Table 1.
Demographic characteristics and ultrasound features of 329 follicular thyroid neoplasms
| Demographic characteristics | No. (%) or mean ± SD (range) | |
|---|---|---|
| Male | 113 (34.3) | |
| Age (years) | 43.5 ± 14.3 (3–82) | |
| Pathological classifications | ||
| FTA | 262 (79.6) | |
| FTC | 67 (20.4) | |
| Minimally invasive | 48 (14.7) | |
| Encapsulated angioinvasive | 12 (3.6) | |
| Widely invasive | 7 (2.1) | |
| Ultrasound features | ||
| Maximum diameters (cm)a | 3.6 ± 1.7 (0.6–12.1) | |
| Maximum diameters > 2 cma | 285 (86.9) | |
| Maximum diameters > 4 cma | 135 (41.2) | |
| Location | Left | 167 (50.8) |
| Right | 157 (47.7) | |
| Isthmus | 5 (1.5) | |
| Composition | Spongiform | 4 (1.2) |
| Cystic | 0 (0) | |
| Mixed | 72 (21.9) | |
| Solid | 251 (76.3) | |
| Undetermined because of calcification | 2 (0.6) | |
| Echogenicityc | Anechoic | 0 (0) |
| Hyperechoic | 11 (3.4) | |
| Isoechoic | 260 (79.0) | |
| Hypoechoic | 58 (17.6) | |
| Very hypoechoic | 0 (0) | |
| Margin | Smooth | 303 (92.1) |
| Ill-defined | 25 (7.6) | |
| Irregular | 1 (0.3) | |
| Calcificationsb | Absent | 282 (85.7) |
| Microcalcification | 16 (4.9) | |
| Macrocalcification | 26 (7.9) | |
| Rim calcification | 7 (2.1) | |
| Shape | Round to oval | 316 (96.0) |
| Irregular | 13 (4.0) | |
| Orientation | Parallel | 328 (99.7) |
| Nonparallel | 1 (0.3) | |
| Peripheral halo | Present | 194 (59.0) |
| Hyperechoic foci | Comet-tail artifacts | 4 (1.2) |
| Indeterminate | 3 (0.9) | |
| Extrathyroidal extension | Present | 1 (0.3) |
| Suspicious cervical lymph node | Present | 3 (0.9) |
| The location of the solid component for mixed-content nodules | Eccentric | 21 (29.2) |
| Non-eccentric | 51 (70.8) | |
| Vascularization | Absent | 11 (3.3) |
| Perinodular | 6 (1.8) | |
| Intranodular | 6 (1.8) | |
| Mixed | 306 (93.1) | |
| Ultrasound-based malignancy risk stratification systems | ||
| ATA | Benign | 0 (0) |
| Very low suspicion | 53 (16.1) | |
| Low suspicion | 213 (64.7) | |
| Intermediate suspicion | 37 (11.3) | |
| High suspicion | 8 (2.4) | |
| Nonclassifiable group | 18 (5.5) | |
| AACE/ACE/AME | Low | 11 (3.4) |
| Intermediate | 293 (89.0) | |
| High suspicion | 18 (5.5) | |
| Nonclassifiable group | 7 (2.1) | |
| K-TIRADS | Benign (K-TR2) | 8 (2.4) |
| Low suspicion (K-TR3) | 258 (78.5) | |
| Intermediate suspicion (K-TR4) | 53 (16.1) | |
| High suspicion (K-TR5) | 8 (2.4) | |
| Nonclassifiable group | 12 (3.6) | |
| EU-TIRADS | Benign (EU-TR2) | 4 (1.2) |
| Low risk (EU-TR3) | 252 (76.5) | |
| Intermediate risk (EU-TR4) | 38 (11.6) | |
| High risk (EU-TR5) | 24 (7.3) | |
| Nonclassifiable group | 11 (3.4) | |
| ACR-TIRADS | Benign (ACR-TR1) | 4 (1.2) |
| Not suspicious (ACR-TR2) | 62 (18.8) | |
| Mildly suspicious (ACR-TR3) | 185 (56.3) | |
| Moderately suspicious (ACR-TR4) | 70 (21.3) | |
| Highly Suspicious (ACR-TR5) | 8 (2.4) | |
| C-TIRADS | C-TR2 | 8 (2.4) |
| C-TR3 | 67 (20.4) | |
| C-TR4A | 224 (68.1) | |
| C-TR4B | 19 (5.8) | |
| C-TR4C | 8 (2.4) | |
| C-TR5 | 3 (0.9) | |
aThe maximum diameters could not be determined in a case due to macrocalcifications
bSome nodules presented multiple types of calcifications
cHyperechoic, isoechoic and hypoechoic: compared to adjacent parenchyma; very hypoechoic: more hypoechoic than strap muscles
Abbreviations: FTA follicular thyroid adenoma; FTC follicular thyroid carcinoma; ATA 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer; AACE/ACE/AME American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinology Medical Guidelines for Clinical Practice for the Diagnosis and Management of Thyroid Nodules (2016 Update); EU-TIRADS European Thyroid Association Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules in Adults; K-TIRADS Revised Korean Society of Thyroid Radiology Consensus Statement and Recommendations; ACR-TIRADS American College of Radiology Thyroid Imaging Reporting and Data System; C-TIRADS 2020 Chinese Guidelines for Ultrasound Malignancy Risk Stratification of Thyroid Nodules