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B R Persson

Publications and source records attributed to B R Persson.

At least 37 records · Page 2Linked to original sources
PubMed1992

MR imaging, flow and motion.

The present work is intended as a nonmathematical review of the role of flow and motion in nuclear magnetic resonance (MR) imaging. A historical review of MR flow measurement techniques is given, followed by a short overview of flow models in vitro and in vivo. The theory behind the influence of motion on the modulus and phase MR signal information is discussed and effects such as washin/washout, flow-induced signal void, phase offset, and phase dispersion are defined. A simple approach to the concept of MR angiography is given, and methods for quantitative flow measurements such as the phase mapping technique, are surveyed. Aspects of the measurement of diffusion and microcirculation are given, and finally, an overview of the role of MR flow imaging in present and future clinical application is given.

Blood Circulation↗
PubMed1985

In vitro interaction between venous blood clots and radiopharmaceuticals.

Clots of 1 ml venous blood formed in glass tubes after 10 min at room temperature were incubated at 37 degrees C with the radiopharmaceutical to be studied. Methods for quality control of the radiopharmaceuticals were compared. Gel chromatography scanning was found to give reliable information. The incorporation into the clot was studied at different pH values and after various time intervals. The highest incorporation was found for 125I-fibrinogen and for 99mTc-macroaggregates of albumin, followed by 99mTc-sulphur colloid and 99mTc-streptokinase at pH less than 2. The titrated initial dose of 99mTc-streptokinase was studied at various pH levels. The lysing effect was less in the pH range 1-2.5, where the best labeling yield was obtained. The inactivation of streptokinase by the labeling procedure was also studied with immunoelectrophoresis and decomposition of casein. In vitro studies of the interaction of radiopharmaceuticals with clots add information for the clinical use of radiopharmaceuticals for thrombus localization.

Fibrinogen↗
PubMed1984

Local hyperthermia in treatment of experimental liver tumors.

An experimental model for local microwave hyperthermia treatment of liver tumors is presented. Fifty-four Wistar rats were inoculated with a transplantable adenocarcinoma (NGW) in the central liver lobe. Ten to 16 days later 28 of the rats were exposed to local hyperthermia. A master thermistor placed in the liver parenchyma adjacent to the tumor controlled the hyperthermia, and the tumor-bearing liver lobe was maintained at 42.0 degrees C for 1 hour. At laparotomy 7 days after treatment, the tumor volume was measured. Four weeks after tumor inoculation, autopsy was performed. The tumor and the surrounding parenchyma was excised for histopathologic examination. A statistically significant reduction in tumor growth was found after exposure to local hyperthermia, the effect of hyperthermia being most pronounced in moderate-sized tumors (300-500 mm3 or 0.5-0.75 g). In larger tumors (greater than 900 mm3 or greater than 1.1 g) extensive necrosis developed after hyperthermia treatment. This indicates good tumoricidal effect even in large tumors, although this is not obvious if reduction in tumor growth is used as the only parameter to evaluate the effect of hyperthermia.

Adenocarcinoma↗
PubMed1983

Evaluation of renal function parameters with simultaneously administered 99mTc-DTPA and 131I-hippuran.

The present study aimed at comparing two renal function tests using 99mTc-DTPA (diethylene triamine penta acetic acid) and 131I-labeled hippuran (o-hippuric acid). A mixture of 80 MBq 99mTc-DTPA and 7.4 MBq 131I-hippuran in a total volume of 1.5 ml or less was injected into an arm-vein. Both radiopharmaceuticals have identical initial distributions in the blood pool when injected in this manner. Seventy-two patients were studied with the present dual radionuclide technique. The following parameters were derived from the renogram: area under curve, uptake ratio, Tmax, decrease ratio, excretion ratio, and rate of decrease. The parameters for 99mTc-DTPA and 131I-hippuran were compared for various kidney groups. Generally the renographic parameters were well correlated. Apart from the systematic differences due to different modes of renal excretion, the curve patterns virtually agreed. The differences that were observed between the two tracers lacked clinical significance.

Humans↗
PubMed1983

97Ru-transferrin uptake in tumor and abscess.

