Evaluation of the acute adverse reaction of contrast medium with high and moderate iodine concentration in patients undergoing computed tomography

Comparison of Safety and Diagnostic Efficacy of Iohexol 240 mgI/mL, Iopamidol 250 mgI/mL, and Iodixanol 270 mgI/mL in Cerebral Angiography: A Prospective, Multicenter Study

PURPOSE

This multicenter prospective study aimed to evaluate the quality and diagnostic effectiveness of cerebral angiography images obtained using low-concentration iodinated contrast agents (iohexol 240 mgI/mL, iopamidol 250 mgI/mL, and iodixanol 270 mgI/mL) and to assess the safety thereof. The study addresses the need for safer contrast agent alternatives without compromising the diagnostic quality of identifying cerebrovascular disease.

MATERIALS AND METHODS

Conducted in 5 medical centers in South Korea, we enrolled patients aged 19 years or older who were referred for diagnostic cerebral angiography under non-emergency conditions, excluding those with specific health conditions and sensitivities. The study design included a prospective, observational approach with a 1-way analysis of variance (ANOVA) for sample size calculation, aiming for a total sample of 231 participants for adequate power. Image quality was evaluated using a 4-level scale by 2 independent, blinded radiologists, and adverse reactions were monitored both immediately and up to 7 days post-procedure. Statistical analysis involved 1-way ANOVA and Kruskal-Wallis tests to assess the image quality and safety profiles of the contrast agents.

RESULTS

Among 266 patients screened, 243 were included in the final analysis. The evaluation revealed no statistically significant differences in image quality among the 3 types of low-concentration contrast agents. Adverse events were observed in 28.8% of patients, with 27.2% experiencing acute reactions, primarily mild reactions, and 3.3% experiencing delayed reactions. The overall safety profile showed no significant changes in vital signs or electrocardiogram readings before and after contrast agent injection.

CONCLUSION

Using low-concentration iodinated contrast agents for cerebral angiography provides image quality comparable to that of conventional high-concentration agents, with no significant increase in adverse events, suggesting a safer alternative for patients.

Incidence and severity of nonionic low-osmolar iodinated contrast medium-related adverse drug reactions in the Republic of Korea: Comparison by generic

We aimed to report the incidence and severity of nonionic low-osmolar iodine contrast medium (ICM)-related adverse drug reactions (ADRs) in the Republic of Korea, by analyzing data from our single tertiary institution and published Korean reports, and to determine whether there is a difference in the incidence of ICM-related ADR by ICM generics. A total of 1,161,419 consecutive contrast-enhanced computed tomography (CT) examinations between January 2016 and December 2021 at Asan Medical Center were included. A systematic search of the literature investigating the incidence of ICM-related ADR in the Republic of Korea published up to December 31, 2021 was performed. We pooled these outcomes with those of our study using a binomial-normal model, and the pooled incidences of ADRs were compared among ICM generics using chi-square tests. Seven studies with a total of 2,570,986 contrast-enhanced CT examinations from 12 institutions were included. The pooled incidences of overall, mild, moderate, and severe ICM-related ADRs in the Republic of Korea were 0.82% (95% CI: 0.61%-1.10%), 0.72% (95% CI: 0.50%-1.04%), 0.11% (95% CI: 0.08%-0.15%), and 0.013% (95% CI: 0.010%-0.018%), respectively. In multiple pairwise comparisons, there were no significant differences in the overall incidence of ADRs between ICM generics, except iomeprol versus iobitridol and iomeprol versus iohexol. For moderate and severe ADRs, there were no significant differences in ADR incidence between ICM generics. The incidence of moderate and severe ICM-related ADRs did not differ among ICM generics. Our results suggest that no restriction is required for selection among nonionic low-osmolar ICMs.

Preprocedural fasting for contrast-enhanced CT: when experience meets evidence

Traditional preparatory fasting policy prior to iodinated contrast media (ICM) assisted contrast-enhanced CT (CECT) examinations lacks methodologically acceptable evidence. Considering the possible negative effects of preprocedural fasting, the latest European Society of Urogenital Radiology guidelines V10.0 and American Committee of Radiology 2021 guidelines clearly state that preprocedural fasting is not recommended prior to routine intravenous ICM administration. This comprehensive and detailed Review presents the current global dietary preparation policies, potential harm of excessive fasting, and a systematical and well-bedded description of practice advancements of dietary preparation. The evidences revealed that there has been no single instance of vomiting-associated aspiration pneumonia due to the undemanding implementation of preparatory fasting prior to CECT yet. Non-fasting would not increase the incidence of emetic symptoms and the risk of aspiration pneumonia. Not every patient should undergo all CECT examinations without preparatory fasting. There is still much more refinement to be done on the preparatory fasting policy. Changes in traditional preparatory fasting policy will make positive and significant implications on clinical practice. This Review aims to provide operational guidance and suggestions for practitioners and policymakers, motivate efficient, reasonable, safe and normative ICM usage, and achieve optimal patient clinical benefits and high-quality radiological care practices.

