Pretreatment with corticosteroids to alleviate reactions to intravenous contrast material

Iodine and Gadolinium Contrast Reactions: What Is the Risk and Role of Premedication, Abbreviated Protocols, Prior History of Reactions, and Cross-Reactivity?

Immediate hypersensitivity reactions to iodinated contrast media and gadolinium-based contrast media can be life-threatening. While corticosteroid premedication or agent-switching may mitigate risk, evidence is largely indirect and based on historical studies; recent literature refutes the efficacy. Guidance on premedication varies between organizations worldwide. No strategy eliminates reactions, and indirect consequences of premedication are substantial. Accelerated regimens are often used for emergencies, but are of questionable efficacy. Identifying "high-risk" patients is complex, but a history of reactions (to the same contrast class) is the biggest risk factor.

Adrenal Vein Sampling for Primary Aldosteronism: Recommendations From the Australian and New Zealand Working Group

Adrenal vein sampling (AVS) is the current recommended procedure for identifying unilateral subtypes of primary aldosteronism (PA), which are amenable to surgery with the potential for cure. AVS is a technically challenging procedure usually undertaken by interventional radiologists at tertiary centres. However, there are numerous variations in AVS protocols relating to patient preparation, sampling techniques and interpretation which may impact the success of AVS and patient care. To reduce practice variations, improve the success rates of AVS and optimise patient outcomes, we established an Australian and New Zealand AVS Working Group and developed evidence-based expert consensus recommendations for the preparation, performance and interpretation of AVS. These recommendations can be used by all healthcare professionals in a multidisciplinary team who look after the diagnosis and management of PA.

Dual-Energy CT Iodine Uptake of Head and Neck: Definition of Reference Values in a Big Data Cohort

BACKGROUND

Despite a considerable amount of literature on dual-energy CT (DECT) iodine uptake of the head and neck, the physiologic iodine uptake of this region has not been defined yet. This study aims to establish reference values for the iodine uptake of healthy organs to facilitate clinical application.

METHODS

Consecutive venous DECT scans of the head and neck were reviewed, and unremarkable exams were included (n = 617). A total of 35 region of interest measurements were performed in 16 anatomical regions. Iodine uptake was compared among different organs/tissues and subgroup analysis was performed (male (n = 403) vs. female (n = 214); young (n = 207) vs. middle-aged (n = 206) vs. old (n = 204); and normal weight (n = 314) vs. overweight (n = 196) vs. obese (n = 107)).

RESULTS

Overall mean iodine uptake values ranged between 0.5 and 9.4 mg/mL. Women showed higher iodine concentrations in the cervical vessels and higher uptake for the parotid gland, masseter muscle, submandibular glands, sublingual glands, palatine tonsils, tongue body, thyroid gland, and the sternocleidomastoid muscle than men (p ≤ 0.04). With increasing age, intravascular iodine concentrations increased as well as iodine uptake for cerebellum and thyroid gland, while values for the tongue and palatine tonsils were lower compared to younger subjects (p ≤ 0.03). Iodine concentrations for parotid glands and sternocleidomastoid muscles decreased with a higher BMI (p ≤ 0.004), while normal-weighted patients showed higher iodine values inside the jugular veins, other cervical glands, and tonsils versus patients with a higher BMI (p ≤ 0.04).

CONCLUSION

physiologic iodine uptake values of cervical organs and tissues show gender-, age-, and BMI-related differences, which should be considered in the clinical routine of head and neck DECT.

Substitution with Low-Osmolar Iodinated Contrast Agent to Minimize Recurrent Immediate Hypersensitivity Reaction

Background The recurrence of hypersensitivity reaction (HSR) to low-osmolar iodinated contrast media (LOCM) remains challenging despite premedication and substitution of the LOCM. Purpose To determine the optimal practical preventive strategy for LOCM substitution in patients with a history of prior immediate HSR to LOCM. Materials and Methods In a retrospective study, patients with an immediate HSR to LOCM before February 2020 and who underwent subsequent exposure to LOCM until March 2021 were enrolled in five tertiary referral hospitals in South Korea. The association of recurrence of an HSR after subsequent LOCM exposures was assessed using multivariate general estimating equation analysis according to age, sex, the severity of the index HSR, premedication, and substituting LOCM based on common carbamoyl side chains, including the N-(2,3-dihydroxypropyl)-carbamoyl and N-(2,3-dihydroxypropyl)-N-methyl-carbamoyl moieties. Results The evaluation included 3800 subsequent LOCM exposures in 1066 patients (mean age, 56.2 years ± 13.5 [SD]; 567 [53%] female and 499 [47%] male patients). The general estimating equation analysis, using 1:1 propensity score matched data for age, sex, HSR severity, and LOCM selection, showed that premedication with corticosteroids significantly reduced recurrent HSR (odds ratio [OR], 0.72; 95% CI: 0.52, 1.00; P = .049). The change to another LOCM with a common side chain had a similar recurrence rate as using the same LOCM (OR, 0.98; 95% CI: 0.64, 1.50; P = .93), whereas the use of a different LOCM without a common side chain significantly lowered HSR recurrence (OR, 0.51; 95% CI: 0.37, 0.69; P < .001) in multivariate general estimating equation analysis. Substitution of an LOCM without a common side chain was effective regardless of the index HSR severity but was more pronounced in moderate-to-severe reactions (OR, 0.30; 95% CI: 0.16, 0.55; P < .001). Conclusion For patients with a previous immediate HSR of any severity to LOCM, alternative LOCM without a common carbamoyl side chain reduced recurrent HSR during subsequent exposures. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by McDonald in this issue.

