[Nuclear magnetic resonance tomography: better images with contrast media. Contrast caused by paramagnetic properties--also imaging of the abdomen].
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Abdominal Neoplasms↗
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Dialysis and iodinated contrast media.
Contrast media are excreted mainly by glomerular filtration. There is thus, a significant correlation between both body and renal clearances of contrast media and glomerular filtration rate, and their renal excretion will be delayed in patients with renal insufficiency. Contrast media can be efficiently removed from blood by hemodialysis (HD). Since most contrast media are middle-sized molecules, the main factors potentially influencing their removal by HD are blood flow, membrane surface area, molecular size, transmembrane pressure, and dialysis time. Peritoneal dialysis is also effective in removing contrast agents from the body but takes longer than HD. Dialysis immediately after radiographic contrast studies has been suggested for two groups of patients. Those on chronic HD and those at very high risk for contrast nephropathy. Three studies have examined the necessity of immediate dialysis after intravascular injection of contrast media in chronic HD patients; the authors found no evidence that it is effective at preventing contrast nephropathy. The reasons why HD treatment was not beneficial in those three studies are not known. Perhaps, the rapid onset of renal injury after administration of contrast media is one answer. It is also possible that HD per se was nephrotoxic and might have offset the beneficial effect of the removal of contrast media. Marenzi et al. randomized 114 consecutive patients with chronic renal failure undergoing coronary interventions to either hemofiltration in an intensive care unit or isotonic saline hydration. The authors concluded that periprocedural hemofiltration given in an intensive care unit setting appears to be effective in preventing the deterioration of renal function due to contrast agent induced nephropathy and is associated with improved in-hospital and long term outcomes. The concentration of contrast media can effectively be reduced by HD and peritoneal dialysis. HD does not offer any protection against contrast media induced nephrotoxicity. Hemofiltration may decrease the risk of contrast induced nephropathy and have some long-term benefits, but additional studies are needed to better define the appropriate population for this treatment.
Contrast Media↗
Multiple myeloma and contrast media.
Contrast media administered intravenously are still thought by many to be a major cause of acute renal failure (ARF) in myeloma patients. Recently, several authors found that the predominant risk factors of ARF in myeloma patients are hypercalcemia, dehydration, infection, and Bence Jones proteinuria rather than contrast media. In a review of seven retrospective studies of myeloma patients receiving contrast media, 476 patients were noted to have undergone 568 contrast media studies, with an ARF prevalence of 0.6%-1.25%. One large series showed the incidence of ARF after administration of contrast media to be 0.15% in the general population. Although the administration of contrast media to myeloma patients is not totally risk free, it may be performed if the clinical need arises and the patient is well hydrated.
Acute Kidney Injury↗
[Water-soluble contrast media and contrast media incidents in urology].
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Contrast Media↗
[Reactions to iodine contrast media].
Contrast media are used in many radiological examinations, but they are responsible for 4.6 to 8.5 percent of the toxic or anaphylactoid adverse reactions observed. The early contrast media were hyperosmolar, whereas those in current use are isosmolar and either ionic or non-ionic. The patient's age, the presence of a pre-existing disease and a history of adverse reactions to contrast media are the most important risk factors. Seventeen to 35 percent of these reactions recur. Several physiopathological mechanisms have been blamed for adverse reactions to contrast media, including complement activation, histamine release, recruitment of inflammation mediators, and antigen-antibody reaction. There is no paraclinical examination that can diagnose or predict such reactions. Various preventive tests have been studied and applied to individuals with or without history of reaction. In a population of patients with previous reaction, the administration of corticosteroids 12 h and 2 h before the radiological examination resulted in a significant reduction of the number of reactions. In patients at risk (i.e. those with previous reactions of this kind) the results varied, but in these 2 groups of subjects non-ionic products given either alone or with corticosteroids or H1-antihistaminics reduced to 1 percent the incidence of reactions. So far, tachyphylaxis has virtually played no role compared with these preventive treatments. It is concluded that patients with a history of anaphylactoid reactions who must receive another injection of contrast medium, a non-ionic product and/or the H1-antihistaminic-corticosteroid combination should be used.
Contrast Media↗
[Asymptomatic blood pressure and pulse rate changes during intravenous urography. Ionic contrast media vs. nonionic contrast media].
