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-Relay v 0.55% post-Relay, P < .001, chi2). 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.

Web-based digital radiology teaching file: facilitating case input at time of interpretation.

OBJECTIVE: Our goal was to develop a software system that allows easy and rapid input of digital radiology images and text reports, at the time of interpretation, into an easily searchable electronic teaching file database using the Internet and the World-Wide Web protocols, servers, and browsers. CONCLUSION: Using the Internet, the World-Wide Web, and our software system, we can rapidly input digital radiology images and associated text reports into an easily searchable database accessed by privileged users. This inexpensive and simple method for building a digital teaching file database allows cross-platform access for users who have a Web browser.

High precision quantitative angiography.

Statistical considerations on the precision in the determination of blood vessel dimensions from digitized cine angiographic images are described. The resolution requirements related to "point measurements" and segmental diameter curve evaluations are discussed. The error associated with inaccurate determination of the vessel's centerline is analyzed. The concepts have been implemented on a high-speed image analyzing system, which measures blood vessel diameters with advanced automation. The performance of the system was evaluated with blood vessel phantoms, ranging in diameter from 0.88 to 6.26 mm. For these phantoms the minimum measurable change in vessel dimension over 20-pixel (-1.1 mm) long segments ranged from 3.4 to 0.2 percent, respectively.

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.

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).

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 operator's 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 operator's 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 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.

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 patient's 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.