Safety review of gadopentetate dimeglumine. Extended clinical experience after more than five million applications

Negligible Risk of Acute Renal Failure Among Hospitalized Patients After Contrast-Enhanced Imaging With Iodinated Versus Gadolinium-Based Agents

INTRODUCTION

The potential adverse renal outcome among patients undergoing iodine-based contrast-enhanced computerized tomography (CT) has been questioned recently, given the caution undertaken in patients' selection, hydration protocols, and the low radiocontrast volume, used with advanced imaging equipment.

MATERIALS AND METHODS

This study is a retrospective assessment of renal outcome in 12,580 hospitalized patients undergoing contrast-enhanced CT, compared with 754 patients subjected to gadolinium-based magnetic resonance imaging, with subsequent propensity matching for clinical characteristics and potential risk factors.

RESULTS

The risk of postcontrast acute kidney injury (PC-AKI) was found to be negligible as compared with patients undergoing enhanced magnetic resonance imaging studies, before and after propensity matching (8% vs 7.3% rate of AKI in the nonmatched iodine-based contrast agents [IBCAs] and gadolinium-based contrast agents [GBCAs], respectively, P = 0.3, and 7% in the matched IBCA group, P = 0.9), including comparisons among subgroups with well-defined risk factors such as chronic renal failure, diabetes, older age, and hypertension. However, lower systolic blood pressure before imaging was associated with higher risk to develop PC-AKI after IBCA administration but not with GBCA (for systolic blood pressure lower than 110 mm Hg, odds ratio for AKI after IBCA was 1.49; 95% confidence interval, 1.16-1.88, and after GBCA; odds ratio, 0.12; 95% confidence interval, 0.003-0.73).

CONCLUSIONS

With the current precautions undertaken, the real-life risk of PC-AKI among inpatients undergoing CT is insignificant. Possible reasons for the diverse impact of blood pressure on the propensity to develop acute kidney failure after iodine-based but not gadolinium-based enhancement imaging are discussed.

Acute adverse events in cardiac MR imaging with gadolinium-based contrast agents: results from the European Society of Cardiovascular Radiology (ESCR) MRCT Registry in 72,839 patients

OBJECTIVES

To assess the incidence of acute adverse events (AAEs) in gadolinium-enhanced cardiac magnetic resonance (CMR) imaging.

METHODS

Gadolinium-based contrast agent (GBCA)-enhanced CMR data from the multinational, multicenter European Society of Cardiovascular Radiology MRCT Registry was included. AAE severity was classified according to the American College of Radiology Manual on Contrast Media (mild, moderate, severe). Multivariable generalized linear mixed effect models were used to assess the likelihood of AAEs in various GBCA, adjusting for pharmacological stressor, main indications (i.e., suspected or known coronary artery disease or myocarditis), age, sex, and submitting center as a random effect.

RESULTS

In the study population of 72,839 GBCA-enhanced CMRs, a total of 260 AAEs were reported (0.36%), with a minority of severe AAEs (n = 24, 0.033%). Allergic-like AAEs were less likely than physiologic AAEs (29% versus 71%). Patients without pharmacological stress imaging had a lower AAE rate (0.22%) compared to stress imaging (0.75%), with the highest AAE rates for regadenoson (2.95%). AAE rates also varied by GBCA subtype (overall p < 0.001). There was significant interaction between GBCA and pharmacological stressor (interaction p = 0.025), with AAE rates ranging between 0 and 10% for certain GBCA/stressor combinations. There was further marginal evidence that higher GBCA volume was associated with higher AAE incidence (OR = 1.02, p = 0.05).

CONCLUSION

GBCA-enhanced CMR imaging demonstrates low AAE rates comparable to those of other body regions. AAE likelihood correlates with GBCA subtype, pharmacological stressor, and imaging indication. Intravenous fluid administration in patients with cardiac impairment might contribute to these findings.

KEY POINTS

• Acute adverse event rates in cardiac magnetic resonance (CMR) imaging with gadolinium-based contrast agents (GBCAs) are low (0.36%), especially for severe adverse events (0.033%). • Mild and moderate adverse events are more frequent during stress CMR imaging. • Physiologic AAEs are more common than allergic AAEs in CMR imaging.

Serum Neutrophil Gelatinase-Associated Lipocalin and Urinary Kidney Injury Molecule-1 as Potential Biomarkers of Subclinical Nephrotoxicity After Gadolinium-Based and Iodinated-Based Contrast Media Exposure in Pediatric Patients with Normal Kidney Function

Background

New renal biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) show promise in early diagnosis of contrast media induced acute kidney injury (CI-AKI). The purpose of our study was to compare the subclinical nephrotoxicity (a condition without changes in standard renal biomarkers) of gadolinium-based contrast media (Gd-DTPA, gadopentetate dimeglumine) and iodinated-based contrast media (iopromide) in pediatric patients with normal kidney function.

Material/Methods

The first group (n=58) of patients included in the study were undergoing angiography with iopromide, and the second group (n=65) were undergoing magnetic resonance (MR) angiography/urography with Gd-DTPA administration. The concentrations of NGAL and KIM-1 were measured four times in the urine (pre-contrast, then at four hours, 24 hours, and 48 hours after contrast administration), and serum NGAL was measured at 0 (baseline), 24 hours, and 48 hours after contrast exposure.

