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Biomedical subjects

R E Coleman

Publications and source records attributed to R E Coleman.

At least 19 recordsLinked to original sources
PubMed1992

Clinical PET scanning. A "short-lived" orphan.

Positron emission tomography (PET) is a method of nuclear medicine imaging that uses short-lived radiopharmaceuticals to detect and quantify the metabolic abnormalities of disease processes. PET initially was developed in a research environment as a research tool; data from these research studies resulted in the gradual recognition that PET studies would be useful for various routine clinical applications. The diffusion of PET into clinical practice has been slow in comparison with other new imaging methods (e.g., magnetic resonance imaging). This slow diffusion is attributable to several factors, including the complexity and high cost of PET, the uncertain role of the U.S. Food and Drug Administration in regulating the radiopharmaceuticals that are produced and used on-site for PET studies, and the apparent slow pace at which the Health Care Financing Administration and other third-party payers are developing policies for reimbursing for PET.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1992

Laboratory and field evaluation of five repellents against the black flies Prosimulium mixtum and P. fuscum (Diptera: Simuliidae).

Deet (N,N-diethyl-3-methyl-benzamide), the lactone CIC-4 ([2-hydroxy-methyl-cyclohexyl] acetic acid lactone), the USDA Proprietary Chemicals AI3-37220 (1- [3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine) and ++[3-35765 (1-[3-cyclohexen-1-ylcarbonyl] piperidine), and the U.S. military extended duration repellent formulation (EDRF) of deet were evaluated for repellency in the laboratory and field against the black flies Prosimulium mixtum and P. fuscum. CIC-4, AI3-37220, and AI3-35765 were as effective as deet at repelling P. mixtum and P. fuscum in laboratory and field experiments. Only the EDRF provided significantly longer protection than the deet standard against these black flies in the field.

Animals↗
PubMed1992

Perfusion quantitation using positron emission tomography.

Positron emission tomography (PET) is assuming increasing importance as a clinical and investigative functional imaging modality. Cerebral blood flow determination with PET is now more easily performed due to improvement in tomography design, increased speed and ease of data analysis, and improvement in radiopharmaceutical synthesis and delivery. This article reviews the historic development of the PET, the evolution of cerebral blood flow measurement techniques with PET, technical considerations in PET imaging, radiopharmaceuticals for cerebral blood flow determination, and tracer kinetic models used for cerebral blood flow determination. Representative examples of PET cerebral blood flow imaging are shown and the evolving applications to brain mapping are discussed.

Animals↗
PubMed1979

Septic arthritis mimicking cellulitis: distinction using radionuclide bone imaging.

Two patients originally diagnosed as having cellulitis involving the dorsum of the foot actually had bacterial arthritis of an underlying joint. In both patients, even after pyarthrosis was suspected, the wrong joint was aspirated. The arthropathies were located by subsequent 99mTc-phosphate bone imaging at a time when roentgenograms were normal. Early diagnosis and aggressive therapy of septic arthritis are essential to prevent joint destruction and osteomyelitis. Radionuclide bone imaging can identify inflammatory joint disease but it cannot specify etiology. In our patients, however, the differential diagnosis was between skin and joint infection. Radionuclide imaging was of great help in making this distinction.

Adult↗
PubMed1978

Adult idiopathic communicating hydrocephalus with and without shunting.

The outcome in 37 adult patients with idiopathic communicating hydrocephalus treated by ventriculoatrial shunting is presented. Only 33% showed definite improvement, and no diagnostic procedures accurately predicted the outcome of surgery. These were compared with a "control" group of 12 patients who were not shunted; 50% of these were stable for up to 36 months. These findings, and the high frequency of serious complications (35%), suggest caution in recommending a shunt procedure.

Aged↗
PubMed1978

Radiography, radionuclide imaging, and arthrography in the evaluation of total hip and knee replacement.

Twenty patients with 21 total joint replacements including 17 hips and 4 knees were studied by plain film radiography, radionuclide imaging, and subtraction arthrography to evaluate these procedures for assessing prosthetic complications. Surgery was performed in 14 patients and confirmed loosening of 8 femoral and 7 acetabular hip prosthesis components and 1 femoral and 4 tibial knee prosthesis components. Plain films suggested loosening of only 9 hip components and no knee components. In contrast, radionuclide imaging and subtraction arthrography were considerably more effective in demonstrating loosening as well as other causes of the painful total joint prosthesis.

Hip Joint↗
PubMed1978

131I-labeled fibrinogen in the diagnosis of deep vein thrombosis of the lower extremities.

