Frequencies, mean, and SD of scores of observers in comparison of complete scans (second part of observer study)
| Aspects & Observers | −2 | −1 | 0 | 1 | 2 | NA | Mean | SD | P |
|---|---|---|---|---|---|---|---|---|---|
| Streak artifacts | |||||||||
| 1 | 0 | 0 | 0 | 18 | 5 | 0 | 1.22 | 0.41 | <.001 |
| 2 | 0 | 0 | 0 | 3 | 20 | 0 | 1.87 | 0.34 | <.001 |
| Visualization brain tissue near skull | |||||||||
| 1 | 0 | 0 | 2 | 21 | 0 | 0.91 | 0.28 | <.001 | |
| 2 | 0 | 0 | 0 | 16 | 7 | 1.30 | 0.46 | <.001 | |
| Visualization hypodense lesion(s) | |||||||||
| 1 | 0 | 0 | 10 | 5 | 1 | 7 | 0.44 | 0.61 | >.05 |
| 2 | 0 | 1 | 6 | 8 | 0 | 8 | 0.47 | 0.62 | >.05 |
| Gray/white matter differentiation | |||||||||
| 1 | 0 | 0 | 22 | 1 | 0 | 0 | 0.04 | 0.20 | >.05 |
| 2 | 0 | 0 | 3 | 20 | 0 | 0 | 0.87 | 0.34 | <.001 |
| Image noise | |||||||||
| 1 | 0 | 4 | 17 | 2 | 0 | −0.09 | 0.50 | >.05 | |
| 2 | 0 | 0 | 0 | 4 | 19 | 1.83 | 0.38 | <.001 | |
| Overall image quality | |||||||||
| 1 | 0 | 0 | 0 | 21 | 2 | 1.09 | 0.28 | <.001 | |
| 2 | 0 | 0 | 0 | 1 | 22 | 1.96 | 0.20 | <.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).