Selective use of low-osmolality contrast media in computed tomography

Doctor I Have an Iodine Allergy

Ophthalmologists frequently face patients who refuse asepsis protocols involving povidone-iodine (PI) due to claims of an allergy to iodine. Such patients usually base this claim on previous reactions to shellfish consumption or to imaging procedures that used iodine-based contrast agents. Allergy to iodine, however, is biologically impossible, and iodine deficiency causes severe developmental problems, including mental retardation. Furthermore, shellfish allergy is due to tropomyosins in muscle tissue, and reactions to intravascular contrast dyes are due to hyperosmolar solutions; neither “allergy” is due to iodine. PI, which contains 9–12% iodine, is the preferred antiseptic for ophthalmic procedures. Experience shows that PI can be administered safely to patients claiming iodine allergy. True allergy to PI is rare and, if indicated, skin patch testing can be performed prior to surgery. Patients who react adversely to highly concentrated (5–10%) PI usually experience toxicity to the corneal and conjunctival epithelium after topical administration. Dilute (0.1–0.25%) PI kills microbes quicker than higher concentrations but for shorter periods of time because the total dose of iodine is smaller. Repeated administration (every 20–30 s) of dilute PI effectively kills microbes for as long as necessary with little risk of epithelial toxicity.

Warmed contrast media temperature loss in traditional manifold systems during angiographic procedures

BACKGROUND

Extrinsic warming of contrast media (CM) to 37 °C before angiographic procedures is performed to improve bolus kinetics and avoid potential adverse effects. Extrinsically warmed CM readily loses temperature after removal from the warming cabinet, but the extent of its cooling has not been previously investigated.

PURPOSE

To assess temperature loss of extrinsically warmed CM in tubing of traditional angiographic manifolds during simulated angiography.

MATERIAL AND METHODS

In total, 35 scheduled diagnostic angiographic procedures were observed in a hospital setting. Relevant time points of CM use during the procedures were recorded. The shortest, median, and longest procedures were then simulated in the experimental laboratory to measure CM temperatures at specific times at three locations along the tubing system.

RESULTS

The angiographic procedures lasted 7.0-26.6 min (median = 11.7 min), with the total duration dependent primarily on the time from contrast being removed from the warming cabinet to the commencement of imaging. During the simulated procedures, consistent patterns of temperature loss were observed. By the last simulated angiographic run, injected CM temperature decreased by 7.4-16.4 °C, depending on procedure length. Most of the heat loss occurred in the tubing between the CM bottle and coronary control syringe.

CONCLUSION

During angiographic procedures, prewarmed CM loses its temperature rapidly with the duration of exposure to ambient room temperature. If no additional measures are employed to maintain its temperature outside of the warming cabinet, extrinsic warming has limited impact on injected CM temperature.

Effect of Extrinsic Warming of Low-Osmolality CT Contrast Media (Iohexol 350) on Extravasations and Patient Reaction Rates: A Retrospective Study

Background: Extrinsic warming of iodinated CT contrast media to body temperature reduces viscosity and injection pressures. However, studies examining the effect of extrinsic warming on clinical adverse events are limited in number and provide conflicting results. Therefore, consensus practice recommendations have been sparse. Objective: To compare rates of extravasation, allergic/allergic-like reactions, and physiologic reactions between iohexol 350 warmed to body temperature (37°C) and maintained at room temperature. Methods: This retrospective study compared adult patients who received CT examinations using IV iohexol 350 that had either been warmed to body temperature or maintained at room temperature. At our institution, contrast media had historically been warmed to body temperature prior to a protocol change unrelated to this investigation. Patient and CT examination characteristics were extracted from the electronic medical record. Adverse events, including extravasations, allergic/allergic-like reactions, and physiologic reactions, were compared between groups. Results: A total of 3939 patients received contrast media warmed to body temperature before the protocol change; 3933 patients received contrast media at room temperature after the protocol change. The body temperature group experienced 11 (0.28%; 95% CI 0.14%, 0.50%) adverse events, all extravasations; allergic/allergic-reaction rate was 0.00% (97.5% CI 0.00%, 0.09%). The room temperature group experienced 17 (0.43%; 95% CI 0.25%, 0.69%) adverse events [13 (0.33%; 95% CI 0.17%, 0.56%) extravasations; 4 (0.10%; 95% CI 0.03%, 0.26%) allergic/allergic-like reactions]. No physiologic reaction occurred in either group. The two groups were not different in terms of overall reaction rate (p=.19), extravasation rate (p=.69), allergic/allergic-like reaction rate (p=.06), or physiologic reaction rate (p>.99). Logistic regression adjusting for patient and CT characteristics (age, sex, conventional CT vs CTA, contrast media volume, injection location, needle gauge) showed no significant association of patient group and adverse reaction rate (odds ratio=2.19, 95% CI 0.68-7.00). Multivariable regression modeling demonstrated an excess of 0.27 adverse events per 100 patients within the room temperature group, below a 0.6% non-inferiority margin. Conclusion: The data suggest that maintaining iohexol 350 at room temperature is non-inferior to warming the agent to body temperature before injection. Clinical Impact: The resources involved to prewarm iohexol 350 before injection may not be warranted.