MRGPRX2 mediates immediate-type pseudo-allergic reactions induced by iodine-containing iohexol

BACKGROUND

Iohexol is a typical iodinated radiocontrast medium and widely used in clinical angiography. Hypersensitivity reactions induced by iohexol are common side effects known to increase the risk for patients. Iodine is the main functional group of iohexol, and it can induce delayed anaphylaxis. However, iohexol also induces immediate-type allergies, but the underlying mechanism is still not clear. MRGPRX2 is a key receptor present on mast cells, which mediates pseudo-allergic reactions induced by various drugs.

METHODS

We aimed to verify the relationship between iohexol-induced anaphylactic reactions and MRGPRX2. MRGPRX2-mediated pseudo-allergic reactions induced by iohexol were investigated in vivo and in vitro using a mouse model of local and systemic anaphylaxis and mast cell degranulation assays, respectively.

RESULTS

Iohexol caused pseudo-allergic reactions in wild-type (WT) mice by activating mast cells to release histamine and cytokines. However, it did not induce a similar phenomenon in Kit^W-sh/W-sh (MUT) mice. Iohexol stimulated intracellular calcium ion (Ca²⁺) influx in MRGPRX2-HEK293, MrgprB2-HEK293, and LAD2 cells but not in NC-HEK293 cells. After knockdown of MRGPRX2 expression in LAD2 cells, the degree of iohexol-induced degranulation was reduced. In addition, after structural modification of iohexol by removal of iodine, a reduction in iohexol-induced effects, such as local and systemic anaphylaxis in mice and degranulation of LAD2 cells, could be observed. Iohexol was shown to induce immediate-type pseudo-allergic reactions via MRGPRX2, which was dependent on the presence of iodine.

CONCLUSIONS

Conclusively, inhibition of MRGPRX2-mediated mast cell degranulation and cytokine release is important to prevent iohexol-induced immediate-type pseudo-allergic reactions.

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.

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.

Is gender still a predisposing factor in contrast-media associated adverse drug reactions? A systematic review and meta-analysis of randomized trials and observational studies

OBJECTIVE

To evaluate the role of gender as a risk factor for developing contrast media-associated adverse drug reactions (CM-ADRs) by comparing the incidence of CM-ADR between male and female patients according to study design, ADR type, and computed tomography (CT) examination.

MATERIAL AND METHODS

We systematically searched three electronic databases for eligible studies. In the studies included (n=18), we assessed effect estimates of the relative incidence of CM-ADR, analysed by experimental design, ADR type and CT examination. This was calculated by using a random effects model if clinical conditions showed heterogeneity; otherwise, a fixed effects model was used.

RESULTS

We identified 10,776 patients administered CM. According to the designs, studies were classified into randomised controlled trials (RCTs) and observational studies. Results were as follows: risk ratio (RR)=1.07 (95% confidence interval (CI): 0.79-1.46, P=0.66) for RCTs, and RR=0.77 (95% CI: 0.58-1.04, P=0.09) for observational studies. The results of analysis according to ADR type and for undergoing CT demonstrated that the incidence of CM-ADR did not differ between males and females.

CONCLUSIONS

We found no significant difference in the incidence of CM-ADRs between male and female patients according to study design, ADR type, or CT examination. Future studies to determine why gender has shown different roles as a risk factor between CM-ADRs and non-CM ADRs are needed.

Cerebral computed tomography angiography using a low tube voltage (80 kVp) and a moderate concentration of iodine contrast material: a quantitative and qualitative comparison with conventional computed tomography angiography

OBJECTIVE

To investigate the feasibility of an 80-kVp protocol using a moderate concentration contrast material (MC-CM) for cerebral computed tomography angiography by comparison with a conventional 120-kVp protocol using a high concentration contrast material (HC-CM).

MATERIALS AND METHODS

Attenuation values and signal-to-noise ratios (SNRs) were determined in a head phantom for 2 tube voltages (80 and 120 kVp) and 2 different iodine concentration contrast materials (HC-CM and MC-CM). Among 90 consecutive patients, 45 patients were scanned with 120 kVp and 150 mAs(eff) after administration of 70 mL of HC-CM (370 mg iodine [mgI]/mL), whereas the other 45 patients were scanned with 80 kVp and 370 mAs(eff) after administration of 70 mL of MC-CM (300 mgI/mL). The Hounsfield units (HU) of the internal carotid artery T junction, SNR, contrast-to-noise ratio (CNR), subjective degree of arterial enhancement, image noise, sharpness of the cerebral arterial boundary, and overall diagnostic image quality were compared between the 2 groups.

RESULTS

The mean attenuation of the internal carotid artery T junction, SNR, and CNR was significantly higher in the 80 kVp with MC-CM group (379.2, 33.7, and 31.1 HU, respectively) than in the 120 kVp with HC-CM group (282.2, 31.1, and 27.2 HU, respectively). The 80-kVp protocol resulted in significantly higher score in arterial enhancement, sharpness of the cerebral arteries, and overall diagnostic image quality. The effective dose of 80 kVp (0.7 mSv) was 22.2% lower than that of 120 kVp (0.9 mSv).

CONCLUSIONS

The use of 80 kVp with MC-CM improved arterial enhancement, SNR, and CNR and provided superior quality images using a smaller amount of iodine and a lower radiation dose than the conventional protocol of 120 kVp with HC-CM.