Stratified premedication strategy for the prevention of contrast media hypersensitivity in high-risk patients

N-(2,3-dihydroxypropyl) carbamoyl side chain: a potentially significant factor for recurrent iodinated contrast medium-related adverse drug reactions

PURPOSE

To determine whether switching to contrast media based on the sharing of N-(2,3-dihydroxypropyl) carbamoyl side chain reduces the recurrence of iodinated contrast media (ICM)-associated adverse drug reactions (ADRs).

MATERIALS AND METHODS

This single-center retrospective study included 2133 consecutive patients (mean age ± SD, 56.1 ± 11.4 years; male, 1052 [49.3%]) who had a history of ICM-associated ADRs and underwent contrast-enhanced CT examinations. The per-patient and per-exam-based recurrence ADR rates were compared between cases of switching and non-switching the ICM from ICMs that caused the previous ADRs, and between cases that used ICMs with common and different carbamoyl side chains from ICMs that caused the previous ADRs. Downgrade rates (no recurrence or the occurrence of ADR less severe than index ADRs) were also compared. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) analysis were additionally performed.

RESULTS

In per-patient analysis, switching of ICM showed a lower recurrence rate (switching, 10.4% [100/965] vs. non-switching, 28.4% [332/1168]), with the adjusted odds ratio (OR) of 0.27 (95% CI: 0.21, 0.34; p < 0.001). The result was consistent in PSM (OR, 0.29 [95% CI: 0.22, 0.39]; p < 0.001), IPTW (OR, 0.28 [95% CI: 0.22, 0.36]; p < 0.001), and in per-exam analysis (5.5% vs. 13.8%; OR, 0.32 [95% CI: 0.27, 0.37]; p < 0.001). There was lower per-exam recurrence (5.0% [195/3938] vs. 7.8% [79/1017]; OR, 0.63 [95% CI: 0.47, 0.83]; p = 0.001) and higher downgrade rates (95.6% [3764/3938] vs. 93.3% [949/1017]; OR, 1.51 [95% CI: 1.12, 2.03]; p = 0.006) when using different side chain groups.

CONCLUSION

Switching to an ICM with a different carbamoyl side chain reduced the recurrent ADRs and their severity during subsequent examinations.

CLINICAL RELEVANCE STATEMENT

Switching to an iodinated contrast media with a different carbamoyl side chain reduced the recurrent adverse drug reactions and their severity during subsequent examinations.

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.

Exploring Factors Affecting the Occurrence of Hypersensitivity Reactions Induced by Nonionic Iodine Contrast Media

Hypersensitivity reactions induced by nonionic iodine contrast media sometimes occur and can be life threatening. However, independent factors affecting their occurrence remain to be fully established. Therefore, the purpose of this study was to clarify independent factors affecting the occurrence of hypersensitivity reactions induced by nonionic iodine contrast media. Patients who received nonionic iodine contrast media at Keiyu Hospital from April 2014 to December 2019 were included. The adjusted odds ratio (OR) and 95% confidence interval (CI) for factors affecting hypersensitivity reactions induced by contrast media were calculated by logistic regression analysis. The multiple imputation method was used to impute missing data. Hypersensitivity reactions occurred in 0.72% (163 cases) of 22,695 cases enrolled in this study. In univariate analysis, 10 variables met the criteria of P < .05 and proportion of missing data <50%. In multivariate analysis, age (OR, 0.98; 95% CI, 0.97-0.99), outpatient status (OR, 2.08; 95% CI, 1.20-3.60), contrast medium iodine content (OR, 1.02; 95% CI, 1.01-1.04), history of drug allergy (OR, 2.41; 95% CI, 1.50-3.88), and asthma (OR, 17.4; 95% CI, 7.53-40.1) were identified as independent factors affecting contrast media-induced hypersensitivity reactions. Among these factors, history of drug allergy and asthma appear to be clinically relevant and reliable due to their high OR and plausible biological mechanisms, but the other three factors require further validation.

