FIG. 1.

a: The pulse sequence diagram of ADIOS bSSFP NC MRA. It is based on the conventional NC MRA sequence which uses a slab-selective inversion RF pulse to suppress background tissue followed by fat-saturation, linear ramp-up catalyzing pulses, and bSSFP block. An additional alpha pulse and central k-space readout (no phase encoding) is appended at the end of each bSSFP block to acquire a self-gating line. Readout gradient is set to superior–inferior direction for maximal sensitivity to respiratory motion. b: The schematic diagram of the ADIOS adaptive gating algorithm used for free-breathing NC-MRA. Cross-correlation coefficient (CCC) is calculated between projection profiles and reference profile. Online gating is executed based on CCC versus the threshold. The threshold is updated in real-time using a heuristic method to maintain scan efficiency. All calculations are performed online. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]