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Biomedical subjects

J A Burdine

Publications and source records attributed to J A Burdine.

At least 19 recordsLinked to original sources
PubMed1986

The QS2/QT ratio as an index of appropriate left ventricular response to autonomic and inotropic stimuli.

Dissociation between duration of electrical and mechanical systole has been seen with increase of myocardial shortening velocity or adrenergic activity. We found a decrease of the QS2/QT ratio after exercise in 10 pts with semisitting bicycle maximal exercise test and a normal radionuclide angiogram. No change was seen in 9 patients with a normal study with beta blockade, and in pts with a abnormal radionuclide test, without beta blockade (11 pts). In 19 normal active individuals, a significant QS2/QT decrease (p less than 0.001) was seen after a submaximal exercise treadmill test, which was inhibited by beta blockade. We believe that QS2/QT diminution is suggestive of an increase of the inotropic state of the left ventricle with exercise, produced through adrenergic stimulation. It is not seen either when an ischemic left ventricle cannot adequately respond to exercise or after beta blockade.

Adult↗
PubMed1985

Phase alterations of spin echoes by motion along magnetic field gradients.

Using a Taylor series expansion of the phase shift of a moving isochromatic spin group in the presence of a magnetic field gradient, the refocusing effects of the Carr-Purcell-Meiboom-Gill pulse sequence on stationary nuclei and those with constant, rectilinear velocity are readily demonstrated. Continuing the analysis to higher orders of motion reveals that nuclei with a constant, rectilinear acceleration have a phase shift at the spin echoes which increases linearly with echo number. Constant, rectilinear jerk (the time rate of change of acceleration) leads to an increase in phase shift from echo to echo which is quadratic in nature with an overlying reduction of the odd-numbered echoes by a constant amount. Motion parameters may be measured by parameter identification techniques. These principles may be applied to phase-sensitive NMR imaging.

Magnetic Resonance Spectroscopy↗
PubMed1985

Correlations of systolic time intervals and radionuclide angiography at rest and during exercise.

Systolic time intervals (STI) were correlated with radionuclide angiography studies (RAS) in 57 patients at rest, during maximal semisitting bicycle exercise, and at 4 minutes following the cessation of exercise. Eleven were judged as being free of coronary artery disease (group 1), while 14 had coronary artery disease without (group 2A), and 27 (group 2B) with a previous transmural myocardial infarction. For RAS, resting radionuclide ejection fraction (REF), the changes in REF and end-systolic volume, and the development of a wall motion abnormality at peak exercise were each highly correlated with the presence of coronary disease (p less than 0.001). The accuracy of STI parameters in predicting the presence of coronary disease was poor (less than 60%). Changes in end-diastolic volume (EDV) correlated significantly with PEP/LVET and LVET1 changes following exercise. Moreover, patients with an abnormal (greater than 25%) increase in EDV at peak exercise had a greater increase in LVET1 in the postexercise period (p less than 0.01). We conclude that STI is not accurate enough a predictor of coronary disease or left ventricular function to serve as a useful screening test. Changes in STI parameters appear to be more related to changes in ventricular volume than to ventricular function.

Adult↗
PubMed1985

Integration of database capabilities into a patient reporting system.

A database design is described which automatically archives computer-generated patient imaging and radioassay reports. Selected phrases are condensed so that data storage will be efficient without sacrificing a prose style of report. An indexed file structure has been used to facilitate rapid record retrieval even when several hundred thousand records are stored. Personnel time is considerably reduced for recalling patient records, preparing periodic summaries of studies completed, and performing administrative functions such as billing and keeping track of checked out images. Complex queries, such as "list all the patients between the ages of 50 and 60 on digitalis referred for a stress cardiac study, with left ventricular ejection fraction less than 40% and apical dyskinesis," become feasible. A system for data backup is described to protect against catastrophic data loss.

Computers↗
PubMed1979

Clinical standardization of the new dual cardiac probe.

A new mobile dual cardiac probe has been introduced for measurements of the left ventricular ejection fraction (LVEF). In 28 patients, correlation between LVEFs measured by the dual probe and biplane contrast ventriculography was 0.83. Central and peripheral injections yielded comparable curves, and the resultant LVEFs correlated well (R = 0.95). Correlation between LFEVs determined by the probe and by gated blood pool imaging in 43 patients was also 0.83. In 21 patients given three serial injections of 99mTc-albumin, the mean variation of the ejection fraction was 4.2 +/- 3.2%; however, reproducibility was unsatisfactory using 99mTc-sulfur colloid due to sequestration in hepatic background tissue.

Heart Ventricles↗
PubMed1979

Radionuclide computed tomography of the body using routine radiopharmaceuticals. I. System characterization.

