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PubMed1991

Evaluation of systolic and diastolic heart function.

The evaluation of cardiac function generated considerable interest in the 1990 literature. Conventional modalities such as contrast angiography, cardiac ultrasound, and radionuclide angiography are being applied in new ways to the investigation of both systolic and, especially, diastolic heart function. Ultrafast CT can be used to precisely quantitate ventricular volumes and ejection fraction. Similarly, spin-echo and cine MR imaging provide accurate estimates of both global and regional ventricular function. However, the high cost of these sophisticated imaging modalities may limit their use for the routine assessment of systolic heart function.

Diagnostic Imaging↗
PubMed1984

[Increased incidence of skull metastases in neuroblastoma].

Children with neuroblastoma sometimes present with skull and peri-orbital metastases. Recent radionuclide studies confirm the increased incidence of skull metastases compared with adult metastatic carcinoma. Malignant tumours generate skeletal metastases by spread to the bone marrow. The relatively large head of a young child results in a relatively larger proportion of bone marrow in the skull, which explains the increased incidence of skull metastases in children with metastatic skeletal neuroblastoma.

Child, Preschool↗
PubMed1998

First-pass radionuclide angiographic analysis with two regions of interest to improve left ventricular ejection fraction accuracy.

UNLABELLED: First-pass radionuclide angiographic (FPRNA) analysis, using the standard, single-fixed region of interest (ROI) drawn at end-diastole, often underestimates the left ventricular ejection fraction (LVEF) as determined by other standard techniques. This study examined the hypothesis that correction for the anatomic motion of the aortic valve plane toward the apex during systole, which results in improper inclusion of aortic counts within the single-fixed ROI, using a two-ROI method to compensate for this motion would eliminate this underestimation. METHODS: In 70 patients who underwent FPRNA and planar gated equilibrium radionuclide angiography (GERNA) on the same day, Fourier transform phase and amplitude images were used to generate functional maps of the aorta and the left ventricle on the FPRNA representative cycle. The region of low amplitude between the aorta and left ventricle, which corresponds to the degree of aortic valve plane motion, was used to guide the manual placement of two ROIs. The first was over the left ventricle at the end-diastole including the aortic valve plane area, and the second was a smaller end-systolic ROI drawn over the first ROI, excluding the valve plane area. RESULTS: Both the fixed- and dual-ROI FPRNA methods had excellent correlation with GERNA (r = 0.92 and 0.91, respectively). The mean FPRNA LVEF using a fixed ROI (45% +/- 14%) was significantly lower than GERNA (51% +/- 15%, p < 0.001), but the mean LVEF calculated from the dual-ROI (51% +/- 14%) was essentially identical to those obtained with GERNA. The method of manual placement of the two ROIs had extremely high levels of inter- and intraobserver reproducibility (r = 0.98 and 0.99, respectively). CONCLUSION: Despite good correlation, the standard, fixed-ROI method of FPRNA analysis systematically underestimates the LVEFs of GERNA. This problem can be eliminated by taking into account valve plane motion during the cardiac cycle by using Fourier-guided, dual-ROI analysis on FPRNA. These differences in methods and results should be considered when substituting or comparing LVEFs derived from these techniques.

Female↗
PubMed2003

Murine S factors for liver, spleen, and kidney.

