Spatial and temporal registration of cardiac SPECT and MR images: methods and evaluation

Image registration may assist in the integration of information from multiple sources by allowing direct point-for-point comparisons of studies. To determine the usefulness of such a technique, a method for the spatial and temporal registration of four-dimensional single photon emission computed tomographic (SPECT) and magnetic resonance (MR) cardiac images was developed. Automatically detected left ventricular endocardial surfaces were used to determine the best transform between the two sets of surface points, and that transform was applied to the original SPECT image. A fused image created from the MR and the transformed SPECT images combined the information in both. The authors tested the method with seven patient studies. Registration reduced the distance between the MR and SPECT left ventricular endocardial surfaces by 30%, to an average of 2.7 mm. The authors found that, by using the fused images, perfusion abnormalities could be easily localized and correlated to high-resolution endocardial wall motion and systolic wall thickening.