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PubMed1996

Abdominal SPECT/MRI fusion applied to the study of splenic and hepatic uptake of radiolabeled thrombocytes and colloids.

The importance of applying MRI (CT)/SPECT fusion in the abdominal and thoracic areas has been recognized in recent studies aiming at radionuclide therapy of cancer. According to our earlier results spleen and liver volume determination with different segmentation methods is inaccurate with SPECT alone. We therefore applied a SPECT/MRI registration procedure to the estimation of spleen and liver volumes and spleen/liver activity ratios in three male volunteers administered 111In-labeled thrombocytes and 99mTc-labeled colloids. The objectives of the study were to investigate if the uptake of thrombocytes in the spleen and liver can be measured more accurately when the anatomical borders of these organs are transferred from MRI to SPECT, and to test a SPECT/MRI registration method for improving three-dimensional dosimetry for radiotherapy treatment planning. A good correlation was found between spleen/liver activity ratios calculated from volumetric average activity per pixel values and from total volumetric counts derived from registered data but not from projection data. The average registration residual with this SPECT/MRI fusion method is approximately 1-2 cm in the abdominal area. Combining anatomical images with SPECT is therefore important for improving quantitative SPECT also in the abdomen.

Abdomen↗
PubMed1995

The value of combined 99mTc-Sn-colloid and 99mTc-RBC scintigraphy in the evaluation of a wandering spleen.

Wandering spleen is the term commonly applied to splenic hypermobility that results from laxity or maldevelopment of its suspensory ligaments. It comes to medical attention usually as an abdominal mass, or when the spleen undergoes torsion. Diagnosis on clinical grounds alone is rarely made, and ultrasonography, CT and MRI findings have no specific characteristics for this condition. 99mTc-labeled colloid taken up by the spleen may provide a specific diagnosis. We report a case of wandering spleen, in which the preoperative diagnosis was made on the basis of sequential liver-spleen scintigraphy with 99mTc-Sn-colloid and blood-pool scintigraphy with 99mTc-RBC. This is a rare case, in which hypermobility was assessed by sequential 99mTc-Sn-colloid scintigraphy, and to our knowledge, is the first case in which 99mTc-RBC scintigraphy provided useful information on splenic blood volume and its location.

Adult↗
PubMed2004

CT-guided lymphoscintigraphy in patients with squamous cell carcinoma of the head and neck: a feasibility study.

Accurate knowledge of lymphatic drainage facilitates planning of surgery for patients with squamous cell carcinoma of the head and neck. The aim of this study was to evaluate the feasibility of a new injection technique for lymph node detection in patients with squamous cell carcinoma of the hypopharynx and larynx, in whom simple peritumoural injection is hampered by the tumour localisation. Computed tomography (CT)-guided lymphoscintigraphy was performed in a total of 13 patients with squamous cell carcinoma of the hypopharynx and larynx who could not be injected by simple visual inspection. In a first step, contrast medium-enhanced axial 5-mm-thick CT slices of the neck were obtained. After tumour localisation on these CT images, 1-2 ml contrast medium and, in the event of appropriate distribution, subsequently 50 MBq technetium-99m colloid were injected at one to three peritumoural sites under CT guidance. Peritumoural tracer distribution was controlled by thin-slice CT. Subsequently, planar scintigrams from anterior, right and left lateral views were obtained. In all patients, peritumoural colloid application was feasible, as shown on control CT scans. Post injection, neither severe nor minor complications were noted. The patients complained of only low pain sensations with an average score of 1.8 on a pain scale from 0 to 10. Lymphatic drainage was identified in nine of the 13 patients, with a total of 14 detected lymph nodes. In six patients, ipsilateral sentinel lymph nodes were visualised; bilateral sentinel lymph nodes were identified in one patient and contralateral lymphatic drainage was observed in two patients. CT-guided lymphoscintigraphy is a feasible and minimally invasive diagnostic tool for sentinel lymph node detection in patients with squamous cell carcinoma of the hypopharynx and the larynx. In contrast to endoscopic colloid injection under general anaesthesia, this technique seems to be a well-tolerated method for lymphatic mapping prior to surgical procedures.

Adult↗
PubMed1999

A deconvolution technique for processing small intestinal transit data.

