Radionuclide and CT diagnosis: cavernous hemangioma of liver.
Explore the source record for details and available documents.
Aged↗
Biomedical subjects
H D Royal
Publications and source records attributed to H D Royal.
Scintigraphic identification of bleeding duodenal varices. A case report.
In this case of active gastrointestinal bleeding, randionuclide blood pool scintigraphy localized the bleeding to the region of the duodenum. Celiac and superior and inferior mesenteric arteriography did not identify the site of bleeding; however, bleeding duodenal varices were found at the time of surgery. The potential role of radionuclides in the management of patients with gastrointestinal bleeding, especially with bleeding from varices, is discussed.
Adult↗
Re: distortion of bar-phantom image by collimator.
Explore the source record for details and available documents.
Optics and Photonics↗
Effects of a reduction in crystal thickness on Anger-camera performance.
The performances of two commerical gamma cameras, with crystals 1.3 and 0.6 cm thick, are compared. Phantom studies simulating clinical conditions showed no significant difference in performance at 140 keV. At 68 keV, the thinner crystal gave marginal improvements in camera performance with phantoms simulating clinical conditions. Frequent use with very low-energy emitters, such as Tl-201, would be needed to justify the expense required to refit the 1.3 cm camera with a 0.6 cm crystal.
Radionuclide Imaging↗
Mobile gamma cameras: a comparative evaluation.
Mobile gamma cameras from three manufacturers were evaluated. Count rate capability, flood uniformity, intrinsic and extrinsic spatial resolution, and sensitivity were compared, using images made under reproducible conditions with phantoms which simulate actual clinical situations.
Humans↗
Misplacement of central venous pressure catheters and unilateral pulmonary edema.
Two instances of misplacement of a central venous pressure monitoring catheter into a pulmonary artery are presented. In one case, reported in detail, unilateral pulmonary edema developed during administration of 0.5N saline for the treatment of diabetic acidosis via the misplaced catheter, and it reverted following repositioning of the catheter in the superior vena caca. Experiments were carried out in dogs to explore possible causes of this phenomenon. The results of these experiments suggest that the release of vasoactive substances, stimulation of neural reflexes, or both are the pathophysiological mechanisms responsible for the development of the pulmonary edema.
Animals↗
Intracoronary thallium-201 assessment of thrombolysis in acute myocardial infarction. Validation of the method of imaging before and after therapy.
In order to study acute changes in perfusion with intracoronary thrombolytic therapy, we have used ten times the pretherapy intracoronary thallium-201 dose for the posttherapy study. Because of the larger posttherapy dose, the posttherapy images had ten times as many counts as the pretherapy images. Since the change in image quality between the pretherapy and posttherapy studies might affect interpretation, we studied the effect of image statistics on interpretation of perfusion scintigraphy. The pretherapy and posttherapy images were scored on a four-point scale in five segments on each of three views. In 31 patients, Poisson-distributed pseudorandom noise was added to the posttherapy study in order to match the statistical accuracy of the pretherapy study. A blinded interpretation of the pretherapy and posttherapy noise-added images was performed in the same way as the initial unblinded interpretation. The mean difference between the unblinded pretherapy and posttherapy scores (the improvement in thallium distribution with therapy) was 2.5+/-0.8 (standard error) compared with the difference between the blinded pretherapy and posttherapy noise-added scores which was 2.6+/-1.0. The correlation between readings of similar pairs of data was higher than the correlation between pretherapy and posttherapy studies. Thus, the difference in statistic quality of the pretherapy and posttherapy studies did not affect the interpretation of these studies. Therefore, our evaluation of pretherapy and posttherapy studies using a ten-fold increase in thallium-201 dosage is valid.
Coronary Vessels↗
Assessment of regional cerebral blood flow (rCBF) in stroke using SPECT and N-isopropyl-(I-123)-p-iodoamphetamine (IMP).
In this study we assessed regional cerebral blood flow in patients with signs and symptoms of acute stroke using single-photon emission computed tomography (SPECT) and N-isopropyl I-123 p-iodoamphetamine (IMP). Twenty-five patients with acute cerebral infarction had both IMP brain perfusion studies and CT scans performed within one week of each other; 22 had positive and three had negative perfusion studies. Of the 22 patients who had positive perfusion studies, six had negative CT studies initially. In the 16 patients who had abnormal CT studies, eight of the studies depicted areas of edema that were smaller than the perfusion deficits noted on the IMP studies and eight had areas of edema that were approximately equal in size to the perfusion defect. Of the three patients with normal IMP studies, two had normal CT studies and one had a positive CT study showing a 3-mm lacunar infarction. Using eight control patients, mean count rates per tissue volume normalized for the injected dose was calculated. Similarly, the quantitative data from regions of interest in the stroke patients were calculated and compared to the control patients or to a normal region in the uninvolved hemisphere in the same patients. SPECT with IMP was used to assess regional brain perfusion in acute cerebral infarction. Perfusion abnormalities were seen in our patients when the CT scan was normal, and quantitative data could be used to approximate regional cerebral blood flow in these patients when compared to the normal patient population.
Amphetamines↗
Magnetic resonance imaging: a critical appraisal.
Explore the source record for details and available documents.
Costs and Cost Analysis↗
Clinical evaluation of imaging tests: Part I--The basics.
Decision matrices and their derived ratios, Bayes theorem, and receiver operating characteristic curves provide simple formulas to evaluate the information content of tests. Despite their shortcomings, these tools are widely used, and they must be understood by all those who develop or use our increasingly complex and expensive technologies.
Bayes Theorem↗
Clinical evaluation of diagnostic tests, part II: The pitfalls.
In a climate of limited health care resources, evaluations of the usefulness of diagnostic tests will flourish. Since the impact of these evaluations will be great, the health care community must ensure that they are performed as carefully as possible. All health care professionals must be able to recognize the errors and limitations of current evaluation techniques. Errors in evaluating diagnostic tests can occur at the time of data collection, the time of data analysis, or when a test is used in a clinical setting. Many errors can be avoided with careful planning. In this article, patient spectrum errors, test result errors, association errors, and test utility errors are discussed.
Diagnostic Errors↗