Table 4. Comparison of malignancy risk according to categories in various guidelines.
| Guideline | Benign nodules (n=1,418) | Malignant nodules (n=891) | Total (n=2,309) | Suggested risk of malignancy (%) | Calculated risk of malignancy (%) | P value |
|---|---|---|---|---|---|---|
| ACR-TIRADS 2017 | <0.01 | |||||
| TR1 (benign) | 98 | 0 | 98 | ≤2 | 0 | |
| TR2 (not suspicious) | 141 | 0 | 141 | ≤2 | 0 | |
| TR3 (mildly suspicious) | 287 | 1 | 288 | <5 | 0.35 | |
| TR4 (moderately suspicious) | 535 | 55 | 590 | 5–20 | 9.32 | |
| TR5 (highly suspicious) | 357 | 835 | 1,192 | >20 | 70.05 | |
| ATA 2016 | <0.01 | |||||
| Benign | 94 | 0 | 94 | <1 | 0 | |
| Very low suspicion | 13 | 0 | 13 | <3 | 0 | |
| Low suspicion | 451 | 4 | 455 | 5–10 | 0.88 | |
| Intermediate suspicion | 342 | 26 | 368 | 10–20 | 7.07 | |
| High suspicion | 442 | 829 | 1,271 | >70–90 | 65.22 | |
| Not specified§ | 76 | 32 | 108 | – | 29.63 | |
| K-TIRADS 2016 | <0.01 | |||||
| K-TIRADS 2 (benign) | 112 | 0 | 112 | <3 | 0 | |
| K-TIRADS 3 (low suspicion) | 458 | 7 | 465 | 3–15 | 1.51 | |
| K-TIRADS 4 (intermediate suspicion) | 508 | 77 | 585 | 15–50 | 13.16 | |
| K-TIRADS 5 (high suspicion) | 340 | 807 | 1,147 | >60 | 70.36 | |
| C-TIRADS 2020 | <0.01 | |||||
| C-TR 2 | 34 | 0 | 34 | 0 | 0 | |
| C-TR 3 | 362 | 0 | 362 | <2 | 0 | |
| C-TR 4A | 579 | 31 | 610 | 2–10 | 5.08 | |
| C-TR 4B | 309 | 188 | 497 | 10–50 | 37.83 | |
| C-TR 4C | 130 | 626 | 756 | 50–90 | 82.80 | |
| C-TR 5 | 4 | 46 | 50 | <90 | 92.00 |
Data in parentheses are the raw data used to calculate the percentages. §, nodules that did not meet the criteria of the ATA guideline for any pattern (isoechoic or hyperechoic solid nodule with 1 or more of the following features: microcalcifications, taller-than-wide shape, extrathyroidal extension). ACR-TIRADS 2017, the 2017 Thyroid Imaging Reporting and Data System of the American College of Radiology (10); ATA 2016, the 2016 American Thyroid Association guideline (11); K-TIRADS 2016, the 2016 Thyroid Imaging Reporting and Data System of the Korean Thyroid Association/Korean Society of Thyroid Radiology (5); the 2020 C-TIRADS, the 2020 Chinese Thyroid Imaging Reporting and Data System (3); TR, TIRADS.