UNLABELLED: Preclinical evaluation of new radiopharmaceuticals is performed in animal systems before testing is started in humans. These studies, often performed in murine or other rodent models, are important in understanding the relationship between absorbed dose and response, which can be translated to preclinical results for humans. In performing such calculations, either electrons are assumed to deposit all of their energy locally or idealized models of mouse anatomy are used to determine absorbed fractions. Photon contributions are generally considered negligible. To improve the accuracy of such absorbed dose calculations, mouse-specific S factors for (131)I, (153)Sm, (32)P, (188)Re, and (90)Y have been generated, and the photon and electron portions have been tabulated separately. Absorbed fractions for 5 monoenergetic electrons, ranging in energy from 0.5 to 2 MeV, are also provided. METHODS: Female athymic mouse MR images were obtained on a 4.7-T MRI device. Fifteen T1-weighted, 1.5-mm-thick slices (0.5-mm gap) were collected. Using a previously developed software package, 3-dimensional Internal Dosimetry (3D-ID), organ contours were drawn to obtain a 3-dimensional representation of liver, kidneys, and spleen. Using a point-kernel convolution, the mean absorbed dose to each organ from the individual contributions of each source organ were calculated. S factor equivalent values were obtained by assuming a uniform distribution of radioactivity in each organ. Results were validated by comparing 3D-ID generated electron S factors for different-sized spheres with published data. Depending on matrix size, sphere size, and radionuclide, 1% (256(2) matrix) to 18% (64(2) matrix) agreement was obtained. RESULTS: S factor values were calculated for liver, spleen, and right and left kidneys. Cross-organ electron-absorbed fractions of up to 0.33 were obtained (e.g., (90)Y right kidney to liver). Comparisons between S factor values and values obtained assuming complete absorption of electron energy yielded differences of more than 190% ((90)Y spleen self-dose). CONCLUSION: The effect of cross-organ and self-absorbed dose is dependent on emission energy and organ geometry and should be considered in murine dose estimates. The approach used to generate these S factors is applicable to other animal systems and also to nonuniform activity distributions that may be obtained by small-animal SPECT or PET imaging or by quantitative autoradiography.

Animals↗
PubMed1981

Measurement of the ventricular stroke volume ratio by gated radionuclide angiography.

The ventricular stroke volume ratio or VSVR (left/right) was measured by gated radionuclide angiography in 33 normal subjects, using a 30 degree caudal slant-hole collimator and computer-generated functional images to aid in definition of the right ventricle. The mean ratio was found to be 1.06 +/- 0.05, compared to the normal value of 1.00. Comparative studies indicated that definition of the right ventricle based on the end-diastolic frame alone or standard collimation without caudal angulation commonly causes overestimation of the VSVR and considerably greater variance between measurements. Such errors are the result of inadequate atrioventricular separation and/or underestimation of the right-ventricular region.

Adult↗
PubMed1987

Zirconium molybdate gel as a generator for technetium-99m--II. High activity generators.

The characteristics of zirconium molybdate gels were described in Part I of this paper. Here it is shown that zirconium molybdate gel, prepared from neutron irradiated molybdenum oxide with 99Mo specific activities between 4.3 and 13.5 GBq g-1 is sufficiently stable for use as a matrix in preparation of high activity 99mTc generators. Elution efficiencies of generators containing from 2 to 6 g of gel ranged from 83 to 50% for 10 mL elutions. Generators containing 150 g of gel were eluted with efficiencies of 80-98%, with the activity peak in the first 50 mL. Radionuclidic impurities were considerably below the limits set by the British Pharmacopoeia. Although the pH of eluates was less than 4, subsequent treatment with a small zirconium oxide bed provided adjustment to within BP limits, and reduced 99Mo impurity levels tenfold to values near 10(-4)%. No significant differences were found between the biodistributions in rats of radiopharmaceuticals prepared with pertechnetate from gel generators and those from other generators.

Animals↗
PubMed1986

Prediction of left ventricular ejection fraction using simple quantitative clinical information.

The left ventricular ejection fraction is useful in characterizing cardiac performance and evaluating prognosis in patients with known or suspected cardiac disease. The purpose of this study was to determine if simple, quantitative clinical information generated as part of a routine patient evaluation could be used to predict ejection fraction determined by radionuclide ventriculography. Multiple regression analysis was used to study a group of 64 patients selected to represent the full range of ejection fraction values. All patients had undergone cardiac catheterization and standard chest radiography in addition to resting and exercise radionuclide ventriculography. Using easily determined clinical variables, a regression formula was developed that predicted the radionuclide ventriculographic ejection fraction (r = 0.73). Plain film heart volume, heart rate, pulse pressure, and thoracic width were highly significant terms in the optimal regression equation. For validation, the formula was applied to a second, independent verification data set composed of 41 cases and revealed similar correlation (r = 0.78). A radionuclide ventriculographic ejection fraction below 40 was identified in the verification data set with a sensitivity of 87 percent and specificity of 83 percent. Use of this method, requiring only direct heart rate, blood pressure, and chest radiographic measurements and simple calculations, may assist physicians in patient management and facilitate the optimal use of more invasive and expensive studies.