In 8,232 examinations of intravenous urography (4,832 examinations with ionic contrast media and 3,400 examinations with nonionic contrast media), systemic blood pressure and pulse rate were continuously monitored by an automatic blood pressure and pulse rate monitoring device before and after injection of contrast media. The intravenous injection of ionic contrast media caused mild to moderate hypotensive reactions (20%-39% decrease of systemic blood pressure) in 7 examinations (0.14%) and severe hypotensive reactions (greater than 40% decrease of systemic blood pressure) in 12 examinations (0.25%). There were no clinical symptoms other than hypotensive reactions in 8 of the 19 examinations (42.1%). On the other hand, the intravenous injection of nonionic contrast media did not cause severe hypotensive reactions but mild hypotensive reactions (20%-29% decrease of systemic blood pressure) in 3 examinations (0.09%). These 3 examinations did not have clinical symptoms other than hypotensive reactions. Of the 19 examinations using ionic contrast media, the hypotensive reactions with significant change of pulse rate (greater than 20%) was associated with increase of pulse rate in 17 examinations and decrease of pulse rate in 2 examinations. On the other hand, the hypotensive reactions had an association with a significant increase (greater than 20%) of the pulse rate in only one of the 3 examinations using nonionic contrast media. The pulse rate was unchanged after injection of contrast media in the remaining 2 examinations although there was mild hypotension. In conclusion, nonionic contrast media caused fewer and less severe changes in blood pressure and pulse rate without obvious clinical symptoms compared with ionic contrast media.
Adolescent↗
Cardiac electrophysiology, arrhythmogenic mechanisms and roentgen contrast media.
Contrast media (CM) affect normal cardiac electrophysiology when injected into the coronary arteries. High-osmolality CM cause more pronounced electrophysiological effects than do low-osmolality CM. Further, both high- and low-osmolality ionic CM have more pronounced effects than the nonionic CM. The CM-induced electrophysiological effects involve regional disturbances of depolarization and repolarization, thereby causing disturbances of impulse conduction as well as dispersion of refractoriness. Recent experimental studies have demonstrated that the addition of sodium or a balanced electrolyte supplement to nonionic CM reduces the risk of ventricular fibrillation (VF), particularly when the CM is injected in a wedged catheter situation. The reduced risk of VF may be due to the small and transient lengthening of repolarization seen in the CM-perfused area of the myocardium. Iodixanol, which is an isotonic nonionic dimer supplemented with NaCl and CaCl(2), is as well tolerated as iohexol during free coronary flow. However, when flow is restricted, such as when CM is injected through a wedged catheter, the risk of VF is less with iodixanol than with iopamidol, iohexol and ioxaglate.
Animals↗
Allergies correlated to adverse reactions induced by non-ionic monomeric and ionic dimeric contrast media for contrast enhanced CT examination.
Although contrast media are indispensable for x-ray diagnosis, they are xenobiotics and may cause undesirable adverse reactions. We have correlated several allergies to the adverse reactions caused by three representative contrast media in order to predict and prevent possible problems. The adverse reactions were observed at probabilities of up to 100%(odds ratio 8.0) in drug allergy and contact dermatitis patients. These allergies were proven in this study to be type IV reactions, and all the observed adverse reactions were classified as allergies of either type I or IV. Thus, one can predict to some extent even the time when the adverse reaction will appear after the injection of contrast medium. Finally, a questionnaire to be administered prior to contrast enhanced CT examinations has been proposed. The questionnaire is designed to predict adverse reactions on the basis of statistical analysis. Since the physicochemical properties of contrast media are different, this questionnaire is also useful for selecting the most suitable contrast medium for the patient.
Contrast Media↗
Does dilution of contrast media affect contrast enhancement? An experimental study in rats.
The effect of contrast media (CM) dilution on contrast enhancement was studied using CM representing four structurally different molecular types at osmolalities ranging from 135 to 1340 mosm/kg. Diatrizoate (ionic monomer), iopamidol (nonionic monomer), ioxaglate (ionic dimer), and iodecol (nonionic dimer) were each given at a dose of 500 mgI/kg and at concentrations of both 300 and 150 mgI/mL. Contrast media concentrations were measured using iodine 125I. Tissue blood volumes were determined using human serum albumin labeled with 131I. For each of the four CM at each of the two concentrations and after each of five time intervals following injection (0, 15, 40, 120, and 300 seconds), five rats were killed (total = 200 rats). Blood and 14 other tissues were studied. Dilution of the CM did not lead to any lower iodine tissue concentrations, iodine distribution volumes, plasma volumes, or hematocrit. The authors conclude that lowering CM osmolality by dilution with water should improve tolerance without affecting CT contrast enhancement.
