Table 2 Descriptive information of skull HU values according to the development of PTBE in the study and skull HU values and BMD in the SHUB registry cohorts

Number

91

15

106

2025

Sex

 Female, n (%)

70 (76.9)

12 (80.0)

82 (77.4)

1704 (84.1)

Age, median (IQR), y

61.0 (54.0–72.0)

72.0 (66.0–75.0)

62.5 (54.8–72.0)

69.0 (59.0–77.0)

Age, mean ± SD, y

62.4 ± 12.2

69.3 ± 9.3

63.3 ± 12.0

67.9 ± 11.9

Overall mean skull HU value, median (IQR)

730.8 (581.5–874.0)

547.8 (430.5–725.8)

711.6 (547.2–860.7)

625.7 (483.8–791.5)

Overall mean skull HU value, mean ± SD

737.9 ± 248.9

584.5 ± 189.4

716.2 ± 246.6

653.0 ± 229.9

Mean HU value at each of four sites in the frontal skull, mean ± SD

 Right lateral

700.3 ± 238.3

582.5 ± 133.7

683.6 ± 229.7

598.1 ± 220.4

 Right medial

780.8 ± 287.3

615.5 ± 229.1

757.4 ± 284.8

704.1 ± 263.6

 Left medial

754.5 ± 283.1

599.5 ± 250.0

732.6 ± 282.8

698.4 ± 262.4

 Left lateral

716.2 ± 255.2

540.7 ± 178.8

691.3 ± 252.7

611.5 ± 224.8

 Average, medial

767.7 ± 281.5

607.5 ± 235.2

745.0 ± 280.1

701.2 ± 257.9

 Average, lateral

708.2 ± 240.1

561.6 ± 153.6

687.5 ± 234.9

604.8 ± 216.5

Time interval between brain CT and BMD, median (IQR), days

N/A

N/A

N/A

151.0 (9.0–487.0)

T-score, mean ± SD

N/A

N/A

N/A

− 1.99 ± 1.22

 Lumbar spine

N/A

N/A

N/A

− 1.65 ± 1.43

 Femur neck

N/A

N/A

N/A

− 1.40 ± 1.20

BMD categories, n (%)

 Normal (T-score > − 1.0)

N/A

N/A

N/A

381 (18.8)

 Osteopenia (T-score > − 2.5 and ≤ 1.0)

N/A

N/A

N/A

902 (44.5)

 Osteoporosis (T-score ≤ -2.5)

N/A

N/A

N/A

742 (36.6)