AUTOMATIC REGISTRATION AND ALIGNMENT ON A TEMPLATE OF CARDIAC STRESS AND REST REORIENTED SPECT IMAGES

Single photon emission computed tomography (SPECT) imaging with Tl-201 or Tc-99m agent is used to assess the location or the extent of myoca rdial infarction or ischemia, A method is proposed to decrease the eff ect of operator variability in the visual or quantitative interpretati on of scintigraphic myocardial perfusion studies, To effect this, the patient's myocardial images (target cases) are registered automaticall y over a template image, utilizing a nonrigid transformation, The inte rmediate steps are: 1) Extraction of feature points in both stress and rest three-dimensional (3-D) images, The images are resampled in a po lar geometry to detect edge points, which in turn are filtered by the use of a priori constraints. The remaining feature points are assumed to be points on the edges of the left ventricular myocardium, 2) Regis tration of stress and rest images with a global affine transformation, The matching method is an adaptation of the iterative closest point a lgorithm, 3) Registration and morphological matching of both stress an d rest images on a template using a nonrigid local spline transformati on following a global affine transformation, 4) Resampling of both str ess and rest images in the geometry of the template. Optimization of t he method was performed on a database of 40 pairs of stress and rest i mages selected to obtain a wide variation of images and abnormalities, Further testing was performed on 250 cases selected from the same dat abase on the basis of the availability of angiographic results and pat ient stratification.