A method and apparatus for measuring impedance for pathology assessment in a living being using convergent bioelectric lead fields is disclosed, including injecting a current between first and second electrodes implanted in a body of a living being, where the first and second electrodes define a first electric lead field oriented between the first and second electrodes. A potential difference is measured between third and fourth electrodes implanted in the body, where the potential difference results from the current injected between the first and second electrodes. The third and fourth electrodes define a second electric lead field oriented between the third and fourth electrodes. The first and second electric lead fields converge near an assessment site within the body, but are substantially separated otherwise. An impedance value is calculated based on the potential difference and the current injection, and is used to assess a pathology near the assessment site.