Blood Pressure↗
PubMed2006

Impact of phosphate industry on the environment: a case study.

This paper presents results obtained from studying the impact of the Syrian phosphate industry on the environment. This work is based on evaluating naturally occurring radionuclide concentrations in the surrounding environment at the locations of this industry, viz. mines, phosphate fertilizers factory and phosphate export platforms. Air particulates, soil, water (river, lake and sea water), biota and plant samples were collected and analyzed. Natural radionuclides ((226)Ra, (nat)U, (210)Po, (210)Pb) were determined by means of low background gamma spectrometry and alpha spectrometry. The results showed that the distribution and enhancement of natural radionuclides in the surrounding environment in these three locations are mainly due to fallout of phosphate dust generated during loading and processing of phosphate ore. The extent of contamination was related to climate conditions. Radon gas and its daughters generated from phosphate ores were found to be the main source of enhanced concentrations of (210)Po and (210)Pb in soil and leafy plants. These results can be considered as baseline data and can be used to prove the effectiveness of any future pollution controls adopted.

Air Pollutants, Radioactive↗
PubMed2000

Damage induced by stannous chloride in plasmid DNA.

Stannous chloride (SnCl(2)) is widely used in daily human life, for example, to conserve soft drinks, in food manufacturing and biocidal preparations. In nuclear medicine, stannous chloride is used as a reducing agent of Technetium-99m, a radionuclide used to label different cells and molecules. In spite of this, stannous chloride is able to generate reactive oxygen species (ROS) which can damage DNA. In this work, plasmid DNA (pUC 9.1) was incubated with SnCl(2) under different conditions and the results analyzed through DNA migration in agarose gel electrophoresis. Our data reinforce the powerful damaging effect induced by stannous ion and suggest that this salt can play a direct role in inducing DNA lesions.

DNA↗
PubMed2004

Experimental evaluation of gamma fluence-rate predictions from Argon-41 releases to the atmosphere over a nuclear research reactor site.

An experimental study of radionuclide dispersion in the atmosphere has been conducted at the BR1 research reactor in Mol, Belgium. Artificially generated aerosols ('white smoke') were mixed with the routine releases of (41)Ar in the reactor's 60-m tall venting stack. The detailed plume geometry was measured with remote sensing (Lidar) of the aerosol plumes while surface radiation levels were measured under the plume using gamma detectors at downwind distances of up to 1500 m from the release point. A database was built with simultaneous measurements of plume geometry and radiation field from (41)Ar decay, together with in-situ measurements of meteorological parameters. The joint tracer/radiation experimental dataset has been subsequently used to evaluate the accuracy of predictions of dispersion parameters and gamma fluence rates obtained by the atmospheric dispersion and dose rate model RIMPUFF.

Air Pollutants, Radioactive↗
PubMed2002

Radioactive waste minimization at a large academic medical facility.