Differences in the Recurrence Rate of Immediate Adverse Drug Reactions According to the Components of Alternative Contrast Media: Analysis of Repetitive Computed Tomography Cases in a Single Tertiary Hospital

INTRODUCTION

The recurrence rates of immediate adverse drug reactions (ADRs) to the alternative radiocontrast media (RCM) are not well known. Previous studies suggest selection of alternative RCM considering carbamoyl side chains; however, its usefulness for preventing the recurrence of ADRs has not been clearly verified.

OBJECTIVE

The aim of this study was to verify the recurrence rate of immediate ADRs according to the alternative RCM.

METHOD

This retrospective study analyzed 6420 contrast-enhanced computed tomography (CT) cases of 2009 patients registered in the ADR system from 861,664 CT cases in a single tertiary hospital between 2015 and 2020. Iohexol, iopromide, iobitridol, and iopamidol were used for CT. According to the carbamoyl side chains present, iohexol belongs to group 1, iopromide belongs to groups 1 and 2, iobitridol belongs to group 2, and iopamidol belongs to group 3.

RESULTS

Replacing iobitridol with iopamidol (odds ratio [OR] 2.595, 95% confidence interval [CI] 1.48-4.550) or iopromide (OR 3.354, 95% CI 1.420-7.926) as the subsequent RCM was associated with increased recurrence, while replacing iopamidol with iobitridol (OR 0.506, 95% CI 0.282-0.908) and iopromide with iohexol (OR 0.355, 95% CI 0.177-0.711) was associated with decreased recurrence. Other changes did not influence the recurrence of ADRs.

CONCLUSIONS

The recurrence of immediate ADRs increased in certain RCM combinations of preceding and subsequent CT scans, and the RCMs did not show cross-reactivity. Therefore, the clinical benefit of the alternative RCM considering cross-reactivity is limited. This result suggests that the side chains of RCM do not have an important role in the recurrence of immediate ADRs.

Pharmacological Prevention of Hypersensitivity Reactions Caused by Iodinated Contrast Media: A Systematic Review and Meta-Analysis

Objectives: Hypersensitivity reactions (HSRs) are uncommon but serious adverse events following the administration of iodinated contrast media (ICM) prior to CT imaging. While premedication is almost universally given in high-risk patients, there is a lack of evidence regarding the efficacy of such premedication. This study aims to determine the efficacy of premedication with corticosteroids prior to ICM administration in the prevention of HSRs through meta-analysis. Materials and Methods: An extensive review of the literature yielded 404 potentially relevant studies. Of these, five studies met the inclusion criteria of this meta-analysis. Pooled HSR event rates were obtained from each of the studies for both patients who had and who had not received premedication with corticosteroids. Heterogeneity between studies was also determined. Results: A total of 736 patients across all five studies were included in the analysis. Patients who did not receive premedication had initial pooled HSR rates of 0.16 (95% CI, 0.07−0.35) across all studies. Following premedication, pooled HSR rates dropped to 0.02 (95% CI, 0.01−0.06). Patients who had prior HSRs were significantly less likely to experience HSRs (OR = 0.09; 95% CI, 0.03−0.25; p < 0.00001) after treatment with premedication. Conclusions: This meta-analysis offers evidence for the reduction in the recurrence of moderate and severe HSRs in patients who have a history of such reactions. Premedication with corticosteroids prior to ICM administration is thus highly recommended in high-risk patients.

Successful Adrenal Vein Sampling Using Dexamethasone Premedication in Patients With Iodine Contrast Media Allergy

Context

Preparation of patients with iodine contrast media (ICM) allergy who require adrenal vein sampling (AVS) to establish source of aldosterone excess of their confirmed primary aldosteronism (PA) is controversial. Usual premedication with high-dose prednisone can interfere with cortisol determinations, possibly altering the aldosterone to cortisol ratios for the identification of lateralized aldosterone excess.

Objective

We aimed to evaluate the efficacy and safety of premedication with high-dose dexamethasone to perform AVS in patients with ICM.

Methods

One hundred and seventy-seven consecutive patients with confirmed PA who underwent bilateral simultaneous basal and post-ACTH bolus AVS at our center between January 2010 and December 2020 were retrospectively analyzed for history of ICM allergy. A total of 7 patients (4%) with previous allergic reactions to ICM were prepared with 3 doses of 7.5 mg dexamethasone premedication rather than the usual 50 mg of prednisone.

Results

No breakthrough allergic reactions were reported in the 7 patients. Despite adequate serum cortisol suppression following dexamethasone, the basal and post-ACTH selectivity index were respectively &gt; 2 and &gt; 5 bilaterally in all patients, confirming adequate cannulation of both adrenal veins. Four patients had lateralized ratios (A/C ratio &gt; 2 basally and &gt; 4 post-ACTH), while 3 had bilateral source during AVS study. In the 3 patients undergoing unilateral adrenalectomy for lateralized source and contralateral suppression and adequate follow-up data, cure of PA was achieved at mean 58 months postoperatively.

Conclusion

AVS using dexamethasone premedication is safe and accurate for diagnosing the source of aldosterone excess in patients with PA and ICM allergy.

