Fig. 5:

Comparison of (a) XD-GRASP against (b) SToRM:Two-Step. For direct comparison of the methods, we rearrange the images obtained using SToRM into respiratory and cardiac phases (bottom-right), identified by the XD-GRASP binning approach, which can be compared to XD-GRASP reconstructions (bottom-left). We also rearrange the XD-GRASP recovered frames to form a temporal profile in the top row. Specifically, we construct a time series by selecting the XD-GRASP frames corresponding to the identified cardiac and respiratory phases. We observe that some of the cardiac/respiratory phases are not well sampled in XD-GRASP due to variability in the breathing cycles, resulting in blurring and aliasing artifacts. Please see the phases outlined by green boxes. By contrast, our soft-binning strategy exploits the similarity between the phases along the time series to reduce these artifacts. The weight patterns for the two frames indicated by the yellow and red arrows are shown in the top row. We note that the weights are high whenever the frames are similar to the chosen frame; the algorithm combines the information in these similar frames to obtain high-resolution reconstructions.We note that XD-GRASP is binning the data to different cardiac and respiratory bins. The averaging of motion within the bins may cause respiratory blurring, which may be the reason for difference in the hepatic vasculature. By contrast, the soft-binning offered by the proposed scheme minimizes the respiratory blurring, thus offering more sharper reconstructions.