Figure 1.
(a) Conventional multi-phase DCE liver imaging workflow. Separate 3D image volumes are acquired in desired contrast-enhancement phases during multiple breath-holds. A bolus timing step is performed before the DCE scan to ensure optimal detection of desired contrast phases. (b) Multi-phase DCE liver imaging using GRASP. Data are continuously acquired under free breathing, and images can be reconstructed with flexible temporal resolutions by grouping a specific number of consecutive spokes as each contrast phase. However, the optimal detection of desired contrast-enhanced phases is not guaranteed, and radiologists must manually select their desired contrast phases. (c) Multi-phase DCE liver imaging using RACER-GRASP. A respiratory motion signal and a ACE (Aortic Contrast Enhancement) signal are extracted from the acquired k-space to guide k-space sorting and image reconstruction. The ACE information can ensure optimal detection of desired contrast phases.