Table 1.
Baseline characteristics of the study population and [18F]FDG-PET/CT parameters
| [18F]FDG-PET/CT-driven group | diagnostic surgery group | ||
|---|---|---|---|
| n | n = 91 | n = 41 | |
| Femalea | 132 | 73 (80%) | 34 (83%) |
| Mean age in years ± SDa | 132 | 54.3 ± 14.6 | 54.5 ± 11.6 |
| Complaints of thyroid nodule | |||
| Painless swelling in the neck | 132 | 55 (60%) | 27 (66%) |
| Incidental finding on imaging | 132 | 24 (26%) | 6 (15%) |
| Growth of known nodule | 132 | 3 (3%) | 7 (17%) |
| Hoarseness | 132 | 3 (3%) | 5 (12%) |
| Dyspnoea or pressure on trachea | 132 | 11 (12%) | 8 (20%) |
| Dysphagia | 132 | 11 (12%) | 12 (29%) |
| Fatigue | 132 | 2 (2%) | 1 (2%) |
| Fear of malignancy | 132 | 2 (2%) | 1 (2%) |
| Cosmetic complaints | 132 | 2 (2%) | 0 (0%) |
| No complaints | 132 | 11 (12%) | 4 (10%) |
| Physical examination | |||
| Palpable thyroid nodule | 127 | 72 (81%) | 32 (84%) |
| Thyroid function | 125 | ||
| Median TSH, mU/L (IQR)b | 125 | 1.65 (1.20–2.35) | 1.54 (0.94–2.40) |
| Median fT4, pmol/L (IQR)c | 94 | 15.0 (13.3–16.7) | 14.3 (13.0–15.7) |
| Ultrasound characteristics | |||
| Solitary nodule | 132 | 64 (70%) | 29 (71%) |
| Multinodular disease | 132 | 27 (30%) | 12 (29%) |
| Median size, mm (IQR)a | 132 | 36 (23–45) | 31 (22–39) |
| Suspicious characteristicsd | 132 | 36 (40%) | 19 (46%) |
| Solid hypoechoic nodule | 23 (25%) | 15 (37%) | |
| Taller-than-wide shape | 0 (0%) | 1 (2%) | |
| Irregular margins | 7 (8%) | 2 (5%) | |
| Microcalcifications | 12 (13%) | 4 (10%) | |
| Cytologya | 132 | ||
| Bethesda III | 60 | 40 (44%) | 20 (49%) |
| Bethesda IV | 72 | 51 (56%) | 21 (51%) |
| FN/SFN | 41 | 28 (31%) | 13 (32%) |
| HCN/SHCN | 31 | 23 (25%) | 8 (20%) |
| [18F]FDG-PET/CT | |||
| [18F]FDG-positive | 132 | 65 (71%) | 26 (63%) |
| Median SUVmax of the nodule, g/cm3 (IQR) | 132 | 4.0 (2.8–10.6) | 3.7 (2.3–8.2) |
| Median SUVpeak of the nodule, g/cm3 (IQR) | 132 | 3.4 (2.3–8.4) | 2.9 (1.9–5.9) |
| Median SUVmax of thyroid background, g/cm3 (IQR) | 132 | 1.9 (1.7–2.5) | 2.0 (1.7–2.5) |
| Median SUVmax ratio (IQR) | 132 | 2.3 (1.3–6.2) | 1.8 (1.1–3.9) |
| Median SUVpeak ratio (IQR) | 132 | 1.9 (1.1–4.8) | 1.4 (0.9–2.7) |
FN/SFN, (suspicious for a) follicular neoplasm. fT4, free thyroxine. HCN/SHCN, (suspicious for a) Hürthle cell neoplasm. IQR, interquartile range. SD, standard deviation. SUVmax, maximum standardised uptake value. SUVmax ratio, ratio between SUVmax of the index nodule and background SUVmax of the surrounding normal thyroid tissue. SUVpeak, peak (ø1-cm sphere) standardised uptake value. SUVpeak ratio, ratio between SUVpeak of the index nodule and background SUVmax of the surrounding normal thyroid tissue. TSH, thyroid-stimulating hormone
aIncluded as stratifying variable in the stratified randomisation
bThe reference range for TSH is 0.4–4.0 mU/L
cThe reference range for fT4 is approximately 10–25 pmol/L (sex and age dependent)
dSuspicious ultrasound characteristics were defined as presence of at least one of the following characteristics: marked hypoechogenicity (in a solid nodule), irregular shape (i.e., taller-than-wide), irregular margins, and/or presence of microcalcifications