PMC

a) Free-breathing respiratory self-gated cine MRI sequence. The non-PE k-space center line is acquired before each imaging segment for every cardiac phase. b) MOCCA respiratory self-gating algorithm. Each k-space segment for each cardiac phase was acquired four times. Each corresponding MOCCA echo was correlated with a MOCCA echo reference. The imaging segment corresponding to the MOCCA echo with maximum cross correlation coefficient (CCC) is included in the final self-gated cine image.

Example cine images in 4-chamber view of diastole (top row) and systole (bottom row) obtained from MOCCA self-gating (a,d), free-breathing without motion gating (b,e) and conventional breath-hold cine (c,f). Significant image artifacts due to respiratory motion can be observed in free-breathing cine that are eliminated in MOCCA.

Example of typical short-axis cine images acquired during (top row) breath-hold and (bottom row) free-breathing with MOCCA self-gating.

A schematic of MOCCA. Motion causes variations in the non-phase-encoded (non-PE) k-space center line signal, subject to modulation by the individual coil sensitivity profiles. In this example scenario, the coil 1 signal decreases while coil 2 signal increases after motion. The concatenated non-PE lines (MOCCA echo) take advantage of the additional information provided by multiple coils, which serve as additional “motion sensors”. The cross correlation coefficient (CCC) between the MOCCA echoes acquired before (reference position) and after motion represents the underlying true motion.