Extrinsic warming of low-osmolality iodinated contrast media to 37°C reduced the rate of allergic-like reaction

Background: Although there is good evidence that warming of contrast media changes the bolus kinetics and injection pressure of iodinated contrast media, there has been little evidence that it affects clinical adverse event rates in a meaningful way. Objective: To determine whether the extrinsic warming of low-osmolality iodinated contrast media to 37°C reduced adverse reactions. Methods: Data on adverse reactions were collected from two cohorts, one of which used contrast media at room temperature and the other in which contrast media were warmed to 37°C before administration. Adverse reactions, including allergic-like and physiological reactions, were reviewed. We compared the incidence rates of adverse reactions between the two cohorts by using the χ2 test. Results: A total of 70,446 injections in cohort 1 and 203,873 injections in cohort 2 were included. Extrinsic warming reduced the rate of allergic-like reactions to iopromide 370, iopamidol 370, and iohexol 350 (0.32% in cohort 1 versus 0.21% in cohort 2, p = 0.003; 0.14% versus 0.10%, p = 0.046; and 0.32% versus 0.13%, p = .003, respectively). However, the physiological reaction rates could not be reduced (p = 0.057, p = 0.107, and p = 0.962, respectively). The extrinsic warming of iopromide 300 could not reduce adverse reaction rates (allergic-like reaction rates: 0.21% versus 0.16%, p = 0.407; physiological reaction rates: 0.17% versus 0.13%, p = 0.504). Conclusion: Extrinsic warming to 37°C before intravenous administration was associated with a reduction in the rate of allergic-like reactions to iopromide 370, iopamidol 370, and iohexol 350.

Contrast Enhanced MRI in the Diagnosis of HCC

Hepatocellular carcinoma (HCC) is the 6th most common cancer worldwide. Imaging plays a critical role in HCC screening and diagnosis. Initial screening of patients at risk for HCC is performed with ultrasound. Confirmation of HCC can then be obtained by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), due to the relatively high specificity of both techniques. This article will focus on reviewing MRI techniques for imaging HCC, felt by many to be the exam of choice for HCC diagnosis. MRI relies heavily upon the use of gadolinium-based contrast agents and while primarily extracellular gadolinium-based contrast agents are used, there is an emerging role of hepatobiliary contrast agents in HCC imaging. The use of other non-contrast enhanced MRI techniques for assessing HCC will also be discussed and these MRI strategies will be reviewed in the context of the pathophysiology of HCC to help understand the MR imaging appearance of HCC.

Cost-Effectiveness of Angiographic Imaging in Isolated Perimesencephalic Subarachnoid Hemorrhage

Background and Purpose—

The purpose of this study is to perform a comprehensive cost-effectiveness analysis of all possible permutations of computed tomographic angiography (CTA) and digital subtraction angiography imaging strategies for both initial diagnosis and follow-up imaging in patients with perimesencephalic subarachnoid hemorrhage on noncontrast CT.

Methods—

Each possible imaging strategy was evaluated in a decision tree created with TreeAge Pro Suite 2014, with parameters derived from a meta-analysis of 40 studies and literature values. Base case and sensitivity analyses were performed to assess the cost-effectiveness of each strategy. A Monte Carlo simulation was conducted with distributional variables to evaluate the robustness of the optimal strategy.

