Table 1 Demographic and ultrasound characteristics of prospectively enrolled patients
Characteristics | Training cohort (n =109) | Test cohort (n= 39) | P value | Validation cohort (n = 70) | P value |
|---|---|---|---|---|---|
Lymph node metastasis | Â | Â | 0.64 | Â | 0.67 |
 No. of metastases | 55 (50.5) | 18 (46.2) |  | 33 (47.1) |  |
 No. of no metastases | 54 (49.5) | 21 (53.8) |  | 37 (52.9) |  |
Age, years (median ± SD) | 42.7 ± 11.7 | 40.7 ± 9.9 | 0.34 | 45.0 ± 11.6 | 0.20 |
Gender | Â | Â | 0.16 | Â | 0.16 |
 No. of males | 24 (22.0) | 13 (33.3) |  | 22 (31.4) |  |
 No. of females | 85 (78.0) | 26 (66.7) |  | 48 (68.6) |  |
No. of tumors | Â | Â | 0.59 | Â | 0.79 |
 1 | 79 (72.5) | 30 (76.9) |  | 52 (74.3) |  |
  > 1 | 30 (27.5) | 9 (23.1) |  | 18 (25.7) |  |
Tumor size, cm (median [IQR]) | 1.21 ± 0.73 | 1.20 ± 0.62 | 0.93 | 0.98 ± 0.66 | 0.03 |
Location | Â | Â | 0.86 | Â | 0.13 |
 Left lobe | 40 (36.7) | 15 (38.5) |  | 29 (41.4) |  |
 Right lobe | 40 (36.7) | 14 (35.9) |  | 31 (44.3) |  |
 Isthmus | 5 (4.6) | 3 (7.7) |  | 4 (5.7) |  |
Bilateral | 24 (22.0) | 7 (17.9) | Â | 6 (8.6) | Â |
Echogenicity |  |  |  > 0.99 |  | 0.08 |
 Hypoechoic | 108 (99.1) | 39 (100.0) |  | 66 (94.3) |  |
 Iso/hyperechoic | 1 (0.9) | 0 (0) |  | 4 (5.7) |  |
Margin | Â | Â | 0.29 | Â | 0.06 |
 Clear | 32 (29.4) | 8 (20.5) |  | 12 (17.1) |  |
 Unclear | 77 (70.6) | 31 (79.5) |  | 58 (82.9) |  |
Shape | |||||
 Regular | 9 (8.3) | 1 (2.6) | 0.29 | 6 (8.6) | 0.94 |
 Irregular | 100 (91.7) | 38 (97.4) |  | 64 (91.4) |  |
Height-to-width ratio |  |  | 0.82 |  |  < 0.001 |
 Taller than wide (> 1) | 47 (43.1) | 16 (41.0) |  | 51 (72.9) |  |
 Wider than tall (< 1) | 62 (56.9) | 23 (59.0) |  | 19 (27.1) |  |
Calcification | Â | Â | 0.75 | Â | 0.08 |
 No calcification | 26 (23.9) | 7 (17.9) |  | 13 (18.6) |  |
 Macro-calcification | 21 (19.3) | 8 (20.5) |  | 24 (34.3) |  |
 Micro-calcification | 62 (56.9) | 24 (61.5) |  | 33 (47.1) |  |
US suspicious lymph node | Â | Â | 0.07 | Â | 0.06 |
 No. of positives | 43 (39.4) | 9 (23.1) |  | 18 (25.7) |  |
 No. of negatives | 66 (60.6) | 30 (76.9) |  | 52 (74.3) |  |
Hashimoto thyroiditis | Â | Â | 0.49 | Â | 0.49 |
 No. of negatives | 93 (85.3) | 35 (89.7) |  | 57 (81.4) |  |
 No. of positives | 16 (14.7) | 4 (10.3) |  | 13 (18.6) |  |
Clinical T stage | Â | Â | 0.43 | Â | 0.38 |
 T1 | 102 (93.6) | 35 (89.7) |  | 63 (90.0) |  |
 T2–T3 | 7 (6.4) | 4 (10.3) |  | 7 (10.0) |  |
Clinical N stage | Â | Â | 0.26 | Â | 0.07 |
 N0 | 63 (57.8) | 26 (66.7) |  | 49 (70.0) |  |
 N1a | 12 (11.0) | 1 (2.6) |  | 10 (14.3) |  |
 N1b | 34 (31.2) | 12 (30.8) |  | 11 (15.7) |  |
Pathological T stage | Â | Â | 0.31 | Â | 0.95 |
 T1 | 103 (94.5) | 35 (89.7) |  | 66 (94.3) |  |
 T2–T3 | 6 (5.5) | 4 (10.3) |  | 4 (5.7) |  |
Type of thyroidectomy | Â | Â | 0.89 | Â | 0.07 |
 Lobectomy | 24 (22.0) | 9 (23.1) |  | 24 (48.6) |  |
 Total thyroidectomy | 85 (78.0) | 30 (76.9) |  | 46 (51.4) |  |
Type of lymph node dissection | Â | Â | 0.75 | Â | 0.27 |
 CLND | 81 (74.3) | 30 (76.9) |  | 57 (81.4) |  |
 CLND + LLND | 28 (25.7) | 9 (23.1) |  | 13 (18.6) |  |