Clinical features and risk factors of iodinated contrast media (ICM)-induced anaphylaxis

PURPOSE

To evaluate the clinical features and risk factors of iodinated contrast media (ICM)-induced anaphylaxis.

METHODS

This retrospective study included all patients undergoing contrast-enhanced computed tomography (CT) with intravenous ICM administration (iopamidol, iohexol, iomeprol, iopromide, ioversol) at our hospital between April 2016 and September 2021. Medical records of patients who experienced anaphylaxis were reviewed, and the multivariable regression model using generalized estimating equations was employed to eliminate the effect of intrapatient correlation.

RESULTS

Of the 76,194 ICM administrations (44,099 men [58 %] and 32,095 women; age, median, 68 years) to 27, 696 patients, anaphylaxis occurred in 45 cases in 45 different patients (0.06 % of administration and 0.16 % of patients), all with onset within 30 min after administration. Thirty-one (69 %) had no risk factors for ADRs, including 14 (31 %) who had previously used the same ICM that caused anaphylaxis. Thirty-one patients (69 %) had a history of ICM use without any ADRs. Four patients (8.9 %) received oral steroid premedication. The only factor associated with anaphylaxis was the type of ICM, with an odds ratio (OR) of 6.8 (p < 0.001) for iomeprol with iopamidol as a reference. No significant differences in OR of anaphylaxis were found for patients' age, sex, or premedication.

CONCLUSION

The overall incidence of anaphylaxis due to ICM was very low. More than half of the cases had no risk factors for ADRs and had no ADRs on past ICM administration, although the ICM type was associated with a higher OR.

Low dose of contrast agent and low radiation liver computed tomography with deep-learning-based contrast boosting model in participants at high-risk for hepatocellular carcinoma: prospective, randomized, double-blind study

OBJECTIVE

To investigate the image quality and lesion conspicuity of a deep-learning-based contrast-boosting (DL-CB) algorithm on double-low-dose (DLD) CT of simultaneous reduction of radiation and contrast doses in participants at high-risk for hepatocellular carcinoma (HCC).

METHODS

Participants were recruited and underwent four-phase dynamic CT (NCT04722120). They were randomly assigned to either standard-dose (SD) or DLD protocol. All CT images were initially reconstructed using iterative reconstruction, and the images of the DLD protocol were further processed using the DL-CB algorithm (DLD-DL). The primary endpoint was the contrast-to-noise ratio (CNR), the secondary endpoint was qualitative image quality (noise, hepatic lesion, and vessel conspicuity), and the tertiary endpoint was lesion detection rate. The t-test or repeated measures analysis of variance was used for analysis.

RESULTS

Sixty-eight participants with 57 focal liver lesions were enrolled (20 with HCC and 37 with benign findings). The DLD protocol had a 19.8% lower radiation dose (DLP, 855.1 ± 254.8 mGy·cm vs. 713.3 ± 94.6 mGy·cm, p = .003) and 27% lower contrast dose (106.9 ± 15.0 mL vs. 77.9 ± 9.4 mL, p < .001) than the SD protocol. The comparative analysis demonstrated that CNR (p < .001) and portal vein conspicuity (p = .002) were significantly higher in the DLD-DL than in the SD protocol. There was no significant difference in lesion detection rate for all lesions (82.7% vs. 73.3%, p = .140) and HCCs (75.7% vs. 70.4%, p = .644) between the SD protocol and DLD-DL.

CONCLUSIONS

DL-CB on double-low-dose CT provided improved CNR of the aorta and portal vein without significant impairment of the detection rate of HCC compared to the standard-dose acquisition, even in participants at high risk for HCC.

KEY POINTS

• Deep-learning-based contrast-boosting algorithm on double-low-dose CT provided an improved contrast-to-noise ratio compared to standard-dose CT. • The detection rate of focal liver lesions was not significantly differed between standard-dose CT and a deep-learning-based contrast-boosting algorithm on double-low-dose CT. • Double-low-dose CT without a deep-learning algorithm presented lower CNR and worse image quality.

