Fig 4. Self-gating steps for ungated acquisitions.

Summation of the first 10 pre-contrast frames was threshold to keep low intensity areas to create mask 1, and maximum intensity map was threshold to keep high intensity areas to be mask 2. Then these two masks were combined and smoothed by a Gaussian filter to identify blood pools in all the simultaneously excited slices. The signals in the blood pool masks of all simultaneously acquired slices were summed together to give a 1D signal that was normalized to be between 0 and 1. Near-systolic and near-diastolic frames were selected from the normalized signal.