Applied potential tomography (APT) images can be collected at a rate of 24 per second and data collection can be synchronised with the ECG. Images thus obtained from a thoracic plane allow the spatial separation of impedance changes originating in the heart, aorta and lungs and have raised the possibility of detecting pulmonary perfusion abnormalities from the cardiac-related impedance changes in the lungs. We have recently started a study to compare isotope perfusion scans with APT images and present here a few initial examples which suggest that further investigation of this field may prove rewarding.