Table 2.
Characteristics and Outcomes of PET Scans Performed
| Initial PET scan (n=111) | Follow-up PET scan (n=89) | |
|---|---|---|
| Indication for PET scan | ||
| +TG with negative 131I scan | 44 (39.6%) | 8 (8.9%) |
| TG antibodies | 9 (8.1%) | 4 (4.5%) |
| Rising TG | 5 (4.5%) | 13 (14.6%) |
| Abnormality on other imaging test | 19 (17.2%) | 3 (3.4%) |
| Evaluation of extent of disease | 30 (27.0%) | 3 (3.4%) |
| Follow-up of previous PET | N/A | 57 (64.0%) |
| Other | 1 (0.9%) | 1 (1.1%) |
| Unknown | 3 (2.7%) | 0 (0.0%) |
| Method of stimulation | ||
| rhTSH | 46 (41.4%) | 51 (57.3%) |
| Hypothyroid | 17 (15.3%) | 4 (4.5%) |
| Unstimulated | 35 (31.5%) | 64 (32.5%) |
| Unknown | 13 (11.7%) | 5 (5.6%) |
| PET positive vs. negative | ||
| Negative | 40 (36.0%) | 36 (40.5%) |
| Positive | 71 (64.0%) | 53 (59.5%) |
| Location of abnormality* | ||
| Thyroid bed | 18 | 7 |
| Neck | 59 | 46 |
| Lung | 11 | 17 |
| Bone | 2 | 2 |
| Other | 8 | 6 |
| Abnormality present on other imaging | ||
| Yes | 53 (74.6%) | 29 (54.7%) |
| No | 8 (11.3%) | 8 (15.1%) |
| Unknown | 10 (14.1%) | 16 (30.2%) |
| Management following PET | ||
| Surgery | 50 (45.0%) | 16 (18.0%) |
| Chemo or radiation (includes 131I) | 9 (8.1%) | 14 (15.7%) |
| Observation | 52 (46.8%) | 58 (65.2%) |
| Palliation | 0 (0%) | 1 (1.1%) |
| PET changed management** | ||
| Yes | 34 (30.6%) | 25 (28.1%) |
| No | 76 (68.5%) | 138 (69.6%) |
| Unclear | 1 (0.9%) | 2 (2.2%) |
*
Patient may have disease in more than one location.
**
PET was considered to have changed management if it identified disease that was not previously identified and resulted in an intervention, led to cancelation of a previously planned intervention, or changed the extent of a previously planned surgery.
TG, thyroglobulin; rhTSH, recombinant human thyrotropin.