How to Manage (Treat) Immediate-type Adverse Reactions to GBCA

Acute nonrenal adverse reactions to gadolinium-based contrast agents are infrequent and occur often unexpectedly. Most reactions are self-limiting and do not require treatment. The remaining adverse reactions are either moderate or severe and they require medical treatment. Prompt and effective treatment is very important and requires knowledge, training, and preparation.

Contrast agents in diagnostic imaging: Present and future

Specific contrast agents have been developed for x ray examinations (mainly CT), sonography and Magnetic Resonance Imaging. Most of them are extracellular agents which create different enhancement on basis of different vascularization or on basis of different interstitial network in tissues, but some can be targeted to a particular cell line (e.g. hepatocyte). Microbubbles can be used as carrier for therapeutic drugs which can be released in specific targets under sonographic guidance, decreasing systemic toxicity and increasing therapeutic effect. Radiologists have to choose a particular contrast agent knowing its physical and chemical properties and the possibility of adverse reactions and balancing them with the clinical benefits of a more accurate diagnosis. As for any drug, contrast agents can cause adverse events, which are more frequent with Iodine based CA, but also with Gd based CA and even with sonographic contrast agents hypersensitivity reaction can occur.

How accurate is the label "allergic to iodinated contrast agents"?

BACKGROUND

Iodinated contrast agents (ICAs) are crucial to the use of many imaging studies. Reported allergies to ICAs in the medical record can interfere with optimal diagnostic imaging workups.

PURPOSE

To investigate the accuracy with which the label "allergic to ICAs" is applied.

MATERIAL AND METHODS

The medical records of 500 patients labeled "allergic to ICAs" at a single tertiary care hospital were reviewed. Patients were separated into three groups based on documentation in their medical records, as follows: Group 1, documented hypersensitivity reaction to ICAs; Group 2, documented ICA exposure with non-hypersensitivity adverse event (Group 2a) or without documented reaction (Group 2b); and Group 3, no documented prior exposure to an ICA. We then further reviewed the EMR to determine whether or not patients had subsequent administration of an ICA, whether or not they were given specific premedication, and whether or not they had a subsequent ICA-related event.

RESULTS

A total of 16.6% of patients (n = 83) listed as "allergic to ICAs" had a documented hypersensitivity reaction following ICA administration (Group 1) while 58.6% (n = 293) of patients (Group 2) had a documented exposure to ICAs with either: (i) a non-hypersensitivity adverse event (23.5%, n = 69) or (ii) no record of a reaction to ICAs (76.5%, n = 224). The remaining 24.8% (n = 124), Group 3, had no record of exposure to an ICA, yet still carried the label.

CONCLUSION

The majority of patients carrying the label "allergic to ICAs" had no record of a prior hypersensitivity reaction to ICAs.

Can a structured questionnaire identify patients with reduced renal function?

OBJECTIVES

To evaluate a structured questionnaire in identifying outpatients with renal dysfunction before MRI or CT in various age groups.

METHODS

All patients completed a questionnaire with five risk factors indicating renal dysfunction: renal disease, renal surgery, hypertension, gout and diabetes. Serum creatinine determined by the point-of-care (POC) technique and estimated glomerular filtration (eGFR) rate was calculated using CKD-EPI equation.

RESULTS

A total of 1,467 patients were enrolled. Thirty-four patients (2%) had an eGFR <30 ml/min/1.73 m(2) and 123 (8%) had an eGFR <45 ml/min/1.73 m(2). Among 55% of the 1,467 patients reporting at least one risk factor, 30 (4%) had an eGFR <30 ml/min/1.73 m(2) and 105 (13%) had an eGFR <45 ml/min/1.73 m(2). Among 651 patients not reporting a risk factor, 4 (0.6%) had an eGFR <30 ml/min/1.73 m(2) and 18 (3%) had an eGFR <45 ml/min/1.73 m(2). All four patients were >70 years old, and 12 of the 18 patients were >70 years old.

CONCLUSION

The questionnaire used in patients <70 years old and determination of eGFR in patients >70 years old identified all patients with an eGFR between 30 and 45 ml/min/1.73 m(2) except 0.4%.

KEY POINTS

• A questionnaire can adequately identify patients under 70 with renal dysfunction • 8% of patients referred to CT/MRI have an eGFR <45 ml/min/1.73 m (2) • 55% reported risk factors, but renal dysfunction was only found in 13% • Patients over 70 years should have eGFR determined before CT • eGFR determination is not beneficial when stable MRI agents are used.