Table 4.
Examination of systematic error in noise-free simulations.
| Vein center position (x,y) | Orientation of magnetic field | PPC (ϵv) | PPC (ppm) | MIV (ϵv) | MIV (ppm) | ICF (ϵv) | ICF (ppm) | ICF (ϵR) | ICF () |
|---|---|---|---|---|---|---|---|---|---|
| (0,0) | 0° | 1.2% | 0.32 | 1.8% | 0.32 | 1.2% | 0.32 | 0.6% | 1.31 |
| (0.25, 0.25) | 0° | 0.7% | 0.31 | 6.8% | 0.39 | 5.5% | 0.37 | −10.8% | 1.16 |
| (0.5, 0.5) | 0° | 3.4% | 0.35 | 7.9% | 0.41 | 6.9% | 0.39 | −12.4% | 1.14 |
| (0,0) | 90° | 0.1% | 0.30 | 0.7% | 0.31 | −0.1% | 0.30 | 1.4% | 1.32 |
| (0.25, 0.25) | 90° | 1.3% | 0.32 | 7.5% | 0.40 | 5.9% | 0.38 | −9.4% | 1.18 |
| (0.5, 0.5) | 90° | 4.2% | 0.36 | 8.9% | 0.42 | 6.9% | 0.39 | −11.5% | 1.15 |
Exact QSM measurements are denoted ppm (ppm = χvein−χbackground). The vein center position is relative to the corner of the voxel [e.g., at (0.5, 0.5) the center of the voxel is aligned with the center of the vein]. All values are reported as signed values, i.e., negative values are under-estimates of the true value. The ground truth OEF was 22%, χvein−χbackground was 0.30 and radius was 1.3 voxels.