Hypersensitivity Reactions to Iodinated Contrast Media

At present, iodinated contrast media (ICM) are mostly non-ionic, have low osmolality, and are safe. Even if adverse drug reactions (ADRs) occur, most are chemo-toxic symptoms and require only observation or H1 antihistamines. However, rare, unpredictable, and even life-threatening hypersensitivity can still occur. The aim of this review is to summarize the issues that all relevant staff need to know about and be able to respond to. The most significant risk factor for ICM hypersensitivity is a history of ICM hypersensitivity. For high-risk populations, we must cautiously weigh the advantages and disadvantages of premedication and be aware that breakthrough reactions may still occur. The best policy for patients with a history of severe ICM hypersensitivity is to avoid the same ICM. If ICM are inevitable, skin tests, in vitro tests, and drug provocation tests may help to find a feasible alternative that is safer. The severity of the hypersensitivity is correlated with the positivity rate of these tests, so there is no need for further investigations for patients with only mild reactions. We should also keep in mind that even excipients in ICM may induce hypersensitivity. Detailed, standardized documentation is essential for correct diagnosis and the prevention of future occurrence.

Radiocontrast Media Hypersensitivity Reactions in Children

Hypersensitivity reactions to radiocontrast media seem to be rare in children. Furthermore, the use of radiocontrast media in children remains quite safe in terms of the severity of reactions. Since pediatric guidelines are lacking, the diagnostic workup employed in adults could be adapted to children, taking into account that results have not yet been validated in this age group. Specific protocols for risk stratification and management of severe reactions have been proposed so far.

Spinal Injections

Spinal pain is a common complaint and cause of disability in the United States, affecting most individuals at some point in their lives. The complex anatomy of the spine leads to multiple potential and coexisting etiologies for pain, and the differentiation of these sources can present a diagnostic challenge. Image-guided spinal injections can provide both diagnostic information identifying pain location as well as prolonged therapeutic relief as an alternative to medical management. Anesthetic and corticosteroid medications can be administered within the epidural space through transforaminal or interlaminar approaches, blocking various sensory nerves, or directly within the facet joints. Proceduralists must be aware of associated patient considerations, techniques, and potential complications to perform the procedures safely. We discuss image-guided spinal injection techniques, based on best practices and our experiences.

Adrenal Vein Sampling in a Patient With Primary Hyperaldosteronism and Severe Contrast Allergy

We report on a case of a 50-year-old female patient with primary hyperaldosteronism, in whom adrenal venous sampling was required to differentiate between unilateral and bilateral disease. Because of a history of severe allergy to iodinated contrast media, premedication with glucocorticoids was indicated. Exogenous glucocorticoids, however, can affect measurements of serum cortisol. To avoid this potential confounding effects on the cortisol assay, we decided to use dexamethasone instead of prednisolone or hydrocortisone. A high-dose adrenocorticotropin (ACTH) stimulation test with the simultaneous use of dexamethasone revealed an adequate adrenal cortisol response. ACTH-stimulated adrenal venous sampling showed reliable results, which provided a solid basis for further clinical decision-making.

Coronary computed tomographic angiography: A review of the techniques, protocols, pitfalls, and radiation dose

Coronary computed tomographic angiography (CCTA) is a viable alternative to catheter coronary angiography for several clinical indications, chiefly because it is fast and non-invasive. For effective clinical use of CCTA, various technical and patient factors should be considered. In this brief review article, we discuss the indication and contraindications for CCTA, technical requirements for CCTA including radiation dose, patient preparation principles, image post-processing, and pitfalls and artifacts of CCTA.

Prevention of Allergic-like Reactions at Repeat CT: Steroid Pretreatment versus Contrast Material Substitution

Background It is unclear whether steroid premedication is an effective means of preventing repeat allergic-like reactions in high-risk patients with a previous allergic-like reaction to iodinated contrast material (ICM). Purpose To compare the effectiveness of ICM substitution (ie, using iohexol in a patient with a previous iopromide reaction) with 12- and 2-hour steroid premedication for preventing repeat acute allergic-like reactions in high-risk patients. Materials and Methods This retrospective study identified all high-risk (ie, having a previous allergic-like reaction) adult and pediatric patients who underwent a contrast-enhanced CT examination at the institution from June 1, 2009, to May 9, 2017. Prophylactic treatments and repeat reactions were identified using chart review. The effectiveness of prophylactic treatments on repeat reaction rates was examined with multivariable regression models that used generalized estimating equations. Results A total of 1973 high-risk patients who underwent 4360 subsequent ICM-enhanced CT examinations were included. Of the 4360 examinations, a total of 280 allergic-like reactions occurred (6%) in 224 of the 1973 patients (11% of patients), with only 19 of 280 reactions (7%) that were more severe than the previous reaction being demonstrated. After adjustment, patients who received a different ICM with and without steroid premedication had a significantly lower rate of repeat reactions than did patients who received steroid premedication and the same ICM (same ICM and steroid premedication: 80 of 423 examinations [19%]; different ICM and no steroid premedication: 10 of 322 examinations [3%]; odds ratio [OR], 0.14 [95% CI: 0.06, 0.33]; P < .001; different ICM and steroid premedication: five of 166 patients [3%]; OR, 0.12 [95% CI: 0.04, 0.36]; P < .001). When examining the first scan only, patients who received the same ICM had a similar risk of repeat reactions regardless of whether they received steroid premedication (steroid premedication: 44 of 172 patients [26%] vs no premedication: 73 of 298 patients [25%]; OR, 1.00 [95% CI: 0.64, 1.57]; P = .99). Conclusion In this cohort, using an iodinated contrast material (ICM) substitution was more effective for preventing repeat allergic-like reactions than using steroid premedication and the same ICM that caused the previous reaction. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Davenport and Weinstein in this issue.