A whole-body computed tomography system for single-photon emitters was evaluated from the standpoint of spatial resolution, sensitivity, and thresholds for count densities with reference to standard doses of currently used radiopharmaceuticals in patients. In air and tissue equivalents, spatial resolution was relatively constant throughout the field of view and attentuation correction algorithms returned uniformity of response to within 10%. In a phantom of the human abdomen 1.5-cm spherical "cold" lesions and 1-cm "hot" lesions could be resolved. Aspects of the partial-volume effect were observed and investigated. To detect 1.5 cm-cold lesions in an abdominal phantom, five million events were required.

Computers↗
PubMed1979

Radionuclide computed tomography of the body using routine radiopharmaceuticals. II. Clinical applications.

A whole-body computed tomography system for single-photon emitters was used to investigate the clinical utility of this imaging modality. We have explored its application in brain, lung, liver, kidney, cardiac, bone, and gallium imaging in over 200 patients. Brain images demonstrated better lesion contrast than that in standard scintiphotos. Images of the lung and liver showed radionuclide distribution that was not readily apparent in standard scintiphotos. Moderate or strongly positive pyrophosphate myocardial images demonstrate the potential for infarct quantitation. ECG-gated cardiac blood-pool images in cross section, displayed in cine formate, permit evaluation of segmental motion of the free and septal walls of both ventricles. These results suggest significant clinical potential for this imaging modality using standard radiopharmaceuticals, but some increase in system sensitivity will likely be necessary to realize the full benefit of the technique.

Abdomen↗
PubMed1979

Scintigraphic, electrocardiographic, and enzymatic diagnosis of perioperative myocardial infarction in patients undergoing myocardial revascularization.

To assess the incidence of perioperative myocardial infarction, 214 consecutive patients were evaluated 1-5 days after coronary bypass surgery, using Tc-99m pyrophosphate (TcPPi) myocardial imaging, serial electrocardiograms (ECG), and enzyme levels (SGOT, LDH, CPK). On the basis of the clinical course and scintigraphic, enzymatic, and ECG changes, the diagnosis of perioperative infarction was definite in 17 of 241 cases (7.9%) and probable in six of 241 (2.8%). In all of these 23 patients, TcPPi scans were abnormal; one additional patient had a false-positive scintigram. Only 13 of the 23 had ECG evidence of infarction, but there were no false positives. We set the threshold for abnormality of enzyme changes quite high, owing to experience in more than 900 postoperative patients (SGOT greater than 200, LDH greater than 500, CPK greater than 500 on the same day). Using these criteria, 22 of the 23 infarct patients had abnormal enzymes, and six others were falsely positive. These results indicate a relatively low sensitivity for the ECG in diagnosing perioperative infarction, but the lack of false positives suggests high specificity. The sensitivity and specificity of the enzymes and the TcPPi image were both excellent and quite similar; the main difference was a reduction of certainty of infarction with the enzyme criteria, caused by the six patients whose enzyme values were falsely positive. Considering its sensitivity, specificity, and ability to locate and to a certain extent quantitate necrosis. TcPPi imaging is probably the most valuable means of diagnosing perioperative myocardial infarction.

Clinical Enzyme Tests↗
PubMed1978

The diagnosis of pneumothorax by ventilation-perfusion imaging.

Two patients with pneumothorax had ventilation-perfusion studies to rule out the possibility of pulmonary embolism; the presence of air in the pleural space was not known to the authors when the study was analyzed. A typical ventilatory pattern characterized by small volume difference at total lung capacity followed by disproportionately greater decrease of the volume of the affected lung at tidal breathing was observed. In one case, the routine chest radiograph failed to demonstrate air in the pleural space. A similar volume difference between the two lungs was noted on the perfusion images.

Adult↗
PubMed1978

Cassette videotape recording of computer images.

Direct videotape recording of images from computer display terminals is often not possible because of the nonstandard outputs of these systems. A video-sync mixer is described that permits black-and-white recording on standard 3/4-in. videotape cassettes.

Data Display↗
PubMed1978

Radionuclide kymography for the assessment of regional myocardial wall motion.

Regional myocardial wall motion is usually evaluated qualitatively from ECG-gated end-systolic and end-diastolic blood-pool images. Radionuclide kymography, which displays a one-dimensional scintigraphic image in time, synchronized with the electrocardiogram, provides a method to quantitate this motion. The technique is analogous to M-mode ultrasound in that one dimension is displayed as a function of time, but the activity distribution is displayed in place of acoustic interfaces. The motion of regional myocardial segments can be measured from multiple kymographic projections across the cardiac blood pool, after equilibration of a radioactive tracer. Radionuclide kymography is potentially better quantitatively than gated blood-pool imaging and is not hindered by viewing windows as are single- and multiple-transducer ultrasonography. Regional wall motion determined from radionuclide kymography correlated well with that determined from contrast left ventriculography in a series of patients. Since the kymographic sweep is initiated by the R wave of the ECG and proceeds continuously throughout the cardiac cycle, the temporal sequence of regional myocardial contraction can be directly assessed and related to corresponding portions of the ECG.

