Table 5 Comparison of image quality in the two groups

Subjective score

κ

score

a n(%)

b n(%)

a n(%)

b n(%)

 5-point subjective scoring criterion*

0.775

0.9114

3

2 (2.00)

3 (3)

2 (2.0)

2 (2)

4

20 (20.0)

19 (19)

18 (17.6)

15 (14.7)

5

78 (78.0)

78 (78)

82 (80.4)

85 (83.3)

 4-level scoring system^#

0.871

< 0.001

1

60 (60.0)

56 (56.0)

27 (26.5)

27 (26.5)

2

33 (33.0)

37 (37.0)

60 (58.8)

58 (56.9)

3

7 (7.00)

7 (7.00)

15 (14.7)

17 (16.7)

Objective evaluation

CT values: median (range) or mean (SD)

 Venous sinus

112 [93.3;143]

153[122;182]

< 0.001

 Jugular vein bifurcation of the LCCA

57.8 [48.5;65.0]

60.9[53.7;71.2]

< 0.001

 Jugular vein bifurcation of the RCCA

59.0 [51.9;66.7]

63.7 [57.1;75.6]

< 0.001

 Right subclavian vein

146 [98.0;209]

258 [187;386]

< 0.001

 Superior vena cava

79.5 [66.8;100]

118 [96.2;149]

< 0.001

 Arcus aortae

357 ± 35.7

411 ± 52.2

< 0.001

 Bifurcation of LCCA

375 ± 40.1

458 ± 62.8

0.013

 Bifurcation of RCCA

375 ± 39.0

451 ± 63.6

< 0.001

 Left MCA M1 segment

321 [307;344]

389 [357;433]

< 0.001

 Right MCA M1 segment

323 [308;343]

390 [357;432]

< 0.001