Table 2 Univariate and multivariate cox analysis of clinico-pathological and semiquantitative [¹⁸F]FDG PET/CT Metabolic Parameters for PFS

Age ≥ 55

5.34

2.86 – 9.97

0.000^*

1.63

0.67 – 3.93

0.28

Male

1.0

0.5 – 1.97

0.98

-

-

-

Aggressive variant and follicular histological subtype

3.81

1.96 – 7.41

0.000^*

1.28

0.49 – 3.3

0.617

ETE of primary tumor

2.18

1.2 – 3.9

0.01^*

2.25

1.22 – 4.16

0.01^*

Stage III-IV at DTC diagnosis

4.98

2.85 – 8.72

0.000^*

1.16

0.48 – 2.78

0.741

Cumulative RAI activities administrated > 600 mCi

1.74

0.9 – 3.38

0.1

-

-

-

Stimulated Tg > 177.9 ng/ml

1.55

0.91 – 2.64

0.108

-

-

-

Thyroid beds

1.3

0.68 – 2.48

0.421

-

-

-

Cervical lymphnode metastases

0.64

0.36 – 1.12

0.118

-

-

-

Distant metastases on [¹⁸F]FDG PET/CT findings

5.19

2.99 – 9.0

0.000^*

2.98

1.62 – 5.5

0.000^*

SUVmax > 6.39 (g/ml)

4.4

2.4 – 8.04

0.000^*

1.63

0.43 – 6.18

0.475

SUVmean > 3.68 (g/ml)

3.87

2.14 – 6.98

0.000^*

0.62

0.12 – 3.23

0.571

SUVpeak > 3.14 (g/ml)

3.71

2.08 – 6.62

0.000^*

1.43

0.4 – 5.07

0.58

tTLG > 4.23 (g/ml x cm³)

5.93

3.13 – 11.2

0.000^*

1.66

0.47 – 5.88

0.43

tMTV > 1.24 (cm³)

7.26

3.74 – 14.1

0.000^*

4.17

2.02 – 8.6

0.000^*