Clinical safety evaluation of contrast agents based on real-world evidence

WHAT IS KNOWN AND OBJECTIVE

This study was aimed at comparing the adverse drug reactions (ADRs) arising from the use of iodinated contrast medium (ICM) and gadolinium-based contrast media (GBCM), and to provide a basis for the clinical selection of contrast media.

METHODS

Retrospective data for ADR cases occurring from the use of ICM or GBCM during enhanced scanning in computed tomography and magnetic resonance imaging were collected between June/2013 and May/2020 from Wenling Hospital of Traditional Chinese Medicine. Chi-square tests were performed based on the characteristics of patients and the classification of contrast medium. Bonferroni correction was applied to the statistical analyses with multiple comparisons of proportions.

RESULTS

Among 27,328 patients who were subjected to enhanced CT scanning, 207 cases (0.76%) showed ICM-related ADRs. Among 16,381 patients who were subjected to enhanced MRI scanning, 25 cases (0.15%) showed ADRs related to GBCM. The incidence of ADR induced by GBCM was significantly lower than ICM-induced ADR (p < 0.01). There were no significant differences in the incidence among different types of ICM, including ioversol and iodixanol, as well as iodixanol from different manufacturers (p > 0.05). Interestingly, the ADR incidence of ICM seemed to be associated with gender, with a significantly higher incidence in females than in male patients, and it was also associated with the age, with a lower occurrence in older (>44 years) compared to younger patients.

WHAT IS NEW AND CONCLUSION

With respect to ADR incidence, the safety profile of ICM of different types and different manufacturers was found to be similar in clinical use, warranting no need of specifically choosing imported or more expensive products. While choosing contrast medium type for clinical use, attention should be paid to certain populations, especially to younger and female patients when the patients are about to undergo a contrast-enhanced examination.

Case Report: A 62-Year-Old Woman With Contrast-Induced Encephalopathy Caused by Embolization of Intracranial Aneurysm

Contrast-induced encephalopathy (CIE) is a rare complication of endovascular treatment and is extensively reported as a transient and reversible phenomenon. This report describes a 62-year-old woman for embolization of an internal carotid artery (ICA) aneurysm. The operation was successful, but postoperation the patient suffered unconsciousness, blindness, hemiplegia, ophthalmoplegia, fever, and seizures. CT of the brain without the contrast showed widespread edema in the right cerebral hemisphere, which is involved in the frontal, parietal, temporal, and occipital lobes. She was diagnosed with CIE in time and treated with supportive management as soon as possible, and fortunately, the patient improved a benign course and was discharged without any neurological deficits. This study emphasizes the prevention of the CIE and the importance of early diagnosis and symptomatic treatment.

Evidence-Based Practices in the Cardiac Catheterization Laboratory: A Scientific Statement From the American Heart Association

Cardiac catheterization procedures have rapidly evolved and expanded in scope and techniques over the past few decades. However, although some practices have emerged based on evidence, many traditions have persisted based on beliefs and theoretical concerns. The aim of this review is to highlight common preprocedure, intraprocedure, and postprocedure catheterization laboratory practices where evidence has accumulated over the past few decades to support or discount traditionally held practices.

Imaging Modalities for Evaluation of Intestinal Obstruction

It is essential for the colon and rectal surgeon to understand the evaluation and management of patients with both small and large bowel obstructions. Computed tomography is usually the most appropriate and accurate diagnostic imaging modality for most suspected bowel obstructions. Additional commonly used imaging modalities include plain radiographs and contrast imaging/fluoroscopy, while less commonly utilized imaging modalities include ultrasonography and magnetic resonance imaging. Regardless of the imaging modality used, interpretation of imaging should involve a systematic, methodological approach to ensure diagnostic accuracy.

Practice parameters for diagnosing and managing iodinated contrast media hypersensitivity

Immediate and nonimmediate hypersensitivity reactions to iodinated contrast media (ICM) have been reported to occur in a frequency of about 0.5%-3% of patients receiving nonionic ICM. The diagnosis and management of these patients vary among guidelines published by various national and international scientific societies, with recommendations ranging from avoidance or premedication to drug provocation test. This position paper aims to give recommendations for the management of patients with ICM hypersensitivity reactions and analyze controversies in this area. Skin tests are recommended as the initial step for diagnosing patients with immediate and nonimmediate hypersensitivity reactions; besides, they may also help guide on tolerability of alternatives. Re-exposition or drug provocation test should only be done with skin test-negative ICMs. The decision for performing either re-exposition or drug provocation test needs to be taken based on a risk-benefit analysis. The role of in vitro tests for diagnosis and pretreatment for preventing reactions remains controversial.

The Use of Contrast Agents in Interventional Pain Procedures: A Multispecialty and Multisociety Practice Advisory on Nephrogenic Systemic Fibrosis, Gadolinium Deposition in the Brain, Encephalopathy After Unintentional Intrathecal Gadolinium Injection, and Hypersensitivity Reactions

This Practice Advisory presents a comprehensive and evidence-based set of position statements and recommendations for the use of contrast media in interventional pain procedures. The advisory was established by an international panel of experts under the auspices of 11 multinational and multispecialty organizations based on a comprehensive review of the literature up to December 31, 2019. The advisory discusses the risks of using gadolinium-based contrast agents. These include nephrogenic systemic fibrosis, gadolinium brain deposition/retention, and encephalopathy and death after an unintentional intrathecal gadolinium injection. The advisory provides recommendations on the selection of a specific gadolinium-based contrast agent in patients with renal insufficiency, those who had multiple gadolinium-enhanced magnetic resonance imaging examinations, and in cases of paraspinal injections. Additionally, recommendations are made for patients who have a history of mild, moderate, or severe hypersensitivity reactions to contrast medium.

