Table 4. Subjective Image Quality Analysis.
| CT* | Difference of Mean Scores | ||||||
|---|---|---|---|---|---|---|---|
| 50 mAs (A) | Denoised 50 mAs (B) | 100 mAs (C) | |(A)−(B)| | |(A)−(C)| | |(B)−(C)| | ||
| Overall image quality | 1.95 ± 0.37 | 3.71 ± 0.32 | 2.80 ± 0.33 | 1.76 | 0.85 | 0.91 | |
| Visibility of anatomical structures | |||||||
| Vertebral body | 2.51 ± 0.55 | 3.82 ± 0.28 | 3.21 ± 0.52 | 1.31 | 0.70 | 0.61 | |
| Transverse and spinous processes | 2.49 ± 0.62 | 3.70 ± 0.37 | 3.24 ± 0.46 | 1.21 | 0.75 | 0.46 | |
| Facet joint | 2.72 ± 0.64 | 3.54 ± 0.49 | 3.47 ± 0.54 | 0.82 | 0.75 | 0.07† | |
| Dural sac | 1.29 ± 0.35 | 2.62 ± 0.80 | 1.90 ± 0.59 | 1.33 | 0.61 | 0.72 | |
| Ligamentum flavum | 1.43 ± 0.50 | 2.85 ± 0.68 | 2.23 ± 0.60 | 1.42 | 0.8 | 0.62 | |
| Psoas muscle | 1.67 ± 0.44 | 3.62 ± 0.46 | 2.64 ± 0.53 | 1.95 | 0.97 | 0.98 | |
| Paraspinal muscle | 1.70 ± 0.49 | 3.35 ± 0.53 | 2.63 ± 0.58 | 1.65 | 0.93 | 0.72 | |
*Data are mean ± standard deviation of the average score of the two reviewers, †Scores were significantly different in all comparisons except for facet joint visualization between (B) and (C).