Assessment of myocardial perfusion by videodensitometry in the canine model.

Assessment of the functional severity of coronary stenoses has become increasingly important as the intrinsic limitations of coronary angiography have been documented. Videodensitometric coronary flow reserve has been proposed as a means to assess the physiologic significance of a coronary stenosis in humans. This study compared videodensitometric assessment of coronary flow with microsphere quantitation in the closed chest canine model. In five dogs, flow rates were assessed at baseline, after vasodilation with adenosine, after vasoconstriction with vasopressin and during rapid cardiac pacing. The videodensitometric peak density, time to one-half peak density and washout time (time from peak to one-half peak density) were compared at each flow state with flow assessed by microsphere injection. Reproducibility of videodensitometric measurements from two different coronary injections during the same flow state was best with peak density (r = 0.94). Videodensitometric flow ratios (flow state under study to flow at rest) using peak density demonstrated a fair correlation with flow ratios by microsphere (r = 0.81). There was poor correlation between flow ratios when time to one-half peak or washout time was used. Videodensitometric flow measurements used in vivo to assess a wide range of drug-induced coronary flows may not accurately reflect coronary flow measured by microsphere.

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.

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.

Ophthalmopathy of Graves' disease: computerized volume measurements of the orbital fat and muscle.

Pixel-calibrated volume measurements of muscle and fat in the bony orbit were made from CT scans of 72 patients with Graves' disease, with and without ophthalmopathy, to define characteristic changes present in clinical subgroups. Measurement abnormalities were detected in 87% of Graves' patients with clinically detectable ophthalmopathy and in 70% of hyperthyroid patients without clinical eye signs. Abnormal enlargement of the fat compartment in addition to muscle enlargement was found in 46% of patients with clinical ophthalmopathy; 8% of patients had only increased size of the fat compartment with normal muscle volumes. The ratio of muscle to fat and the volumes of orbital muscle and fat all varied widely in each clinical subgroup. Statistically significant (p less than 0.0001) total muscle-volume increase (range = 3.68-17.06 cm3) and borderline significant (p less than 0.06) fat-compartment increase (range = 6.05-22.63 cm3) were documented in all clinical subgroups. The degree of change of muscle and fat volumes was independent of the clinical group. Abnormal changes were found in the contralateral orbit in six of seven patients who appeared to have unilateral ophthalmopathy on clinical examination. A higher frequency of medial and inferior muscle enlargement was documented in all clinical subgroups.

Superficial temporal-middle cerebral artery bypass: clinical pre- and postoperative angiographic correlation.

Between 1974 and 1982, an anastomosis between a pedicle of the superficial temporal artery (STA) and a cortical branch of the middle cerebral artery (MCA) was performed in 163 carotid systems in 157 patients for internal carotid artery occlusion in whom postoperative angiograms were available for analysis. The angiographic opacification of the arterial system was correlated with the patient's preoperative neurological function and stroke in the follow-up period. From this analysis, the following observations were made: 1) 96% of bypasses were patent; 2) 80% of bypasses achieved a high or medium MCA filling score; 3) there was hypertrophy of the STA in 70% of the cases; 4) greater bypass filling occurred in hemispheres with nonvisualized preoperative collateral circulation than in those with readily visualized collateral flow; 5) a meaningful correlation between angiographically assessed postoperative bypass function and stroke rate was not possible because only four patients suffered an ipsilateral hemispheric stroke in the 8-year follow-up period; and 6) patients who were neurologically unstable before the procedure were at greatest risk for a stroke in the follow-up period. It is apparent that objective analysis of the effectiveness of an STA-MCA bypass, or any other form of extracranial bypass, must await the development of new diagnostic studies in which high-resolution three-dimensional quantification of cerebral blood flow is possible. These studies will necessarily be correlated with preoperative and follow-up clinical data.

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.

READS: a radiology-oriented electronic analysis and display station.

READS is a picture archiving and communications system (PACS) display program that is tailored to allow a radiologist to efficiently perform image review tasks. In this study, the image review process was observed and functional patterns were identified. These were used to define a design that was considered to represent the optimal balance of compromises for a low-cost review station that also allowed easy addition of new functionality. As a result, a program was designed and implemented that has been found to be acceptable for image review and for special image processing function development.

Cerebrospinal fluid-iophendylate contrast on gradient-echo MR images.

