Dale G. Gehring

Orbital volume measurements in enophthalmos using three-dimensional CT imaging.

The purpose of this study was to investigate enophthalmos by measuring the volume of various orbital structures using off-line computer techniques on images generated by a CT scanner. Eleven patients with enophthalmos had CT scans of the orbits consisting of 30 to 40 adjacent 1.5-mm slices. The data from the scans were analyzed on a Nova 830 stand-alone computer system using software programs that allowed measurement of total bony orbital volume, total soft-tissue volume, globe volume, orbital fat volume, neuromuscular tissue volume, and apex-to-globe distance in the horizontal plane. These data were analyzed comparing the volumes in the normal eye with the volumes in the enophthalmic eye in each patient. The analysis demonstrated a statistically significant increase in bony orbital volume in the enophthalmic eye, but the total soft-tissue volume, fat volume, neuromuscular tissue volume, and globe volume were the same as in the normal eye. The apex-to-globe distance, a measure of the degree of enophthalmos, was less in the enophthalmic eye than in the normal eye. These results suggest that in the majority of patients, the cause of posttraumatic enophthalmos is increased bony orbital volume rather than by soft-tissue loss or fat necrosis. (Several patients showed no volume discrepancies, and it is likely that cicatricial contracture is responsible for the enophthalmos in these cases.) This study suggests that the objective of surgery for correction of enophthalmos in patients with a volume discrepancy should be to decrease the volume of the bony orbit and to increase the anterior projection of the globe.

Image display for clinicians on medical record workstations.

Image display on electronic medical record (EMR) workstations is an important step in widespread implementation of picture archiving and communications systems (PACS). We describe a pilot project for implementing image display capability that is integrated with the EMR software, and will allow display of images on the physician’s workstation. We believe this pilot will provide valuable information about usage patterns in image display needs, which will be valuable in planning further expansion of PACS in our institution.

Functional requirements of a desktop clinical image display application

ConclusionThe requirements for a clinical viewing station have some similarities to requirements of an interpretation workstation, but have some important differences. The user base is a heterogeneous group, and the tasks the clinicians perform vary substantially, increasing the variation in the requirements. However, it is possible to determine a list of requirements that satisfy most clinicians under most circumstances. In addition to the standard image manipulation tools, we have found that integration with the other clinical tools is essential to maintaining or increasing their efficiency. Providing for varying levels of functionality/complexity is also useful, because of the variation in the user base.

Comparison of monoplane and biplane assessment of regional left ventricular wall motion after thrombolytic therapy for acute myocardial infarction

Regional left ventricular (LV) function was assessed using serial biplane orthogonal LV angiograms recorded before and after reperfusion therapy for acute myocardial infarction (AMI) in 24 patients. Improvement in regional LV function was seen in only 5 patients after reperfusion therapy when only the right anterior oblique view was analyzed; improvement in regional wall motion was seen in 14 when biplane views were analyzed. Biplane analysis was particularly important in the 12 patients with right coronary artery occlusion, among whom the right anterior oblique view showed improvement in only 1 patient but the left anterior oblique view showed improvement in 6 patients (p less than 0.05). Biplane analysis is more sensitive than monoplane right anterior oblique analysis alone for detecting improvement in LV function after reperfusion therapy for AMI. However, both views are complementary, adding information about regional function not revealed by either view alone.

Clinician image review patterns in an outpatient setting

We have previously described a system for delivering radiology information to the desktop computers used for the electronic medical record (EMR). The system was built with the ability to record physician usage to a database. This usage information was then studied to help understand the value and requirements of an application that could display radiology information on the EMR workstations. This system was used by both primary care physicians and specialists primarily in the out-patient setting. We found that while there was substantial variation in usage both within and between the two physician groups, there was a high degree of support for maintaining image display capabilities on the workstations.

Current status of the joint Mayo Clinic-IBM PACS project

A multi-phase collaboration between Mayo Clinic and IBM-Rochester was undertaken, with the goal of developing a picture archiving and communication system for routine clinical use in the Radiology Department. The initial phase of this project (phase 0) was started in 1988. The current system has been fully integrated into the clinical practice and, to date, over 6.5 million images from 16 imaging modalities have been archived. Phase 3 of this project has recently concluded.

Therapeutic implications of intraoperative pressure measurements after the fontan operation

Central venous pressure (CVP) and left atrial pressure (LAP) were monitored continuously for the first 72 hours postoperatively in 32 patients who underwent a Fontan operation in whom preoperative measurements of the pulmonary artery index were available. Integrated mean values were generated for each patient for the following time frames: (1) the first 12 hours after operation, (2) the first 24 hours after operation, (3) postoperative day 2, and (4) postoperative day 3. We found no difference in the CVP, LAP, or transpulmonary gradient, derived as CVP-LAP, measured in the operating room at the completion of the operation versus that measured on the third postoperative day: CVP, 18 +/- 2 mmHg versus 19 +/- 3 mmHg; LAP, 10 +/- 2 mmHg versus 10 +/- 3 mmHg; and transpulmonary gradient, 8 +/- 2 mmHg versus 8 +/- 2 mmHg. The combined incidence of hospital mortality and postoperative takedown associated with the Fontan repair was 12.5%. These findings suggest that a poor hemodynamic result from the Fontan operation can be predicted from intraoperative pressure measurements, because the CVP, LAP, and transpulmonary gradient are unlikely to change significantly in the early postoperative period. Therefore, a decision to take down or fenestrate the repair can reasonably be made in the operating room or the early postoperative period.

A Skeptical Look At A (DIGITAL) Sacred Cow

Digital imaging in one form or another is being used for virtually every aspect of medical imaging. Many are predicting that the diagnostic department of the future will be entirely digital. However, upon careful consideration, many questions remain to be answered concerning the monumental quantities of digital data which must be acquired, processed, transmitted, displayed, stored, and recalled. In order to be acceptable to the clinician the digital systems of the future must be able to produce images with image quality which is at least as good as that presently available, at costs similar to those incurred in todays imaging environment, and with the same ease of use as the clinician experiences today. If future digital systems only meet these goals without providing additional significant benefits then one must wonder if digital imaging will ever be adopted as the sole means of image acquisition, display, and storage. This paper attempts to answer the question--is the total digital medical imaging department of the future a dream or a nightmare?

Integration of PACS image display with an electronic medical record

The ability to display medical images on electronic medical record (EMR) workstations appears to be an important step for both widespread implementation of the EMR and of picture archival and communications systems. We describe a system which we have implemented for achieving image display on EMR workstations, which is integrated with the EMR. Some of the important questions we hope to answer at the end of this pilot project are also outlined.

Performance of the Mayo-IBM PAC system

The Mayo Clinic and IBM (at Rochester, Minnesota) have jointly developed a picture archived system for use with Mayos MRI and CT imaging modalities. This PACS is made up of over 50 computers that work cooperatively to provide archival, retrieval and image distribution services for Mayos Department of Radiology. This paper will examine the performance characteristics of the system.