FIGURE 7.

Distribution of scan duration Δτ _scan, delay between back‐to‐back scans Δτ _end−start, and the resulting interval between contiguous scans Δτ _{start−start}. We show data from 2722 fetal half‐Fourier single‐shot turbo spin‐echo (HASTE) stacks acquired in 450 neurologically indicated sessions. The median interval is $\overline{\mathrm{\Delta }{\tau }_{\text{start}-\text{start}}}=67.0\mathrm{s}$, representing the average time between the last known head pose and the acquisition of slices based on that pose, during which head‐pose changes may occur and cause incorrect anatomical orientation. We emphasize that the data shown include acquisitions that are interrupted early due to extreme subject motion. Dark red bars indicate the location of the median