Results—

The base case scenario showed performing initial CTA with no follow-up angiographic studies in patients with perimesencephalic subarachnoid hemorrhage to be the most cost-effective strategy ($5422/quality adjusted life year). Using a willingness-to-pay threshold of $50 000/quality adjusted life year, the most cost-effective strategy based on net monetary benefit is CTA with no follow-up when the sensitivity of initial CTA is >97.9%, and CTA with CTA follow-up otherwise. The Monte Carlo simulation reported CTA with no follow-up to be the optimal strategy at willingness-to-pay of $50 000 in 99.99% of the iterations. Digital subtraction angiography, whether at initial diagnosis or as part of follow-up imaging, is never the optimal strategy in our model.

Conclusions—

CTA without follow-up imaging is the optimal strategy for evaluation of patients with perimesencephalic subarachnoid hemorrhage when modern CT scanners and a strict definition of perimesencephalic subarachnoid hemorrhage are used. Digital subtraction angiography and follow-up imaging are not optimal as they carry complications and associated costs.

Immediate and nonimmediate reactions induced by contrast media: incidence, severity and risk factors

Background

The pattern of the contrast media-induced adverse reactions has not been investigated extensively in Mexico.

Objective

To estimate the incidence and the degree of severity of the adverse reactions to contrast media, administered for the first time, in hospitalized subjects.

Methods

We studied 99 patients longitudinally on whom computed tomography with contrast media (iopamidol) was carried out. The adverse reactions were identified by clinical examination; subsequently, they were classified as mild, moderate and severe, following the Manual on Contrast Media version 9 guides, and as immediate and nonimmediate. In addition, the vital functions, oxygen saturation, serum creatinine levels and the total number of eosinophils were measured before and after the procedure.

Results

The incidence of immediate and nonimmediate adverse reactions was of 26.3% and 10.1%, respectively. The mild immediate reactions were 18 (69.2%), the most common being the sensation of warmth, nausea and pruritus; among the more delayed reactions, nephrotoxicity stood out (5.1%). The serum creatinine median showed no difference either before or after the intravenous injection of contrast media (p = 0.13); in contrast, there was a significant difference in the total number of eosinophils (p ≤ 0.001). The values of high baseline systolic blood pressure and the diminished baseline amounts in pulse oximetry were significantly related with any type of the adverse reactions to contrast media.

Conclusion

The incidence of the adverse reactions to contrast media was greater with respect to previous reports; the majority of these reactions were of the immediate type and of a mild nature. The risk factors that have mostly been implicated in the adverse reactions to contrast media could not be identified in our cohort.

Quantitatively defining washout in hepatocellular carcinoma

OBJECTIVE

Washout on delayed phase (or equilibrium phase) imaging of an arterially hyperenhancing lesion is an excellent predictor of hepatocellular carcinoma (HCC). The purpose of our study was to quantitatively define washout in pathologically proven HCC. A quantitative definition of HCC may minimize interobserver variability and facilitate more accurate diagnosis.

MATERIALS AND METHODS

We identified 47 liver lesions that were hyperenhancing in the arterial phase from 24 patients who underwent triphasic MDCT as part of preoperative evaluation for liver transplantation. All HCCs were pathologically proven. Regions of interest were obtained of lesions and areas of adjacent liver on arterial, portal venous, and delayed phase images. Enhancement profiles were assessed by three radiologists.

RESULTS

Of the 47 hypervascular lesions, 14 HCCs were identified. There was a statistically significant difference in percentage attenuation ratio (defined as 100 × ratio of attenuation of adjacent liver to that of the lesion) between lesions that were HCC (median percentage attenuation ratio, 121) and those that were not (median percentage attenuation ratio, 101) on delayed phase. Percentage attenuation ratio ≥ 107 on delayed phase imaging achieved maximal sensitivity (100%) with good specificity (75.8%), positive predictive value (PPV) (63.6%), and negative predictive value (NPV) (100%) in HCC detection. Percentage attenuation ratio also correlated well with radiologists' assessments of enhancement profiles of lesions (multinomial logistic regression McFadden R(2), 0.72; chi-square p, < 0.01).

