The reproducibility of optical mammography in healthy volunteers

This study was designed to determine the reproducibility of optical mammography. Eight healthy pre-menopausal volunteers were scanned at different time intervals (minutes, weeks and months apart) to investigate the effects of within-subject variation, between-subject variation and systematic variations on both the raw data and images. The study shows that the greatest source of variation in optical mammography raw data and images is between different subjects, and scans of the same subject are very reproducible. The averaged total haemoglobin concentration from the eight volunteers was (24 ± 10) µM, and the average tissue oxygen saturation was (70 ± 10)%, which is comparable with other data in the literature. The average absorption coefficient at 780 nm was (0.0048 ± 0.0017) mm(-1) and the average reduced scatter coefficient at 780 nm was (0.80 ± 0.12) mm(-1). Again, this is comparable with published values. When our data are combined with the published values, the weighted average total haemoglobin concentration and tissue oxygen saturation for pre-menopausal breasts are (29 ± 8) µM and (73 ± 3)%, respectively. The results of our study show that we can be reassured that any changes within the tumour region seen during neoadjuvant therapy are likely to be due to a real physiological response to treatment, as the physiological properties of the breast remain relatively constant. However, in this study, we cannot distinguish between a tumour response to treatment and systemic changes in the healthy breast.