The University of Texas Medical Branch (UTMB) at Galveston is a large academic medical center with about 12,700 employees, 350 radioisotope research labs and 200 permitted radioactive materials users. Consequently, UTMB generates a fairly large amount of radioactive waste. The majority of this waste contains short-lived radionuclides, such as 32P, 33P, and 35S, which are held for decay and then disposed at a sanitary landfill. However, some waste, including long-lived waste and stock vials, is compacted into drums and stored in a warehouse facility, on-site, until disposal at a low-level radioactive waste (LLRW) facility. Space in the warehouse is limited but disposal is currently cost prohibitive. A reevaluation of our program was conducted to see if volumes of LLRW requiring disposal at a commercial LLRW facility could be reduced. A reevaluation of the waste streams resulted in the shifting of most of the material that was being drummed for shipment to a LLRW facility to disposal by landfill or incineration. Materials that were previously assumed to be radioactive are now being evaluated prior to disposal to determine if they may be disposed of as non-radioactive waste. Following the initial evaluation, the amount of compacted dry solids assumed to contain long-lived radionuclides was reduced. The space that was saved due to the decrease in drumming for disposal is now used to hold the increased volume of decay-in-storage material. The monetary savings will amount to about $45,000 per year. This program is currently being expanded to reduce other waste streams at the university.

Academic Medical Centers↗
PubMed2000

[Evaluation of cardiac function by radioisotope angiography].

Cardiac function can be assessed with noninvasive radionuclide technique. Radioisotope angiography can be performed either using equilibrium acquisition or first pass technique. The most commonly generated measurements are as follows; 1) chamber-to-chamber transit time, 2) cardiac output, 3) left-to-right shunt ratio, 4) left and right ventricular ejection fractions, 5) left ventricular end-diastolic and end-systolic volumes, 6) regional wall motion, 7) peak ejection rate, and 8) peak filling rate. The ejection fraction, the systolic function and the diastolic function are calculated from ventricular volume curves. The left ventricular volume can be determined by two approaches, the geometric method using the left ventricular image to calculate the area and length of the chamber, and the count-based method. Generally, left ventricular wall motion is observed in right anterior oblique(RAO) view for the first pass method and the left anterior oblique(LAO) view for the equilibrium method. On the other hand, three dimensional multigated imaging was superior in allowing evaluation of left ventricular wall motion in all directions and in assessment of the left ventricular function. Three dimensional multigated imaging is very useful for observation of both left ventricular wall motion and left ventricular function in patients with ischemic heart disease, because it is a noninvasive examination. The quantitative gated myocardial SPECT(QGS) was considered to be useful for assessment of left ventricular function and myocardial perfusion.

Cardiac Output↗
PubMedDate not supplied

[Technetium-99m radiopharmaceuticals for in vivo diagnostics].

INTRODUCTION: Technetium-99m is an ideal radionuclide with optimum decay characteristics. It can be obtained in sterile, pyrogen-free and carrier-free condition, as sodium pertechnetate (Na99mTcO4), from 99Mo/99mTc generator. Because of its six-hour physical half-life and monochromatic 140 keV photons free of -radiation, administration of small amounts of 99mTc solution is possible, without a significant radiation damage to the patient. Technetium eluted from the 99Mo/99mTc generator is in the highest oxidation form (+ 7). It can be used for diagnostic purposes alone, but it is often used for labeling different organic and inorganic compounds. As it is unreactive, reduction with a chemical reductant, (+1), (+3) and (+5) oxidation are necessary before use. Nowadays almost 80% of radiopharmaceuticals are based on 99mTc. RADIOPHARMACEUTICALS: Radiopharmaceuticals are radionuclides or radioactive compounds used in diagnosis and therapy of human diseases. A pharmaceutical is chosen based on its localization in the organ, or its participation in its physiological function. Radiation emitted from a radionuclide is detected by a radiation detector. The ability to incorporate available radionuclides into tracer molecules has been the main goal in developing radiopharmaceuticals. As radionuclides with nuclear characteristcs used as either diagnostic or therapeutic radiopharmaceuticals, are predominantly metals, they can be designed as metal essential, whereby biological distribution is determined by coordination compound, or metal tagged, in which case the properties of the carrier molecule (ligand system) determine the biological distribution. This paper reviews the development of 99mTc-radiopharmaceuticals.

Humans↗
PubMed1985

Measurement of left-ventricular volumes using an internal standard.

