Richard E. Sayre

Methods for evaluating cardiac wall motion in three dimensions using bifurcation points of the coronary arterial tree.

An accurate three-dimensional (3D) representation of heart wall motion would be an important means of evaluating cardiac function. To accomplish this, we have developed an interactive computer graphics system designed to enter the time-dependent 3D positions of bifurcations of the coronary arterial tree. These bifurcations are precise markers of the epicardial surface, and their motions accurately represent the motion of the underlying heart wall. We demonstrate techniques for calculating local wall motion, including displacement and velocity, for determining a time-dependent center-of-contraction point towards which the epicardium tends to move and for tracking the mechanical contraction wave using cross-correlation methods. We have applied these techniques to study seven patients with normal left ventriculograms and coronary arteriograms. We have found these methods to be generally applicable and to provide information not obtainable without 3D analysis.

Three-dimensional left ventricular wall motion in man. Coordinate systems for representing wall movement direction.

We have studied the three-dimensional (3D) motion of left ventricular (LV) epicardial points by tracking one to three dozen coronary artery bifurcations in eleven human subjects. Wall motion was analyzed using several different coordinate systems: (1) cylindrical centered about the LV long axis, (2) spherical with origin at the LV center-of-gravity (COG), and (3) spherical with origin at the LV center-of-contraction (COC), the best-fit 3D point toward which the wall moves. The coordinate systems were studied both fixed and moving with time. Three-dimensional motions were decomposed into three directional components, with high radial (in and out) percentages being regarded as the figure-of-merit of a given coordinate system. Average percentage radial motions were fixed cylindrical 16%, fixed spherical COG 35%, fixed spherical COC 47%, moving cylindrical 17%, moving spherical COG 30%, moving spherical COC 91%. Spherical systems were generally better than cylindrical systems, with the COC representing a better origin than the COG. Moving systems were appreciably better than fixed only for the COC model, indicating that the COC, which traverses up and down the LV midline, moves significantly while the other systems are more stationary. At each instant in time, almost all (91%) of the 3D motion of the entire heart wall is directed toward a single moving 3D point, the COC. Thus, there exists in principle a near-perfect 3D heart wall motion model. Approximately 25% of 3D wall motion is unseen in conventional monoplane views. Also, any model that represents 3D wall motion only along fixed straight 3D lines (eg, end-diastole to end-systole) necessarily ignores 27% of the true 3D heart wall motion.

Interacting with the GALATEA film analysis system

GALATEA is an interactive animated graphics system providing a tool for the man-machine analysis of moving images recorded on film. The system relies on the users recognition of phenomena of interest and his manipulation of simple graphical objects to build up a kinegram, an animated representationof the film. Display of the kinegram superimposed on the original film facilitates the entry and refinement of the animation. The net result is an analysis by synthesis. In this paper we describe the current production version of GALATEA from the standpoint of the user. Included are a functional description of the constituent hardware, demonstration of various aspects of system behavior, and some examples of interactions common in user applications.

A system for interactive film analysis

Abstract An interactive, minicomputer system has been constructed for analyzing dynamic phenomena recorded on movie film in a developmental biology laboratory. The minicomputer interfaces a stop-motion, variable speed projector, a digitizing pen, and real-time graphics display equipment. An analyst uses the pen to digitize features in a film, e.g. by following a cell. A computer-generated animation portraying all data entered is superimposed on the film image and synchronized with it. Noteworthy system features include: image overlays on a large screen, data entry with the projector running, large data capacity, computer control of the projector, and convenient data entry tools.

Graphics input tools for interactive motion analysis

Abstract The use of Galatea, an interactive animated graphics system for analyzing dynamic phenomena recorded on movie film, is discussed. An analyst views a film with a stop-motion projector and uses a digitizing pen to transcribe features of interest, for example, by following a wandering amoeba. Simultaneously, an animated graphics image corresponding to the data entries is generated and, using a projection kinescope, is superimposed on the film image, synchronized with it as it runs. The system acts like “dynamic tracing paper” for the film and provides a set of real-time hand-eye input tools and graphical data types useful for motion analysis. After a brief overview of Galatea and a discussion of the advantages of interactive motion analysis systems, the paper lists the input tools and data types that have been used. An accuracy experiment is described. The use of the system to solve a number of different motion analysis problems is discussed, illustrated by applications in cell biology, anatomy, and radiology.

1978 memorial award paper: A computer-aided technique for overlaying cerebral angiograms onto computed tomograms

We have developed a method which uses a digital computer to combine angiographic images of the cerebral vasculature with a computed tomogram of the brain. The procedure is simple and could be implemented in any radiology department equipped with both a CT scanner and a bi-plane angiography suite. We have performed the entire process in prototype on phantoms and on a patient and have produced images that appear accurate and informative.