Results

After 24 hours, serum NGAL increase of ≥25% was noticed in 32.6% of the patients in the iopromide group and in 25.45% of the patients in the gadolinium group, with significantly higher average percent of this increase in first group (62.23% vs. 36.44%, p=0.002). In the Gd-DTPA group, we observed a statistically significant increase in urinary KIM-1 24 hours after the procedure. Normalized urinary KIM-1, 24 hours after contrast exposure, was a better predictive factor for CI-AKI than other biomarkers (AUC 0.757, cut off 214 pg/mg, sensitivity 83.3%, specificity 54.2%, p=0.035).

Conclusions

In children with normal renal function, exposure to iodinated-based and gadolinium-based media might lead to subclinical nephrotoxicity, which could be detected using serum NGAL and urinary KIM-1.

Magnetic resonance angiography in perforator flap breast reconstruction

Magnetic resonance angiography (MRA) is an extremely useful preoperative imaging test for evaluation of the vasculature of donor tissue to be used in autologous breast reconstruction. MRA has sufficient spacial resolution to reliably visualize 1 mm perforating vessels and to accurately locate vessels in reference to a patient's anatomic landmarks without exposing patients to ionizing radiation or iodinated contrast. The use of a blood pool contrast agent and the lack of radiation exposure allow multiple studies of multiple anatomic regions in one examination. The following article is a detailed description of our MRA protocol developed with our radiologists with examples that illustrate the utility of MRA in perforator flap breast reconstruction.

[Modern imaging of kidney tumors]

If a renal mass is suspected on clinical examination or ultrasound the finding has to be confirmed by cross-sectional imaging. Methods that are used include multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI). Also contrast-enhanced ultrasound has been successfully implemented in renal imaging and now plays a major role in the differentiation of benign from malignant renal masses. In expert hands it can be used to show very faint vascularization and subtle enhancement. The MDCT technique benefits from the recently introduced dual energy technology that allows superior characterization of renal masses in a single-phase examination, thereby greatly reducing radiation exposure. For young patients and persons allergic to iodine MRI should be used and it provides excellent soft tissue contrast and visualizes contrast enhancement kinetics in multiphase examinations.This article aims at giving a comprehensive overview of these different imaging modalities, their clinical indications and contraindications, as well as a description of imaging findings of various renal masses.

Lack of nephrotoxicity of gadopentetate dimeglumine-enhanced non-vascular MRI and MRI without contrast agent in patients at high-risk for acute kidney injury

Background

Gadolinium chelates (GCs) have been traditionally considered as non-nephrotoxic magnetic resonance imaging (MRI) contrast materials. However, it has been suggested in some recent articles that GCs may have a nephrotoxic potential, but most of these reports are retrospective. However, the evaluated contrast agents, their doses, and the tests used to determine the kidney function were not consistent across studies. We aimed to investigate the effect of magnetic field and an MRI contrast agent, gadopentetate dimeglumine (GD), on renal functions in patients at high risk for acute kidney injury (AKI).

Material/Methods

We designed a prospective case-control study with 2 age- and sex-matched groups of patients at high-risk for AKI (n=72 for each group). Patients in Group 1 received a fixed dose of (0.2 mmol/kg) GD-enhanced non-vascular MRI and patients in Group 2 received MRI without GD. Before the MRI and at 6, 24, 72, and 168 hours after the MRI, biochemical tests, estimated glomerular filtration rate (eGFR), albumin/creatinine ratio in spot urine, and early AKI biomarkers (cystatin C, N-Acetyl-Glucosaminidase [NAG], Neutrophil gelatinase-associated lipocalin [NGAL]) were measured.

Results

Serum creatinine, albumin/creatinine ratio, and eGFR were not different between Group 1 and 2 (p>0.05). There were no significant changes in renal function tests and AKI biomarkers (Δ_{serum creatinine}, Δ_{albumin/creatinine ratio}, Δ_GFR, Δ_{cystatin C}, Δ_NAG, and Δ_NGAL) for either groups 6, 24, 72, and 168 hours after the procedures (p>0.05).

Conclusions

MRI without contrast agent and non-vascular contrast-enhanced (GD, 0.2 mmol/kg) MRI are not nephrotoxic procedures for patients at high risk for AKI.

A pilot study of the effect of spironolactone therapy on exercise capacity and endothelial dysfunction in pulmonary arterial hypertension: study protocol for a randomized controlled trial

BACKGROUND

Pulmonary arterial hypertension is a rare disorder associated with poor survival. Endothelial dysfunction plays a central role in the pathogenesis and progression of pulmonary arterial hypertension. Inflammation appears to drive this dysfunctional endothelial phenotype, propagating cycles of injury and repair in genetically susceptible patients with idiopathic and disease-associated pulmonary arterial hypertension. Therapy targeting pulmonary vascular inflammation to interrupt cycles of injury and repair and thereby delay or prevent right ventricular failure and death has not been tested. Spironolactone, a mineralocorticoid and androgen receptor antagonist, has been shown to improve endothelial function and reduce inflammation. Current management of patients with pulmonary arterial hypertension and symptoms of right heart failure includes use of mineralocorticoid receptor antagonists for their diuretic and natriuretic effects. We hypothesize that initiating spironolactone therapy at an earlier stage of disease in patients with pulmonary arterial hypertension could provide additional benefits through anti-inflammatory effects and improvements in pulmonary vascular function.

