David E. Beecher

Altered regional myocardial metabolism in congestive cardiomyopathy detected by positron tomography

The present study was performed to determine whether positron emission tomography performed after intravenous injection of 11C-palmitate permits detection and characterization of congestive cardiomyopathy. Positron emission tomography was performed after the intravenous injection of 11C-palmitate in 13 normal subjects, 17 patients with congestive cardiomyopathy, and six patients with initial transmural myocardial infarction (defined electrocardiographically). Regionally depressed accumulation of 11C-palmitate was assessed, characterized, and quantified in seven parallel transaxial reconstructions in each patient. Normal subjects exhibited homogeneous accumulation of 11C-palmitate within the left ventricular myocardium, with smooth transitions in regional content of radioactivity. Patients with cardiomyopathy exhibited marked spatial heterogeneity of the accumulation of palmitate throughout the myocardium, easily distinguishable from that in normal subjects and distinct from that observed in patients with transmural infarction, in whom discrete regions of depressed accumulation of palmitate were observed with residual viable myocardium accumulating palmitate homogeneously. Patients with cardiomyopathy exhibited a larger number of discrete noncontiguous regions of accumulation of palmitate within the myocardium than either control subjects or patients with transmural infarction (17.4 +/- 0.6 [SEM] versus 11.8 +/- 0.7 versus 10.3 +/- 0.6, p less than 0.005). Similarly, regions of accumulation of palmitate were irregularly shaped in patients with cardiomyopathy, with a longer normalized perimeter than either control subjects or patients with transmural infarction (2.0 +/- 0.05 versus 1.8 +/- 0.06 versus 1.9 +/- 0.09, p less than 0.05). Regional abnormalities of the accumulation of 11C-palmitate could not be explained by regional differences in left ventricular wall motion or myocardial perfusion. Thus, marked heterogeneity of regional myocardial accumulation of 11C-palmitate is detectable and quantifiable in patients with congestive cardiomyopathy by positron emission tomography and may be particularly valuable for early detection and characterization of cardiomyopathy.

DICOM shareware: a public implementation of the DICOM standard

This software was designed to satisfy the requirements of the 1993 DICOM demonstration and is not intended to provide a complete system. However, this software does provide an example implementation which can be used to gain understanding about the DICOM Standard and has successfully communicated with the 20 vendors who participated in the DICOM demonstration at the 1993 RSNA. This software is written in ANSI-C and has been compiled under the following operating systems: SunOS, Solaris, Ultrix, OSF/1, Irix, NextSTEP. This poster describes the implementation of the software, how the software can be used, and how the software can be obtained.

The super PET 3000-E : A PET scanner designed for high count rate cardiac applications

Objective Mathematical models for the delineation of regional myocardial perfusion and metabolism with PET require faithful reconstruction of arterial and myocardial time-activity curves following administration of radiotracers. High temporal resolution is often required in such measurements. Many commercially available tomographs exhibit long dead times that limit their count rate capabilities. To overcome these limitations, we developed and tested a whole-body tomographic device (Super PET 3000-E) with high count rate capabilities. The use of cesium fluoride scintillation detectors coupled with a one-to-one detector photomultiplier configuration reduces the system resolving and dead times. Materials and Methods The Super PET 3000-E was subjected to a series of tests with phantoms to determine its resolution, sensitivity, linearity, count rate capabilities, dead time, and random coincidence contribution. Results The system sensitivity is 136 kcounts/s/μCi/ml and its transverse and longitudinal resolutions are 8.5 and 10.5 mm full width at half-maximum, respectively. The system can easily record a total event rate of 2.0 Mcounts/s with minimal dead time loss and excellent linearity. Conclusion The system fulfills its design goals and allows the very high count rate performance needed for the application of the physiological models used in our cardiac studies.

Computer-based image analysis of one-dimensional electrophoretic gels used for the separation of DNA restriction fragments.

A stand-alone, interactive computer system has been developed that automates the analysis of ethidium bromide-stained agarose and acrylamide gels on which DNA restriction fragments have been separated by size. High-resolution digital images of the gels are obtained using a camera that contains a one-dimensional, 2048-pixel photodiode array that is mechanically translated through 2048 discrete steps in a direction perpendicular to the gel lanes. An automatic band-detection algorithm is used to establish the positions of the gel bands. A color-video graphics system, on which both the gel image and a variety of operator-controlled overlays are displayed, allows the operator to visualize and interact with critical stages of the analysis. The principal interactive steps involve defining the regions of the image that are to be analyzed and editing the results of the band-detection process. The system produces a machine-readable output file that contains the positions, intensities, and descriptive classifications of all the bands, as well as documentary information about the experiment. This file is normally further processed on a larger computer to obtain fragment-size assignments.

