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PubMed2002

Mathematical generation of normal data for evaluating myocardial perfusion studies.

In this paper, we present a new mathematical method that synthesizes normal data sets for quantification of regional myocardium perfusion. In clinical practice, regional myocardial perfusion is often measured with a gamma camera and quantified via circumferential profile analysis. Normal reference profile data is used to increase the accuracy of the clinical interpretations. Our goal is to create reference data from an existing set of archived studies. An iterative mathematical method, based on two statistical hypotheses, was used to generate the study set instead of collecting normal examinations from a healthy population. Clinical validation is based on interpretations by six independent observers. Results of evaluation with synthesized normal data and its validation are presented.

Algorithms↗

PubMed1980

The College of American Pathologists Phantom Series--an assessment of current nuclear imaging capabilities.

Twelve sets of emission phantoms were distributed semiannually to laboratories of nuclear medicine from 1973 through 1978. This survey aimed to create a national peer group within which it might become possible to compare and standardize nuclear imaging technics, and to evaluate and define the current state of the art in a clinical setting. Results were analyzed in terms of sensitivity (percentage of true-positives), nonspecificity (percentage of false-positives), and performance indices (true-positive/false-negative ratios) for conventional gamma cameras and for rectilinear scanners. The chief determinants of target detectability proved to be target-to-surface depth, target diameter, and intrinsic target contrast. Operational variables and instrument type produced relatively minor effect upon subscriber performance. Gamma cameras tended to show slightly more sensitivity than rectilinear scanners, but were somewhat troubled by nonspecificity. Improvements in the intrinsic resolution of second- and third-generation gamma cameras increasingly employed since 1975 showed negligible impact on performance indices. A consideration of the overall survey performance indices. A consideration of the overall survey performance permits the beginning of a quantitative estimate of current detection capability in day-to-day nuclear imaging.

Evaluation Studies as Topic↗

PubMed1977

[Various complications of primary echinococcosis].

Secondary echinococcosis occurs as a complication of a primary cyst. The importance of operative technique during the removal of the primary cyst is emphasized, because the intraoperative disemination occurs most frequently after a surgical performance. Secondary echinococcosis generates by asexual regressive metamorphosis of larval element intro larval forms. Two cases of secondary abdominal echinococcoosis will be described ensuing after removal of the primary liver cyst. One patient, who has been operated because of the pulmonary echinococcosis cyst before, was cured in our hospital having the secondary echinonoccosis of the lungs and pleural cavity.

Echinococcosis↗

PubMedDate not supplied

Immunotherapy with monoclonal antibodies in metastatic melanoma.

Therapy for metastatic melanoma has been disappointing to date. Treatment with chemotherapy only uncommonly results in complete responses and rarely results in long-term survivors. The identification of human melanoma cell surface antigens has led to the development of an array of mouse monoclonal antibodies (MAb) for use in the diagnosis and therapy of patients with metastatic melanoma. Strategies utilizing MAbs based on immunologic approaches have been developed. Naked MAbs directed against glycoprotein surface antigens or conjugated to toxins or radionuclides have shown little biologic or clinical activity. However, phase I studies of MAb directed against glycolipid antigens have yielded objective tumor shrinkage with occasional complete responses. Severe toxicity has been seen infrequently. Possible anti-tumor mechanisms include complement activation and antibody-dependent cellular cytotoxicity utilizing natural killer cells or monocytes as effector cells. Strategies to enhance the anti-tumor effects of MAb, including combinations with cytotoxic agents and cytokines, have been introduced with limited success thus far. The development of a human IgG anti-mouse antibody has been seen in nearly all treated patients. A new generation of MAb engineered to overcome the immunogenicity of mouse MAb and to enhance immune effector function will soon enter clinical trials.

Antibodies, Monoclonal↗

PubMed2004

Experiences in methods to involve key players in planning protective actions in the case of a nuclear accident.