METHODS/DESIGN

Seventy patients with pulmonary arterial hypertension without clinical evidence of right ventricular failure will be enrolled in a randomized, double-blinded, placebo-controlled trial to investigate the effect of early treatment with spironolactone on exercise capacity, clinical worsening and vascular inflammation in vivo. Our primary endpoint is change in placebo-corrected 6-minute walk distance at 24 weeks and the incidence of clinical worsening in the spironolactone group compared to placebo. At a two-sided alpha level of 0.05, we will have at least 84% power to detect an effect size (group mean difference divided by standard deviation) of 0.9 for the difference in the change of 6-minute walk distance from baseline between the two groups. Secondary endpoints include the effect of spironolactone on the change in placebo-corrected maximal oxygen consumption; plasma markers of vascular inflammation and peripheral blood mononuclear cell gene expression profiles; sympathetic nervous system activation, renin-angiotensin-aldosterone system activation and sex hormone metabolism; and right ventricular structure and function using echocardiography and novel high-resolution magnetic resonance imaging-based techniques. Safety and tolerability of spironolactone will be assessed with periodic monitoring for hyperkalemia and renal insufficiency as well as the incidence of drug discontinuation for untoward effects.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01712620.

Use of magnetic resonance imaging contrast agents in the liver and biliary tract

This article presents an overview of liver and biliary contrast agents including their mechanisms of action, dosage and elimination, current clinical indications, and potential future uses.

Efficacy and Safety of Gadobutrol (1.0 M) versus Gadopentetate Dimeglumine (.5 M) for Enhanced Mri of Cns Lesions: A Phase Iii, Multicenter, Single-blind, Randomized Study in Chinese Patients

The aim of this study was to compare the efficacy and safety of macrocyclic gadobutrol (1.0 M) with linear gadopentetate dimeglumine (0.5 M) for contrast-enhanced magnetic resonance imaging (MRI) of central nervous system (CNS) lesions in Chinese patients (N = 147) with known or suspected CNS lesions, who were enrolled in this single-blind, randomized, parallel-group study. Three blinded independent readers evaluated all efficacy variables. The primary efficacy variable was the difference between the two agents for the change in contrast-to-noise ratio (CNR) between non-enhanced and contrast-enhanced scans of lesions. Secondary outcomes included mean change in number of lesions detected before and after contrast enhancement, diagnostic confidence, and safety and tolerability parameters. Gadobutrol was non-inferior to gadopentetate dimeglumine in respect to the difference in the mean change in CNR (6.94; 95% confidence interval [CI] lower limit: -3.90; predefined maximum 95% CI lower limit: -6.52). The mean change in the number of CNS lesions detected was greater with gadobutrol versus gadopentetate dimeglumine (1.2 vs. 0.2 lesions). Diagnostic confidence was classified as ‘high’ for more patients with gadobutrol versus gadopentetate dimeglumine by the investigators (58.8% vs. 55.4%) and by the three blinded readers (63.6% vs. 55.7%, 23.7% vs. 18.0% and 81.7% vs. 81.0%). Both agents were well tolerated by participating patients. We concluded that in Chinese patients with CNS lesions, gadobutrol (1.0 M) was as effective and well tolerated in contrast-enhanced MRI as gadopentetate dimeglumine (0.5 M). Gadobutrol provided improved visualization of CNS lesions compared with gadopentetate dimeglumine, with a comparable tolerability profile.

Contrast-enhanced magnetic resonance angiography

With technological advances in magnetic resonance angiography (MRA), spatial resolution of 1-mm perforating vessels can reliably be visualized and accurately located in reference to patients' anatomic landmarks without exposing patients to ionizing radiation or iodinated contrast, resulting in optimal perforator selection, improved flap design, and increased surgical efficiency. As their experience with MRA in breast reconstruction has increased, the authors have made changes to their MRA protocol that allow imaging of the vasculature in multiple donor sites (buttock, abdomen, and upper thigh) in one study. This article provides details of this experience with multiple donor site contrast-enhanced MRA.

Tolerability and diagnostic value of gadoteric acid in the general population and in patients with risk factors: results in more than 84,000 patients

PURPOSE

To review the tolerability and diagnostic effectiveness of gadoteric acid under daily practice conditions in the general population and at-risk patients.

MATERIALS AND METHODS

A total of 84,621 patients (45.4% men, 54.6% women, mean age 52.0 ± 16.9 years) were studied in 129 German centers. Patients underwent contrast-enhanced magnetic resonance imaging (MRI) using gadoteric acid (Gd-DOTA, Dotarem(®), Guerbet, Roissy CdG, France) as IV contrast medium (mean volume, 16.4 ml). 22.9% of the patients had at least one risk factor (e.g., allergies, previous allergic reaction to a contrast medium, and renal impairment). 554 patients received pretreatment before contrast medium administration (0.7%). Adverse events were documented and image quality was assessed.

RESULTS

A diagnosis was possible in 99.7% of all cases. Image quality was rated good or excellent in 97.1%. Adverse events (e.g., nausea, vomiting, and urticaria) were observed in 0.34% of the examinations and were mostly rated as minor. There were 8 patients with serious adverse events. The adverse event rate was significantly higher in patients with a history of allergies (0.62%; p<0.001) and in patients with a previous allergic reaction to contrast medium (1.23%; p<0.001). There was no elevated incidence of adverse events in patients with renal impairment.

CONCLUSION

Gadoteric acid is a well-tolerated MRI contrast medium in patients with and without risk factors that is associated with a low rate of adverse events and good or excellent image quality in most patients.