Contrast Agent Selection to Prevent Recurrent Severe Hypersensitivity Reaction to Iodinated Contrast Media Based on Nationwide Database

OBJECTIVE

To investigate the incidence of severe iodinated contrast media (ICM)-related hypersensitivity reaction (HSR) and to find the optimal alternative ICM to reduce the risk of severe HSR recurrence.

METHODS

We retrospectively reviewed 23,383,183 cases of ICM administration between January 2015 and December 2019 from the nationwide health insurance database. We classified ICMs based on generic profiles and the presence of N-(2,3-dihydroxypropyl) carbamoyl side chains. The incidence of severe and recurrent severe HSRs was calculated, and χ2 tests were performed to compare the prevalence of severe HSR according to ICM groups. In addition, logistic regression analyses were used to assess differences between ICM groups.

RESULTS

The incidence of severe HSRs was 1.92% (450,067 of 23,282,183). Among 1,875,245 individuals who received ICM twice on different days, severe HSR occurred in 40,850 individuals, and severe HSR recurred in 3319 individuals (8.12%). The risk of recurrence significantly decreased when the ICM changed (9.24% vs 7.08%, P < 0.001), especially when the ICM changed to one with a different side chain (6.74%, P < 0.001). In addition, compared with the reuse of the culprit agent, using combinations of iobitridol/iohexol (odds ratio [OR], 0.696; P = 0.04), iohexol/iopamidol (OR, 0.757; P = 0.007), iopamidol/iohexol (OR, 0.447; P < 0.001), and ioversol/iohexol (OR, 0.683; P = 0.04) reduced the risk of recurrence of severe HSR.

CONCLUSIONS

Changing the culprit ICM to that with a different side chain can reduce severe HSR recurrence. The optimal choice of an alternative ICM depends on the causative agent.

Stratified assessment and warning regimen for prevention of acute adverse reactions to iodinated contrast media: results of 150,343 cases in a tertiary hospital

For contrast-enhanced CT examinations, there is a lack of comprehensive optimal management strategies of risk factors to reduce the risk of iodinated contrast media (ICM)-induced acute adverse reactions (AAR). Here, we determine the relationship between the rate of ICM-AAR and a stratified assessment and warning (SAW) regimen, which integrated risk identification, stratification, early warning, and prevention. A total of 120,822 cases in the conventional assessment period (58 years ± 15, 55.25% men) and 150,343 cases (58 years ± 14, 55.83% men) in the SAW period were enrolled. The results showed that the total AAR incidence in the SAW period (414/150,343, 0.28%) was lower than that in the conventional assessment period (506/120,822, 0.42%, P < 0.001), in which the proportion of AAR patients decreased by one-third. It mainly presented as decreases in mild and moderate reactions (P < 0.001), and a decrease in the proportion of moderate AAR patients (P = 0.001). Subgroup analysis showed lower mild and moderate AAR incidence in patients with different risk levels and with different ICM injection parameters following SAW regimen. We concluded that SAW regimen was associated with lower incidence of mild and moderate AAR, and decreased proportion of moderate AAR patients, which held potential for improved ICM safety.

Validation of Practical Pathway in Patients With Anaphylaxis to Low Osmolar Contrast Media: A Retrospective Cohort Study

BACKGROUND

An optimal strategy for choosing safe alternative low osmolar contrast media (LOCM) has not yet been established in patients with a history of LOCM-induced anaphylaxis.

OBJECTIVES

To validate the practical pathway in patients with anaphylaxis to LOCMs and to compare 2 different doses of challenge testing with skin test-negative LOCM.

