation is necessary to compare images at predefined phases of the cardiac cycle. This paper presents an interpolation method for temporal image sequences. We derive our interpolation scheme from the optical flow equation. The spatiotemporal velocity field between the images is determined using an optical flow based registration method. Here, an iterative algorithm is applied, using the spatial and temporal image derivatives and a spatiotemporal smoothing step. Afterwards, the calculated velocity field is used to generate an interpolated image at the desired time by averaging intensities between corresponding points. The behavior and capability of the algorithm is demonstrated on synthetic image examples. Furthermore, quantitative measures are calculated to compare this optical flow based interpolation method to linear interpolation and shape-based interpolation in 5 cine MRI data sets. Results indicate that the presented method statistically significantly outperforms both linear and shape-based interpolation.