Autologous 131I-labeled fibrinogen was administered to 17 patients during 19 episodes of suspected lower extremity deep vein thrombosis in an attempt to assess its diagnostic accuracy. Serial rectilinear scanning and probe counting of the lower extremities and pelvis were performed and compared with ascending contrast venography. The sensitivities of imaging and counting were 67% and 47%, respectively, and both had a specificity of 95%. The experience with evaluation of deep vein thrombosis of the pelvic and iliac veins was small but suggested that 131I fibrinogen will be of limited use in those vessels.

Fibrinogen↗
PubMed1977

Imaging of the inflammatory response in ischemic canine myocardium with 111indium-labeled leukocytes.

Myocardial leukocyte infiltration is one hallmark of acute myocardial infarction. In order to detect noninvasively this inflammatory response associated with acute myocardial infarction, we produced coronary occlusion in eight dogs, intravenously administered autologously labeled indium-111 (111In) leukocytes and scintigraphically monitored accumulation of radionuclide in myocardium. Seventy-two hours after coronary occlusion, 111In-labeled white cells accumulated in regions corresponding to myocardial infarcts, and positive images with 111In-labeled leukocytes correlated well with images obtained with technetium-99m pyrophosphate and computer-reconstructed tomograms obtained with nitrogen-13-labeled ammonia. In contrast, two control dogs subjected to sham operation did not exhibit positive 111In-leukocyte images. Scintigraphic results with 111In-labeled leukocytes were verified in vitro by analysis of radioactivity in normal myocardium and in infarcts. Thus, leukocytic infiltration associated with acute myocardial infarction can be detected noninvasively in vivo.

Ammonia↗
PubMed1977

Mechanisms contributing to myocardial accumulation of technetium-99m stannous pyrophosphate after coronary arterial occlusion.

The relation between the accumulation of pyrophosphate and technetium-99m in myocardium with reversible and irreversible ischmic injury was studied in dogs subjected to transitory or persistent coronary arterial occlusion. Among four dogs with coronary occlusion maintained for less than 20 minutes, none had either increased MB creatine kinase (CK) (the "myocardial" CK isoenzyme) activity serum or a positive 99mTc stannous pyrophosphate image. Seven dogs with coronary occlusion maintained for 30 or more minutes had elevated serum MB CK activity, and five of the seven had positive (abnormal) images. Thus, although false negative images may occur occasionally despite myocardial damage, both increased serum MB CK and abnormal images generally accompanied prolonged coronary occlusion. In contrast, ischemia without infarction was not associated with abnormal images. Both 99mTc and 32P labeled pyrophosphate were accumulated extensively and proportionally in myocardium from zones of infarction, and uptake of both tracers was comparable although modest in isolated mitochondria. Similar results were obtained after myocardial infarction in animals with induced profound leukopenia. Thus, phagocytosis of the radiopharmaceutical agent by leukocytes migrating into the infarct is not an essential mechanism accounting for uptake. These results indicate that abnormal images reflect uptake of pyrophosphate, associated with 99mTc, by irreversibly injured myocardium rather than leukocytic infiltration involved in the inflammatory response in the heart.

Animals↗
PubMed1977

Technetium-99m stannous pyrophosphate scintigrams in normal subjects, patients with exercise-induced ischemia and patients with a calcified valve.

Although technetium-99m stannous (99mTc[Sn]) pyrophosphate has been shown to be a specific and sensitive index of myocardial infarction, abnormal images have been reported in patients with unstable angina or ventricular aneurysm. Sixty-one subjects--33 patients subjected to maximal treadmill stress testing, 23 normal subjects and 5 patients with a calcified aortic or mitral valve--underwent imaging with 99mTc(Sn) pyrophosphate to determine whether abnormal images are associated with (1) exercise-induced ischemia, (2) delayed clearance of tracer from the blood pool, or (3) calcified intracardiac structures. Myocardial injury was excluded on the basis of normal MB creatine kinase (CK) values in all patients with stress testing. All eight patients with an abnormal exercise stress test had normal images. Four of 25 patients with a normal exercise stress test had diffusely abnormal images. In some normal subjects diffusely abnormal images were present 60 minutes after injection of the tracer, but became normal 90 to 120 minutes after injection. Variations in clearance of tracer from the blood pool were noted in this group. Patients with a calcified aortic or mitral valve had normal images. We conclude that (1) exercise-induced ischemia is not associated with abnormal 99mTC(SN) pyrophosphate images; (2) images are not necessarily abnormal in patients with a calcified valve; and (3) delayed removal of tracer from the cardiac blood pool may result in diffusely abnormal images even in normal subjects; in these cases, repeat images should be obtained at least 2 hours after injection of the tracer to avoid false abnormal images.

Adult↗
PubMed1977

Indium-111-labeled leukocytes for the localization of abscesses: preparation, analysis, tissue distribution, and comparison with gallium-67 citrate in dogs.