METHODS

A retrospective cohort study was performed in patients with LOCM-induced anaphylaxis. Patients were challenged with intravenous LOCMs showing negativity in the skin test according to 2 different protocols: low-dose and high-dose (maximum dose 10 and 30 mL, respectively). Challenge-negative LOCMs were selected for use during computed tomography scans, and patients received intravenous pretreatment with 4 mg chlorpheniramine and 40 mg methylprednisolone.

RESULTS

Of the 110 challenge tests, there were 4 (3.6%) positive challenges. Among 106 enhanced computed tomography scans performed using challenge-negative LOCMs, breakthrough reactions occurred in 8 (7.6%). Breakthrough reaction rates were not statistically different between the 2 protocols (8.9% and 6.0% in the low-dose challenge and the high-dose challenge, respectively). Compared with the low-dose protocol, the number needed to test of the high-dose challenge test decreased 2.5-fold. Moreover, none of the patients in the high-dose challenge group incurred severe reactions during computed tomography scans with challenge-negative LOCM, whereas 80% of reactions were severe in the low-dose challenge group.

CONCLUSIONS

We validated a pathway consisting of a battery of skin testing to LOCMs and challenge with skin test-negative LOCM in patients with LOCM-induced anaphylaxis.

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.

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.

Allergic-like Hypersensitivity Reactions to Gadolinium-based Contrast Agents: An 8-year Cohort Study of 154 539 Patients

Background With the widespread use of gadolinium-based contrast agents (GBCAs), the incidence of allergic-like hypersensitivity reactions (HSRs) to GBCAs is increasing. Research on the incidence and risk factors for HSRs to GBCAs is needed for their safe use. Purpose To determine the incidence of acute and delayed reactions to GBCAs and to discuss the risk factors and strategies for the prevention of HSRs to GBCAs. Materials and Methods All cases of HSRs to contrast media that occurred at the Seoul National University Hospital from July 1, 2012, to June 30, 2020, were assessed. Information including age, sex, GBCA type, onset, and severity of HSRs was retrospectively analyzed. Results Among the 331070 cases of GBCA exposure in 154539 patients, 1304 cases of HSRs (0.4%) were reported. Acute HSRs accounted for 1178 cases (0.4%), while 126 cases (0.04%) were delayed HSRs. While both premedication (odds ratio [OR] = 0.7, P = .041) and changing the type of GBCA (OR = 0.2, P < .001) showed preventative effects in patients with a history of acute HSRs, only premedication (OR = 0.2, P = .016) significantly reduced the incidence of HSRs in patients with a history of delayed reactions. The risk of an HSR to GBCA was higher in those with a history of an HSR to iodinated contrast media (OR = 4.6, P < .001). Conclusion The rate of hypersensitivity reactions (HSRs) to gadolinium-based contrast agents (GBCAs) was 0.4%. The absence of premedication, repeated exposures to the culprit GBCA, and a history of HSRs to iodinated contrast media and GBCAs were risk factors for HSRs to GBCAs. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Kallmes and McDonald in this issue.

Diagnosis and Prevention of Hypersensitivity Reactions to Iodinated Contrast Media

Iodinated contrast media (ICM) have become one of the major causes of drug hypersensitivity reactions (HSRs) related to increasing numbers of ICM-based radiological imaging procedures. Strategies for diagnosing and preventing ICM-induced HSRs have not been uniformly standardized yet. However, advances have been made based on the results of recent research. A previous history of hypersensitivity to ICM is the most significant risk factor for developing HSR by ICM. Avoidance of culprit agents and premedication is the main strategy to prevent recurrences of HSRs in high-risk patients. In addition, we strongly recommend identifying sensitized ICM using skin tests to determine immunoglobulin E-mediated or delayed-type allergy and to guide the choice of an alternative contrast agent. ICM provocation test procedures have been established and are helpful in selected cases. In this paper, we review how to evaluate patients who have experienced immediate or delayed HSRs caused by ICM to minimize the risk of recurrence and discuss unmet needs that require further research.

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.

