Beta 1


Title Registration and Analysis of myocardial perfusion MRI
Author Ólafsdóttir, Hildur (Image Analysis and Computer Graphics, Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Supervisor Larsen, Rasmus (Image Analysis and Computer Graphics, Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2004
Abstract This thesis presents the registration and analysis of myocardial perfusion magnetic resonance images. Registration is carried out by a method based on Active Appearance Models (AAM). Extensions to the basic AAM include clustering of texture vectors in temporal dimension in addition to slice-coupled modelling. A training set for the AAM is generated semi-automatically. This involves implementation of a tool to allow manual marking of points on object outlines and interpolation of the points by cubic splines to generate a full shape contour. Given the shape contours, point correspondences are obtained by Minimum Description Length (MDL) shape modelling. Requirements for the MDL approach imply that the cardiac shape cannot be optimised directly. Consequently, it is splitted into five contours at anatomical and pseudo landmarks and each contour set is optimised with influence from the full shape. After registration of the set of images, perfusion assessment is carried out by providing pixel-wise signal intensity curves from the myocardium. Subsequently, perfusion maps are generated for three parameters derived from the curves: Maximum upslope, peak and time-to-peak. Qualitative and quantitative validation is carried out on the presented methods. Data from 10 patients with acute myocardial infarction is provided for this purpose. MDL optimisations resulted in 10 --14% improvement in terms of the description length and 10 - 28% improvement in terms of the total model variance. A leave-one-out cross validation was carried out for the registration method. This resulted in mean point to curve distance of 1.25 ± 0.36 pixels. Perfusion maps for maximum upslope and time-to-peak positioned ischemic segments in most of the patients.
Keywords Motion-compensation; registration; myocardial perfusion MRI; active appearance models; minimum description length; cubic splines; contour extraction tool; perfusion assessment; perfusion map
Fulltext
Original PDF imm3154.pdf (2.46 MB)
Admin Creation date: 2006-06-22    Update date: 2009-12-21    Source: dtu    ID: 154786    Original MXD