Acta radiologica. Supplementum最新文献

To assess the usefulness of Dy-DTPA-BMA-induced signal reduction, as an indicator of myocardial viability, myocardial infarction was induced in 17 domestic pigs by ligating a diagonal branch of the left anterior descending coronary artery (LAD). In 6 pigs, Dy-DTPA-BMA (1 mmol/kg b.w.) was administered 4 hours after induction of ischaemia. In 5 additional pigs, Gd-DTPA-BMA (0.3 mmol/kg b.w.) and Dy-DTPA-BMA (1 mmol/kg b.w.) were simultaneously injected after 4 hours of ischaemia to ascertain whether Dy-DTPA-BMA counteracted the signal enhancement effect of Gd-DTPA-BMA. A further 6 pigs with infarctions, not administered contrast medium, served as controls. All pigs were sacrificed after 6 hours of ischaemia, and the extirpated hearts were investigated with MR (ex vivo). The concentrations of Dy and Gd were determined in tissue samples from infarcted and non-ischaemic myocardium. The extracellular concentrations of both contrast media were monitored over time during 2 hours in the double-contrast group (in vivo), using a microdialysis technique and analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES). The infarctions demonstrated a high SI in the proton density- and T2-weighted sequences, in both the Dy-DTPA-BMA and control groups, although the former group demonstrated a 3-fold greater concentration of Dy in infarcted compared with non-ischaemic myocardium. Dy-DTPA-BMA did not counteract the Gd-DTPA-BMA-induced enhancement of the infarcted tissue despite a 3-fold higher concentration. This lack of detectable susceptibility effects of Dy may be caused by a loss of cell membrane integrity in the infarcts, resulting in a homogeneous intra- and extracellular distribution of the contrast agent. This hypothesis of an expanded volume of distribution in infarcted tissue was further supported by the microdialysis data, demonstrating a similar extracellular concentration of contrast agents in infarcted and non-ischaemic myocardium, despite a proven 3-fold greater concentration in infarcted tissue samples. To investigate whether Gd-DTPA-BMA-enhanced MR imaging (ex vivo) permits differentiation between reperfused and non-reperfused myocardial infarction, and whether Dy-DTPA-BMA-enhanced MR imaging enables a differentiation between reversible and irreversible myocardial injury following reperfusion, myocardial infarction was induced in 24 domestic pigs (divided into 4 groups) by placing a patched ligature around a diagonal branch of the LAD. Four additional hearts were reperfused after 2 min of brief occlusion, not long enough to cause irreversible injury.(ABSTRACT TRUNCATED AT 250 WORDS)

During angiography contrast media (CM) induces changes in vessel tone. The pathophysiological reasons for this are poorly understood. In this short review the anatomical structures and physiological factors involved in vessel tone are described, and previous and recent findings in vitro and in vivo concerning the effect of CM on vessel tone are discussed. Although multifactorial, the main effect seems to result from a direct action of the CM on the vessel wall. For a particular CM formulation, the effect is due to a combination of its osmolality, molecular properties as well as electrolyte content. In vitro experiments performed in iso-osmolar solutions of pure CM suggest the CM interfere with the cellular mechanisms controlling intracellular calcium. When injected intravascularly, CM may cause either vasodilatation and vasoconstriction. Vasodilatation is the most frequent effect when CM is injected into a vessel while vasoconstriction is relatively uncommon. Both vasodilatation and vasoconstriction can be caused by all types of CM.

Changes in contractile function induced by modern roentgen contrast media (CM) were examined in isolated rat hearts. Four coronary perfusions were undertaken in each heart with increasing volumes of each CM in order to test a wider spectrum of potential side-effects. Left ventricular developed pressure (LVDP) and heart rate (HR) were recorded. Six commercially available or investigational CM were examined: A, Hexabrix (ioxaglate 320 mg I/ml, Na 146 mM); B, Iosvist (iotrolan 300 mg I/ml, Na 6 mM);C, Visipaque (iodixanol 320 mg I/ml, Na 19 mM, Ca 0.3 mM); D, "Iodixanol high Ca-Mg" (iodixanol 320 mg I/ml, Na 19 mM, Ca 1.2 mM, Mg 0.6 MM); E, "Iohexol I 350" (iohexol 350 mg I/ml, Na 28 mM); and F, "Iohexol I 150" (iohexol 150 mg I/ml Na 28 mM). A, E and F were low-osmolal (400-940 mosm/kg H2O) CM whereas B, C and D were essentially isosmolal. Contractile changes (transient LVDP depression) was volume-dependent. Maximal values for LVDP depression were "Iohexol I 150" 11-22%