A widely used method in the planning of protective actions is to establish a stakeholder network to generate a comprehensive set of generic protective actions. The aim is to increase competence and build links for communication and coordination. The approach of this work was to systematically evaluate protective action strategies in the case of a nuclear accident. This was done in a way that the concerns and issues of all key players could be transparently and equally included in the decision taken. An approach called Facilitated Decision Analysis Workshop has been developed and tested. The work builds on case studies in which it was assumed that a hypothetical accident had led to a release of considerable amounts of radionuclides and, therefore, various types of countermeasures had to be considered. Six workshops were organised in the Nordic countries where the key players were represented, i.e. authorities, expert organisations, industry and agricultural producers.

Decision Support Systems, Management↗

PubMedDate not supplied

[Model for calculation of fish contamination by 137Cs and its application for Lake Kozhanovskoe (Bryansk Region)].

A dynamic model was developed for evaluation of the fish contamination by 137Cs. The dynamics of the accumulation of the radionuclide and the elimination is calculated taking into account the ecological and physiological characteristics of the fish, such as growth and metabolic rates, its position in the food chains of the aquatic ecosystem. The biological elimination of 137Cs from the freshwater fish is proportional to the metabolic rate of the fish. The dimensionless coefficient of the proportionality is equal to epsilonA = 0.3 +/- 0.1. The model was applied for the reconstruction of the long-term dynamics of 137Cs in the food chain "goldfish-pike" from Lake Kozhanovskoe (Bryansk Region, Russia). In 1990-1999 the specific activity of 137Cs in goldfish (generation of 1990) varied in range about 5-20 kBq/kg, whereas the specific activity of 137Cs in pike (generation of 1989) varied in range about 20-40 kBq/kg. The comparison with the data of the observations confirmed that the presented method allows to evaluate adequately the levels and the dynamics of 137Cs accumulation by the freshwater fish.

Animals↗

PubMed1987

Aluminemic disturbance of technetium-99m DTPA renal function measurement.

During follow-up study of a patient with surgically corrected unilateral renal ischemia, using computer image generated [99mTc]diethylenethiaminepentaacetic acid (DTPA) glomerular filtration rate (GFR) and [131I]orthoiodohippurate estimated renal plasma flow (ERPF), we observed prominent gastric and intestinal uptake of 99mTc. Profound alteration in the GFR results, but not the ERPF results, was also observed. Radiopharmaceutical breakdown was suspected and shown to be endogenous and due to hyperaluminemia at 28 ng/ml. These case findings add DTPA to the list of 99mTc radiopharmaceuticals that have previously been reported to have altered biodistribution when hyperaluminemia is present. The case findings also reaffirm the benefits of obtaining images to corroborate the validity of quantitative data and demonstrate that quantitative radionuclide renal function data are not independent of renal chemical handling.

Aluminum↗

PubMed2004

Evaluation of a model for leaf to fruit transfer of radionuclides in processing tomato plants using an independent set of data.

Because of their varied possibilities of consumption, tomatoes are an important component of the human diet. This paper presents results of the evaluation of a dynamic model (Ventomod) for the short-term behaviour of radionuclides deposited on tomato plants following a direct contamination event. To check its forecasting capability in assessing the risk of radionuclide contamination of the human diet, it has been tested with an independent dataset on the leaf to fruit transfer of 134Cs in a typical Hungarian tomato variety, "Dwarf of Kecskemet". Data obtained from this pot experiment were used to evaluate model behaviour. Model constants were varied according to the differences between the Hungarian dataset and the one used to calibrate it. Results show that the model output well reproduces the observed activity of fruits for various levels of contamination and at different contamination dates. The main part of this report summarises the experimental protocol, compares the experimental results with model predictions generated by Ventomod and makes recommendations for both updating model parameters and undertaking further experimental work.

Agriculture↗

PubMed1993

Radioimmunodetection of prostate cancer by 111In-labeled monoclonal antibody against prostatic acid phosphatase.

