William B. Hanlon

Quantitative computer-assisted analysis of left ventricular wall thickening and motion by 2-dimensional echocardiography in acute myocardial infarction

Quantitative regional wall motion analyses of 2-dimensional echocardiograms (2-D echo) have usually focused on large arcs (greater than 45 degrees) of the left ventricular (LV) perimeter rather than on small LV zones. Few studies have assessed changes in wall thickness. To determine normal ranges of regional LV function, the endocardial and epicardial contours of short-axis 2-D echoes obtained at the papillary muscle level of 10 normal subjects were manually traced. Then, 15 patients with acute myocardial infarction (MI) were studied, comparing their contours at admission with ranges determined from the normal subjects. In all patients with MI, 2-D echoes located abnormal wall motion involving at least the region identified as abnormal by the electrocardiogram and often extending into adjacent regions. All 9 patients with transmural MI had either decreased wall thickening or abnormal endocardial wall motion; all except 1 had focal thinning in the region of the MI. Of the 6 patients with nontransmural MI, 2 had abnormal endocardial wall motion, and all had decreased wall thickening. Evaluating regional wall motion at multiple points around the LV circumference should permit more precise delineation of LV function in health and disease than has been heretofore possible.

Computer Reconstruction of Luminal Cross-Sectional Shape from Multiple Cineangiographic Views

Knowledge of coronary luminal shape, in addition to diameter information as routinely obtained from a cineangiogram, may be useful in assessing lesions which deviate from circular symmetry. We have developed an image analysis system for automated tracking of luminal edges and measurement of diameter form cine frames digitized by a video camera/digitizer interfaced to a Vax 11/780 computer. Between vessel edges, cinedensitometric profiles across the vessel long axis are used to provide a rotationally invariant measure of relative luminal cross-sectional area. A maximum entropy iterative algorithm is used to reconstruct the lumen cross section from a set of projection data consisting of the cinedensitometric profiles from multiple radiographic views. Nonaxisymmetric model coronary lumena, such as a crescent shape and a double lumen simulating a coronary artery dissection, were filmed under cineradiographic conditions similar to clinical exposures. Radiographic views at 10° increments about the model lumen long axis over 360° were available for analysis. Graphic display of reconstructed model lumena indicate that as few as three to five radiographic views may be useful in reconstructing coronary luminal shape.

Spinal Bone Mineral Determination Using Automated Contour Detection: Application To Single And Dual Energy CT

The measurement of spinal bone mineral content has been achieved by using automated contour detection on CT images. The method reproducibly provides a definition of the cortical area and calibrates a region of interest over essentially the whole spongeous bone. The algorithm can be used in single and dual energy CT studies. In single energy examinations the analyses employ a correction procedure based upon the method introduced by Cann and Genant. The procedures were tested on 40 randomly selected vertebral images.

Modality interfacing: The impact of a relay station

We evaluated the effect of a deploying a relay station on demographic discrepancies, image segmentation for routing, quality control (QC), and technologist workflow in a distributed architecture type picture archiving and communication system (PACS) environment. A currently existing PACS environment for computed tomography (CT) was evaluated before and after the implementation of a relay station for demographic error-rate and correct study routing to the workstations. Assessment of the technologists’ perceptions with respect to numerous workflow factors was performed with a questionnaire. Statistical analysis was performed using a chi-square test. The demographic error rate for CT examinations was nearly abolished with relay station deployment (14.0% pre-Relayv 0.55% post-Relay,P<.001, χ2). The technologists’ perception was favorable, with a substantial majority indicating that a positive impact is made on correcting demographic errors (90%), facilitating QC (67%), and ensuring proper routing (77%). A majority also felt the user interface was intuitive (93.3%) and preferred relay (90%) over film handling but that training should be provided both by didactic sessions and “hands on” time with a trainer. The times to perform tasks were favorable for the relay station (1 to 5 minutes) versus film production and handling (2 to 15 minutes). In conclusion, the relay station prospectively eliminates demographic errors, effectively segments images from the same study routing them to different workstations, and can be seamlessly integrated into the technologists’ current workflow. This can be scalable and a lower cost solution as opposed to deploying dedicated PACS QC workstations. *** DIRECT SUPPORT *** A00RM031 00006

Data storage and management requirements for the multimedia computer-based patient medical record

