Table 1.
Summary characteristics of the samples used in the different analysis.
| Study samples | Sample 1 | Sample 2 |
|---|---|---|
| Purpose | To evaluate the concordance by comparing with MDa | To assess the test-retest reproducibility |
| Inclusion criteria | Patients underwent digital mammography within 6 months from the date of MRI scan | Patients received test-retest scans (For each test-retest scan, the patient left the scanner and was immediately repositioned in the scanner, re-registered and re-localized) |
| Exclusion criteria for the analysis | The change of MD was larger than 10% between baseline and follow-up mammograms (1–2 years apart).b | n/a |
| Number of patients (age) | n=40 (age mean ± SD: 56.1 ± 8.4 years) | n=10 (age mean ± SD: 56.4 ± 10.4 years); 7 with test-retest at 3 time-points, 2 with test-retest at 2 time-points, 1 with test-retest at 1 time-point; for the same patient, scans are 6 months apart |
| Number of scans | 40 (35 from GE scanner, 5 from Siemens scanner) | 26 × 2 (24 from GE scanner, 2 from Siemens scanner) |
| Number of unaffected breasts | 42 (both breasts of 2 patients from GE scanner were unaffected) | 26 × 2 (all patients had one unaffected breast) |
a
MD: mammographic density
b
This is to exclude patients with large breast density fluctuations