Prognostic implications of prior contrast reaction in patients with emergency premedication before undergoing percutaneous coronary intervention

BACKGROUND

Patients with iodinated contrast material (ICM) adverse reactions are at increased risk for breakthrough reactions. Previous studies suggest that the severity of a prior ICM adverse reaction corresponds to the severity of a repeat reaction.

OBJECTIVE

We investigated whether the severity of prior ICM adverse reactions in patients receiving emergency premedication therapy prior to PCI predicts outcomes.

METHODS

A retrospective observational study of percutaneous coronary intervention (PCI) encounters between January 1, 2005, and May 30, 2018, was conducted at Geisinger Medical Center. Patients with ICM adverse reactions premedicated with an emergency premedication regimen prior to PCI were included in the study. PCIs were stratified based on the severity of the index ICM adverse reactions; PCIs with a prior severe reaction were compared to PCIs with a prior mild-moderate reaction.

RESULTS

We evaluated 604 PCI, of these, 144 (23.8%) had prior severe reactions and 460 (76.2%) had mild-to-moderate reactions. Nine patients had breakthrough reactions, of which seven were of the same or decreased severity in comparison to the index reactions. The overall breakthrough reactions occurred in 1 of 144 patients (0.7%) with an initial severe reaction and in 8 of 460 (1.7%) with an initial mild/moderate reaction (p = 0.69). Outcomes including length of hospital stay and 30-day mortality were similar for PCI with or without severe index ICM reactions.

CONCLUSION

Frequency and severity of breakthrough reaction and clinical outcomes in patients treated with emergency premedication regimen prior to PCI were independent of the severity of index ICM reactions.

Contrast Reaction Readiness for Your Department or Facility

Moderate and severe contrast reactions are rare but can be life threatening. Appropriate contrast reaction management is necessary for the best patient outcome. This review summarizes the types and incidences of adverse events to contrast media, treatment algorithms, and equipment needed to treat common contrast reactions, the current status of contrast reaction management training, and preventative strategies to help mitigate adverse contrast events.

Emergent Premedication for Contrast Allergy Prior to Endovascular Treatment of Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Management of contrast media allergies may lead to treatment delays in patients with acute ischemic stroke undergoing endovascular therapy. The optimal premedication strategy remains unclear. The aim of this report was to analyze our experience with emergent administration of premedication regimens before endovascular therapy.

MATERIALS AND METHODS

We retrospectively reviewed prospective data for all patients undergoing endovascular therapy from 2012 to 2019 at an academic comprehensive stroke center. Records of patients with documented contrast allergy were reviewed and analyzed. Data collected included stroke risk factors and characteristics, historical contrast reaction details, premedication regimens administered, and signs or symptoms of allergic reaction developing post-endovascular therapy. Hospital arrival time to endovascular therapy was compared with that in those who did not have a history of contrast allergy.

RESULTS

We analyzed 1521 patients undergoing endovascular therapy; 60 (4%) had documented contrast allergies and constituted the study cohort. The median age was 73 years (interquartile range, 66-81 years), and 65% were women. The median time from premedication to contrast was 24 minutes (interquartile range, 0-36 minutes). Forty-three patients (72%) proceeded directly to endovascular therapy; in 17 patients, the first contrast exposure was CTA. Time from hospital arrival to endovascular therapy was not slower for patients with documented allergies (96 versus 134 minutes, P = .32). No patients experienced a contrast media reaction.

CONCLUSIONS

In a single-institution cohort study of 60 consecutive patients with documented contrast allergies undergoing endovascular therapy with emergent premedication en route to (or in) the neuroangiography suite, no patients experienced allergic symptoms. This pragmatic approach may be safe for patients who have documented contrast media allergies.

SIRM-SIAAIC consensus, an Italian document on management of patients at risk of hypersensitivity reactions to contrast media

Hypersensitivity reactions (HRs) to contrast media (CM) can be distinguished in immune-mediated (including allergic reactions) and non-immune-mediated reactions, even if clinical manifestations could be similar. Such manifestations range from mild skin eruptions to severe anaphylaxis, making it important for radiologists to know how to identify and manage them. A panel of experts from the Società Italiana di Radiologia Medica e Interventistica (SIRM) and the Società Italiana di Allergologia, Asma e Immunologia Clinica (SIAAIC) provided a consensus document on the management of patients who must undergo radiological investigations with CM. Consensus topics included: the risk stratification of patients, the identification of the culprit CM and of a safe alternative by an allergy workup, as well as the use of premedication and the correct procedure to safely perform an elective (i.e., scheduled) or urgent examination. The most important recommendations are: (1) in all patients, a thorough medical history must be taken by the prescribing physician and/or the radiologist to identify at-risk patients; (2) in patients with hypersensitivity reactions to CM, the radiologist must consider an alternative, non-contrast imaging study with a comparable diagnostic value, or prescribe a different investigation with another class of CM; (3) if such options are not feasible, the radiologist must address at-risk patients to a reference centre for an allergy evaluation; (4) if timely referral to an allergist is not viable, it is recommended to use a CM other than the responsible one, taking into account cross-reactivity patterns; in the case of patients with histories of severe reactions, the presence of an anesthesiologist is also recommended and a premedication is suggested.