The deconvolution technique can be used to compute small intestinal impulse response curves from scintigraphic data. Previously suggested approaches, however, are sensitive to noise from the data. We investigated whether deconvolution based on a new simple iterative convolving technique can be recommended. Eight healthy volunteers ingested a meal that contained indium-111 diethylene triamine penta-acetic acid labelled water and technetium-99m stannous colloid labelled omelette. Imaging was performed at 30-min intervals until all radioactivity was located in the colon. A Fermi function=(1+e-alphabeta)/(1+e(t-alpha)beta) was chosen to characterize the small intestinal impulse response function. By changing only two parameters, alpha and beta, it is possible to obtain configurations from nearly a square function to nearly a monoexponential function. Small intestinal input function was obtained from the gastric emptying curve and convolved with the Fermi function. The sum of least squares was used to find alpha and beta yielding the best fit of the convolved curve to the observed small intestinal time-activity curve. Finally, a small intestinal mean transit time was calculated from the Fermi function referred to. In all cases, we found an excellent fit of the convolved curve to the observed small intestinal time-activity curve, that is the Fermi function reflected the small intestinal impulse response curve. Small intestinal mean transit time of liquid marker (median 2.02 h) was significantly shorter than that of solid marker (median 2.99 h; P<0.02). The iterative convolving technique seems to be an attractive alternative to ordinary approaches for the processing of small intestinal transit data.

Adult↗
PubMed1986

Interobserver variation in the detection of metastases on liver scans.

Two specialists in nuclear medicine and two trainees independently read 106 liver scans for abnormalities suggestive of metastases. The four observers made a positive diagnosis with a significantly different frequency. The overall agreement between pairs of observers was 0.83-0.87. After adjusting for the expected chance agreement, kappa-values between 0.66 and 0.74 were obtained. No difference was found in the level of agreement between the two specialists or between the two trainees. After a consensus conference where the observers tried to unify their diagnostic interpretation, another 106 scans were read for abnormalities suggestive of metastases. The conference did not increase the level of agreement. Scintigraphic lesions that especially imply a risk of disagreement are pointed out.

Colloids↗
PubMed1982

Ytterbium-169-phytate: a potential new radiopharmaceutical for functional scintigraphy of the liver.

A new radiopharmaceutical for liver scintigraphy has been prepared by reacting 169YbOCl with Na phytate under conditions which yield a labelling efficiency of more than 99% over a wide pH range. In rabbits the resultant colloidal preparation shows a rapid elimination from the blood and high initial uptake in liver. Subsequently about 90% of the liver activity is lost within 3 days, the remainder being eliminated more slowly. The radiopharmaceutical is non-toxic and has a shelf-life of about 3 months. Scintigrams obtained in patients with hepatomegaly suggest that this new agent gives better visualization of space occupying lesions of the liver than 99mTc-Sn colloid. The radiation dose to the patient from this agent is low and comparable with that from other radiopharmaceuticals used for liver scintigraphy.

Adult↗
PubMed1986

Inhibition of arm regeneration by Ophioderma brevispina (Echinodermata, Ophiuroidea) by tributyltin oxide and triphenyltin oxide.

Effects of water-bourne toxicants on regeneration of arms by the brittle star, Ophioderma brevispina, are described. Regeneration was inhibited by 0.1 micrograms liter-1 bis(tri-n-butyltin)oxide and bis(triphenyltin)oxide. Both substances are known to act upon the nervous system, and it is suggested that inhibition was caused by neurotoxicological action of the tin compounds or by their direct effect upon tissue at the breakage point. The former is most likely because regeneration is mediated by the radial nerves of brittle stars.

Animals↗
PubMed2005

Relative uptake of technetium 99m stannous colloid by neutrophils and monocytes is altered by gram-negative infection.

Gram-negative infection alters phagocytic cell function; hence, it could affect phagocytic uptake of inorganic colloids by these cells. Neutrophil and monocyte uptake of technetium 99m stannous colloid (99mTc SnC) in whole blood was measured in 10 patients with gram-negative infection (Burkholderia pseudomallei) and 7 controls. Mean uptake per individual neutrophil was reduced in infection. Uptake per monocyte was not significantly different. Blood from six normal individuals was incubated with lysed B. pseudomallei and colloid, which showed reduced neutrophil uptake, but increased monocyte uptake. These results indicate that uptake of 99mTc SnC stannous colloid can be used to measure alteration in phagocytic cell function. They suggest that infection with B. pseudomallei is associated with reduced phagocytosis by individual neutrophils, possibly through toxic effects of bacterial products. This could have immunopathogenic consequences for this gram-negative infection and may explain why it responds to granulocyte colony-stimulating factor.