Performance characterization of a whole body PET system designed for dynamic cardiac imaging

Specifications were developed for a PET (positron emission tomography) system that emphasizes high-count-rate performance and is specifically designed for the estimation of myocardial perfusion using oxygen-15 water and dynamic imaging protocols. The seven-slice CsF detector array is a one-on-one configuration, and has a reconstructed FOV (field of view) of 52 cm and an axial FOV of 10.7 cm. Wobble and axial translation are used. The gantry and associated electronics were interfaced to a new computer system, data collection and image reconstruction software was developed and the performance of the system was characterized with phantom, animal, and human studies. The system sensitivity is 136000 cts/s/ mu Ci/cm/sup 3/ and the reconstructed resolution is better than 9 mm. Imaging a 20-cm uniform phantom with 4.3 mu Ci/cm/sup 3/, the system collects a total rate of 1.57 Mcts/s with a loss fraction of 0.72 and a ratio of randoms/trues of 0.64.<<ETX>>

Perfusion measures from dynamic ICG scanning laser ophthalmoscopy

Movies acquired from fundus imaging using Indocyanine Green (ICG) and a scanning laser ophthalmoscope provide information for identifying vascular and other retinal abnormalities. Today, the main limitation of this modality is that it requires esoteric training for interpretation. A straightforward interpretation of these movies by objective measurements would aid in eliminating this training barrier. A software program has been developed and tested that produces and visualizes 2D maps of perfusion measures. The program corrects for frame-to-frame misalignment caused by eye motion, including rigid misalignment and warp. The alignment method uses a cross-correlation operation that automatically detects the distance due to motion between adjacent frames. The d-ICG movie is further corrected by removing flicker and vignetting artifacts. Each pixel in the corrected movie sequence is fit with a least-squares spline to yield a smooth intensity temporal profile. From the dynamics of these intensity curves, several perfusion measures are calculated. The most effective of these measures include a metric that represents the amount of time required for a vessel to fill with dye, a metric that represents the diffusion of dye, and a metric that is affected by local blood volume. These metrics are calculated from movies acquired before and after treatment for a neovascular condition. A comparison of these before and after measures may someday provide information to the clinician that helps them to evaluate disease progression and response to treatment.

Image acquisition system for a hospital enterprise

Hospital enterprises are being created through mergers and acquisitions of existing hospitals. One area of interest in the PACS literature has been the integration of information systems and imaging systems. Hospital enterprises with multiple information and imaging systems provide new challenges to the integration task. This paper describes the requirements at the BJC Health System and a testbed system that is designed to acquire images from a number of different modalities and hospitals. This testbed system is integrated with Project Spectrum at BJC which is designed to provide a centralized clinical repository and a single desktop application for physician review of the patient chart (text, lab values, images).

Performance of a teleradiology medical doctor's workstation supported by narrow-band integrated services digital networking

This paper describes deployment of a Medical Doctors Workstation (MDWS) hosting access to the Institutes radiology image and information system testbed. On-line acquisition of CT, MR and CR images for the physicians patients was supported. JPEG-compressed images reduced image data communications requirements by a factor of ten. Image interpretation at the remote site was supported by access to on-line radiology reports. The communications link to the MDWS was provided by a pair of Combinet ethernet-to-ISDN bridges interfaced to a basic rate (two B channel) ISDN line. Results of two successive trials in a referring physicians office are reported, along with the steps taken to improve limitations identified by the systems user.

ENGINEERING ASPECTS OF PETT VI

PETT VI is a circular ring, multislice positron emission tomograph designed for small field studies. Features such as wobble and rotate motions, bimodal resolution, cesium flouride scintillators, fast timing circuits and dual buffer histogram memories allow a flexible data acquisition environment. Efficient modularized software concepts are implemented to facilitate concurrent tasks of data acquisition, processing and display. The ability to effectively manage high count rate situations and collect continuous time frames makes PETT VI ideally suited for dynamic studies.