The paradox image: a noninvasive index of regional left-ventricular dyskinesis.
The paradox image, a functional image of regional dyskinesis derived from the equilibrium (gated) radionuclide ventriculogram, was constructed by subtracting the background-corrected end-diastolic frame from the background-corrected end-systolic frame. In 11 patients showing dyskinesis by contract ventriculography, the percentage of left-ventricular picture elements containing paradox ranged from 3.6 to 55.6% (21.44% +/- 4.45 s.e.m.). In 11 patients with normokinesis and in eight patients with hypokinesis by contract ventriculography, the left-ventricular picture elements demonstrating paradox were less than 1.1% in all cases. In nine patients with akinesis, the percentage of left-ventricular picture elements containing paradox was 2.05% +/- 0.96 s.e.m. and was less tha 2% in seven patients. There was also an excellent agreement between the location of dyskinesis on the paradox image and that by contrast ventriculography. The paradox image is a sensitive indicator of left-ventricular dyskinesis and should be useful in the evaluation of patients with suspected left-ventricular asynergy.