Finding the Optimal Alternative for Immediate Hypersensitivity to Low-Osmolar Iodinated Contrast

OBJECTIVES

Avoiding culprit agents is recommended for subjects who have had previous hypersensitivity reaction (HSR) to low-osmolar contrast media (LOCM). However, the guidelines for choosing optimal alternatives have not been determined. We investigated the outcomes of reexposure in patients with previous immediate HSRs to provide a safe option.

MATERIALS AND METHODS

The outcomes of reexposure were assessed in a cohort with previous LOCM-associated HSR based on skin testing results and the presence of a common N-(2,3-dihydroxypropyl) carbamoyl side chain.

RESULTS

Among 482 skin tests, 38.7% (31/80), 45.8% (99/216), and 64.0% (119/186) of mild, moderate, and severe index HSRs showed positivity to at least 1 LOCM, of which 62.8% showed positivity to at least 2 different LOCM. The overall recurrent HSRs were reduced from 43.8% upon reexposure to the culprit LOCM to 12.3% upon using nonculprit skin test negative LOCM (P = 0.004); those with severe index HSRs exhibited a significant reduction (11.3% vs 100%), but those with non-severe HSRs to LOCM did not. In subjects with severe index HSRs, the skin test cross-reactivity between LOCM was associated with sharing the common side chain (20.7% vs 11.5%, P = 0.003), and the recurrence rate of HSRs was effectively reduced by avoiding the common side chain (24.0% vs 7.8%, P = 0.039). However, these differences were not observed in those with non-severe index HSRs.

CONCLUSIONS

In patients who experienced a severe index HSR to LOCM, skin test negative LOCM without a common side chain could be suggested as an option for safe reexposure.

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.

COVID-19 Vaccination in Mastocytosis: Recommendations of the European Competence Network on Mastocytosis (ECNM) and American Initiative in Mast Cell Diseases (AIM)

Mastocytosis is a neoplasm characterized by an accumulation of mast cells in various organs and increased risk for severe anaphylaxis in patients with concomitant allergies. Coronavirus disease 2019 (COVID-19) is a pandemic that is associated with a relatively high rate of severe lung disease and mortality. The mortality is particularly high in those with certain comorbidities and increases with age. Recently, several companies have developed an effective vaccination against COVID-19. Although the reported frequency of severe side effects is low, there is an emerging discussion about the safety of COVID-19 vaccination in patients with severe allergies and mastocytosis. However, even in these patients, severe adverse reactions are rare. We therefore recommend the broad use of COVID-19 vaccination in patients with mastocytosis on a global basis. The only well-established exception is a known or suspected allergy against a constituent of the vaccine. Safety measures, including premedication and postvaccination observation, should be considered in all patients with mastocytosis, depending on the individual personal risk and overall situation in each case. The current article provides a summary of published data, observations, and expert opinion that form the basis of these recommendations.

Risk of Hypersensitivity Reactions to Iopromide After Intra-Arterial Versus Intravenous Administration: A Nested Case-Control Analysis of 133,331 Patients

Objective

The aim of this study was to compare the risk of hypersensitivity reactions to iopromide after intra-arterial (IA) administration and intravenous (IV) administration.

Materials and Methods

Four observational studies were pooled. Almost half of the study population (48.1%) was from Europe, and one quarter each from China (27.6%) and other Asia countries (24.1%). All patients received iopromide either intra-arterially or intravenously for angiographic procedures (mostly cardio-angiography) or contrast-enhanced computed tomography. A nested case-control analysis, including a multivariable logistic regression model, was performed. Cases were defined by patients with a typical and unequivocal hypersensitivity (assumed non–IgE-mediated) reaction; controls were patients without any recorded reaction. The primary target variable is the odds ratio of having a hypersensitivity reaction after IA versus IV administration.

Results

A total of 133,331 patients met the inclusion criteria, 105,460 and 27,871 patients received iopromide IV or IA, respectively. Hypersensitivity reactions were recorded for 822 patients, and 132,509 patients served as controls.