Animals↗
[Magnetic resonance tomography: new results of contrast media research. 8th contrast media expert discussion, 1993].
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Contrast Media↗
[Nephrotoxic action of contrast media].
Contrast induced nephrotoxity [CIN] is a common form of hospital-acquire renal failure. Prevention can decrease the need for dialysis, morbility, and reduce health care costs. All patiens receiving iodine-contrast medium should be assessed for risk of developing CIN. Prophylaxis can reduce CIN. Patients at risk requiring injection of contrast medium [CM] with important clinical indications should receive a small dose of non-ionic iso-osmolar dimeric or non-ionic low osmolar monomeric CM and hydratation with normal saline before and after exposure. This brings the best protection with the fewest adverse effects.
Contrast Media↗
New media. Particulate contrast media.
Particulate contrast agents, when compared to water-soluble media, offer the advantage of allowing the administration of high doses without creating hypertonicity gradients and ionic imbalances. Since these radiopaque particles are accumulated in the reticuloendothelial system, they could be ideal hepatic CT contrast agents. We have developed a method for making particles of 2 +/- 1 microns by precipitating from an organic solvent. Preincubation of these particles in human serum albumin overcomes the very serious problem of in vivo particle aggregation and embolization. The ethyl esters of iothalamic and iodipamic acid have been injected intravenously into mice, rats, and rabbits. Radiopacification of the liver is maximal within 2-3 hours postinfusion, with radiopaque material subsequently clearing through the biliary system. Elimination from the organism seems to be complete within a few days postinfusion. Efforts to decrease the subacute toxicity of these agents are underway.
Animals↗
Contrast media and metformin: guidelines to diminish the risk of lactic acidosis in non-insulin-dependent diabetics after administration of contrast media. ESUR Contrast Media Safety Committee.
The purpose of this study was to establish guidelines on how to avoid metformin-induced lactic acidosis following intravascular use of contrast media. We reviewed articles published in international journals. No conclusive evidence was found to indicate that the intravascular use of contrast media precipitated the development of metformin-induced lactic acidosis in patients with normal S-creatinine (< 130 mumol/l). The complication was almost always observed in non-insulin-dependent diabetic patients with decreased renal function before injection of contrast media. Guidelines for the use of contrast media in this group of patients are proposed.
Acidosis, Lactic↗
[Measuring periodontal pockets with contrast media. 1. Preparation of contrast media].
Periodontal pocket is main clinical symptom of periodontitis. Measurement of periodontal pocket depth is the most important examination. The purpose of this study was to get contrast medium radiography of periodontal pocket. The present study was compared with contrast media of varying concentration. Contrast medium-sample containing 40% Sodium Iothalamate and 30% Meglumine Adipiodone had slight higher radiopacity than the others. These contrast media-sample were adequate to clinical practice over 40% concentration. Using Sodium Iothalamate and Meglumine Adipiodone, radiopacity was able to differ from radiopacity of teeth at 60%-100%.
Contrast Media↗
Risk of clot formation with ionic and nonionic contrast media in cerebral angiography. Tama Contrast Media Study Group.
RATIONALE AND OBJECTIVES: The introduction of low-osmolality contrast media has improved patient tolerance to angiographic procedures. However, nonionic contrast media may be associated with an increase in the risk of clot formation. The objective of this study was to test whether there is more clotting with nonionic agents than with ionic agents. METHODS: Ninety-eight patients undergoing transfemoral cerebral angiography were randomly assigned to receive ionic (ioxaglate) (n = 62) or nonionic (iopamidol or iohexol) (n = 36) contrast material. Incidence of clot formation was examined by observation of catheters. RESULTS: Clot formation was found in 4.8% of patients in the ionic contrast material group and 22.2% of patients in the nonionic contrast material group (P < .05). CONCLUSION: Nonionic contrast media resulted in a statistically significantly higher incidence of clot formation than ionic media during cerebral catheter angiography. These results suggest that ionic contrast media are preferable in patients with risk of thrombosis.
