A system and method for non-invasively generating a report of cardiac electrical activities of a subject includes determining, using cardiac electrical activation information, equivalent current densities (ECDs). The ECDs are assembled into time-course ECD information and a spectrum of the time-course ECD information is analyzed to determine peaks for spectral characteristics of atrial fibrillation (AF). The spectral characteristics of AF are correlated with potential electrical sources of the AF and a report is generated indicating the potential electrical sources of the AF spatially registered with the medical imaging data.