Preoperative imaging techniques for perforator selection in abdomen-based microsurgical breast reconstruction

The clinical application of perforator-based flaps for microsurgical breast reconstruction has increased exponentially over the past 10 years. The benefits of the procedure are thought to be that it produces less postoperative pain, lowers abdominal morbidity, and allows for better preservation of muscles at the donor site compared with conventional musculocutaneous flaps. The disadvantages of perforator flaps are that they are more difficult to harvest, which can result in a longer operative time and higher costs. The vascular anatomy of the deep inferior epigastric artery and its perforating branches in the abdominal wall varies greatly not only among individuals but also from one side of the abdomen to the other. Perforator location, number, caliber, and the intramuscular trajectory of the branches all impact the design and harvest of the flap. The creation of a presurgical map of the vessels on the abdomen can facilitate surgical planning and could decrease operating room time, reduce intraoperative complications, and lead to improved outcomes. This article reviews the available techniques for preoperative planning with the currently available imaging modalities: hand-held Doppler, color Doppler (duplex) ultrasound, CT angiography, and MR angiography.

Basics of Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy

In this chapter, the basic principles of magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) (Sects. 2.2, 2.3, and 2.4), the technical components of the MRI scanner (Sect. 2.5), and the basics of contrast agents and the application thereof (Sect. 2.6) are described. Furthermore, flow phenomena and MR angiography (Sect. 2.7) as well as diffusion and tensor imaging (Sect. 2.7) are elucidated.

MR contrast agents for liver imaging: what, when, how

The major classes of contrast agents currently used for magnetic resonance (MR) imaging of the liver include extracellular agents (eg, low-molecular-weight gadolinium chelates), reticuloendothelial agents (eg, ferumoxides), hepatobiliary agents (eg, mangafodipir), blood pool agents, and combined agents. Mechanisms of action, dosage, elimination, toxic effects, indications for use, and MR imaging technical considerations vary according to class. Gadolinium chelates are the most widely used. Ferumoxides are a useful adjunct for detection of hepatocellular carcinoma, particularly when used in combination with gadolinium to achieve improved lesion-to-liver contrast over that achievable with gadolinium alone. Mangafodipir is a prototype hepatobiliary agent that is taken up by lesions with functioning hepatocytes. It may be used for MR cholangiography as well as liver imaging. Although mangafodipir is no longer commercially available in the United States, it is currently marketed and used in Europe. Blood pool agents have not yet been approved for human use in the United States. However, a new combined MR contrast agent, gadobenate dimeglumine, recently was approved, and other agents are in various stages of development.

Toxicological assessment of gadolinium release from contrast media

In vivo gadolinium release was evaluated for MultiHance, Omniscan and Gadovist estimating gadolinium content in liver, kidneys, spleen, femur and brain after single or repeated intravenous administrations to rats at 1 mmol/kg. Gadolinium acetate (GdAc) at a daily dose of 0.03 mmol/kg and physiological saline were used as positive and negative controls, respectively. No changes in blood chemistry, haematology nor histopathology were seen with any of the tested contrast media, whereas an increase in white blood cell count and in serum cholesterol were found after GdAc at 0.18 mmol/kg cumulative dose. Analogously, gadolinium content in target organs (as % of injected dose) after any of contrast media was 100-200 times lower than after GdAc, either after single or repeated administrations. Under these experimental conditions, the rank of residual gadolinium found in these organs was GdAcOmniscan >Gadovist >MultiHance. Depopulation of lymphocytes in periarteriolar lymphatic sheaths (PALS) areas of the spleen was noted in rats treated with a single dose of GdAc sacrificed 24h post-dosing, but not in repeated dose rats sacrificed 48 h after last dosing. It was, therefore, concluded that this was a transient phenomenon and that PALS are rapidly repopulated with lymphocytes. With all contrast media, gadolinium content after a 2-day washout following a 3-week repeated administration period was lower than the amount found 24h after a single administration. Accordingly, the observed gadolinium content in organs should actually be in a complexed form (possibly the injected complex) which is subjected to elimination.

Assessment of Utilization and Pharmacovigilance Based on Spontaneous Adverse Event Reporting of Gadopentetate Dimeglumine as a Magnetic Resonance Contrast Agent After 45 Million Administrations and 15 Years of Clinical Use

PURPOSE

Although contrast agents have become indispensable tools in magnetic resonance and their safe and effective use the foundation of many essential diagnostic procedures, only limited summary information on their utilization and pharmacovigilance is available to the community. After voluntary access to the manufacturer spontaneous adverse event database, we assessed the available data for gadopentetate dimeglumine.

MATERIAL AND METHODS

Gadopentetate dimeglumine (Gd-DTPA, Magnevist; Berlex/Schering AG, Berlin, Germany) became commercially available in 1988 and is currently marketed in 101 countries. Using the manufacturer's continuous and cumulative database on product distribution and spontaneous adverse event (AE) reporting, we categorized AEs and assessed their cumulative occurrence after 10, 20, and 45 million applications that occurred in 1993, 1997, and 2002, respectively. Furthermore, we reviewed publications in Medline to assess prevalence of the 4 most common MR contrast agents in the indexed literature.

RESULTS

Gd-DTPA has been used in more than 45 million magnetic resonance imaging procedures since 1988 and is currently used globally in more than 5 million applications annually. The broadest category of spontaneously reported AEs, subjective symptoms, occurs in less than 0.01% of procedures. Within the total AEs reported, the distribution of serious and nonserious reports was 9.3% and 90.7%, respectively. The rates of AE reporting have changed over time, with increased rates in the second reporting period (1993 to 1997), followed by substantially lower rates in subsequent years. AE reporting rates are the most comprehensive data available; however, there will always be some underestimation of the true event rates. Although no substantial differences were noted among major age groups, substantial differences in reporting frequency were found among regions, with the United States reporting nearly twice as many AEs as Europe in the postmarketing phase.