A review is given of the development of the water-soluble contrast media (CM) with particular attention to the frquency of neurological complications. A remarkable improvement was achieved following the introduction of the nonionic agent metrizamide in 1974, and a further decrease in neurotoxicity was obtained with the newer nonionic monomers, which have multlple hydroxyl groups included at different sites of the molecule. Theoretical considerations and experimental studies suggest that the neurotoxicity of the new nonionic dimeric agents shuold be at least within the low range seen with the monomeric ones, but further experience is needed before definite conclusions can be drawn in this respect. The mechanisms responsible for the neurological complications seen with CM are unknown but certain critical groups on the CM molecules are known. Several animal models have been developd, which may help predict the degree of neurotoxicity.

Contrast media (CM) given orally for roentgen examination of the upper gastrointestinal tract may inadvertently enter the lungs. The present paper describes the local effects on the lungs of rats after a single intratracheal instillation of the nonionic, iso-osmolar, dimer CM iodixanol and iotrolan, and the ionic hyperosmolar, monomeric CM diatrizoate. Hydrochloric acid (HCl) and saline were included as positive and negative controls, respectively. The test compounds were given by intratracheal instillation to anesthetized rats at low dose volumes of 0.5 ml/kg b.w. The animals were killed 6 hours, 24 hours or 7 days after dosing, and the trachea and lungs subjected to histopathological examination. Acute signs of dyspnea were observed in 7 out of 15 animals that received HCl. No clinical signs could be related to treatment with any of the CM. Histomorphological assessment of the respiratory tract did not reveal any CM-related adverse effects, whereas animals treated with HCl showed marked histopathological changes. The results indicate that accidental exposure of the respiratory system to iodixanol, iotrolan or diatrizoate is unlikely to cause any significant tissue damage or lead to respiratory complications.

An attempt was made to assess the usefulness of using animal models to predict the neural tolerability in man of iodinated contrast media (CM) in general, and of the new nonionic dimer iodixanol in particular. For this purpose, the results from 6 animal experiments evaluating excitative and depressive effects of subarachnoidally injected CM in nonanesthetized rabbits were compared with the results from 22 randomized double-blind clinical trials dealing with post-myelographic adverse reactions. Comparisons were made as regards the nonionic monomers metrizamide, iohexol, and iopamidol, and the dimer iotrolan. The results seem to justify the conclusion that the convulsive effects of CM can be reliably predicted from animal experiments. The animal model cannot be used to predict specific types of nonconclusive adverse reactions in man, but reflects well the differences in frequencies of minor reactions following clinical myelography with different nonionic CM. In general, the neural tolerability of iodixanol may be expected to be better than that of the nonionic monomers and approximately equal to that of iotrolan.

The iodine-specific detection techniques X-ray fluorescence spectrometry, neutron activation analysis and radiochemical detections of (125)I-labelled substance are well suited for quantification of iodixanol in biological samples. The limit of detection is 60 microgram iodixanol/ml for X-ray fluorecence analysis and 1 to 10 microgram iodixanol/ml for neutron activation analysis. Reversed-phase high-performance liquid chromatography (HPLC) has been employed when selective determination of iodixanol was needed for identificational purposes or when quantification of very small amounts of iodixanol was essential. An optimized HPLC method for quantification of iodixanol in rat serum and urine is presented. The limit of detection for this method is 0.20 microgram iodixanol/ml for rat serum and 3.0 microgram iodixanol/ml for rat urine. When samples were analyzed by HPLC and thin layer chromatography, no metabolites of iodixanol were observed in rat, monkey or human urine, or in rat kidney and bile. Studies with equilibrium dialysis and HPLC determination of iodixanol showed no protein binding of the contrast agent in human plasma; the 95% confidence interval for the result was 0.0+/-2.1%.