CONCLUSION

Our analysis of simple CT attenuation measurements indicates that percentage attenuation ratio offers excellent sensitivity, specificity, PPV, and NPV for HCC detection and very good correlation with radiologists' assessments of washout.

The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed

BACKGROUND

Radiocontrast agents are some of the most commonly used medications in the emergency department. However, both physicians and patients misunderstand the role that allergies play in reactions to radiocontrast media, especially with regards to shellfish and iodine.

OBJECTIVES

We sought to review the literature describing rates of contrast reactions and risk of contrast administration to patients with iodine allergy, shellfish or seafood allergies, or prior reactions to intravenous iodinated contrast.

METHOD

Both authors independently performed literature reviews, including position statements of stakeholder organizations, to gain perspective on important issues. They subsequently performed a systematic search for articles that estimated the risk of administration of iodinated contrast to those with a prior history of contrast reaction, "iodine allergy," or reaction to seafood or shellfish.

RESULTS

The risk of reactions to contrast ranges from 0.2-17%, depending on the type of contrast used, the severity of reaction considered, and the prior history of any allergy. The risk of reaction in patients with a seafood allergy is similar to that in patients with other food allergies or asthma. A history of prior reaction to contrast increases the risk of mild reactions to as high as 7-17%, but has not been shown to increase the rate of severe reactions. Severe reactions occur in 0.02-0.5% and deaths in 0.0006-0.006%; neither have been related to "iodine allergy," seafood allergy, or prior contrast reaction. Low-osmolality contrast media became available in 1988, and many of the higher risk estimates were from the era before it was widely available.

CONCLUSIONS

Iodine is not an allergen. Atopy, in general, confers an increased risk of reaction to contrast administration, but the risk of contrast administration is low, even in patients with a history of "iodine allergy," seafood allergy, or prior contrast reaction. Allergies to shellfish, in particular, do not increase the risk of reaction to intravenous contrast any more that of other allergies.

Effects of contrast media on the hepato-pancreato-biliary system

AIM: To determine the effects of high osmolarity contrast media (HOCM) and iso-osmolar contrast media (CM) application, with or without pressure, on hepato-pancreato-biliary (HPB) system.

METHODS: Sixty rats were divided into six equal groups as follows: Group 1: (0.9% NaCl, control), Group 2: (diatrizoate meglumine Na, ionic HOCM, Urographin^®), Group 3: (iodixanol, iso-osmolar non-ionic CM, Visipaque^®); each of which was applied without pressure, whereas the animals of the remaining three groups (1p, 2p, 3p) were subjected to the same CM with pressure. We performed a duodenal puncture and introduced a catheter into the ampulla. After the catheterization, 0.2 mL CM or 0.9% NaCl was injected with or without pressure. Blood samples were taken for biochemical evaluations. The histopathological examinations of liver, common bile duct, and pancreas were performed.

RESULTS: There were no significant differences between the six groups for blood amylase, alanine aminotransferases, aspartate aminotransferases, bilirubin levels (P > 0.05). Alkaline phosphatase and γ glutamyl transaminase levels were higher (P < 0.05) in the Urographin^® groups (2, 2p) than the Visipaque^® groups (3, 3p), or control groups (1, 1p). Hepatocyte necrosis, portal area inflammation, and Kupffer’s cell hyperplasia were higher (P < 0.05) in the study groups than the control group. However, there were no significant differences (P > 0.05) between HOCM (2, 2p) and iso-osmolar CM (3, 3p) groups. Bile duct proliferation and regeneration in the Urographin^® groups (2, 2p) were significantly higher (P < 0.05) than the Visipaque^® groups (3, 3p) or the control groups (1, 1p). Although CM caused minor damage to the pancreas, there were no statistically significant differences (P > 0.05) between the groups. Application of the CM with pressure did not cause additional damage to the HPB system.

CONCLUSION: Iso-osmolar, non-ionic CM could be more reliable than the ionic HOCM, whereas the application of pressure during the CM application had no effect on the HPB system.