When performing equilibrium radionuclide angiocardiography with two successive acquisition views, absolute left-ventricular volumes can be calculated using an 'internal standard' generated by a computer in the left-ventricular cavity. The method is based on the computed ratio of maximum to global activity in the 40 degree-left-anterior-oblique view after background correction and on the measured depth of the left ventricle in almost-orthogonal, 30 degree-left-posterior-oblique Fourier first-harmonic images. The method does not require blood sampling or correction for self attenuation. The intra- and interobserver reproducibility is excellent, even in patients with severe impairment of the ventricular-contractility pattern. When compared with a classical method requiring venous-blood counting and an attenuation correction factor, the accuracy of the internal-standard method was fairly good, with a regression coefficient of 0.90.

Adult↗
PubMed1994

[Dynamic cardiomyoplasty. Preliminary experience].

INTRODUCTION AND OBJECTIVES: The purpose of this study is to show our experience in clinical dynamic cardiomyoplasty. PATIENTS, MATERIALS AND METHODS: Six patients with end-stage heart failure and 2 patients with left ventricular aneurysm underwent dynamic cardiomyoplasty using the latissimus dorsi muscle. The latissimus dorsi was electrically conditioned before the procedure through a lead placed under local anesthesia and connected to an external cardiac pace-maker. Surgical technique--including dissection of the latissimus dorsi and encircling of the ventricles with the muscle flap--was performed in general terms as described at the Broussais Hospital. In the first 3 patients a bipolar lead connected to a single impulse generator was used. In the other 5 patients a train of impulses cardiomyostimulator was used. Changes in systolic function were studied through Doppler-echocardiography and radionuclide studies. Changes in diastolic function were evaluated through E wave velocity and deceleration time. RESULTS: Mean follow up was 9 +/- 5.7 months. No early deaths were recorded. One patient underwent emergency surgery, one week after the procedure, because of a tear of the patch used to close the wall defect after left ventricular aneurysm resection. In 2 patients a subcutaneous serous collection secondary to muscle dissection was evacuated. One patient died due to a stroke 4 months after the procedure. Another patient died after an unsuccessful coronary transluminal percutaneous angioplasty 11 months after the procedure. An improved functional class was observed in all patients. No changes in systolic function were observed after surgery when the cardiomyoestimulator was turned-off either with echocardiography (26.7 +/- 8.6 vs 24.8 +/- 5.8% [NS]) or radionuclides (24.5 +/- 9.5 vs 20.2 +/- 8.3% [NS]). When the cardiomyostimulator was turned-on a statistically significant increase of the left ventricular ejection fraction was observed either with echocardiography (24.8 +/- 5.8 vs 37 +/- 10.3%; p < 0.05) or radionuclides (20.2 +/- 8.3 vs 33.3 +/- 12.2%; p < 0.05). This significant increase of the ejection fraction has been observed in subsequent studies. Nevertheless the differences when the cardiomyostimulator is turned-on and turned-off have decreased several months after the procedure. A significant increase of the left ventricular outflow velocity (cm/seg) was observed when the generator was turned-on (57.7 +/- 20.4 vs 75.1 +/- 17.8%; p < 0.01). A significant increase of the dP/dt (mmHg/seg) was observed when the generator was turned-on (706.3 +/- 291.5 vs 592.6 +/- 181.6%; [NS]). No significant changes were observed on E wave velocity. A significant decrease of the deceleration time was observed several months after the procedure (p < 0.05). CONCLUSIONS: We believe that dynamic cardiomyoplasty is a safe and valid surgical procedure for some patients with end stage cardiomyopathies as well as in association with Jatene's technique for the management of left ventricular aneurysms. An improvement in functional class is present and a significant increase of the left ventricular systolic function. Nevertheless it is necessary to find new systolic parameters, independent of volumetric calculations, to evaluate the mechanical support of the muscle as well as to determine the long-term pattern of electrical stimulation.

Adult↗
PubMedDate not supplied

A comparison of intravascular source designs based on the beta particle emitter 114mIn/114In. Line source versus stepping source.