Major risk factors for hypersensitivity reactions were method of injection (IV vs IA), age (18 to <50 years vs ≥65 years), history of allergy or previous contrast media reaction (all P < 0.001), and asthma (P = 0.005).

A total of 766 patients (0.7%) and 56 patients (0.2%) were recorded with hypersensitivity reactions after IV or IA administration, respectively (P < 0.0001).

Adjusted odds ratio (IA vs IV) was 0.23 (95% confidence interval, 0.16–0.32) for all countries together: for China only, 0.22 (0.11–0.44); for all countries without China, 0.36 (0.25–0.53).

Most frequent reactions were erythema/urticaria/rash, pruritus, and cough/sneezing.

Conclusions

Hypersensitivity reactions to iopromide were significantly less frequently recorded after IA administrations. This could be related to the delayed and diluted arrival of iopromide to the lungs.

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.

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.

Acute Adverse Reactions to Nonionic Iodinated Contrast Media: A Meta-Analysis

OBJECTIVES

We aimed to meta-analytically compare the incidence of acute adverse reactions (AARs) to nonionic iodinated contrast media (ICM) according to the type of ICM in patients who underwent radiologic examinations with administration of ICM via intravascular route.

MATERIALS AND METHODS

A systematic literature search identified studies evaluating the incidence of AARs to 7 nonionic ICM (iobitridol, iohexol, iomeprol, iopamidol, iopromide, ioversol, and iodixanol) with extractable outcomes. These outcomes were pooled using a random-effects model, and the effect of ICM type on the incidence of overall and severe AARs was evaluated using meta-regression analysis.

RESULTS

Thirty studies with 1,360,488 exposures to ICM were included. The pooled incidences of overall and severe AARs to nonionic ICM were 1.03% (95% confidence interval [CI], 0.81%-1.30%; I = 0.99) and 0.0141% (95% CI, 0.0108%-0.0183%; I = 0.56), respectively. Iomeprol had the highest overall AAR incidence (1.74%; 95% CI, 0.79%-3.76%; I = 0.99), followed by iohexol (1.21%; 95% CI, 0.67%-2.17%; I = 0.99), iopamidol (1.10%; 95% CI, 0.60%-2.03%; I = 0.99), ioversol (0.88%; 95% CI, 0.43%-1.83%; I = 0.96), iodixanol (0.85%; 95% CI, 0.36%-1.95%; I = 0.99), iopromide (0.82%; 95% CI, 0.43%-1.55%; I = 0.99), and iobitridol (0.77%; 95% CI, 0.36%-1.62%; I = 0.99). Multivariable meta-regression analysis revealed that study design (P = 0.0014) and premedication (P = 0.0230) were statistically significant determinants affecting the incidence of overall AARs. Iodinated contrast media type did not affect the incidence of overall and severe AARs (P = 0.1453 and 0.4265, each).

CONCLUSIONS

The varying pooled incidences of overall and severe AARs to specific types of nonionic ICM do not remain as significant after adjusting confounders. Our results may support nonrestriction of certain types of nonionic ICM in the context of AAR avoidance.

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.

Hypersensitivity Reactions to Iodinated Contrast Media: A Multicenter Study of 196 081 Patients

