Variation in breast EIT measurements due to menstrual cycle

We conducted a short study on 8 volunteer subjects to establish whether physiological changes occurring as a result of the menstrual cycle affect tissue electrical properties. For this study subjects submitted to electrical impedance tomographic breast measurement four times, over two cycles at two different points in the cycle. Statistical analysis based on reconstructed values of conductivity and permittivity were conducted using the t-test for difference of means. The results were inconsistent, with some subjects showing a difference between the two phases and in all tests, while others showed differences only in some of the tests. At this time we can only conclude that a difference is more likely than not, although it could be a phenomenon only measurable in some individuals and not others. It seems that a larger study may be in order to establish this fact definitively.