BACKGROUND: Catheter-based intravascular brachytherapy (IVB) sources of the next generation will have to meet high demands in terms of miniaturization, flexibility, safety, reliability, costs and versatility. The radionuclide pair 114mIn/114In (half-life 49.51 days, maximum beta energy 2.0 MeV, average beta energy 0.78 MeV) is an attractive beta emitter for application in such a source. METHODS: Since metallic indium is unfit for the manufacture of a brachytherapy source, the feasibility, safety and dosimetric properties of a design concept comprising a linear array of ceramic In2O3 spheres within a thin-walled, superelastic Ni/Ti capsule are investigated. RESULTS: Neutron activation of enriched In2O3 spheres yields a specific activity sufficiently high for the manufacture of a stepping source, keeping treatment times limited to a few minutes. Although 114mIn/114In also emits some gamma radiation, the effective doses received by members of the medical staff are an order of magnitude lower than those received from fluoroscopy. The dose distributions about a 40-mm line source and a 5-mm stepping source (outer diameter 0.36 mm) are calculated using MCNP4C. Dose-volume histograms (DVHs) are calculated for the line source (centered and noncentered) and the stepping source (centered) using the geometry of a human coronary artery. CONCLUSION: The results show that a centered stepping source with optimized dwell times delivers the most homogenous dose within the target volume.

Angioplasty, Balloon, Coronary↗
PubMed1999

Sensitivity of concentration and risk predictions in the PRESTO and MMSOILS multimedia models: regression technique assessment.

This paper describes the application of two multimedia models, PRESTO and MMSOILS, to predict contaminant migration from a landfill that contains an organic chemical (methylene chloride) and a radionuclide (uranium-238). Exposure point concentrations and human health risks are predicted, and distributions of those predictions are generated using Monte Carlo techniques. Analysis of exposure point concentrations shows that predictions of uranium-238 in groundwater differ by more than one order of magnitude between models. These differences occur mainly because PRESTO simulates uranium-238 transport through the groundwater using a one-dimensional algorithm and vertically mixes the plume over an effective mixing depth, whereas MMSOILS uses a three-dimensional algorithm and simulates a plume that resides near the surface of the aquifer. A sensitivity analysis, using stepwise multiple linear regression, is performed to evaluate which of the random variables are most important in producing the predicted distributions of exposure point concentrations and health risks. The sensitivity analysis shows that the predicted distributions can be accurately reproduced using a small subset of the random variables. Simple regression techniques are applied, for comparison, to the same scenarios, and results are similar. The practical implication of this analysis is the ability to distinguish between important versus unimportant random variables in terms of their sensitivity to selected endpoints.

Algorithms↗
PubMed1987

[Experimental considerations of myocardial single photon emission CT image with a cardiac phantom].

We studied the quantity of thallium-201 myocardial single photon emission CT (SPECT) image with a cardiac phantom. The myocardial SPECT image is influenced by several causes, i.e., the absorption of gamma rays, collimator aperture, statistical noise and limited angle of rotation in data acquisition. The attenuation correction under the assumption of uniform distribution is not sufficient, so we have to consider the actual distribution of absorption. The effects of the nonuniform attenuation are most prominently appeared when we evaluate the quantity by the integral method. The aperture characteristics of a collimator are decided by the distance between the rotational center of the gamma camera and the collimator surface. Simultaneously scattered gamma rays affect the reconstructed image in the low frequency component, so the effective attenuation coefficient varies gradually. The statistical noise intermixed in the projection data generate artifacts like as lump-shaped pattern. The noise are clearly appeared in the spatial frequency upper than 0.25 cycle, so the low-pass filter are required with that of cut-off frequency. Moreover to enhance the details of the radionuclide distribution of cardiac muscle, the Wiener filter should be applied. The scan area also affects the appearance of the artifact in the myocardial SPECT image. The 180-degree scan usually generates false defects just nearby the center of reconstructed cross section. And the positions are changed with the conditions of gamma ray absorber and its relative position to the myocardial area. The 360-degree scan should be used from the standpoint of reconstructing more quantitative image.

Gamma Rays↗