Table 2 MRI qualitative features of thyroid nodules in training and validation cohorts

High signal intensity on T2WI

<0.001*

<0.001*

0.879

0.123

 Absence

58 (25.2)

133 (79.6)

19 (17.8)

53 (77.9)

 Presence

172 (74.8)

34 (20.4)

88 (82.2)

15 (22.1)

High signal intensity on T1WI

<0.001*

<0.001*

0.884

0.867

 Absence

160 (69.6)

160 (95.8)

76 (71.0)

64 (94.1)

 Presence

70 (30.4)

7 (4.2)

31 (29.0)

4 (5.9)

Hypointense on T2WI

<0.001*

<0.001*

0.725

0.015*

 Absence

187 (81.3)

45 (26.9)

98 (91.6)

23 (33.8)

 Presence

43 (18.7)

122 (73.1)

9 (8.4)

45 (66.2)

Restricted diffusion

<0.001*

<0.001*

0.914

0.312

 Absence

211 (91.7)

23 (13.8)

100 (93.5)

11 (16.2)

 Presence

19 (8.3)

144 (86.2)

7 (6.5)

57 (83.8)

Cystic degeneration

0.002*

0.034*

0.92

0.924

 Absence

201 (87.4)

161 (96.4)

94 (87.9)

66 (97.1)

 Presence

29 (12.6)

6 (3.6)

13 (12.1)

2 (2.9)

Flow-void signal

0.316

0.907

0.831

0.111

 Absence

215 (93.5)

160 (95.8)

97 (90.7)

62 (91.2)

 Presence

15 (6.5)

7 (4.2)

10 (9.3)

6 (8.8)

Reversed halo sign in delay phase

<0.001*

<0.001*

0.818

0.255

 Absence

213 (92.6)

35 (21.0)

103 (96.3)

15 (22.1)

 Presence

17 (7.4)

132 (79.0)

4 (3.7)

53 (77.9)

Pseudocapsule

<0.001*

<0.001*

0.899

0.151

 Absence

109 (47.4)

154 (92.2)

44 (41.1)

61 (89.7)

 Presence

121 (52.6)

13 (7.8)

63 (58.9)

7 (10.3)

Fissure-filling enhancement

0.001*

0.005*

0.874

0.082

 Absence

195 (84.8)

161 (96.4)

84 (78.5)

64 (94.1)

 Presence

35 (15.2)

6 (3.6)

23 (21.5)

4 (5.9)

Hyperintense on T2WI with enhancement

<0.001*

0.001*

0.893

0.676

 Absence

117 (50.9)

142 (85.0)

55 (51.4)

56 (82.4)

 Presence

113 (49.1)

25 (15.0)

52 (48.6)

12 (17.6)

Wash-out pattern

<0.001*

0.002*

0.909

0.325

 Absence

142 (61.7)

49 (29.3)

66 (61.7)

26 (38.2)

 Presence

88 (38.3)

118 (70.7)

41 (38.3)

42 (61.8)

Hyperenhancement in early phase

<0.001*

0.001*

0.900

0.399

 Absence

169 (73.5)

156 (93.4)

76 (71.0)

62 (91.2)

 Presence

61 (26.5)

11 (6.6)

31 (29.0)

6 (8.8)

Change of lesion size in multiphasic enhancement

<0.001*

<0.001*

0.743

0.239

 Absence

117 (50.9)

17 (10.2)

58 (54.2)

10 (14.7)

 Presence

113 (49.1)

150 (89.8)

49 (45.8)

58 (85.3 )