Leukocytes have been labeled with indium-111-8-hydroxyquinoline complex. Seventy-five to 85 per cent of the initial activity has been obtained in the complex form of which 75 to 95 per cent is incorportaed with leukocytes. The polymophonuclear leukocytes are predominantly labeled, and the label has been found stable for at least 27 hours after invivo administration. The radioactivity clears from the circulating blood with a half time of 8 to 9-hours and accumulates in normal liver and spleen and in experimentally induced abscesses. The cells which have been labeled and damaged by heat concentrate mainly in the lungs. The in vivo distribution of the indium-111 labeled cells has been compared with the gallium-67 administered as citrate. The abscess to blood ratios of the indium-111 activity varied between 35 to 117, compared to 1.2 to 8 of the gallium-67. The abscess to liver, spleen, and kidney ratios are several fold higher with indium-111 leukocytes than with gallium=67 citrate. These results plus the suitable physical characteristics of indium-111 make the labeled leukocytes a better agent for the localization of abscesses.

Abscess↗
PubMed1977

Gallium-68 labeled red cells and platelets: new agents for positron tomography.

Red cells and platelets are labeled with Ga-68 by preparing the tga-68-hydroxy-quinoline (oxide) complex and mixing the complex with the separated cellular components. The complex is prepared by first breaking the Ga-68 EDTA chelate with concentrated hydrochloric acid, adsorption of the galluim on a strong anionic ion-exchange column, and elution of the gallium activity with distilled water. Oxine is added, the oxine complex extracted into chloroform, and--following evaporation and dissolution--the solution is added to either red cells or platelets that have been centrifuged from whole blood, washed, and suspended in normal saline. After 15 min of incubation , labeling efficiencies of greater than 90% and yields of 7 mCi are obtained from 18 mCi of Ga-68 EDTA eluted from the generator. After injection of the gallium-labeled red cells in dogs, excellent blood pool images were obtained by positron tomography. The distribution corresponded to that of 11CO-labeled red cells. When labeled platelets were injected into dogs with experimentally induced intimal injury of on carotid artery, the area of injury was clearly visualized 40 min after tracer injection.

Animals↗
PubMed1977

Conventional methods of diagnosis using nuclear scan and recent progress with radionuclide transaxial tomography.

Radionuclide brain imaging, a simple, noninvasive test for evaluating patients with suspected cerebral pathology, has a high degree of accuracy when compared with more complex neuroradiologic procedures such as angiography and pneumoencephalography. The detection of brain tumors with use of radionuclide scans is related to the tumor cell type and their location in the brain. Transmission computed cranial tomography (CCT) offers another simple procedure for evaluating cerebral pathology. Even though CCT gives more anatomic detail than the radionuclide study, the two procedures are often complementary. Radionuclide transaxial tomography appears promising as a means of evaluating cerebral metabolism and metabolic changes associated with cerebral pathology.

Adult↗
PubMed1977

Radioiodinated plasminogen: an imaging agent for pre-existing thrombi.

We have reinvestigated radioiodinated plasminogen as an agent for localizing preformed thrombi. Canine plasminogen was isolated from fresh plasma by the affinity chromatography technique on a lysine-sepharose 4B column and tagged with I-123 or I-131, at less than one iodine atom per molecule of enzyme, by the conventional ICI method. When injected into dogs more than 2 days after thrombus induction, radioiodinated plasminogen produced thrombus-to-blood activity ratios of 7.8 +/- 2.4. Thrombi as old as 6 days can be visualized in 80% of the cases. Both the weight of the thrombus and the thrombus-to-blood ratio are more variable for 1-day-old thrombi; this may be associated with plasminogen release accompanying thrombus retraction. The results suggest that radioiodinated plasminogen has potential as an imaging agent for pre-existing thrombi.

Animals↗
PubMed1977

Transaxial tomographic imaging of canine myocardium with 11C-palmitic acid.

Radiopharmaceuticals incorporated directly into the metabolic pathways in myocardium provide a useful means for evaluating such processes. Palmitic acid, a major physiologic substrate of myocardium, has a well-understood role in myocardial metabolism. Accordingly, 11C-palmitic acid was the substrate chosen for use in conjunction with positron emission transaxial tomography to obtain images of canine myocardium. This procedure provides high-contrast images of tranverse sections of the myocardium, with good target-to-nontarget ratios (in the image), over a period of 5 to 85 minutes. Clearance half-times for blood and myocardial tissue were found to be 4.8 and 330 min, respectively. In normal myocardium, images obtained with 11C-palmitic acid were those obtained with 13NH3 and 11CO-hemoglobin. In vivo images of hearts with myocardial infarcts showed a clear delineration of infarcts and normal tissue.

Ammonia↗