Current comments on contrast media administration in patients with renal insufficiency

Contrast media administration has been associated with complications such as nephropathy, cardiovascular morbidity, and neurovascular events, particularly in patients with renal insufficiency. This association has been questioned in recent studies. This review was performed to summarize the most current evidence on contrast induced nephropathy (CIN), contributing factors, and considerations in patients with renal insufficiency. The risk of CIN was over-estimated by the previous studies, due to a lack of control groups or presence of non-randomized control groups, which led to a selection bias. However, the thresholds associated with an increased risk of CIN are controversial and require risk-benefit analysis on an individual basis. Regarding the administration of contrast media (CM) in the emergency setting, the majority of studies suggested that CM exposure does not meaningfully increase the risk of acute kidney injury in critically ill patients (including trauma patients). Several strategies have been suggested to reduce the risk of CIN, including volume expansion to increase renal blood flow, sodium bicarbonate or N-acetylcysteine administration, and use of low-osmolal contrast media in end-stage renal disease.

Preventive Effect of Changing Contrast Media in Patients With A Prior Mild Immediate Hypersensitivity Reaction to Gadolinium-Based Contrast Agent

OBJECTIVES

Currently, the prevention of recurrent immediate hypersensitivity reactions (HSRs) to contrast media (CM) requests premedication and changing the culprit contrast agent. However, strategies for the prevention of immediate HSRs to gadolinium-based magnetic resonance contrast agents (GBCAs) have not yet been established. This study aimed to evaluate the effectiveness of changing the contrast agent and single-dose premedication for HSR recurrence prevention in patients with a history of mild immediate HSR to GBCA.

MATERIALS AND METHODS

The outcomes of patients with mild immediate HSR to GBCA who subsequently underwent enhanced magnetic resonance imaging between October 2012 and July 2017 were analyzed. The institutional CM monitoring system was retrospectively reviewed, and data on the application of premedication and choice of CM were obtained. Gadolinium-based magnetic resonance contrast agents were classified into 3 classes according to their molecular structure (macrocyclic ionic, macrocyclic nonionic, and linear ionic). Intravenous chlorpheniramine 4 mg, 30 minutes before the GBCA administration, or intravenous methylprednisolone sodium succinate 40 mg plus chlorpheniramine 4 mg, 1 hour before the GBCA administration, was administrated as premedication regimen. Recurrence rates of immediate HSR were compared according to prevention strategies.

RESULTS

A total of 185 patients with a history of mild immediate HSR to GBCA were re-exposed to GBCA 397 times during the study period. The overall recurrence rate was 19.6% (78/397). Changing the culprit GBCA significantly reduced the recurrence rate, compared with reusing the culprit GBCA (6.9%, 9/130 and 25.8%, 69/267; P < 0.001). The recurrence rate was lowest when the GBCA was changed to a different molecular structure class from the culprit agent, followed by changing to CM with the same molecular structure and reusing the culprit GBCA (6.2%, 7/113 vs 11.8%, 2/17 vs 25.8%, 69/267; P < 0.001 with χ test for trend). Single-dose premedication demonstrated no significant prophylactic effect on recurrence (20.4%, 17/98 vs 17.3%, 61/299 with and without premedication, respectively; P = 0.509). Premedication in addition to changing CM also showed no additional prophylactic effect (7.2%, 7/97 and 6.1%, 2/33, respectively; P = 0.821).

CONCLUSIONS

Changing the CM from the culprit agent could reduce the chance of HSR recurrence in patients with prior mild immediate HSR to GBCA, especially when the CM was changed to one of a different molecular structure class. However, single-dose premedication administration did not show significant HSR recurrence rate difference.

Updated guidelines for intravenous contrast use for CT and MRI

Intravenous (IV) contrast material is used extensively for CT and MRI scans done in emergency departments (ED). Its use is essential to make many critical diagnoses in ED patients. While adverse reactions can occur, newer research has added to our knowledge of IV contrast media tolerance and safety leading to improved and more liberal guidelines for intravenous contrast use. The updated information described in this review article indicates how intravenous contrast can be used safely in more patients, more expeditiously and with fewer precautions than with prior guidelines. This review article explains the basis for the new recommendations for intravenous contrast material use and describes indicated precautions and preparations to avoid adverse reactions for iodinated agents used for CT and gadolinium agents for MRI.

Relationship between Lower Dose and Injection Speed of Iodinated Contrast Material for CT and Acute Hypersensitivity Reactions: An Observational Study

BackgroundThere are few data on the relationship between acute hypersensitivity reactions and the dose and injection rate of iodinated contrast material for CT.PurposeTo determine the relationship between lower dose and injection speed of iodinated contrast material for CT and the rate of acute hypersensitivity reactions.Materials and MethodsThis retrospective study included adults (age ≥18 years) undergoing nonionic iodinated contrast material-enhanced abdominal CT between August 2016 and January 2017 (control period) and between August 2017 and January 2018 (intervention period); all examinations were conducted in an outpatient setting. Compared with CT during the control period, CT during the intervention period involved a reduced dose of contrast material achieved by lowering the CT tube voltage. CT examinations in the control period were performed with 120 kVp, a contrast material dose of 2 mL/kg (maximum, 150 mL), and an injection speed of 3 or 4 mL/sec. CT examinations in the intervention period were performed with 100 kVp, a contrast material dose of 1.5 mL/kg (maximum, 130 mL), and an injection speed of 2.5 or 3 mL/sec. Per-examination rates of acute hypersensitivity reactions to iodinated contrast material were compared between the control and intervention periods with use of a multivariable Poisson regression model, the parameters of which were estimated by using generalized estimating equations with an independence correlation structure.ResultsA total of 21947 adults (mean age ± standard deviation, 59 years ± 12; 8797 women [40%]) underwent 25119 CT examinations during the control period; 23019 adults (mean age, 59 years ± 12; 9538 women [41%]) underwent 26491 CT examinations during the intervention period. The rate of acute hypersensitivity reactions was 1.42% (376 of 26491 examinations; 95% confidence interval [CI]: 1.28%, 1.57%) in the intervention period and 1.86% (468 of 25119 examinations; 95% CI: 1.70%, 2.04%) in the control period, with a multivariable-adjusted relative risk of 0.85 (95% CI: 0.74, 0.99; P = .03).ConclusionReduction in the dose and injection speed of iodinated contrast material for CT was associated with a lower rate of acute hypersensitivity reactions to iodinated contrast material.© RSNA, 2019Online supplemental material is available for this article.

