Subtraction ictal SPECT co-registered to MRI improves clinical usefulness of SPECT in localizing the surgical seizure focus. - O'Brien,T.J.; So,E.L.; Mullan,B.P.; Hauser,M.F.; Brinkmann,B.H.; Bohnen,N.I.; Hanson,D.; Cascino,G.D.; Jack,C.R.; Sharbrough,F.W. (Neurology, 1998)