The uptake of 97Ru-transferrin (Ru-TF) in tumor and abscess bearing animals was compared with 67Ga-citrate (Ga), 123I-transferrin (I-TF), and several other plasma proteins. Maximal concentration in tumor of Ru-TF in mice was three times higher than 67Ga-citrate (16.80 +/- 4.20 vs 5.08 +/- 0.58% D/g) although it occurred later (24 h compared with 67Ga which reached its maximum 2 h after injection). Whole body autoradiography (WBARG) with 103Ru-transferrin (103Ru-TF) in tumor and abscess bearing rats demonstrated details of the distribution within these lesions. Turpentine-induced abscesses in the rabbits could be visualized with the gamma camera as early as 30 min post-injection of Ru-TF. It seems, therefore, that Ru-TF can be used for tumor and abscess localization. The results indicate that Ru-TF may have some advantages over 67Ga-citrate because of the higher concentration in the lesions. 123I-transferrin reached a concentration in tumor similar to 67Ga (6.89 +/- 1.67 vs 5.08 +/- 0.58% D/g) but had a very low tumor to blood ratio (0.64). The three compounds investigated (Ru-TF, I-TF and ionic Ga, which binds instantaneously to TF in vivo) have a common ligand, transferrin. It appears, therefore, that tumor affinity is a property of the radionuclide-ligand complex rather than of the radionuclide itself.

Abscess↗
PubMed1983

Particle sizing and biokinetics of interstitial lymphoscintigraphic agents.

The biokinetics of inert lymphoscintigraphic agents strongly depends on their particle size. Different techniques for characterization of colloids are discussed. Experiments have been performed on eight different colloids. The particle size has been investigated with scanning electron microscopy. Activity distributions have been obtained with ultrafiltration and gel-column scanning technique. The colloids suggested for lymphoscintigraphy were found to have a median size of about 40-50 nm except one minimicro-aggregated human serum albumin colloid which has a median particle size around 10 nm. The biokinetics were studied with a scintillation camera in rabbits after a subcutaneous injection. Time-activity curves were generated. After 5 hr the rabbits were dissected and the activity content in different tissues measured. A compartment model for the biokinetics was designed and rate constants evaluated. The total and specific activity uptake in parasternal lymph nodes was highest for the small-particle colloids. The compartment model showed a good fitting to the experimental data.

Absorption↗
PubMed1980

Quality control of 99mTc-radiopharmaceuticals. Evaluation of GCS minicolumns in routine clinical work with scintillation cameras.

Gel chromatography columnm scanning (GCS) is a rapid and reliable method for the quality control of 99mTc-radiopharmaceuticals. With this method the labelled compound and various impurities such as free pertechnetate, hydrolyzed reduced technetium or other 99mTc-complexes are obtained in one testing procedure. Using minicolumns results can be obtained with a simple testing procedure within a few minutes after the sample is taken; this is significant in routine radiopharmaceutical work. The resolution of the recording system is important, so as to be able to utilize fully the good separation ability of the minicolumn. Minicolumns were studied with some commonly used radiopharmaceuticals. A scintillation camera was used to record minicolumn data under various conditions and the results were conpared to those obtained using a scanner to reveal optimal recording conditions for the scintillation camera.

Chromatography, Gel↗
PubMed1979

Quantitative lymphoscintigraphy I: Basic concepts for optimal uptake of radiocolloids in the parasternal lymph nodes of rabbits.

The activity-size distribution of radiocolloids has been studied using gel-chromatography scanning (GCS) of columns filled with Sepharose 4B gel. Rabbits were injected subcutaneously with the colloid of interest, laid supine beneath a gamma camera, and imaged every 15 sec for 2 to 4 hr. From the stored data, the uptakes in the parasternal lymph nodes were analyzed in terms of two-compartment model, and the rate constants measured. The substances tested were Au- 198 colloid, Tc-99m antimony sulfide colloid, Tc-99m tin colloid, Tc-99m phytate, and Tc-99m sulfur colloid. It was shown that the optimal particle size for the colloid in the range 1-10 nm. The large and most rapid uptake was found for Au- 198 colloid, with a particle size of 5 nm, which appeared as a single peak in the GCS spectrum. The percentage uptake after 2 hr for Au- 198 colloid 8%, while it was 5% for antimony-sulfide colloid, which was the best of the Tc-99m-labeled colloids. The GCS spectrum for the antimony product showed a single-peaked size distribution with a somewhat broader range: 5-15 nm. The particles of the other colloids were either too large to pass into the lymphatic system, or too small to be trapped.

Animals↗
PubMed1978

Trapping and re-use system for radioactive xenon in nuclear medicine.