Background Multicenter studies may be required for establishing guidelines for safe usage of iodinated contrast media (ICM). Purpose To identify the prevalence, patterns, risk factors, and preventive measures for ICM-related hypersensitivity reactions (HSRs). Materials and Methods Between March 2017 and October 2017, a total of 196 081 patients who underwent ICM administration were enrolled from seven participating institutions. The occurrence of HSRs and baseline patient information were recorded. χ² and Student t test were performed, and logistic regression analyses were used to identify risk factors that predict occurrence and recurrence of HSR. Results Among 196 081 patients (mean age ± standard deviation, 59.1 years ± 16.0; 105 014 men and 91 067 women) who underwent ICM administration, the overall prevalence of HSRs was 0.73% (1433 of 196 081), and severe reactions occurred in 0.01% (17 of 196 081). Conditional logistic regression for patients with HSR (n = 1433) and a control group (1:1 matched group for age, sex, ICM product, and institution) demonstrated that a patient's previous individual history of an ICM-related HSR (adjusted odds ratio [OR], 198.8; P < .001), hyperthyroidism (adjusted OR, 3.6; P = .04), drug allergy (adjusted OR, 3.5; P < .001), and other allergic diseases (adjusted OR, 6.8; P < .001) and a family history of ICM-related HSRs (adjusted OR, 14.0; P = .01) were predictors of HSR occurrence. Logistic regression analysis showed that use of premedication with antihistamine (OR, 0.5; P = .01) and change in the generic profile of ICM (OR, 0.5; P < .001) were preventive against recurrent HSR. Conclusion Family history as well as previous individual history of hypersensitivity reactions (HSRs) to iodinated contrast media (ICM) were risk factors for HSR occurrence, suggesting a potential genetic predisposition. A change in the culprit ICM and premedication with antihistamine are useful for reducing the recurrence of HSRs. © RSNA, 2019 Online supplemental material is available for this article.

Practical administration of intravenous contrast media in children: screening, prophylaxis, administration and treatment of adverse reactions

Administration of intravenous contrast media to children is a routine practice at many clinical imaging centers, that can involve special considerations. In this paper, we provide practical information to facilitate optimal performance and oversight of this task. We provide targeted screening questions that can help to identify high-risk pediatric patients for both iodine-based and gadolinium-based intravenous contrast media administration. These include children at risk for allergic-like reactions, thyroid dysfunction, contrast-induced nephropathy, and nephrogenic systemic fibrosis. We make recommendations for addressing "yes" responses to screening questions using risk stratification schema that are specific to children. We also present criteria for selecting children for premedication prior to intravenous contrast administration, and suggest pediatric regimens. Additionally, we discuss practical nuances of intravenous contrast media administration to children and provide a quick-reference table of appropriate treatments with pediatric dosages for adverse contrast reactions.

Management of Adverse Reactions to Iodinated Contrast Media for Computed Tomography in Korean Referral Hospitals: A Survey Investigation

Objective

To evaluate the current status of managing adverse reactions to iodinated contrast media (ICM) for computed tomography in referral hospitals in South Korea compared with hospitals in other countries.

Materials and Methods

This survey investigation involved 59 Korean and 15 overseas hospitals using guideline-based questionnaires consisting of 24 items in 7 main categories related to managing adverse reactions to ICM.

Results

Informed written consent with risk factor evaluation was appropriately performed in most of the Korean hospitals. There was considerable variability in assessing renal function across the hospitals; serum creatinine level was used as a reference in 76.4% of Korean hospitals. The Korean hospitals preferred a more stringent approach to determining normal renal function (p = 0.01), withholding metformin (p = 0.01), and fasting before ICM exposure (p < 0.001) compared with overseas hospitals. All the Korean hospitals had an emergency protocol and in-hospital system for adverse reactions to ICM. The Korean (87.7%) and overseas hospitals (100%) were similarly equipped with epinephrine (p = 0.332), but only 38.6% of Korean hospitals were equipped with a bronchodilator (p = 0.004). For patients with a previous hypersensitivity reaction to ICM, 62.3% of Korean hospitals pre-medicated with anti-histamine and corticosteroid according to the severity of the previous reaction, and changed the culprit ICM in 52.8%, while skin test was performed in 17%.

Conclusion

In general, Korean referral hospitals were well-prepared regarding informed consent, protocol, and an in-hospital system for managing adverse reactions to ICM. Nevertheless, there was considerable variability in details and management, thus requiring standardization by reflecting current guidelines.

