Value of ellipsoid volume masking in myocardial tomography.

The circumferential profile technique, used to obtain a bull's eye image from short axis slices in myocardial perfusion tomography, requires isolation of the reconstructed volume from other neighbouring structures that may take up the radiopharmaceutical used. If this is not possible, some regional artefacts can be introduced in the polar map that do not represent the actual myocardial perfusion at the corresponding level. In this case report we describe a method for volume masking that permits the myocardium inside in ellipsoidal volume to be enclosed. This technique is compared with the spherical method used in a Sophy 20P system in a case with impaired perfusion of an inferolateral segment and an extracardiac "hot" structure located in the same area. The results obtained show the usefulness of our method in such cases.