Premedication for Iodinated Contrast Media Induced Immediate Hypersensitivity Reactions

Purpose of the review

Premedication using antihistamines and/or corticosteroids has been widely used to prevent reoccurrence of immediate hypersensitivity reactions (iHR) after iodinated contrast media (ICM). However, efficacy has been debated, especially in high-risk patients. Novel findings on the role and risks of premedication and preventive strategies are summarized.

Recent findings

The rate and severity of iHR occurring despite premedication indicate that premedication is not a panacea and the intensity usually reflects that of the initial reaction. Next, the number needed to treat (NNT) to prevent one serious ICM-mediated event using corticosteroid-based premedication is high and associated with a diagnostic delay. Randomly changing the ICM has been suggested as an additional preventive measure, whilst others used a skin test–based approach to identify a subgroup of ICM allergic patients and negative skin test–based alternatives with a high negative predictive value.

Summary

Growing evidence indicates the need to discriminate between non-allergic iHR that are most likely non-obligatory and susceptible to premedication, and rare type I allergic iHR that can be identified using skin testing, especially in those with a severe iHR. Although premedication reduces reoccurrence of mild iHR, it is not always efficacious and should be balanced against side effects, a high NNT and an uncertain efficacy physicians should not blindly rely on. Future work should evaluate combined approaches of an allergy-driven ICM selection and endotype-driven premedication regimens in patients with non-allergic iHR.

Intradermal Testing With Radiocontrast Media to Prevent Recurrent Adverse Reactions

OBJECTIVE. Adverse drug reactions (ADRs) to radiocontrast media are a significant social and economic burden and are difficult to predict. Because some ADRs to radiocontrast media may be immunologically induced, a skin test with diluted 1:10 radiocontrast media has been used to predict ADRs. However, using this test in clinical practice is difficult because of its low sensitivity. SUBJECTS AND METHODS. This study enrolled 36 patients with a history of immediate ADR to radiocontrast media who visited the Allergy and Asthma Clinic of Severance Hospital from 2017 to 2018. Patients underwent intradermal testing (IDT) with five types of diluted (1:10) and undiluted radiocontrast media (iohexol, iobitridol, iopamidol, iopromide, and iodixanol). The IDT result was regarded as positive if at least one radiocontrast medium elicited a positive reaction. Positivity of IDT and sensitivity to the culprit radiocontrast medium were calculated and compared. For subsequent CT examinations with a radiocontrast medium, the contrast agent eliciting a negative skin reaction in IDT was selected, excluding the previous culprit radiocontrast medium. RESULTS. IDT positivity and sensitivity for the culprit radiocontrast medium at 1:10 dilution were 47.2% and 47.2%, respectively, whereas the positivity and sensitivity for the undiluted radiocontrast medium were 86.1% and 75.0%, respectively. The positivity and sensitivity were higher with frequent radiocontrast medium use or with severe reaction. Of 22 patients who underwent another CT examination with the contrast medium selected on the basis of IDT results, 21 (95.5%) did not experience an ADR. CONCLUSION. IDT to prevent ADR should be performed with undiluted radiocontrast medium. Selecting an alternative radiocontrast agent on the basis of IDT results can be clinically useful to prevent recurrent ADRs to radiocontrast media.

Patients with a history of hypersensitivity reaction to iodinated contrast medium and given iodinated contrast during an interventional pain procedure

In patients with a history of a hypersensitivity reaction to iodinated contrast medium, iodinated contrast medium is avoided, antihistamine and steroid premedication are given, or a gadolinium-based contrast agent is employed. Six patients with a history of a hypersensitivity reaction to iodinated contrast medium and who were not premedicated had an unintentional injection of iodinated contrast. None of the patients developed a moderate or severe reaction. All patients had gadopentetate dimeglumine in one of their injections; three had repeated injections of the gadopentetate. The lack of a significant reaction may be due to any or all of the following: questionable history of iodinated contrast reaction, low dose of iodinated contrast given, concomitant injection of (epidural) steroid, and slower absorption from epidural compared with intravenous injection. While it is reassuring to know that there is a low possibility of a moderate to severe reaction in these patients, every effort should be made to avoid this scenario, appropriate drugs and resuscitation equipment should be immediately available, and the patients should be observed adequately and followed for the possibility of late reactions. Recent publications have called for caution in the use of gadolinium-based contrast agents.