Managing Adverse Reactions to Contrast Agents

Adverse reactions to iodinated and gadolinium-based contrast agents occur at an incidence of less than 1%. Although the exact pathophysiologic mechanisms are not completely understood, the treatment regimens are well accepted. Skin testing may be helpful in patients with a history of severe allergiclike reaction to aid in the selection of alternative contrast agents. Premedication should only be used for a history of allergiclike reaction. Imaging team members should be familiar with signs and symptoms of contrast reactions to allow for prompt assessment and treatment. A plan of action should be in place for contrast reactions and rehearsed regularly.

Nausea and vomiting after exposure to non-ionic contrast media: incidence and risk factors focusing on preparatory fasting

OBJECTIVE

To prospectively evaluate the incidence of nausea and vomiting after exposure to non-ionic iodinated contrast media (ICM), and to identify potential risk factors, with a focus on fasting duration for solid food and fluids, separately.

METHODS

From January to March 2017, 1175 patients (605 males, 570 females; median age, 60 years; range, 20-91 years) undergoing ICM-enhanced CT were included in this study. Patients received instructions for a 6 h preparatory fast from solid food. Nausea and vomiting after ICM exposure were assessed on a 3-point scale (mild, moderate, severe). Patients' characteristics and the fasting duration were evaluated to identify risk factors using logistic regression analysis.

RESULTS

Of the 1175 patients, 34 [2.9%; 95% confidence interval (CI) (2.0-4.0)] experienced mild nausea. No patients experienced vomiting [95% CI (0.0000-0.0005)]. 1173 (99.8%) carried out a 6 h fast, and the median fasting durations were 14 h for solid food (interquartile range, 12.5-15.5 h) and 11 h for fluid (interquartile range, 0-13.5 h), respectively. Fasting durations for solid food and fluids were not associated with nausea on univariate regression analyses (p = 0.282-1.000 and  0.146-1.000, respectively). Multivariate regression analysis revealed that a history of drug hypersensitivity [odds ratio = 4.33; 95% CI (1.85-17.52); p = 0.039] was independent risk factors for nausea, whereas iobitridol was less nauseous [odds ratio = 0.32; 95% CI (0.11-0.90); p = 0.032].

CONCLUSION

Mild nausea occurred in 2.9% of patients and none vomited in our study population with a 6 h preparatory fast from solid food. Many patients underwent excessive fasting for fluids as well as solid food and their fasting durations were not associated with nausea. Advances in knowledge: We firstly evaluated fasting durations for solid food and fluids, and their impacts on vomiting or nausea after ICM exposure with an instruction of 6 h preparatory fast for solid food: many patients underwent excessive fasting for fluids and the fasting duration was unrelated to nausea.

Incidence of Breakthrough Reaction in Patients with Prior Acute Allergic-Like Reactions to Iodinated Contrast Media according to the Administration Route

Objective

This study assessed the risk of acute allergic-like reactions (AARs) after extravascular administration of iodinated contrast media (ICM) in at-risk patients compared with that after intravascular ICM administration.

Materials and Methods

From July 2012 to January 2016, 264 patients with a history of moderate or severe reactions to ICM, with re-exposure to ICM intravascularly or extravascularly were included. The incidence of recurrent AARs after ICM re-exposure were assessed according to the administration routes by reviewing electronic medical records and comparison between the two routes.

Results

Among 264 patients, 244 patients had been subsequently exposed to ICM intravascularly, 7 patients via an extravascular route and 13 patients with dual re-exposure. Of 257 patients with intravascular ICM re-exposure, 87 (33.9%) had mild to severe recurrent AARs and 143 (19.5%) cases of recurrent AARs occurred among 733 cases of intravascular ICM re-exposure on a case-by-case basis. However, there was no case of recurrent ARR after extravascular administration of ICM in 20 patients (45 cases) with ICM administrated extravascularly.

Conclusion

For high-risk patients with a history of moderate or severe reactions to ICM, AARs upon extravascular administration of ICM are significantly infrequent compared with intravascular ICM administration.