Diagnostic apparatus includes a plurality of antennas, which are configured to be disposed at different, respective locations on a thorax of a living body so as to direct radio frequency (RF) electromagnetic waves from different, respective directions toward a heart in the body and to output RF signals responsively to the waves that are scattered from the heart. Processing circuitry is configured to process the RF signals over time so as to provide a multi-dimensional measurement of a movement of the heart.