Different methods of trapping radioactive xenon are reviewed. Trapping by adsorption on activated charcoal has the advantage of being simple and cheap and also makes it possible to recycle the xenon. An activated charcoal trapping system is described which can extract 133Xe from 1001 of expired air in 10 min from patients undergoing diagnostic pulmonary or circulation studies. Details of the construction are discussed. The trapped gas can be rapidly released and returned to the spirometer. Substantial reduction of costs can be achieved with 133Xe; this becomes even more important as accelerator-produced 127Xe comes into more general use.

Adsorption↗
PubMed1978

Quantitative lymphoscintigraphy for detection of metastases to the internal mammary lymph nodes. Biokinetics of 99Tcm-sulphur colloid uptake and correlation with microscopy.

Dymanic quantitative activity determination and accurate scintigraphic localization of parasternal lymph nodes were obtained from antero-posterior measurements with a scintillation camera. The scintigraphic observations were compared with microscopy of the nodes removed at operation. The 99Tcm-sulphur colloid indicated a high frequency (7/16) of absent uptake in normal lymph nodes. However, the technique used indicates that a similar technique with smaller particle size may be a useful method for proper classification of the clinical stage of carcinoma of the breast.

Breast Neoplasms↗
PubMed1977

The dual photopeak-area method applied to scintillation camera measurements of effective depth and activity of in vivo 123I-distributions.

Attenuation curves and photopeak ratios of 159 keV and 28 keV photons emitted in the decay of 123I have been studied using a scintillation camera equipped with an extra ADC for recording the pulse height distribution of the energy signal. Cavities of various sizes containing 123I-solution were placed at different depths in a water phantom in order to vary the effective depth i.e., the thickness of attenuating material above the cavity plus the distance to the centre of activity in the cavity. The centre of activity varies with the distribution of activity in the cavity, size of cavity, and the effective attenuation coefficient derived from the attenuation curves. From the photopeak ratio an average effective depth is determined which can be used for calculating the attenuation correction factor. The dual photopeak ratio has been used in clinical evaluation of thyoid 123I uptake measurements where effective depths ranging from 21 to 43 mm were obtained for the activity in the thyroid. Applications of the photopeak ratio method for renography with 123I-hippuran and blood flow studies using 133Xe or 127Xe and studies with many other radionuclides are also discussed.

Adult↗
PubMed1977

Imaging 123I with a scintillation camera. A study of detection performance and quality factor concepts.

Image quality, resolution and sensitivity of a scintillation camera equipped with various collimators have been investigated using high purity 123I. Pulse height distributions of 123I from a thyroid phantom partly in air and partly immersed in water demonstrate the substantial septa penetration of the 440 and 529 keV gamma rays of 123I with high resolution collimators. Line spread functions recorded first with the line source in air and then in water show that the area under the 'wings' is attributed mainly to septa penetration but with a marked contribution from scattering in water. The modulation transfer function evaluated from the line spread functions shows a sudden drop at low frequencies for high resolution collimators due to their high degree of septa penetration. The two concepts of 'figure of merit' also used are Qb=Sa [MTF]2, where Sa is the plane sensitivity and Qc=S2/(S+2B), where S is the true signal from the object and B is the total background or noise due to septa penetration and scatter. The image reproduction per unit time which is described by Qb is best for a high resolution converging collimator. The statistical accuracy per unit time which is used in dynamic studies is described by Qc and is best for a medium energy collimator.

Air↗
PubMed1976

Quality control and testing of 99mTc-macroaggregated albumin.

99mTc-labelled macroaggregated albumin particles prepared from a commercial "kit" have been tested in detail. With the introduction of the method of gel chromatography column scanning it became possible to make fast and simple quantitative measurements of the radiochemical purity. This was found to be the only reliable method for quantitative determination of non-aggregated 99mTc-labelled albumin. The measuring results of the kit in question have shown a labelling efficiency of about 97--99%. In addition to a few percent of 99m-Tc-pertechnetate less than 0.5% of disturbing radioactivity was found. The labelling was stable for at least 5--6 h. About 80% of the particles are in the size-range of 10--80 mum. A rough estimation of the number of particles in the solution resulted in 0.4-10(6) per mg of MAA. The dynamic studies of the lung uptake and the elimination of 99mTc-MAA in man resulted in a biological half-time in the lungs of about 1--2 h. The radiation absorbed dose to the lungs per mCi administered 99mTc-MAA was estimated to 0.1 rad. Less than 1% of the radioactivity was accumulated in liver, spleen or kidneys during the first 25 minutes after injection.

Animals↗