Immediate adverse reactions to intravenous iodinated contrast media in computed tomography

This exploratory-descriptive, non-experimental quantitative research aimed to learn about immediate adverse reactions to intravenous iodinated contrast media in hospitalized patients submitted to computed tomography at a teaching hospital in the South of Brazil. During the study period, all adverse reactions showed mild intensity, at a frequency of 12.5% with ionic iodinated contrast media, and 1% with non-ionic contrast agent. The extravasation of contrast occurred in 2.2% of the injections in a peripheral vein without complications in any of the cases. The results are within the limits cited in international literature and suggest that tomography service professionals should know their own rates of adverse reactions to iodinated contrast agent, as well as the conditions in which they occur, in order to obtain evidence to evaluate the respective care delivery processes.

Adverse effects associated with SonoVue®use

Conventional ultrasonography (US) has limited accuracy in the detection and characterisation of solid focal liver lesions (FLL). Contrast-enhanced ultrasound (CEUS) significantly improves the diagnostic performance of US in the assessment of FLL. Rare reports of serious adverse events have been reported with CEUS. The rates of adverse reactions reported from the use of ultrasound contrast agents seem comparable to, or lower than, those observed for other imaging modalities that use contrast agents such as computed tomography and magnetic resonance imaging. Improved diagnostic results and diagnostic confidence achieved in conventional CEUS studies of the liver and during the investigational use in the intraoperative CEUS exploration appear to justify the use of this promising modality.

Cost-effectiveness of iodixanol in patients at high risk of contrast-induced nephropathy

BACKGROUND

Acute renal failure after contrast-induced nephropathy is a clinically important and costly complication after the use of iodine-based contrast media. We investigated the cost and cost-effectiveness of 2 contrast media in patients at high risk of contrast-induced nephropathy.

METHODS

The analyses were based on a randomized, prospective, multinational clinical study comparing the nephrotoxic effects of an isosmolar nonionic contrast medium, iodixanol, with those of a low-osmolar nonionic contrast medium, iohexol. Resource utilization data were obtained from the study and from a retrospective review of patients' hospital records. Swedish, German, and French unit prices were applied to resources used. Between-group differences in average costs were analyzed using a nonparametric bootstrap method.

RESULTS

Resource utilization data for 125 patients were analyzed. Seven contrast media-related serious adverse reactions, of which 6 were acute renal failures, were noted in 6 patients receiving iohexol. Two patients in the iodixanol group had 1 nonserious reaction each. The mean hospitalization cost per patient was Euros 489, Euros 573, and Euros 393 lower after iodixanol than after iohexol using Swedish, German, and French unit prices, respectively. The mean per-patient costs of treating adverse drug reactions were Euros 371, Euros 399, and Euros 445 lower after iodixanol than after iohexol, using the respective unit prices (P < or = 0.01). Iodixanol was cost-effective compared with iohexol, with both lower costs and better effects related to fewer adverse drug reactions.

CONCLUSIONS

The isosmolar contrast medium iodixanol appears to be cost-effective when compared with a low-osmolar contrast medium, iohexol, in diabetic patients with renal impairment undergoing angiography.

Drug Evolution Concept in Drug Design: 1. Hybridization Method†

A novel concept, "drug evolution", is proposed to develop chemical libraries that have a high probability of finding drugs or drug candidates. It converts biological evolution into chemical evolution. In this paper, we present "hybridization" drug evolution, which is the equivalent of sexual recombination of parental genomes in biological evolution. The hybridization essentially shuffles the building blocks of the parent drugs and ought to drug(s); no drug evolution can otherwise occur. We hybridized two drugs, benzocaine and metoclopramide and generated 16 molecules that include the parent drugs, four known drugs, and two molecules whose therapeutic activities are reported. The unusually high number of drugs and drug candidates in the library encourages high expectations of finding new drug(s) or drug candidate(s) within the remaining eight compounds. Interestingly, the therapeutic applications of the eight drugs or drug candidates in the library are fairly diverse as 38 therapeutic applications and 25 molecular targets are counted. Therefore, the library fits as a general chemical library for unspecified therapeutic activities. The hybridization of other two drugs, aspirin and cresotamide, is also described to demonstrate the generality of the method.