Immediate Allergic Reactions to Gadolinium-based Contrast Agents: A Systematic Review and Meta-Analysis

Purpose To perform a systematic review and meta-analysis to determine if there are differences in rates of immediate allergic events between classes of gadolinium-based contrast agents (GBCAs). Materials and Methods PubMed and Google Scholar databases were searched for studies in which rates of immediate adverse events to GBCAs were reported. The American College of Radiology classification system was used to characterize allergic-like events as mild, moderate, or severe, and the total number of administrations of each GBCA was recorded. Where necessary, authors of studies were contacted to clarify data and eliminate physiologic reactions. Relative risks of GBCA types were estimated by using the Mantel-Haenszel type method. Results Nine studies in which immediate reactions to GBCA were recorded from a total of 716 978 administrations of GBCA met the criteria for inclusion and exclusion. The overall rate of patients who had immediate allergic-like reactions was 9.2 per 10 000 administrations and the overall rate of severe immediate allergic-like reactions was 0.52 per 10 000 administrations.. The nonionic linear chelate gadodiamide had the lowest rate of reactions, at 1.5 (95% confidence interval [CI]: 0.74, 2.4) per 10 000 administrations, which was significantly less than that of linear ionic GBCAs at 8.3 (95% CI: 7.5, 9.2) per 10 000 administrations (relative risk, 0.19 [95% CI: 0.099, 0.36]; P < .00001) and less than that for nonionic macrocyclic GBCAs at 16 (95% CI: 14, 19) per 10 000 administrations (relative risk, 0.12 [95% CI: 0.05, 0.31]; P < .001). GBCAs known to be associated with protein binding had a higher rate of reactions, at 17 (95% CI: 15, 20) per 10 000 administrations compared with the same chelate classification without protein binding, at 5.2 (95% CI: 4.5, 6.0) per 10 000 administrations (relative risk, 3.1 [95% CI: 2.4, 3.8]; P < .0001). Conclusion These data show the lowest rate of immediate allergic adverse events with use of the nonionic linear GBCA gadodiamide in comparison with those of ionic linear or nonionic macrocyclic GBCAs. A higher rate of immediate allergic adverse events was associated with ionicity, protein binding, and macrocyclic structure. © RSNA, 2017 An earlier incorrect version of this article appeared online. This article was corrected on August 31, 2017.

Radiographic and magnetic resonances contrast agents: Essentials and tips for safe practices

With extended and continued expansion of medical imaging utilization in modern medical practice over last decade, radiologists as well as other faculty staff dealing with radiographic and magnetic resonances contrast media (CM) have to be well oriented with their potential hypersensitivity reactions and recognize high-risk groups liable to develop it and enable early recognition. Radiologists and other medical staff involved in administration and dealing with CM have to be ready to implement prompt, practical and effective management plan to deal with these scenarios should they emerge. Strategies to prevent potential contrast-induced acute and delayed renal injuries have to be routinely exercised. Paying attention to the pregnant and nursing women, pediatrics, diabetics, as well as other fragile populations is of utmost importance for patient safety during contrast administrations. Radiologists should play a pivotal role in orienting patients about necessity to use CM for their imaging studies, in case it is needed, and assure them about its safety. Moreover, they have to be oriented with the medico-legal issues related to use of CM. These will pay as improved patient safety as well as safe daily working environmentat different levels of radiology practices.

Outcomes of corticosteroid prophylaxis for hypersensitivity reactions to low osmolar contrast media in high-risk patients

BACKGROUND

Corticosteroid prophylaxis has been widely adopted for the prevention of acute allergic-like reactions to iodinated contrast media, but its use is still controversial because there is no strong evidence supporting its efficacy before administration of nonionic low osmolar contrast media (LOCM).

OBJECTIVE

To assess the outcomes of premedication in patients with previous acute allergic-like reactions to LOCM in clinical practice.

METHODS

A retrospective study was performed on 322 high-risk patients who were reexposed to LOCM after premedication composed of antihistamines and/or systemic corticosteroids because of a previous history of acute allergic-like reactions to LOCM.

RESULTS

After premedication, 275 patients (85.4%) did not experience any reaction, but 47 patients (14.6%) still experienced a breakthrough reaction. The premedication rate and amount of corticosteroid administered were significantly higher in the nonrecurrence group than in the recurrence group (P = .04 and P = .04, respectively), and a linear trend was observed in the use of corticosteroid premedication and the efficacy of prevention (P for trend = .02). Multivariate binary logistic regression revealed that corticosteroid premedication was effective in preventing recurrence (odds ratio, 0.284; 95% confidence interval, 0.103-0.784). Nonetheless, despite corticosteroid premedication, 3.4% of high-risk patients still experienced moderate to severe reactions, and 14.3% of patients with a severe index reaction again had a severe reaction.

CONCLUSION

Premedication with corticosteroids seems to be helpful in reducing the overall rate of recurrence of acute allergic-like reactions to LOCM in high-risk patients, but patients with severe index reactions are still at risk of developing severe reactions despite corticosteroid premedication.

Safe and Appropriate Use of lodinated Radiographic Contrast Agents: Is There a Reason to Use High-Osmolality lodinated Contrast Agents?

The improved safety profile of low-osmolality compared with high-osmolality iodinated radiographic contrast agents supports the use of low-osmolality iodinated contrast agents in patients with a high risk for adverse reactions to contrast agents. Current pressures in the health care industry to minimize costs may warrant the continued use of high-osmolality agents in patients with relatively low risk for contrast reactions. Health-system management and pharmacists should continue to review the clinical and pharmacoeconomic issues surrounding the use of high-osmolality agents, because market factors have caused the prices of high-osmolality agents and second-generation low-osmolality agents to fluctuate. Moreover, the introduction of new agents will continue to change the risk—benefit–cost relationship.

Administration guidelines and appropriate patient monitoring are important, because both low-osmolality and high-osmolality agents carry the risk of adverse reactions. Pharmacologic pretreatment to alleviate adverse reactions to contrast agents when high-osmolality agents are used should be encouraged. Pharmacists—in cooperation with diagnostic imaging departments—should ensure that the use of iodinated radiographic contrast agents conforms to accepted guidelines.