Summary of differences in Hounsfield unit attenuation, contrast-to-noise, and image noise at 70 and 40 keV
| 40 keV (Median) (IQR) | 70 keV (Median) (IQR) | Difference (40-70 keV) (Median) (IQR) | P | Comparison (P) | |
|---|---|---|---|---|---|
| Hounsfield unit attenuation | |||||
| Thyroid | |||||
| Absolute (HU) | 158 (133–264) | 84 (74–113) | +67 (55–142) | <.001 | Par |
| <.001 | SCM | ||||
| % Change | +89% (66–123) | <.001 | Par | ||
| <.001 | SCM | ||||
| Parathyroid | |||||
| Absolute (HU) | 42 (29–59) | 32 (22–41) | +9 (4–17) | <.001 | Thy |
| .22 | SCM | ||||
| % Change | +29% (13–58) | <.001 | Thy | ||
| .09 | SCM | ||||
| Sternocleidomastoid | |||||
| Absolute (HU) | 67 (63–75) | 57 (54–59) | +11 (10–16) | <.001 | Thy |
| .22 | Par | ||||
| % Change | +22% (17–28) | <.001 | Thy | ||
| .09 | Par | ||||
| Contrast-to-noise | |||||
| Thy/Par | 4.7 (3.3–6.0) | 3.8 (2.4–4.8) | +0.8 (0.2–1.2) | <.001 | |
| Thy/SCM | 3.6 (1.7–5.0) | 2.3 (0.9–3.1) | +1.3 (0.7–1.9) | <.001 | |
| Image noise (HU) | 32 (23–37) | 16 (12–19) | +14 (11–20) | <.001 |
Note:—Thy indicates thyroid; Par, parathyroid; SCM, sternocleidomastoid.