Figure 5.

Effect of sequence variant on b-value bias of G_Y-channel in presence of gradient nonlinearity (GNL), imaging gradients (G_IM) and background gradients (G_BG) theoretically predicted for SSE (a) and DSE (b); and ADC bias measured by two scanners of the same model that used SSE (c) and DSE (d), respectively. Similar shim error (G_BG) for both scanners (c, d) is detected from an apparent ROI drift (stars), normalized by the SI-offset and fit to a sloped (dotted) line. Nearly linear bias asymmetry trend (green), obtained as mean difference between fit values at positive and negative SI-offsets from the isocenter, is over-plotted above the quadratic fit (blue) for the observed fractional ADC bias. Note negligible bias asymmetry predicted and observed for DSE (b, d). The dashed horizontal lines in (c) and (d) mark ±0.05 bias error.