CONCLUSION

The postmarketing utilization and pharmacovigilance analysis of Gd-DTPA has revealed temporal changes and regional differences, overall with an excellent safety profile. Its extensive utilization and safety information have firmly established it as highly used and safe magnetic resonance imaging agent.

Effects of ionic and non-ionic paramagnetic contrast media on brain bio-electric activity

The potential neurotoxic effects of gadolinium (Gd)-based compounds for enhanced MRI are not completely understood. We investigated electroencephalography changes induced by ionic and non-ionic Gd-based compounds administered intravenously in patients affected by lesions of the central nervous system (CNS) characterized by breakdown of the blood-brain barrier. This double-blind, randomized, study of two parallel groups involved 40 patients scheduled for an MRI examination with contrast medium for known CNS lesions. Twenty patients were randomly allocated to receive non-ionic Gd-DTPA-BMA/gadodiamide and 20 patients were randomly allocated to receive ionic Gd-DTPA/gadopentetate. For both groups the intravenous dose was 0.1 mmol/kg body weight. Three electroencephalography recordings were performed: immediately before, during, and 15 min after contrast medium injection. Mean and peak frequencies of the beta band and absolute power of the delta and/or theta bands of the electroencephalograms (EEGs) were noted. Each EEG was also evaluated to detect any alterations. The values of the 8-12 Hz band showed a significant increase during and after injection versus baseline in the gadopentetate group (P<0.05) and a significant decrease during injection in the gadodiamide group (P<0.05). The values of the 12-16 Hz band showed a significant increase versus baseline during and after injection in the gadopentetate group (P<0.05). The electrophysiological method based on computerised spectral analysis is a sensitive tool for evaluating effects of contrast media on brain bio-electric activity. EEG changes are detectable, even in the absence of any clinical evidence. It would appear that there might be clinical advantages in the use of non-ionic compounds.

Acute Allergic Reaction upon First Exposure to Gadolinium-DTPA: A Case Report

This is a case report of allergic reaction to Gadolinium-DTPA on first exposure, with a brief review of safety of MR contrast agents.

The role of magnetic resonance imaging in diagnosis and management of breast cancer

A review of the literature on the current applications of breast magnetic resonance imaging (MRI) indications, their rationale and their place in diagnosis and management of breast cancer was given. Contrast-enhanced breast MRI is developing as a valuable adjunct to mammography and sonography. Its high sensitivity for invasive breast cancer establishes its superiority in evaluation of multifocality/multicentricity, tumor response to neoadjuvant chemotherapy, detection of recurrence, and staging. Emerging applications include spectroscopy, usage of new contrast agents, and MRI-guided interventions, including noninvasive treatment of breast cancer. Its potential benefit in screening high-risk women has yet to be established with prospective studies, particularly with regard to false positive results.

Interaction between iopamidol and gadopentetate dimeglumine: an in-vitro experimental study of direct mixing

OBJECTIVE

To determine whether or not there is any interaction between iopamidol and gadopentetate dimeglumine (Gd-DTPA) in test tubes using the direct mixing manner.

MATERIALS AND METHODS

The test solution was prepared by mixing iopamidol (Iopamiron 300) and Gd-DTPA (Magnevist) at a ratio of 1:1. The color, viscosity, and pH of the mixed solutions were assessed immediately after mixing and 1,3,6, and 24 hours after mixing. The concentration of aromatic primary amines, content of iopamidol, concentration of free iodine ion, and content of Gd-DTPA in the mixed solution were determined, and the presence or absence of spots, other than those resulting from iopamidol and Gd-DTPA, was determined using thin layer chromatography. These tests were carried out immediately, and 24 hours after mixing. Using iopamidol alone and Gd-DTPA alone as controls, the same items were examined.

RESULTS

There was no significant change in the appearance or pH of the mixed iopamidol and Gd-DTPA solution immediately and 1, 3, 6, and 24 hours after direct mixing. The study of iopamidol alone or Gd-DTPA alone showed no apparently abnormal values or findings.

CONCLUSION

The direct mixing of iopamidol and Gd-DTPA in a test tube results in no significant interaction.

Angiografia por ressonância magnética: aspectos técnicos de um método de estudo vascular não-invasivo

As primeiras técnicas de angiografia por ressonância magnética (angio-RM) utilizavam seqüências sensíveis ao fluxo sanguíneo para estabelecimento do contraste vascular. Há três técnicas fundamentadas neste princípio: contraste de fase ("phase-contrast"), TOF ("time-of-flight") e as técnicas de sangue escuro ("black blood"). Estas seqüências, de aquisição demorada, são mais suscetíveis a artefatos de movimento, perda de sinal em áreas de estenoses ou turbilhonamento de fluxo, e apresentam ainda baixa sensibilidade à detecção do fluxo lento. O uso do contraste paramagnético para estudos angiográficos pela ressonância magnética ofereceu um método simples, rápido e de excelente detalhamento vascular, baseando o contraste da imagem no realce do sinal vascular em oposição à supressão dos demais tecidos. Metodologias modernas que priorizam a obtenção do espaço k central, responsável pelo contraste da imagem, e o aperfeiçoamento das técnicas de planejamento do intervalo temporal para aquisição dos dados foram fatores fundamentais para o aprimoramento técnico da angio-RM. O papel atual da angio-RM como ferramenta diagnóstica merece destaque na avaliação de anomalias anatômicas, estenoses, oclusões e complicações vasculares pós-cirúrgicas, principalmente nos casos de transplantes de órgãos. Suas principais vantagens estão na não utilização do contraste iodado ou radiação ionizante, rapidez e fácil execução, mínima invasividade e possibilidade de avaliar complementarmente o parênquima de órgãos adjacentes de interesse diagnóstico.

