ABSTRACT
A preliminary evaluation of the potential utilization of osmium-191/iridium-191m for pulmonary blood flow imaging was performed. This evaluation was part of a more general study concerning the use of 191mIr for first-pass radionuclide angiocardiography (FPRNA). In eight selected patients with suspected pulmonary disease, we generated, from the data collected during FPRNA, an image representing blood flow distribution to the lungs. A software program was developed in order to differentiate the lungs from the heart, to define the wash-in lung phase and finally to construct an image representing pulmonary blood flow distribution. We compared that image with a standard lung perfusion image using technetium-99m macroaggregated albumin (MAA) and plain chest X-ray and computerized tomography (CT). The obtained 191mIr perfusion images showed a spatial activity distribution similar to that seen on 99mTc-MAA lung perfusion scans, and in most cases the same perfusion defects. Disease revealed by plain chest X-ray and CT was nicely correlated with perfusion defects seen on the 191mIr images. The combined information of lung perfusion and dynamic cardiac parameters obtained by FPRNA (right and left ventricular ejection fractions) added another relevant dimension to the clinical picture of patients with pulmonary embolism, chronic obstructive lung disease, lung tumour or suspected congestive heart failure. We conclude that 191mIr may become a practical tool for achieving the conceptually promising approach of combined lung-heart real-time imaging.
Subject(s)
Iridium Radioisotopes , Pulmonary Circulation , Ventriculography, First-Pass , Humans , Lung/diagnostic imaging , Lung Diseases/diagnostic imaging , Osmium , Radioisotopes , Stroke Volume , Ventilation-Perfusion RatioABSTRACT
The influence of four pH adjustment agents on the biologic behavior of osmium-191 (191Os) impurity in 191Os/191mIr generator eluates was studied. Extended body clearance and biodistribution studies were performed in mice. The solutions to be injected were obtained by eluting generators with a 0.9% NaCl solution at pH 1. The pH of these eluates was adjusted to 5-9 with succinate, phosphate, lysine or NaOH solution. Our results demonstrate that the biologic behavior of these generator eluates is significantly dependent on the agent used for pH adjustment. Buffering with lysine leads to the best results: (a) the mice show no adverse reaction after injection of 150 human doses and the body clearance is very rapid and (b) more than 75% I.D. at 24 hr postinjection. Preliminary calculations based on these results suggest a significant decrease in the estimated patient radiation dose when lysine buffered 191Os/191mIr generator eluates are used for radionuclide angiography.
Subject(s)
Isotopes , Osmium , Radioisotopes , Radionuclide Generators , Animals , Buffers , Hydrogen-Ion Concentration , Iridium , Lysine/pharmacology , Mice , Mice, Inbred ICR , Osmium/pharmacokinetics , Phosphates/pharmacology , Sodium Hydroxide/pharmacology , Succinates/pharmacology , Succinic Acid , Tissue DistributionABSTRACT
A new separation system for an 191Os/191mIr generator is described. The system is composed of two columns in a series: a main column, packed with silica gel impregnated with tridodecylmethylammonium chloride (loaded with high activity 191Os as an osmyl chloride); and a scavenger column, packed with activated charcoal. Iridium-191m is eluted from the generator by pH 1 saline. For clinical use the eluate is buffered by succinate solution before injection. This new system is characterized by high performance (approximately 25% 191mIr recovery with 5 X 10(-4)% 191Os breakthrough) and long shelf-life (3 wk). The buffered eluate is sterile, pyrogen-free, and nontoxic, and contains no 192Ir. It is suitable for first-pass radionuclide angiocardiography with a very low radiation dose to the patient.
Subject(s)
Iridium/isolation & purification , Osmium/isolation & purification , Radioisotopes/isolation & purification , Radionuclide Generators , Adult , Animals , Gels , Humans , Isotopes/isolation & purification , Mice , Quaternary Ammonium Compounds , Radiation Dosage , Silicon DioxideABSTRACT
Iridium-191m would appear to be a highly useful agent for first-pass radionuclide angiocardiography (FPNA), with its very short half-life (4.96 sec), dual photopeaks (65 and 129 keV), and high injectable activity levels (greater than 100 mc). In order to compare 191mIr FPNA to current methods used to define cardiac function, 20 patients referred for cardiac catheterization were studied. Count rate data, right ventricular (RV), and left ventricular ejection fraction (LVEF), LV and diastolic volume (EDV), and end diastolic long axis (AXIS) were evaluated. Count rate data using 191mIr FPNA was consistently better than similar data obtained by 99mTc FPNA. There were acceptable correlations between 191mIr and 99mTc FPNA RVEF (r = 0.848), 191mIr FPNA and contrast angiography LVEF (r = 0.944), LVEDV (r = 0.917), and LV AXIS (r = 0.866). The data thus suggests that 191mIr FPNA has great potential in the evaluation of cardiac function.
Subject(s)
Heart/diagnostic imaging , Iridium , Radionuclide Angiography/methods , Adolescent , Adult , Aged , Heart/physiopathology , Heart Ventricles , Humans , Isotopes , Middle Aged , Stroke Volume , TechnetiumABSTRACT
The simultaneous detection and quantitative determination of a very large number of metabolites in physiological fluids or tissues, and the subsequent comparison of these data with reference values, is a process which has commonly been called 'metabolic profiling' analysis. Profiles generated by gas-liquid chromatography on packed or capillary columns are readily analyzed by mass spectrometry, utilizing reverse library search procedures to identify individual components. Emphasis will be given here to procedures for the pre-purification of organic acids from plasma, to the use of quartz capillaries for metabolic profiling analysis, and to the sensitivity of this method for trace components.
Subject(s)
Carboxylic Acids/analysis , Carboxylic Acids/urine , Gas Chromatography-Mass Spectrometry , Humans , Wine/analysisABSTRACT
A method has been developed for qualitative screening of carboxylic acids in human urine. The method uses direct chemical inoization mass spectrometry with isobutane as reagent gas. The carboxylic acids are separated from the urine samples by ion exchange. Normal carboxylic acid profiles have been determined and are compared with the profiles of patients suffering from certain metabolic disorders.
Subject(s)
Carboxylic Acids/urine , Mass Spectrometry/methods , Amino Acids/urine , Child , Child, Preschool , Chromatography, Ion Exchange , Humans , Hydroxy Acids/urine , Infant, Newborn , Maple Syrup Urine Disease/urine , Phenylketonurias/urine , Reye Syndrome/urineABSTRACT
A semi-quantitative method has been developed for rapid determination of amino acids and other nitrogenous compounds in human urine. The method uses direct chemical ionization mass spectrometry with isobutane as reagent. The nitrogenous compounds are separated from the urine samples by ion exchange. Disorders in amino acid metabolism have been determined by this method in patients suffering from phenylketonuria, cystinuria and maple-syrup urihe disease.
