David L. Pope

Three-dimensional reconstruction of moving arterial beds from digital subtraction angiography

A system for three-dimensional reconstruction of dynamic (moving) vascular bed structures has been developed and is described. Input images are obtained from two-view (bi-plane or ECG correlated) X-ray angiograms. A target structure consisting of vessel branch points (nodes) and lines between the branch points is entered on the first of a sequence of images in one view. The movement of the nodes is indicated on subsequent images and on the images of the second view. The target is linearly warped according to the motion of the node points. Automatic edge detection (with subsequent operator correction) is used to detect centerlines and edges of vessels. Three-dimensional reconstruction is accomplished using a distance minimizing point matching technique. Finally, angle-corrected densitometric methods are used to refine the vessel cross section. Standard shaded surface display techniques are then used to display the moving arterial bed. Flow measurements are obtained by tracking the leading edge of the bolus down the three-dimensional arterial tree.

Characterization of leukemic and normal white blood cells by Curie-point pyrolysis—mass spectrometry: I. Numerical evaluation of the results of a pilot study

Abstract A preliminary study was undertaken to determine the usefulness of Curie-point pyrolysis—mass spectrometry followed by computer analysis for character diseased white blood cells. White blood cells from normal, infected, polyeyrhemic and leukemic persons were pyrolyzed in front of the electron impact ion source of a quadrupole mass spectrometer on 510°C and 355°C Curie-point filaments. Visual inspection and computer assisted pattern analysis using the ARTHUR program revealed marked differences in the spectra among the different diagnostic categories. The 510°C pyrolysis—mass spectra from leukemic patients were found to have increased intensity at mass peaks related to RNA and DNA as well as decreased intensity at mass peaks related to choline containing phospholipids when compared to controls. The spectra from the polyeyrhemic patient and the two infected patients were found to have intermediate intensities for these two characteristic series. Pyrolysis at 355°C was found to enhance the differences seen in the 510°C pyrolysis spectra. Though the number of patients is too small to allow rigorous statistical analysis of the observed differences, numerical analysis of the spectra appears to hint at the possibility of using Curie-point pyrolysis—mass spectrometry as a diagnostic tool in discriminating different types of leukemias. An investigation with many more samples is needed to confirm these preliminary findings.

Three Dimensional Reconstruction of Vascular Beds

This chapter discusses the mathematics and computer processing required to generate three dimensional representations of vascular beds from multiple digital angiographic projections. In order to compensate for the deficiencies of conventional reconstruction techniques, a method is presented which directly reconstructs a vascular tree structure. This method appears to take good advantage of vessel characteristics such as connectivity and uniform internal density. Direct reconstruction takes full advantage of the information contained in multiple images, using a dynamic programming technique to determine the vessel centerline, edges, and densitometric profiles in each of the views. With the knowledge of the artery locations from each projection, reconstruction of the arterial tree centerline is overdetermined and averaging or least squares techniques can be used. The vessel lumen geometry may be estimated using the edge information and attenuation profile. The lumen geometry can then be refined by densitometric reprojection of the vascular tree and comparison with original profiles. Examples of direct reconstruction and perspective display of a pig heart coronary artery cast are given.

Three Dimensional Reconstruction Of Vascular Beds From Digital Angiographic Projections

The reconstruction of a three dimensional representation of arbitrary vascular beds from multiple projections is discussed. Operator notation is used to represent algorithms used in the reconstruction process. These operators provide the interconversion of the various data structures. The flow of the reconstruction process is reviewed and examples of reconstruction are given. Applications to fluid dynamic analysis of vascular function are presented.

Improving left ventricular border recognition using probability surfaces

The authors present a method for automating the generation of search targets used in finding borders of the left ventricle (LV) from digital-subtraction angiography (DSA) images and thus further automating LV-border determination. This method uses a large clinical database of LV borders to generate a probability surface of expected border locations. A composite image of all observed border points is used to create a set of extraction lines that is overlaid on the LV of interest. Border points are found by using a dynamic search on the density matrix formed by extracting pixel values at the points defined by the extraction matrix. User interaction is only needed to define the valve plane, confirm the final border, and make corrections if needed. LV contours then be used to find end-diastole and end-systole volume and ejection fraction.<<ETX>>

Blood Flow Measurements in Digital Cardiac Angiography using 3D Coronary Artery Reconstructions

Impaired blood flow, which can result in ischemia and death to tissues of critical organs, is a byproduct of several disease states. Examples of angiographic techniques which study blood flow include those 1. which measure uptake and washout of contrast media, 2. which measure the contrast dilution as an indicator, and 3. transit time measurements which measure the time it takes for the fluid to traverse a known volume. This last technique provides the ability to measure absolute blood flow within individual segments and is the subject of this paper.

Three-dimensional Reconstruction and Cross-section Measurements of Coronary Arteries using ECG-Correlated Digital Coronary Arteriography

The advent of digital image processing has facilitated accurate quantitative analysis of coronary artery morphology [1–7]. To optimally utilize the morphological information available in multi-view cine-angiography and potentially completely replace inaccurate visual determinations of lesion severity [8–13], it is desirable to consolidate the information available into a single densitometric analysis of the arterial tree. In recent years the problem of three-dimensional reconstruction of vascular beds from multi-view angiography has been addressed by several research groups [14–20]. Methodology utilized include the centerline reconstruction methods of Potel et al. [15] and Kim [16], circular reconstructions of Mol et al. [18], the morphologic cross-section reconstructions of Reiber et al. [17] and other multi-view tomographic techniques such as those of Kruger [19] and Mawko [20].