Pre-surgical mapping of primary motor cortex by functional MRI at 3 T: effects of intravenous administration of Gd-DTPA

The functional magnetic resonance imaging (fMRI) is often performed at the end of a routine MRI examination during which, dependent on the clinical indication, contrast agent has been administered; however, the effects of Gd-DTPA injection on the results of blood oxygenation level dependent (BOLD)-fMRI remain unknown. The present study was conducted to investigate the effects of the intravenous administration of Gd-DTPA on the results of pre-surgical localization of the primary motor cortex by BOLD-fMRI at 3 T. Eight normal subjects were included in this study. After the anatomical scans, pre- and post-contrast fMRI scanning was performed. The number of significantly activated voxels and the mean percentage signal change were compared. The mean number of significantly activated voxels was 115.0+/-27.0 in pre-contrast runs and 90.8+/-27.1 in post-contrast runs (mean value of all 8 volunteers+/-standard deviation; p<0.05). The mean mean percentage signal change was 4.07+/-0.39 in pre-contrast runs and 3.86+/-1.91 in post-contrast runs ( p=0.16). Pre-surgical localization of the motor area by BOLD-fMRI should be performed before the administration of Gd contrast material.

Safety of contrast-enhanced MR angiography employing gadobutrol 1.0 M as contrast material

Our objectives were to evaluate the safety of intravenous 1.0-M gadobutrol injections in patients with an indication for contrast-enhanced magnetic resonance angiography (CE MRA) of supra-aortal, pelvic, or peripheral arteries by examining and assessing adverse events, laboratory values, vital signs and ECG findings for clinical significance. In 435 patients, recruited in three multicenter trials for safety evaluations of the new contrast agent 1.0-M gadobutrol, CE MRA was performed with 1.0- to 1.5-T scanners using three-dimensional gradient-echo sequences and phased-array coils. The study population comprised 312 men and 123 women with a mean age of 60.9 years. Two hundred seven patients had an indication for imaging of body arteries and 228 had an indication for imaging of peripheral arteries. Blood laboratory values and urinalysis results of 124 patients as well as heart rate, blood pressure, and 12-lead-electrocardiogram readings of 93 patients obtained during a follow-up period of up to 72 h after the injection of contrast media were available for safety analysis. Contrast media application was performed as intravenous bolus injection of 1.0-M gadobutrol in fixed doses according to the patients' body weight (b.w.) and indication for CE MRA and was followed by a 20- to 40-ml saline flush. Mean dose actually applied was 0.1 0.27 mmol/kg b.w. Flow rate ranged between 0.2 and 2.0 ml/s. Safety evaluations found a good tolerability with only 4.6% of at least "possibly related" adverse reactions and no clinically relevant changes in blood and urine samples including no transmetallation effect on serum zinc values. Analysis of renal tolerance showed no influence on renal function irrespective of preexisting renal impairment. The ECG analysis (rhythm analysis, pace-setting disturbances, conduction disturbances, and time interval measurements, including uncorrected and corrected QT) showed no clinically relevant effect of the injection of 1.0-M gadobutrol on the cardiac conduction system. Intravenous injection of 1.0-M gadobutrol at a dose of up to 0.1 0.27 mmol/kg b.w. in the indication CE MRA is safe and causes no clinically relevant changes in safety parameters such as heart rate, blood pressure, blood and urine laboratory values, and cardiac conduction system.

Contrast agents in patients on dialysis

Contrast media are used to enhance the structural and functional information that is provided by imaging methods. They are used particularly in conventional radiographic (X-ray) investigations, but are also used in magnetic resonance imaging (MRI) and increasingly in ultrasound (US). The water-soluble, iodinated, intravascular radiographic agents are commonly used, and in large doses. They are excreted almost exclusively by the kidney and may have nephrotoxic effects. The use of these agents in patients with renal impairment may potentially be problematic. In this article the chemical composition and pharmacokinetics of these contrast agents are reviewed, as are their potentially toxic effects on the heart, neural tissues, kidney, and endothelium. Their safety for use in the patient with end-stage renal disease (ESRD) and those on dialysis is discussed. This aspect is also addressed briefly for the contrast agents used to augment MRI and US.

Gadolinium-based contrast agents in angiography and interventional radiology

Gadolinium is useful as an alternative contrast agent for diagnostic angiographic and interventional procedures in patients with renal insufficiency or a history of a severe reaction to iodinated contrast material. Gadolinium usually is used as a "problem solver" to answer specific diagnostic questions or guide interventional procedures that cannot adequately be defined with CO2 angiography. Because of dose limitations with Gd, careful planning is required prior to its use with angiography or interventional procedures.

Side-effects after inhalational anaesthesia for paediatric cerebral magnetic resonance imaging

BACKGROUND

The aim of this study was to evaluate the type, incidence and duration of postprocedure side-effects in 168 children within the first 72 h after inhalational anaesthesia for magnetic resonance imaging (MRI).

METHODS

Premedication and induction followed standardized routines. Maintenance of anaesthesia was performed with inhalational anaesthetics solely: isoflurane (n=60 of 112; 53%), sevoflurane (n=32 of 112; 29%), desflurane (n=12 of 112; 11%) or halothane (n= 8 of 112; 7%) using a strapped on face mask (FiO2=0.4; flow 5 l.min-1). When indicated, gadolinium was administered (n=45; OF 112; 40%).

