Detection of muscular ventricular septal defect by the phase image

A case of muscular ventricular septal defect shown by the phase image derived from Fourier analysis of gated equilibrium radionuclide angiocardiography is presented. The diagnostic feature of the defect on the phase image was a marked phase delay localized mainly in the trabecular portion of the right ventricle. This characteristic finding seemed to be caused by the left to right shunt flow through the defect located in the muscular portion of the interventricular septum.