Patient Characteristics
| Characteristic | Category I (n = 21) | Category II (n = 10) | Category III (n = 2) | All patients (n = 33) |
| Age (y) | ||||
| Mean | 57 | 61 | 55 | 58 |
| Range | 43–78 | 48–77 | 54–56 | 43–78 |
| Sex (n) | ||||
| Male | 0 | 0 | 0 | 0 |
| Female | 21 | 10 | 2 | 33 |
| Menopausal status (n) | ||||
| Premenopausal | 1 | 0 | 0 | 1 |
| Postmenopausal | 16 | 10 | 2 | 28 |
| Unknown | 4 | 0 | 0 | 4 |
| Breast cancer stage (n) | ||||
| Suspected distant recurrence | 12 | 0 | 2 | 14 |
| Metastatic | 9 | 10 | 0 | 19 |
| Prior lines of endocrine therapy (n)* | ||||
| 0 | 13 | 0 | 2 | 15 |
| 1 | 5 | 4 | 0 | 9 |
| >1 | 3 | 6 | 0 | 9 |
| Time between primary diagnosis and 18F-FES PET (y) | ||||
| Mean | 8 | 10 | 3 | 8 |
| Range | 0–18 | 3–22 | 2–4 | 0–22 |
↵* Does not include adjuvant antihormonal therapy.
18F-FES PET examination was requested to evaluate equivocal or conflicting conventional imaging (category I), a patient's ER status (category II), or origin of metastases (category III).