RESULTS

One hundred and twelve of 168 parents (67%) responded to questionnaires. In these 112 children, pathological MR findings were found supratentorially (n=31; 28%), infratentorially (n=9; 8%), extracerebrally (n=12; 11%) or combined (n=9; 8%). In 56 of these 112 children (50%), 14 different side-effects were reported. One hour after anaesthesia, 55 children suffered between one and four side-effects. Neurological side-effects were associated with age > or = 5 years (P < 0.01) or infratentorial pathophysiology (P < 0.01) and abdominal side-effects (P < 0.02), especially nausea (P < 0.001) with age > or = 5 years.

CONCLUSIONS

Our findings indicate the need to inform parents of the incidence and variability of side-effects after inhalational anaesthesia for minimally invasive, diagnostic procedures, such as MRI.

Double-blind, efficacy evaluation of gadobenate dimeglumine, a gadolinium chelate with enhanced relaxivity, in malignant lesions of the brain

BACKGROUND AND PURPOSE

The diagnostic efficacy of gadobenate dimeglumine (Gd BOPTA) was compared with that of gadodiamide (Gd DTPA-BMA) in patients with primary malignant tumors or metastases of the brain.

METHODS

A subset of patients was evaluated from the 410 enrolled in the United States in phase III central nervous system clinical trials with gadobenate dimeglumine. From these trials, there were 82 patients with intraaxial malignant neoplasms of the brain, the focus of the current study. Patients were randomized to one of three incremental dosing regimens. Imaging with gadodiamide at doses of 0.1 and 0.3 mmol/kg was compared with gadobenate dimeglumine at doses of 0.05 and 0.15 mmol/kg and at doses of 0.1 and 0.2 mmol/kg. The on-site physician, patient, and all off-site reviewers were blinded to the agent injected and the administered dose. Scans were obtained before contrast administration and within 5 minutes after administration of each dose. The two contrast injections in any one patient were separated by 15 minutes. An independent laboratory performed signal intensity measurements. The magnetic resonance (MR) films were evaluated for level of diagnostic information, number of lesions detected, and confidence in MR imaging diagnosis by two independent board-certified neuroradiologists unaffiliated with any study site.

RESULTS

The lesion-to-brain signal intensity ratio after a dose of 0.1 mmol/kg gadobenate dimeglumine was higher than that after a dose of 0.1 mmol/kg gadodiamide, with this result statistically significant (P = 0.02). After the second dose of contrast, results were comparable in all three groups. The level of diagnostic information contained on the MR films increased significantly for all three groups from pre- to postcontrast for both the first and second administered doses. In between-group comparisons, the level of diagnostic information was similar after the first contrast dose for all three dosing regimens. This was also true after the second contrast dose. For all three groups, the number of lesions detected increased significantly postdose (whether first or second). Confidence in MR diagnosis increased from predose to postdose for all three groups, with no statistically significant difference between groups.

CONCLUSION

Gadobenate dimeglumine, used at slightly lower doses, is comparable to gadodiamide in terms of efficacy in imaging of malignant intraaxial brain lesions. As with other gadolinium chelates, higher doses (0.15 and 0.2 mmol/kg) of gadobenate dimeglumine offer greater diagnostic information.

Gadolinium chelates in angiography and interventional radiology: a useful alternative to iodinated contrast media for angiography

Gadolinium has physical properties that are well suited for radiographic imaging. Digital subtraction angiography with a gadolinium chelate as contrast medium can provide images of suitable quality for diagnosis and intervention. The overall safety profile of gadolinium-based contrast media is excellent. In particular, these contrast media are well tolerated in patients with renal insufficiency when administered intraarterially in doses of less than 0.3-0.4 mmol per kilogram body weight, with a decreased incidence of contrast medium-induced nephropathy, as compared with similar volumes of iodinated contrast material. The currently available formulations of gadolinium chelates can be injected safely into every arterial and venous structure. However, substantial data are lacking on the intraarterial use of gadolinium in patients with renal insufficiency, particularly at doses that exceed those routinely used in magnetic resonance angiography. Gadolinium chelates in appropriate volumes are useful alternative contrast media in selected high-risk patients undergoing angiographic studies.

Percutaneous carotid angioplasty and stenting with the use of gadolinium in lieu of iodinated contrast medium: technical case report and review of the literature

OBJECTIVE AND IMPORTANCE

We describe a patient who underwent percutaneous transluminal carotid angioplasty and stent placement with the use of intra-arterial gadolinium (Gd-DTPA) instead of iodinated contrast medium. This represents one of the first published reports of the use of Gd-DTPA as an angiographic contrast agent for an interventional neuroradiological procedure.

CLINICAL PRESENTATION

A 75-year-old man with renal insufficiency and multiple comorbidities developed amaurosis fugax. Doppler examination revealed high-grade stenosis of the right internal carotid artery.

INTERVENTION

The patient underwent percutaneous transluminal balloon angioplasty with endovascular stent placement for 95% narrowing of the proximal right internal carotid artery. Because of his impaired renal function, the procedure was performed with the use of Gd-DTPA as the sole contrast agent. Approximately 60 ml of contrast medium (twice the volume typically used for a magnetic resonance imaging study) was used. There were no neurological, renal, or other complications.

CONCLUSION

Intra-arterially administered Gd-DTPA may be substituted for iodinated contrast agents in complex neuroendovascular procedures. This capacity expands the armamentarium for interventional neuroradiological procedures.

