Fig. 4.

(A) MSDI and (B) nMEDI summary statistics for a reproducibility experiment in which the same “3T Multi-Echo” sequence was used to scan the same 38 y. o. healthy male subject on five consecutive days. (Top row) Representative sagittal, coronal and axial slices for mean QSM over five time-points. (Middle row) Standard deviation (σ) over the same five time points, with <σ> inset representing the average σ across the whole brain. (Bottom row) Coefficient of QSM variation across repetitions (CV = σ/mean). Arrows indicate regions of greater unexplained variation for nMEDI than for MSDI. Though for simplicity arrows are shown unilaterally, regions of high variance are typically bilateral. The opposite behaviour (greater variation for MSDI) was not observed.