Adult↗
PubMed2006

Neutrophil labeling with [(99m)Tc]-technetium stannous colloid is complement receptor 3-mediated and increases the neutrophil priming response to lipopolysaccharide.

INTRODUCTION: [(99m)Tc]-technetium stannous colloid (TcSnC)-labeled white cells are used to image inflammation. Neutrophil labeling with TcSnC is probably phagocytic, but the phagocytic receptor involved is not known. We hypothesised that complement receptor 3 (CR3) plays a key role. Phagocytic labeling could theoretically result in neutrophil activation or priming, affecting the behaviour of labeled cells. Fluorescence-activated cell sorter (FACS) analysis side scatter measurements can assess neutrophil activation and priming. METHODS: We tested whether TcSnC neutrophil labeling is CR3-mediated by assessing if neutrophil uptake of TcSnC was inhibited by a monoclonal antibody (mAb) directed at the CD11b component of CR3. We tested if TcSnC-labeled neutrophils show altered activation or priming status, comparing FACS side scatter in labeled and unlabeled neutrophils and examining the effect of lipopolysaccharide (LPS), a known priming agent. RESULTS: Anti-CD11b mAb reduced neutrophil uptake of TcSnC in a dose-dependent fashion. Labeled neutrophils did not show significantly increased side scatter compared to controls. LPS significantly increased side scatter in control cells and labeled neutrophils. However, the increase was significantly greater in labeled neutrophils than unlabeled cells. CONCLUSIONS: Neutrophil labeling with TcSnC is related to the function of CR3, a receptor which plays a central role in phagocytosis. TcSnC labeling did not significantly activate or prime neutrophils. However, labeled neutrophils showed a greater priming response to LPS. This could result in labeled neutrophils demonstrating increased adhesion on activated endothelium at sites of infection.

CD11b Antigen↗
PubMed2006

In whole blood, LPS, TNF-alpha and GM-CSF increase monocyte uptake of 99mtechnetium stannous colloid but do not affect neutrophil uptake.

INTRODUCTION: (99m)Technetium stannous colloid (TcSnC) is used in white cell scanning. It labels neutrophils and monocytes via phagocytosis, with uptake mediated by the phagocytic receptor CD11b/CD18 in neutrophils. Uptake of TcSnC is altered by gram-negative infection, possibly due to the endotoxin component lipopolysaccharide (LPS) or to cytokines released during infection (e.g., TNF-alpha and IFN-gamma). Endotoxemia and increased TNF-alpha levels also occur in inflammatory bowel disease. Another potential confounder in cell labeling is that sepsis patients may be treated with GM-CSF and G-CSF, which alter phagocytic cell function. This study aimed to determine how these factors affect TcSnC cellular uptake. METHODS: Whole blood from six healthy volunteers was incubated with LPS, TNF-alpha, IFN-gamma, GM-CSF or G-CSF. Samples were then mixed with TcSnC. Blood was separated across density gradients and imaged using a gamma camera. Three radioactive count peaks were observed in each tube: free plasma activity, mononuclear cell uptake and neutrophil uptake. RESULTS: Compared with controls, significant increases in mononuclear cell uptake were induced by LPS, TNF-alpha and GM-CSF stimulation. It was incidentally noted that exogenous estrogens appear to affect TcSnC labeling and may influence the neutrophil response to stimulation. Neutrophil uptake and plasma activity were not significantly affected. IFN-gamma and G-CSF had no significant effect. CONCLUSIONS: In whole blood, the effect of LPS on TcSnC monocyte uptake is different to its effect on neutrophils, consistent with previously reported differences in CD11b/CD18 expression. TNF-alpha response parallels LPS response. GM-CSF also increases TcSnC uptake by monocytes. These effects should be considered when using TcSnC for imaging purposes, as they will tend to increase monocyte labeling. Estrogens may also affect TcSnC labeling. Responses to IFN-gamma and G-CSF are consistent with previously reported effects of these cytokines on CD11b/CD18 expression.