Blood Coagulation↗
[Comparative studies on the radioactivity of bone cements containing x-ray contrast media and of the contrast media].
Various PMMA bone cements containing zirconium oxide (ZrO2) as an X-ray contrast medium and zirconium oxides of several manufacturers were tested for their radioactivity by means of a gamma spectrometer. All the bone cements tested (Implast, Palacos R, and Sulfix-6) showed a certain degree of radioactivity. The radiation source in the bone cement is the added zirconium oxide, which is polluted by radioactive elements. The examination of various zirconium oxides showed some high radioactive emissions. The risk of radiation-induced cancer seems to be small, because the cements are normally implanted in humans older than 60 years. In view of the fact that these X-ray contrast media remain in the body for decades as components of the bone cement, the radioactive zirconium oxides should be replaced by high-purity radiation-free zirconium oxide or barium sulphate as soon as possible.
Bone Cements↗
Low osmolar (non-ionic) contrast media versus high osmolar (ionic) contrast media in intravenous urography and enhanced computerized tomography: a cost-effectiveness analysis.
The cost-effectiveness of three alternative policies for the use of intravenous contrast media for urography and enhanced computerized tomography (CT) are analyzed. Alternative #1 is to use high osmolar contrast media (HOCM) in all patients, the historical policy. Alternative #2 is to replace it with low osmolar contrast media (LOCM) in all patients. Alternative #3 is to use LOCM only in the high risk patients. Data on the 6,242 patients who underwent intravenous urography and enhanced CT at the Department of Radiology, Chulalongkorn Hospital in 1989 were used. Both societal and hospital viewpoints were analyzed. The incremental cost-effectiveness (ICE) between #2 and #1 was 26,739 Baht (US$1,070) per healthy day saved (HDS), while the ICE between #3 and #1 was 12,057 Baht (US$482) per HDS. For fatal cases only, ICE between #2 and #1 was 35,111 Baht (US$1,404) per HDS, while the ICE between #3 and #1 was 18,266 Baht (US$731) per HDS. The incremental cost (IC) per patient was 2,341 Baht (US$94) and 681 Baht (US$27) respectively. For the hospital viewpoint the ICE between #2 and #1 was 13,744 (US$550) and between #3 and #1 was 6,127 Baht (US$245) per HDS. The IC per patient was 1,203 Baht (US$48) and 346 Baht (US$14), respectively. From the sensitivity analysis, #3 should be used if the LOCM price is reduced more than 75% (equal to 626 Baht or less) and more than 80% of the patients are able to pay for the contrast media.
Adult↗
Effect of iodine concentration of contrast media on contrast enhancement in multislice CT of the pancreas.
The purpose of this study was to determine the influence of two different iodine concentrations of the non-ionic contrast agent, Iomeprol, on contrast enhancement in multislice CT (MSCT) of the pancreas. To achieve this MSCT of the pancreas was performed in 50 patients (mean age 57+/-14 years) with suspected or known pancreatic tumours. The patients were randomly assigned to group A (n=25 patients) or group B (n=25 patients). There were no statistically significant differences in age, height or weight between the patients of the two groups. The contrast agent, Iomeprol, was injected with iodine concentrations of 300 mg ml(-1) in group A (130 ml, injection rate 5 ml s(-1)) and 400 mg ml(-1) in group B (98 ml, injection rate 5 ml s(-1)). Arterial and portal venous phase contrast enhancement (HU) of the vessels, organs, and pancreatic masses were measured and a qualitative image assessment was performed by two independent readers. In the arterial phase, Iomeprol 400 led to a significantly greater enhancement in the aorta, superior mesenteric artery, coeliac trunk, pancreas, pancreatic carcinomas, kidneys, spleen and wall of the small intestine than Iomeprol 300. Portal venous phase enhancement was significantly greater in the pancreas, pancreatic carcinomas, wall of the small intestine and portal vein with Iomeprol 400. The two independent readers considered Iomeprol 400 superior over Iomeprol 300 concerning technical quality, contribution of the contrast agent to the diagnostic value, and evaluability of vessels in the arterial phase. No differences were found for tumour delineation and evaluability of infiltration of organs adjacent to the pancreas between the two iodine concentrations. In conclusion the higher iodine concentration leads to a higher arterial phase contrast enhancement of large and small arteries in MSCT of the pancreas and therefore improves the evaluability of vessels in the arterial phase.
Adult↗