Table 2.
Noise and signal-to-noise ratio
| Level | 10 mm ROI |
Noise (HU)
|
SNR
|
||||
|
ULDCT
|
SDCT |
P value
|
ULDCT
|
SDCT
|
P value
|
||
| Aortic arch | Aortic lumen | 22.28 ± 3.6 | 21.06 ± 2.9 | 0.149 | 2.86 ± 0.8 | 1.53 ± 0.3 | < 0.001 |
| Paraspinal muscles | 20.86 ± 3.6 | 27.29 ± 4 | < 0.001 | 2.84 ± 0.7 | 1.89 ± 0.4 | < 0.001 | |
| Carina | Aortic lumen | 23.8 ± 12.4 | 22.98 ± 4.2 | 0.359 | 2.63 ± 0.9 | 1.57 ± 0.6 | < 0.001 |
| Paraspinal muscles | 22.33 ± 4.4 | 28.28 ± 4.9 | < 0.001 | 2.35 ± 1.1 | 1.72 ± 0.5 | < 0.001 | |
| Max. cardiac diameter | Aortic lumen | 23.14 ± 7.9 | 27.7 ± 12.9 | 0.061 | 2.14 ± 0.9 | 1.17 ± 0.6 | < 0.001 |
| Paraspinal muscles | 23.44 ± 3.2 | 23.37 ± 4 | 0.472 | 1.66 ± 0.6 | 1.61 ± 0.6 | 0.318 | |
Bold face P value indicates statistical significance.
Comparison of objective quantitative measures of image noise and signal-to-noise ratio at three levels from the ultra-low dose computed tomography (ULDCT) with model-based iterative reconstruction and standard dose computed tomography chest protocols. Overall, there is a statistically significant increase in signal to noise ratio in the ULDCT imaging protocol. HU: Hounsfield units, SNR: Signal to noise ratio; ROI: Region of interest; ULDCT: Ultra-low dose computed tomography; SDCT: Standard dose computed tomography.