[Anaphylactoid reactions and late skin reactions to iodinated contrast media: present state of the question--idea development]

PURPOSE

Adverse reactions to iodinated contrast media (ICM) share various mechanisms. Anaphylactoid reactions are among the most serious reactions when they are characterized by the elevation of seric tryptase. Pretreatment with corticosteroids and anti-H1 or the use of non-ionic contrast media do not prevent anaphylaxis. Late skin reactions could be mostly related to delayed hypersensitivity. Previous reactions to contrast media, cardiovascular disorders, beta-blockers, asthma, and atopy are risk factors. Female gender and age increase the severity.

CURRENT KNOWLEDGE AND KEY POINTS

Anaphylaxis can be demonstrated by intradermal tests and the identification of specific IgEs. Delayed hypersensitivity is shown by the results of epicutaneous tests and the immunohistology of the skin.

FUTURE PROSPECTS AND PROJECTS

Allergologic tests are advised in the case of previous reactions. In case of emergency, gadopentetate dimeglumine can be alternatively used. The other risk factors lead to the combination of pretreatment and use of non-ionic monomeric contrast media. Immediate hypersensitivity to iodinated media might increase in the near future with the use of divalent molecules.

Magnetic resonance hysterography and hysterosalpingography using hyperpolarized (3)He: demonstration of feasibility in an animal model

Assessment of the uterine cavity and patency of the fallopian tubes remains a difficult goal with magnetic resonance imaging (MRI). The purpose of this paper is to describe the development of a new magnetic resonance hysterography (MR-HG) and hysterosalpingography (MR-HSG) technique employing hyperpolarized (3)He. Two-dimensional (2D) and 3D gradient-echo imaging sequences were developed and optimized using a phantom. An optimized sequence was then applied in swine cadavers. J. Magn. Reson. Imaging 2000;12:1009-1013.

Safety of approved MR contrast media for intravenous injection

In the last 10 years, the use of intravenous contrast media in magnetic resonance (MR) has become well-established clinical practice. Contrast media provide critical additional diagnostic information in many instances. The gadolinium chelates constitute the largest group of MR contrast media and are considered to be very safe. These agents are thought to be safer than nonionic iodinated contrast agents. Unlike x-ray agents, the gadolinium chelates are not nephrotoxic. Minor adverse reactions, including nausea (1%-2% for all agents) and hives (<1% for all agents), occur in a very low percent of cases. Health care personnel should be aware of the (extremely uncommon) potential for severe anaphylactoid reactions in association with the use of MR contrast media and be prepared should complications arise. The four gadolinium chelates currently available worldwide, gadopentetate dimeglumine, gadoteridol, gadodiamide, and gadoterate meglumine, cannot be differentiated on the basis of adverse reactions. Far fewer patients have been examined to date with the two other agents that have widespread approval, mangafodipir trisodium and ferumoxides. These latter two agents are considered to be very safe but have a higher percentage of associated adverse reactions (7%-17% with mangafodipir trisodium and 15% with ferumoxides). This review discusses the safety issues involved with administration of intravenous contrast media in MR imaging, focusing on the six agents (four gadolinium chelates, one manganese chelate, and the last a large iron particle) with widespread use world-wide.

Lower extremity arteriography with use of iodinated contrast material or gadodiamide to supplement CO2 angiography in patients with renal insufficiency

PURPOSE

To determine if the use of nonionic contrast material, as compared to the use of gadodiamide to supplement carbon dioxide angiography in patients with peripheral vascular disease (PVD) and chronic renal insufficiency (CRI), results in significant worsening of renal function.

MATERIALS AND METHODS

Lower extremity angiographic procedures (diagnostic and diagnostic/intervention) were performed in 40 patients with CRI (baseline serum creatinine [Cr] > 1.5 mg/dL) using CO2 alone or CO2 supplemented with the use of either nonionic contrast material or gadodiamide (up to 0.4 mmol/kg). Serum creatinine levels were obtained before the procedure and at 48 hours after the procedure. The peak Cr level was also determined for patients with a significant (> 0.5 mg/dL) Cr elevation.

RESULTS

Forty-two lower extremity angiographic procedures (19 diagnostic and 23 diagnostic/interventions) were performed in 40 consecutive patients from August 1997 to October 1998, with a mean preprocedure Cr of 2.2 mg/dL and a mean postprocedure Cr of 2.4 mg/dL. Twenty-five of the 40 patients (63%) had diabetes mellitus. Fifteen procedures, including six interventions, were performed utilizing CO2 and nonionic contrast material in 15 patients. Six of these 15 patients (40%) demonstrated a Cr increase > 0.5 mg/dL at 48 hours. Seven procedures, including two interventions, were performed with CO2 alone in seven patients. No patients in this group demonstrated an increase in serum creatinine of greater than 0.5 mg/dL at 48 hours. Twenty procedures, including 15 interventions, were performed with CO2 and gadodiamide in 18 patients. In one of these 20 procedures (5%) there was an increase in Cr > 0.5 mg/dL at 48 hours The difference in worsening renal function for the nonionic contrast group (six of 15) compared with the CO2/gadodiamide group (one of 20) was statistically significant (P = .03). When comparing the use of CO2 and nonionic contrast material versus CO2 alone and with gadodiamide (six of 15 versus one of 27), the difference is also statistically significant (P < .01). The average volume of supplemental contrast material was similar in the nonionic contrast material and gadodiamide groups, as was the average volume of supplemental nonionic contrast material in the six patients with an increased Cr.

CONCLUSION

The use of small volumes of nonionic contrast material to supplement CO2 angiography in patients with PVD and CRI can be associated with a significant increased risk of worsening renal function when compared to angiography performed with CO2 alone or CO2 and gadodiamide.