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragments were labeled with indium-111 chloride. This labeled antibody was tested in 15 prostate cancer patients who underwent staging pelvic lymphadenectomy; 9 of them received labeled antibody alone whereas 6 received simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blood measurements and imaging procedures indicated that simultaneous injection of unlabeled antibody reduced both the blood elimination rate and the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a couple of patients accumulation was noted also in normal lymph nodes. The method cannot in its present design replace staging pelvic lymphadenectomy and further studies are needed for elaboration of clinically useful radioimmunodetection methods.

Acid Phosphatase↗

PubMed1987

Non-interventional background corrections for scintigrams.

A method is presented for the interpolation of optimally 'smooth' background correction matrices within arbitrarily shaped boundaries. Practical means of implementing this technique are discussed, along with series expansions for the special cases of square and round boundaries. This class of interpolation methods has the advantages over previous techniques of providing a unique mathematical solution, connecting exactly to count rates on the boundary, and containing no singularities. Clinical scintigraphic images and mathematically generated surfaces are used to test the different cases of the method, and it is shown that confining the boundary to a circle produces the most rapid convergence with the minimum deviation from ideal surfaces. Under common clinical conditions, these techniques lend themselves well to automated, non-interventional computer processing.

Humans↗

PubMed1996

High-resolution electron microscopy of technegas and pertechnegas.

Once inhaled, technegas remains in the lungs for a long period of time, whereas pertechnegas rapidly disappears. To investigate this difference, the morphology of technegas and of pertechnegas was investigated using high-resolution transmission electron microscopy. The technegas and pertechnegas were generated in an atmosphere of pure argon and in 3% oxygen in argon, respectively, using a commercially available technegas generator. For the technegas, the technetium crystals were observed to be covered with carbon, whereas they were found to have no carbon coating with the pertechnegas. Whether or not the technetium is coated with carbon appears to be responsible for the differences in behaviour of technegas and pertechnegas after deposition on the lung epithelium following inhalation.

Carbon↗

PubMed1998

Geographical distribution of radiation risks in The Netherlands.

Risk assessment of exposure to sources of radiation is an important tool for national governments in regulating radionuclide emissions and thus reducing radiation doses for the general public. For this reason radiation doses from sources throughout The Netherlands have been analyzed. For sources with well-defined locations and doses that were thought to vary significantly throughout The Netherlands, radiation dose maps were produced. Average dose values were calculated or derived from the literature for doses considered to be evenly distributed throughout the country or for which no information on the geographical distribution of dose was available. Emission, dispersion, and individual dose were modeled for each source using various pathways and exposure routes. Indoor radon and gamma radiation from building materials generate the highest dose values. The highest human induced radiation doses for industries of which the doses showed to be geographically distributed are found in the cement industry, elemental phosphorus production, phosphoric acid production, and iron and steel production. Radiation dose from some of these sources has a very local peak and decreases rapidly with distance. The elemental phosphorus production causes relatively high radiation doses throughout a large part of The Netherlands. Cumulation of doses from various sources occurs, but these are often masked by doses from a few large industries.

Eating↗

PubMed1995

Specific absorbed fractions of energy from internal photon sources in brain tumor and cerebrospinal fluid.