Quantitative assessment of atherosclerosis from arteriograms was applied in clinical follow-up trials for the evaluation of lipid-modulating treatment or risk factors. Computer-estimated lumen volume and arterial edge roughness in the femoral artery and in the aorta, visual scoring of aorto-femoral arteriograms and manual measuring of coronary artery stenosis were used. In each of 276 hypercholesterolaemic patients two femoral arteriograms were made, with a 10-minute interval. The reproducibility of the computer analysis method was found to be constant over the years, with slightly better reproducibility for lumen volume than for edge roughness. A small but significant drift in the radiological equipment was confirmed by the use of phantoms. In 290 patients, atherosclerosis assessments from the femoral artery (lumen volume and roughness) and visual scoring of the aorto-femoral arteriogram were correlated with clinical symptoms of coronary artery disease or previous myocardial infarction to test whether femoral atherosclerosis estimates can replace coronary studies in clinical trials. Both men and women with coronary artery disease had lower values for femoral lumen volume and more edge roughness than patients without these symptoms. Men with previous myocardial infarction had higher mean visual scores than those without. Thus, femoral atherosclerosis is an expression of a more generalized disease associated with clinical symptoms of coronary heart disease. The 290 patients were tested for correlation between degree of peripheral atherosclerosis and various metabolic risk factors. In women, high serum triglyceride values were associated with more extensive atherosclerosis. High fasting glucose values were associated with more extensive atherosclerosis in men. In men and women, high uric acid values were associated with greater roughness in the femoral artery. The effects of smoking, hypertension, poor physical fitness and body mass index on the development of peripheral atherosclerosis in hypercholesterolaemia were also investigated. The results indicated that the hypercholesterolaemic patients most likely to develop peripheral atherosclerosis are male and female smokers who do not take any physical exercise, and who have increased values of systolic blood pressure, uric acid and fasting glucose concentrations. Aortograms from 293 subjects were digitized and circular lumen volume and edge roughness were computer-estimated in a 7.35-cm segment of the distal aorta. A correlation between atherosclerosis in the aorta and in the femoral arteries indicated that aortic atherosclerosis is a manifestation of a more general disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Prostate cancer is the most common malignancy among Swedish men. In order to select patients to appropriate treatment, transrectal ultrasound (TRUS) and guided core biopsies is commonly used. The aim of this study was to define prognostically important factors in prostate cancer and the accuracy of TRUS and core biopsies as diagnostic tools. Fifty-one patients with localized prostate cancer were prostatectomized and followed up after a mean observation time of 73 months. The adverse influence on progression by tumor volume, Gleason grade, seminal vesicle invasion and lymph node metastases was statistically significant in the univariate analyses. However, tumor volume was the only parameter with an independent prognostic impact on progression. It is important to find a diagnostic method which can accurately determine these parameters in the pretreatment work-up. Thirty-four patients with localized prostate cancer were examined with TRUS prior to radical surgery. The ultrasound examination failed to detect 24% of the tumors, and was not reliable for the determination of tumor size and capsular penetration. TRUS can not be used as the sole method for the diagnosis of prostate cancer. Biopsies might improve the results. Ultrasound-guided core biopsies targeting hypoechoic lesions suspicious for prostate cancer in combination with systematic biopsies sampling the whole gland were performed on 251 men. By adding the results of systematic biopsies to the results of target biopsies, additional information was obtained for the detection of cancer, on tumor volume and seminal vesicle invasion. Grading was not improved. By taking multiple TRUS-guided biopsies considerable trauma is inflicted to the patient. A 1.2-mm cutting needle is commonly used for sampling. A thinner needle may possibly cause less pain. It was shown that a 0.9-mm core biopsy needle can be used without compromising diagnostic accuracy. The results obtained with two thinner needles, 0.8- and 0.7-mm, were unsatisfactory. Complications following TRUS-guided biopsies are infections, bleeding and urinary retention. A total of 347 consecutive men were extensively biopsied. We studied the impact of patient age, final diagnosis, number of biopsies taken, and different regimes for prophylactic norfloxacin treatment. The administration of antibiotics for 3 days, when the first dose was given before the examination began, was the only parameter statistically associated with a reduced risk for complications. Multiple biopsies can be taken without an increased risk for complications if prophylactic antibiotic treatment is given.