Mean and SD of SNR in various CT protocols with either IR or FBPa
| Tube Current 320 mAs | Tube Current 275 mAs | Tube Current 225 mAs | ||||
|---|---|---|---|---|---|---|
| IR | FBP | IR | FBP | IR | FBP | |
| Non-Enhanced | ||||||
| WM | 8.8 ± 2.1 | 7.9 ± 1, P = 0.01 | 8.0 ± 1.7 | 7.0 ± 1.3, P < .0001 | 7.6 ± 1.5 | 6.7 ± 1.4, P = .006 |
| GM | 10.9 ± 2 | 9.4 ± 1.4, P < .0001 | 9.8 ± 1.4 | 8.3 ± 1.3, P < .0001 | 9.7 ± 1.8 | 8.4 ± 1.6, P < .0001 |
| LQ | 1.4 ± 0.5 | 1.2 ± 0.4, P < .0001 | 1.3 ± 0.4 | 1.0 ± 0.3, P < .0001 | 1.2 ± 0.3 | 1.0 ± 0.3, P < .0006 |
| BG | −448 | −302, P < .0001 | −385 | −210, P < .0001 | −295 | −244, P < .0001 |
| Contrast-Enhanced | ||||||
| WM | 8.9 ± 1.8 | 7.6 ± 1.4, P < .0001 | 7.9 ± 1.5 | 6.8 ± 1.1, P < .0001 | 7.8 ± 1.4 | 6.5 ± 1.0, P < .0001 |
| GM | 11.2 ± 1.7 | 10.2 ± 1.6, P = .001 | 10.2 ± 1.7 | 9.0 ± 1.4, P = .0008 | 9.4 ± 2.1 | 8.6 ± 1.7, P = .02 |
| LQ | 1.3 ± 0.6 | 1.0 ± 0.4, P < .0001 | 1.2 ± 0.5 | 1.0 ± 0.4, P = 0.004 | 1.1 ± 0.3 | 0.9 ± 0.4, P < .001 |
| BG | −385 | −328, P < .0001 | −222 | −192, P < .008 | −221 | −191, P < .0001 |
Note: —LQ indicates liquor; BG, background.
↵a Data are shown for WM, GM, LQ, and BG measurements in air outside the skull. P values refer to differences between IR and FBP.