The effect on the signal intensities of cerebrospinal fluid (CSF) and iophendylate (Pantopaque) and on CSF-iophendylate contrast was studied in vitro with a small-nutation-angle (alpha) gradient refocused magnetic resonance (MR) imaging technique (GRASS) as alpha, repetition time (TR), and echo time (TE) were varied. CSF signal intensity was consistently greater than that of iophendylate. Therefore, retained intraspinal iophendylate may be considered in the differential diagnosis of focal areas of low signal intensity at the periphery of the spinal canal on GRASS images. At constant TE and TR, an increase in alpha from 6 degrees to 45 degrees increased the signal intensities of CSF and iophendylate but decreased CSF-iophendylate contrast. At constant alpha and TR, an increase in TE from 13 to 28 msec decreased the signal intensities of CSF and iophendylate but increased contrast. At constant alpha and TE, an increase in TR from 50 to 400 msec increased the signal intensities of CSF and iophendylate, as well as contrast. Clinical examples of the contrast behavior of retained intraspinal iophendylate on both spin-echo and GRASS images corroborate the experimental findings. Retained intraspinal iophendylate may mimic the appearance of intra-or extra-dural lesions, magnetic susceptibility artifact, and flow on gradient-echo MR images of the spine.

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.

Clinician usage patterns of a desktop radiology information display application.

We developed a system for delivering radiologic images and reports to desktop computers used for the electronic medical record (EMR). This system was used by both primary care physicians and specialists primarily in the out-patient setting. The system records all physician interactions with the application to a database. This usage information was then studied in order to understand the value and requirements of an application that could display radiology information (reports and images) on EMR workstations. In this report we describe some of the differences and similarities in usage patterns for the two physician groups. A very high percentage of physicians indicated that having image display capabilities on the workstations was very valuable.

Volume measurements of normal orbital structures by computed tomographic analysis.

Computed tomographic digital data and special off-line computer graphic analysis were used to measure volumes of normal orbital soft tissue, extraocular muscle, orbital fat, and total bony orbit in vivo in 29 patients (58 orbits). The upper limits of normal for adult bony orbit, soft tissue exclusive of the globe, orbital fat, and muscle are 30.1 cm3, 20.0 cm3, 14.4 cm3, and 6.5 cm3, respectively. There are small differences in men as a group compared with women but minimal difference between right and left orbits in the same person. The accuracy of the techniques was established at 7%-8% for these orbit structural volumes in physical phantoms and in simulated silicone orbit phantoms in dry skulls. Mean values and upper limits of normal for volumes were determined in adult orbital structures for future comparison with changes due to endocrine ophthalmopathy, trauma, and congenital deformity.

Requirements for an enterprise digital image archive.

This report describes several image archival problems facing the authors' department and the results of their attempt to define the requirements for an enterprise digital image archive. The problems identified include the costs of supporting multiple distinct archives, the increased complexity of supporting multiple archive interfaces, the differences in data handling policies and resulting variations in data integrity, and variability in support for nonimage data. The authors also describe the data collected including image volumes and trends and imaging device trends. Finally, the resulting specification for an enterprise digital image archive, including storage and retrieval performance and interface requirements are presented.

Temporal lobe volume measurement from MR images: accuracy and left-right asymmetry in normal persons.

The effect of several magnetic resonance (MR) variables on the accuracy of volume measurements in phantom objects was investigated by use of an off-line automatic border-outlining and internal area pixel-counting computer program, and an optimal set of imaging variables was identified. Measurements were made of the temporal lobe volumes of a gross fixed brain specimen from MR image data. The range in accuracy was from -2 to +7%, and the standard deviation of the difference in right minus left lobe volume measurements obtained from the MR images and those obtained by use of Archimedes' principle was 1 cm3. This volumetric technique was applied to 25 normal persons, most of whom were right-handed. The median ratio of right to left temporal lobe volume was 1.16 (range 0.99-1.23). The nondominant temporal lobe was significantly larger than the dominant. The mean difference (95% confidence interval) between right and left volumes was 7 cm3 (6-9 cm3). This confidence interval was similar to that obtained when the variability within a subject (estimated from the gross fixed brain specimen) was taken into account. Unilateral temporal lobe atrophy, particularly in patients with temporal lobe epilepsy, should be interpreted from MR images with this range of discrepancy in normal left-right size in mind.