Computers↗
PubMed1977

Large-field-of-view (LFOV) scintillation cameras.

Large-field-of-view scintillation cameras are general purpose, cost effective, imaging devices if one maximizes the use of the crystal with respect to the size of the object under study. This means using parallel-hole collimation for large-organ systems to reduce the number of views necessary to complete a study or to obtain a better appreciation of continuity of structure. A further increase in photon utization is gained for small-organ imaging with converging collimators, which produce images with superior resolution and sensitivity to that obtained with equivalent parallel-hole collimators. The disadvantages of converging collimators, including decreasing field of view and distortion with depth, have been insignificant in light of the advantages gained. Larger detectors with converging collimation result in much higher photon input rates to the scintillation crystal in routine clinical studies than has occurred in the past. This requirement places added burdens on electronic circuitry of the cameras. Count rate processing capabilities of 200,000 counts per second are currently available and are necessary for present generation first-pass cardiovascular studies.

Asthma↗
PubMed1977

Distortion in converging collimator scintiphotography.

Distortion is intrinsic to converging collimator scintiphotography although converging collimation offers improved resolution and sensitivity. The nature of the distortion is defined and compared to nondistorted parallel-hole collimator images. The analogy between long and short focal-film-distance radiographs, and parallel and converging hole collimators, is discussed.

Humans↗
PubMed1977

Radionuclide emission computed tomography of the head with 99mTc and a scintillation camera.

To investigate the potential application of radionuclide computed tomography (RCT) to nuclear medicine imaging using 99mTc, a tomographic system using a lightweight scintillation camera for brain imaging was constructed, and lesion contrast with RCT and conventional scintigraphy were compared. The detector revolves once around the patient's head at constant angular velocity, requiring approximately 20 min. Nine sections are reconstructed from the data, using either a Fourier transform or a filtered back-projection algorithm. In a phantom simulating the radionuclide distribution observed during brain imaging, quantitative lesion contrast was far superior in the RCT images. In a series of 25 patients with intracranial lesions, the average RCT lesion contrast was superior to that of standard scintigraphy by a factor of more than 2. An RCT image of an experimentally infarcted dog's heart, taken after the injection of 99mTc-MAA into the left atrium, also showed excellent correspondence to the gross anatomic defect. Although problems of photon absorption may occur in imaging larger body areas, RCT imaging in this feasibility study produced surprisingly good results that warrant further investigation of the technique.

Aged↗
PubMed1976

Acute cerebral vascular accident associated with hyperperfusion.

Cerebral radionuclide angiography can demonstrate decreased or normal radioactivity in the affected region during the arterial phase in patients who have sustained a cerebral vascular accident and thus enhances the diagnostic specificity of the static brain image. In an occasional patient, however, a seemingly paradoxical pattern of regional hyperperfusion with a return to normal or subnormal perfusion following the acute phase has been observed. This phenomenon, called "luxury perfusion," has been defined using intra-arterial 133Xe for semiquantitative cerebral blood flow measurements and should be kept in mind as a potentially misleading cerebral imaging pattern.

Brain Neoplasms↗
PubMed1975

Converging collimation and a large-field-of-view scintillation camera.

Three low-energy multihole converging collimators were evaluated in reference to accepted imaging parameters using a prototype large-field-of-view scintillation camera. A substantial improvement in resolution and/or sensitivity with depth was observed. Because of the large detector, the inherent reduction in field size due to convergence was not detrimental to satisfactory imaging of most target volumes. Such collimation should prove to be of significant clinical value.

Radionuclide Imaging↗
PubMed1975

Clinical efficacy of a large-field-of-view scintillation camera.

In evaluating the clinical application of a prototype large-field-of-view scintillation camera, a significant increase in the quality of static and cynamic images was observed. With parallel-hole collimation, imaging time for large areas was reduced by more than 50% and a marked enhancement in resolution and sensitivity of lung images occurred in relation to those obtained with diverging collimation on a conventional camera. Using converging collimation, the prototype camera produced images of brain and other organs with considerably better depth response than comparative studies performed with standard size cameras. These results demonstrate that further clinically relevant improvement in scintillation camera performance is possible.

Aged↗