Table 5 Comparison of clinical and quantitative MRI data between active and inactive AS groups

Clinical data

 Age, y

26.38 ± 3.82

28.00 ± 8.05

0.899^a

 Sex/M

6 (75%)

21 (72.4%)

1.000^b

 BMI, kg/m²

20.41 ± 3.78

20.94 ± 3.11

0.731^c

 Disease duration, y

3.37 ± 2.51

7.03 ± 4.71

0.021^a

 ESR, mm/H

45.75 ± 46.79

16.65 ± 17.12

0.008^a

 CRP, mg/L

42.24 ± 46.08

14.50 ± 20.07

0.016^a

 BASFI Score (0–10)

0.91 ± 1.27

0.22 ± 0.35

0.118^a

 BASDAI Score (0–10)

5.91 ± 1.59

1.52 ± 1.06

0.000^a

Quantitative MRI assessments

 L3/4 MF CSA, mm²

534.38 ± 69.42

524.81 ± 82.21

0.766^a

 L3/4 ES CSA, mm²

1619.63 ± 396.71

1563.36 ± 270.45

0.642^a

 L4/5 MF CSA, mm²

863.75 ± 122.51

816.87 ± 160.76

0.451^a

 L4/5 ES CSA, mm²

1288.00 ± 240.29

1272.98 ± 241.47

0.877^a

 L3/4 MF FF, %

27.32 ± 8.63

28.16 ± 9.29

0.871^c

 L3/4 ES FF, %

30.38 ± 9.26

31.38 ± 7.13

0.814^c

 L4/5 MF FF, %

32.07 ± 9.05

30.43 ± 7.51

0.299^c

 L4/5 ES FF, %

35.70 ± 9.97

35.99 ± 7.16

0.651^c

 L3/4 MF T2_non-fatsat value, ms

54.69 ± 9.64

50.46 ± 6.64

0.124^c

 L3/4 ES T2_non-fatsat value, ms

50.98 ± 6.84

47.94 ± 5.94

0.226^c

 L4/5 MF T2_non-fatsat value, ms

55.91 ± 8.96

51.56 ± 6.52

0.132^c

 L4/5 ES T2_non-fatsat value, ms

56.52 ± 7.86

51.68 ± 7.20

0.108^c

 L3/4 MF T2_fatsat value, ms

42.74 ± 4.75

39.69 ± 2.72

0.024^a

 L3/4 ES T2_fatsat value, ms

40.09 ± 2.62

38.07 ± 2.03

0.026^a

 L4/5 MF T2_fatsat value, ms

40.11 ± 4.89

39.04 ± 4.48

0.559^a

 L4/5 ES T2_fatsat value, ms

40.73 ± 2.68

39.17 ± 2.41

0.123^a