The business of healthcare management is changing rapidly, heading in the direction of managed care, capitation, and integrated delivery systems. Information management is crucial to the success and competitiveness of these new care delivery systems. A major goal of medical systems designers is to develop a model for a multimedia, computer-based patient medical record (CPR). The fundamental function of a CPR system is to record, monitor, retrieve, and analyze all events associated with an encounter between the patient and the healthcare system. Data components of the CPR include all forms of multimedia information, gathered from various departments within the institution. Users of the data will be diverse and widely distributed. The amount of digital data generated will be approximately two terabytes (TB) of information per year for a medium-sized metropolitan medical institution. Most of the data (by volume) are diagnostic radiological images. This information must remain on-line or near-line for 7-10 years, or longer in many cases. Image and other data of the CPR will be stored as self-defining information objects in a data repository (DR). The DR will be comprised of distributed storage subsystems and a high-level communications interface. Mass storage subsystems and information management systems being developed now will be core technologies of the DR and the CPR.

Automated calvaria analysis from computerized axial tomographic scans.

Abstract An automated off-line computer analysis that determines calvarial properties from CT images is described. The method provides 180 measurements of bone mass and thickness around the calvaria. The analysis also attempts to separate trabecular and cortical bone at segments in which characteristic differences are apparent. It compares these quantities for the left and right sides of the skull and finally it computes calvarial circumference.

Automated Morphologic Evaluation of Pulmonary Arteries in Primary Pulmonary Hypertension

Pulmonary wedge angiograms have been shown to reflect the severity of pulmonary vascular disease in congenital heart disease. Thirteen pulmonary wedge angiograms with a balloon occlusion catheter were performed in 11 adult patients (five normals and six with primary pulmonary hypertension [PPH]) and their features related to the resting pulmonary artery pressure (PAP). Individual cine frames from each study were selected and digitized with a computer-assisted operator-interactive program. By fitting densitometric profiles from the vessel segments, serial arterial cross-sectional diameters were calculated from mathematically derived points. There was a strong correlation between arterial taper (T, change in vessel caliber per unit axial length) and a power function of mean PAP with T = 0.304 X PAP-0.59, R = .91, P less than .001. These results demonstrate a correlation between an angiographically derived morphologic characteristic of the pulmonary vasculature (taper) and a hemodynamic parameter (PAP) in PPH. This offers a method to follow the course of the disease and the effects of drug therapy by assessing anatomic changes in the vessels.

Left ventricular wall motion analysis using operator-independent contour positioning

A method has been developed for the analysis of left ventricular wall motion which obviates the operators involvement in the relative positioning of the systolic and diastolic contours. This was achieved by maximizing the cross-correlation function for the two silhouettes . The technique was compared with a standard method requiring the operators definition of a long axis for the left ventricle. The results for 21 normal angiograms showed that with the cross-correlation technique the confidence region of the wall motion curves was markedly narrower and the symmetry in the contractile pattern between the anterior and posterior wall segments was better than with the standard technique. Statistical concepts for narrowing the normal group and the sources of errors in the analysis are discussed.

Quantitative analysis of left ventricular wall motion and thickness using two-dimensional echocardiography☆

The real time two-dimensional ultrasonic imaging of the left ventricle made possible segmental echocardiographic measurements of wall motion and thickening and thinning. The underlying hypothesis is that measurements of regional wall motion could quantify the extent of myocardial ischemia and infarction; the method could be used as a truly non-invasive tool to assess the severity of damage from infarction and the effects of interventions designed to limit infarcts. The method is operator interactive. Each patients data could be compared with data for a normal group. The selection criteria for the normal patients have been described. The confidence region of the normal group and the effect of averaging over three tracings for three heartbeats have been computed. Technical difficulties inherent in the method and possible improvements are discussed.

Computer-assisted, operator-interactive technique for calculating pulmonary arterial taper.

We have developed a computer-assisted, operator-interactive technique which performs fast, precise computations of pulmonary artery taper. Individual 35-mm cineframes from balloon-occlusion pulmonary arteriograms are digitized into a 640 X 480 matrix in 8-bit depth and loaded into a VAX 11/780 computer for analysis. After operator identification of the arterial segment, an automated process of caliber analysis is initiated. By fitting a cubic spline function to the densitometric profiles extracted from the arterial segment, serial arterial cross-sectional diameters are calculated from the mathematically-derived points along the fitted curves. Spurious profiles, caused by sectioning at bifurcations, can be overridden by an operator-interactive subroutine. Taper is derived from the slope of the least-squares fit of vessel caliber with respect to its distance along the arterial segment. Results obtained by calculations from the computer-assisted caliber measurements were compared with those obtained by hand-tracing the same vessel segments. Correlation between computer-traced inflection points and hand-traced taper was very significant (r = .96, n = 13, P less than 0.001).