Transferrin, when injected intracranially into glioblastoma multiforme lesions, acts as a cytotoxic substance. Transferrin, radiolabeled with In-111, can be coinjected and subsequent scintigraphic imaging can demonstrate the biokinetics of the cytotoxic transferrin. The administration of 111In transferrin into a brain tumor results in distribution of radioactivity in the brain, brain tumor, and the cerebrospinal fluid (CSF). Information about absorbed radiation doses to these regions, as well as other nearby tissues and organs, is important for evaluating radiation-related risks from this procedure. The radiation dose is usually estimated for a mathematical representation of the human body. We have included source/target regions for the eye, lens of the eye, spinal column, spinal CSF, cranial CSF, and a 100-g tumor within the brain of an adult male phantom developed by Cristy and Eckerman. The mathematical models of the spinal column, spinal CSF, and the eyes were developed previously, however, these source/targets have not been routinely included in photon transport simulations. Specific absorbed fractions (SAFs) as a function of photon energy were calculated using the ALGAMP computer code, which utilizes Monte Carlo techniques for simulating photon transport. The ALGAMP code was run three times, with the source activity distributed uniformly within the tumor, cranial CSF, and the spinal CSF volumes. These SAFs, which were generated for 12 discrete photon energies ranging from 0.01 to 4.0 MeV, were used with decay scheme data to calculate S-values needed for estimating absorbed doses. S-values for 111In are given for three source regions (brain tumor, cranial CSF, and spinal CSF) and all standard target regions/organs, the eye and lens, as well as to tissues within these source regions. S-values for the skeletal regions containing active marrow are estimated. These results are useful in evaluating the radiation doses from intracranial administration of 111In transferrin. The SAFs are also generally useful for calculation of absorbed dose from any radionuclide in these source regions.

Adult↗

PubMed1991

Computerized system for nuclear emergency response in the ENEA Nuclear Research Center of Frascati.

At the National Committee for Research and Development of Nuclear Energy and Alternate Energy Sources (ENEA) Center of Frascati, there are several radiation-producing machines: two tokamaks and three electron accelerators; moreover, a neutron generator will begin to operate in a short time. A completely automatic monitoring system has been developed. Radiation control is performed by means of classical active and passive detectors. An automatic acquisition system has been developed: Measured quantities are acquired and stored in a specific data base; information regarding radioactivity levels, machines status, personnel dosimetry and meteorological parameters are available in real time. If any of the radiometric quantities exceeds appropriate reference levels, the following operations automatically activate: An automatic switch turns off the machines and an alarm signal is broadcast to the Health Physics group. In addition, the "Nuclear Emergency" software module starts if a radionuclide emission is detected. This module has been implemented to provide response to radiological emergencies in the ENEA nuclear research centers. The modularity of the computer-based system allows its utilization also in other nuclear centers, such as at nuclear power plants. When activated, the "Nuclear Emergency" displays an alarm signal and informs the Health Physics group about the monitor's location and characteristics and the measured data exceeding the reference level. If emission of radionuclides occurs, a preliminary evaluation of their diffusion in the atmosphere and an estimation of the population dose are performed. Statistical analysis of the event is also possible.

Computer Systems↗

PubMed2004

Spiral computed tomography for acute pulmonary embolism.

There is still considerable debate about the optimal diagnostic imaging modality for acute pulmonary embolism. If imaging is deemed necessary from an initial clinical evaluation such as d-dimer testing, options include nuclear medicine scanning, catheter pulmonary angiography, and spiral CT. In many institutions, spiral CT is becoming established as the first-line imaging test in daily clinical practice. With spiral CT, thrombus is directly visualized, and both mediastinal and parenchymal structures are evaluated, which may provide important alternative or additional diagnoses. However, limitations for the accurate diagnosis of small peripheral emboli, with a reported miss rate of up to 30% with single-slice spiral CT so far, have prevented the unanimous embrace of spiral CT as the new standard of reference for imaging pulmonary embolism. The clinical significance of the detection and treatment of isolated peripheral pulmonary emboli is uncertain. Evidence is accumulating that it is safe practice to withhold anticoagulation in patients with suspected pulmonary embolism on the basis of a negative spiral CT study. Remaining concerns about the accuracy of spiral CT for pulmonary embolism detection may be overcome by the introduction of multidetector-row spiral CT. This widely available technology has improved visualization of peripheral pulmonary arteries and detection of small emboli. The most recent generation of multidetector-row spiral CT scanners appears to outperform competing imaging modalities for the accurate detection of central and peripheral pulmonary embolism. In this review, we assess the current role and future potential of CT in the diagnostic algorithm of acute pulmonary embolism.