Adult↗
PubMed2005

Reaction pathways and mechanisms of the electrochemical degradation of phenol on different electrodes.

Laboratory experiments were carried out on the kinetics and pathways of the electrochemical (EC) degradation of phenol at three different types of anodes, Ti/SnO2-Sb, Ti/RuO2, and Pt. Although phenol was oxidised by all of the anodes at a current density of 20 mA/cm2 or a cell voltage of 4.6 V, there was a considerable difference between the three anode types in the effectiveness and performance of EC organic degradation. Phenol was readily mineralized at the Ti/SnO2-Sb anode, but its degradation was much slower at the Ti/RuO2 and Pt anodes. The analytical results of high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC/MS) indicated that the intermediate products of EC phenol degradation, including benzoquinone and organic acids, were subsequently oxidised rapidly by the Ti/SnO2-Sb anode, but accumulated in the cells of Ti/RuO2 and Pt. There was also a formation of dark-coloured polymeric compounds and precipitates in the solutions electrolyzed by the Ti/RuO2 and Pt anodes, which was not observed for the Ti/SnO2-Sb cells. It is argued that anodic property not only affects the reaction kinetics of various steps of EC organic oxidation, but also alters the pathway of phenol electrolysis. Favourable surface treatment, such as the SnO2-Sb coating, provides the anode with an apparent catalytic function for rapid organic oxidation that is probably brought about by hydroxyl radicals generated from anodic water electrolysis.

Acids↗
PubMed1987

What is the significance of the abnormal oesophageal scintigram?

In a review of 52 oesophageal scintigrams carried out in 46 patients with a variety of oesophageal problems, there was no correlation between the results of this test and the findings in other tests of oesophageal function, or between the scintigram results and the patients' symptoms, with the possible exception of regurgitation. We conclude that the test is of little value.

Adolescent↗
PubMed2001

Tris(2,2'-bipyridyl)ruthenium(III)-based electrochemiluminescence detector with indium/tin oxide working electrode for capillary electrophoresis.

A novel tris(2,2'-bipyridyl)ruthenium(III) [Ru(bpy)3(3+)]-based electrochemiluminescence (ECL) detector for capillary electrophoresis (CE) has been developed. The detector was of the wall-jet configuration and an indium/tin oxide (ITO)-coated glass plate was used as the working electrode for end-column detection. Potential control of the ITO electrode was provided using a DC battery, without decoupling the detector from the CE field. Electrochemical behavior of Ru(bpy)3(2+) at the ITO electrode was found to be analogous to that at a Pt electrode. In the presence of tertiary or some secondary amines, ECL emission due to reaction between in situ generated Ru(bpy)3(3+) and analytes can be observed at the ITO surface. With 15 mM sodium borate (pH 9.5) plus 1 mM Ru(bpy)3(2+) present in the detection cell and the ITO electrode biased at 1.5 V (vs. Pt wire reference), a detection limit of 1 microM proline with a theoretical plate number of 4000 was obtained using the developed CE-ECL detection system. The detector response was found to be analyte-dependent, e.g. tryptophan gives no response, and the response for histidine is about 13-fold lower than that of proline.

2,2'-Dipyridyl↗
PubMed2000

Determination of butyltin species in water and sediment by solid-phase microextraction-gas chromatography-flame ionization detection.

A procedure for determination of tetraethyltin (TeET) and tetrabutyltin (TeBT) in water by solid-phase microextraction (SPME) using the headspace approach has been developed. The method has been adapted for the simultaneous determination of mono-, di- and tributyltin species (MBT, DBT and TBT) after derivatization with sodium tetraethylborate in water and sediment samples. The analytical procedures were optimized with respect to stirring conditions, extraction time and extraction temperature. The pH and the amount of derivatizing reagent were also considered in derivatization reaction procedures. The analysis was carried out using gas chromatography equipped with flame ionization detection. The detection limits obtained for TeET and TeBT, in equilibrium conditions (room temperature for TeET and 40 degrees C for TeBT) were 28 and 20 ng/l (as Sn), respectively. The detection limit for butyltin species in water, which was limited by signals which are non-specific for the tin compounds and the sensitivity of the FID system, was found ca. 1 microg/l (as Sn). The SPME method was validated for analysis of sediments by analyzing the certified reference material PACS-2 finding a good agreement with the certified values.

