Table 1. Quantitative comparison of AutoVOI and manual VOI prescription.
Comparison of AutoVOI against manual VOI prescriptions by expert MRS investigators shows improved inter- and intra-subject spatial consistency (a), and inter-subject tissue content variations (b) by AutoVOI, indicating improvement of the precision of VOI prescriptions. In the inter-subject overlap, normalized VOI masks from each head data is used to compute a single inter-subject GDC. In contrast, intra-subject overlap first computes the GDC value among the VOI prescriptions of different scans of each subject, then computes the average and SD of the GDC values across subjects. ROI overlap analysis (c) confirms improvement of accuracy in VOI placement with AutoVOI over manual placement, based on higher GDC values and lower variability (standard deviation, SD and coefficient of variance, CV) among subjects.
| (a) Inter and intra-subject VOI overlap analysis
| ||||
|---|---|---|---|---|
| VOI overlap analysis | Inter-subject overlap GDC | Intra-subject overlap Mean (SD) of GDC |
||
| AutoVOI | Manual | AutoVOI | Manual | |
| PCC | 0.79 | 0.45 | 0.90 (0.05) | 0.85 (0.06) |
| LHC | 0.77 | 0.72 | 0.89 (0.07) | 0.82 (0.06) |
| Vermis | 0.80 | 0.80 | 0.89 (0.04) | 0.85 (0.05) |
| (b) Tissue fraction analysis
| ||||||
|---|---|---|---|---|---|---|
| Tissue % Mean (SD) |
GM | WM | CSF | |||
| AutoVOI | Manual | AutoVOI | Manual | AutoVOI | Manual | |
| PCC | 70.24 (3.85) | 68.61 (3.81) | 19.06 (1.54) | 20.18 (3.22) | 10.70 (3.39) | 11.21 (1.65) |
| LHC | 61.52 (4.08) | 64.40 (5.55) | 33.27 (2.44) | 30.96 (5.11) | 5.20 (2.56) | 4.64 (2.19) |
| Vermis | 72.21 (1.50) | 69.49 (2.21) | 19.13 (1.74) | 20.30 (1.60) | 8.66 (2.00) | 10.21 (3.00) |
| (c) ROI overlap analysis
| ||||
|---|---|---|---|---|
| ROI overlap (GDC) | PCC | LHC | ||
| AutoVOI | Manual | AutoVOI | Manual | |
| Mean (SD) | 0.23 (0.02) | 0.17 (0.03) | 0.46 (0.03) | 0.47 (0.04) |
| CV | 11.01 | 19.41 | 6.97 | 8.35 |