Acute Disease↗

PubMed2004

Reverse echelon node and a lymphatic ectasia in the same patient during breast lymphoscintigraphy: the importance of injection and imaging technique.

Lymphoscintigraphy, along with triangulated patient body marking, can serve as a guide for surgeons during sentinel lymph node harvesting. Unique drainage patterns have been noted, especially with areolar or intradermal based injections, which are becoming increasingly popular. The images lymphoscintigraphy provide have been invaluable in delineating these patterns. The authors present a case that simultaneously illustrates two separate points in the same patient, a reverse echelon node and a lymphatic ectasia. To our knowledge, this combination has never been described in the same patient. Perilesional and areolar-cutaneous junction injections were performed sequentially and generated these patterns that could potentially have resulted in added morbidity and a false-negative sentinel node if not realised before surgery. Lymphoscintigraphy added valuable information in the management of this patient, which can occasionally present with complex patterns of activity during sentinel node harvesting.

Adult↗

PubMed1992

[Metabolism of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in blood--mainly in vitro].

Metabolism of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in blood was studied mainly in vitro. When 99mTc-ECD was mixed with blood taken from 12 subjects, the octanol extraction ratio of ECD (y) decreased rapidly and the octanol extraction ratio-time profile well fitted a monoexponential curve (y = Ae-kt/1000, A, k: constant, t: time after mixing). The k value and hematocrit (Ht) were significantly correlated (k = 0.376Ht-3.27, r = 0.897, p less than 0.001), therefore, it was suggested that the majority of the enzyme which dissolves ECD exists in red blood cells. When ECD was mixed with blood, there were more hydrophilic products of ECD in plasma than those generated by the enzyme in plasma. In vivo input function of 99mTc-ECD was calculated by arterial blood sampling and octanol extraction. The duration of effective input was relatively short, which was attributed to rapid decrease of octanol extraction ratio in vivo.

Brain↗

PubMed2001

Incremental prognostic value of RNA ejection fraction measurements during pharmacologic stress testing: a comparison with clinical and perfusion variables.

UNLABELLED: This investigation examined the prognostic power of first-pass radionuclide angiocardiography (RNA) ejection fraction compared with clinical information and myocardial perfusion imaging in patients undergoing pharmacologic stress testing. The value of RNA and myocardial perfusion imaging in predicting death or nonfatal myocardial infarction (MI) is well established. However, limited information exists on the usefulness of combined myocardial perfusion imaging and RNA to predict prognosis, especially in patients undergoing pharmacologic stress testing. METHODS: We identified 240 patients who underwent pharmacologic stress testing with myocardial perfusion imaging and combined RNA. The patients were followed for a mean of 1.4 y. Cox proportional hazards models were used to assess the value in predicting death and MI. Multivariable models were generated to assess the independent incremental predictive value of clinical and nuclear imaging variables. Kaplan-Meier survival and event-free survival estimates were examined in patients with low (< or = 45%) versus high (>45%) ejection fractions. RESULTS: Clinical information, myocardial perfusion imaging, and RNA ejection fraction were significant predictors of the death/MI composite outcome (chi(2) = 7.4, 14.0, and 21.8, respectively). The addition of myocardial perfusion imaging to the clinical information provided incremental prognostic information (chi(2) = 15.2). The addition of RNA ejection fraction provided further predictive information (chi(2) = 22.5). However, when RNA ejection fraction was first added to the clinical information, myocardial perfusion imaging had no incremental prognostic value. CONCLUSION: For hard cardiac events, RNA ejection fraction provides prognostic information besides that provided by clinical and myocardial perfusion imaging. In patients who cannot exercise and are undergoing noninvasive evaluation with pharmacologic stress testing and myocardial perfusion imaging, ejection fraction should be measured simultaneously for risk assessment optimization.

Adenosine↗