Calibration↗
PubMed1989

Ultrasonography and scintigraphy in liver disease in developing countries. A retrospective survey.

In a study of the value of hepatic ultrasonography (US) and scintigraphy (SG) in detecting liver disease in developing countries 425 US scans and 304 SG scans of patients with focal or diffuse liver disease or normal livers were reviewed. The accuracy of both US and SG in distinguishing between normal and diseased livers was low (68% and 74%, respectively). Both techniques did better at detecting focal than diffuse liver disease; the sensitivity of US and SG in focal and diffuse disease was 88% and 92%, and 27% and 54%, respectively. The specificity of both procedures was high for both types of liver disease (91-96%). Overlap between US features of amoebic liver abscess, hepatocellular carcinoma, and metastatic carcinoma resulted in a correct final diagnosis being made in only 81% of patients with amoebic liver abscess, 29% with hepatocellular carcinoma, and 43% of patients with metastatic carcinoma who had a US scan. This study indicates that these techniques are neither accurate in detecting diffuse liver disease nor capable of determining the cause of diffuse liver disease. When diffuse parenchymal liver disease is suspected biopsy would be needed. Although the accuracy of both imaging modalities in detecting focal disease is high, overlap between the US features of the common causes of space-occupying lesions may result in an incorrect final diagnosis in some cases. In consequence, biopsy or aspiration might be required.

Biopsy↗
PubMed1999

The effect of combined administration of cadmium and furosemide on auditory function in the rat.

A number of heavy metals have been associated with toxic effects to the peripheral or central auditory system. These include lead, arsenic, mercury, platinum and organic tin compounds. In addition, the ototoxic effects of some metals may be potentiated by other factors. However, the auditory effects of cadmium have not previously been reported. The purpose of the present study was to investigate the potential ototoxic effects of cadmium from an acute dosage, and its potentiation by furosemide. Auditory brainstem response (ABR) thresholds were measured in adult Sprague-Dawley rats. Rats received either cadmium chloride (5 mg/kg, i.p.) followed by saline (4 ml/kg, i.p.). cadmium chloride followed by furosemide (200 mg/kg, i.p.), or furosemide alone. Follow-up ABRs were carried out 7 days post-treatment and threshold changes were compared between each treatment group. No significant threshold change was seen for the cadmium chloride plus saline treated or the furosemide treated animals. However, significant threshold elevations were observed in animals receiving cadmium chloride plus furosemide. In addition, scanning electron microscopy revealed extensive hair cell loss in animals treated with cadmium chloride and furosemide. Although functional auditory changes were not seen after the administration of cadmium alone, the potentiation of threshold changes by furosemide suggests that cadmium may be ototoxic under certain conditions.

Animals↗
PubMed1998

Mutational potentiality of stannous chloride: an important reducing agent in the Tc-99m-radiopharmaceuticals.

Stannous chloride (SnCl2) is frequently used in nuclear medicine as a reducing agent to label many radiopharmaceutical products with technetium-99m (99mTc). The aim of the present paper was to study the role of DNA repair genes in the repair of SnCl2-induced damage, using mutant strains of Escherichia coli lacking one or more DNA repair genes. Our results suggest that the product of the xthA gene, exonuclease III, is required for the repair of lesions induced by SnCl2. We further investigated the mutagenic properties of SnCl2 to a molecular level by using the supF tRNA gene as target in a forward mutational system. We have found that the survival of E. coli cells was strongly reduced with increasing concentrations of SnCl2. Moreover, when the shuttle vector pAC189 carrying the supF gene was treated with SnCl2, and then transfected to E. coli, we observed that its transformation efficiency dropped when compared to the non-treated control, with a parallel increase in mutation frequency after the damaged plasmids have replicated in bacterial cells. The mutation spectrum induced by SnCl2 reveals a high frequency of base substitutions, involving guanines. Sequence analysis of 41 independent supF mutant plasmids revealed that 39 mutants contained base substitutions, with 21 G:C to T:A and 17 G:C to C:G transversions. G to T transversions presumably resulted from 8-oxoG. However, the G to C one may be due to a yet unidentified lesion.

DNA Damage↗