Frequencies, mean, and SD of scores of observers in pairwise comparison of images (first part of observer study)
| Aspects & Observers | −2 | −1 | 0 | 1 | 2 | NA | Mean | SD | P |
|---|---|---|---|---|---|---|---|---|---|
| Streak artifacts | |||||||||
| 1 | 0 | 0 | 0 | 44 | 22 | 166 | 1.33 | 0.47 | <.001 |
| 2 | 0 | 0 | 7 | 29 | 33 | 163 | 1.38 | 0.66 | <.001 |
| Visualization brain tissue near skull | |||||||||
| 1 | 0 | 2 | 105 | 106 | 19 | 0.61 | 0.65 | <.001 | |
| 2 | 1 | 10 | 75 | 104 | 42 | 0.76 | 0.81 | <.001 | |
| Visualization hypodense lesion(s) | |||||||||
| 1 | 1 | 22 | 33 | 39 | 1 | 136 | 0.18 | 0.83 | >.05 |
| 2 | 2 | 31 | 24 | 40 | 7 | 128 | 0.18 | 1.00 | >.05 |
| Gray/white matter differentiation | |||||||||
| 1 | 1 | 8 | 182 | 32 | 0 | 9 | 0.10 | 0.43 | >.05 |
| 2 | 3 | 53 | 70 | 84 | 5 | 17 | 0.16 | 0.87 | >.05 |
| Image noise | |||||||||
| 1 | 1 | 49 | 92 | 90 | 0 | 0.17 | 0.77 | >.05 | |
| 2 | 1 | 52 | 52 | 115 | 12 | 0.37 | 0.90 | <.001 | |
| Overall image quality | |||||||||
| 1 | 1 | 28 | 64 | 103 | 36 | 0.63 | 0.90 | <.001 | |
| 2 | 3 | 42 | 35 | 118 | 34 | 0.59 | 0.99 | <.001 |
Note:—NA indicates not applicable. Scores range from −2 (preference for sequential technique) to +2 (preference for spiral technique). The tabulated P values are the those of the Wilcoxon signed-rank test multiplied by 24, which is the total number of significance tests performed (Bonferroni correction).