“Permanent” records: Experience with data migration in radiology information system and picture archiving and communication system replacement

In the replacement of both a radiology information system (RIS) and a picture archiving and communication system (PACS) archive, data were migrated from the prior system to the new system. We report on the process, the time and resources required, and the fidelity of data transfer. We find that for two PACS archives, both organized according to the Digital Imaging and Communications in Medicine (DICOM) information model, data may be transferred with full fidelity, but the time required for transfer is significant. Transfer from off-line backup media was found to be faster than transfer from our robotic tape library. In contrast, the RIS replacement required extensive labor to translate prior data between dissimilar information models, and some data were inevitably lost in the translation. Standards for RIS information models are needed to promote the migration of data without loss of content.

3D Galatea: Entry of three-dimensional moving points from multiple perspective views

We describe an interactive graphics system for the entry of three-dimensional moving points from multiple perspective views. This work represents a major extension of Galatea, our system for graphics-assisted 2D motion analysis. 3D Galatea permits reconstruction of 3D time-dependent positions from 2D entries in two or more perspective views. The system supports a general approach for calibrating perspective views. This method, based on work of Sutherland, uses a known 3D reference object to calibrate completely arbitrary perspective projections. A somewhat restricted class of perspective views may be calibrated without an explicit calibration object using another approach developed from photogrammety. In 2D Galatea, we have used an animated graphics overlay onto the source image to give the analyst feedback regarding current and previous data entries. This capability is extended in 3D Galatea by overlaying auxiliary lines, which are the backprojections of previous 2D entries from one view into other views. This concept amounts to a fourth interpretation of the well-known Roberts homogeneous matrix equation describing perspective projections of 3D space into a 2D image. The auxiliary line is useful in locating a point which is obscured in one of the images, or in determining the correspondence of projected points as seen in different views, which may be ambiguous or easily confused.

Left ventricular wall motion: its dynamic transmural characteristics.

Cardiac wall motion has been studied extensively. It is usually determined by indirect two-dimensional measurements for the true three-dimensional (3D) motion with its specific speed and direction. Errors are also introduced by using internally fixed reference systems and by the inability to identify precise points on the heart wall during the cardiac cycle. Because of these limitations, the endocardial and epicardial wall motion and their relationship are still unclear. This study was designed to assess endocardial and epicardial wall motion by measuring the direction and speed of implanted markers in an externally fixed 3D coordinate system. Fifty-seven pairs of endocardial and epicardial metallic markers were placed at anterior, lateral, posterior, basal, and apical regions of the left ventricles of 14 normal mongrel dogs. Biplane cineradiographs were performed at 50 frames/sec, and the 3D motions of the markers were analyzed using a specially designed computer system. It was found that the speeds, directions, displacements, and phases of the movements of corresponding endocardial and epicardial points were highly correlated. The correlation coefficients were 0.77 to 0.95 for the mean directions, 0.61 to 0.96 for the mean speeds, and 0.59 to 0.96 for the mean displacements at various regions of the heart, and the periodic movements of the endocardium and epicardium were always in phase. The mean epicardial speeds and displacements are fixed proportions (approximately 70%) of the mean endocardial speeds and displacements despite the differences in absolute values between regions in the same dog and the same regions in different dogs. The correlation coefficients for endocardial and epicardial instantaneous speeds, directions, and velocities ranged from 0.68 to 0.83, 0.81 to 0.88, and 0.77 to 0.86, respectively, for different regions of the heart. The correlation coefficients were significant for both the mean values and the instantaneous values. Thus, when only fixed epicardial points are accessible for wall motion measurements in clinical situations, it is possible to infer the endocardial motion from the epicardial motion.

C-QUAL : a system for computer-aided transcription of videotaped action sequences

C-QUAL is a system for the computer-aided transcription of action sequences from videotape. The system is designed for research on face-to-face interaction focusing on sequences of action involving speech and body motion. When the analyst indicates the beginning or the ending of a specified action, C-QUAL associates that event with the frame number on which it was transcribed and enters the information in a database. In this manner, all transcribed actions are located sequentially with respect to each other to the accuracy of a single video frame. Entered data can be superimposed on the video image for checking and editing. By using the Sequel-Analysis Module, an innovative device for visually representing speech, C-QUAL permits speech transcription (including syllables, pauses, intonation, and paralanguage) to be fully integrated with body-motion transcription. The system supports the transcription of both speech and body motion in either tape direction or at any tape speed, including stop frame.