Recovery of the moving dipole from surface potential recordings.

Abstract Two methods of recovering the equivalent dipole of variable locus and moment from voltages of 140 or fewer surface recording sites have been examined: (1) summation of all available elements (Gabor and Nelson 8 ) and (2) lead-vector search (Helm and Chou 11 ). Summation requires many recording sites but is rapidly done on a digital computer, whereas lead-vector search requires fewer recording sites but involves much longer computing times. Recovery of a single noise-free factitial input dipole by summating over 140 points was good as to locus and moment. Recovery by lead-vector search was also good whether 7 or 28 electrodes were employed. Increasing error of estimation—especially of locus—was noted, however, with the lead-vector search with (1) increasing the noise level, (2) diminishing the number of electrode sites (from 28 to 20 to 7), and (3) increasing the complexity of the generator (from single dipole input, to double dipole input, to "live data"). Clinical application awaits improved methodology—perhaps by compromise between slow-recording, fast-computing summation, and fast-recording, slow-computing lead-vector search.