Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA)

Gadolinium-Sensitive Artificial Nanochannel Membrane for Information Encryption

Inspired from ion channels in the myelinated axon of Xenopus laevis found to be affected by gadolinium on axonal currents, we present a solid nanochannel membrane sensitive to gadolinium (Gd3+), which can be achieved via the use of the macrocyclic triacetic acid derivative in the host-guest chemistry approach. The macrocyclic nanochannel has good responsiveness toward Gd3+, even at the nanomolar concentration level, evidenced by discernible changes in rectification, ionic conductance, and XPS analyses. Notably, the Gd3+-sensitive nanochannel membrane can be switched by the addition of a diethylenetriaminepentaacetic acid (DTPA) derivative. Further studies have indicated that the gated behavior of Gd3+ in the nanochannel can be attributed to the strong binding strength between DO3A and Gd3+, which induces a surface charge reversal within the nanochannel. The mechanism has been confirmed through several experimental techniques, including isothermal titration calorimetry (ITC) experiments, fluorescence titration experiments, and finite element analysis. Based on its Gd3+ responsiveness of the constructed ion channel, we successfully developed an advanced multilevel information encryption application of the artificial solid nanochannel membrane. Furthermore, it is anticipated that a more effective encryption system will be built by utilizing the bionic ion channel system's ease of use and straightforward functionalization.

Genotoxic effects of gadobutrol and gadoversetamide active substances used in magnetic resonance imaging in human peripheral lymphocytes in vitro

Gadobutrol and gadoversetamide are gadolinium-based contrast agents (GBCAs) widely used during magnetic resonance imaging examination. In this study, the genotoxicity of two GBCAs, gadobutrol and gadoversetamide, was investigated by using different endpoints: chromosome aberration (CAs), sister chromatid exchange (SCEs), and micronucleus (MNi). Human peripheral lymphocytes (PBLs) were treated with five concentrations (7 000, 14 000, 28 000, 56 000, and 112 000 μg/mL) of both agents. While a few concentrations of gadobutrol significantly increased abnormal cell frequency and CA/Cell, nearly all the concentrations of gadoversetamide significantly elevated the same aberrations. Similarly, the effect of gadoversetamide on the formation of SCEs was higher than those of gadobutrol. Only one concentration of gadoversetamide significantly increased MN% but no gadobutrol. The comet assay was applied for the only gadobutrol which induced a significant increase in tail intensity at the highest concentration only. On the other hand, significantly decreased mitotic index (MI) was observed following both substances, again gadoversetamide was slightly higher than those of the gadobutrol. The results revealed that both the contrast agents are likely to induce genotoxic risk in PBLs. However, different concentrations and treatment periods should be examined in vitro and specifically in vivo with different test systems for the safer usage of these contrast agents.

Gadolinium contrast agents for CNS imaging: current concepts and clinical evidence

SUMMARY

The aim of this article was to review the properties of the various gadolinium-based contrast agents used for CNS imaging along with the clinical evidence and published data that highlight the impact these different properties can have on diagnostic performance. In addition, approaches to optimizing image acquisition that take into account the different properties of specific gadolinium-based contrast agents and an extensive review of the safety profiles of the various agents are presented.

MR imaging of neoplastic central nervous system lesions: review and recommendations for current practice

MR imaging is the preferred technique for the diagnosis, treatment planning, and monitoring of patients with neoplastic CNS lesions. Conventional MR imaging, with gadolinium-based contrast enhancement, is increasingly combined with advanced, functional MR imaging techniques to offer morphologic, metabolic, and physiologic information. This article provides updated recommendations to neuroradiologists, neuro-oncologists, neurosurgeons, and radiation oncologists on the practical applications of MR imaging of neoplastic CNS lesions in adults, with particular focus on gliomas, based on a review of the clinical trial evidence and personal experiences shared at a recent international meeting of experts in neuroradiology, neuro-oncology, neurosurgery, and radio-oncology.

Safety of gadoversetamide in patients with acute and chronic myocardial infarction

PURPOSE

To assess the safety data from two large, multicenter, phase 2 trials on the use of gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO) as a contrast agent in delayed hyperenhancement magnetic resonance imaging (DE-MRI) in patients with acute and chronic myocardial infarction (MI).

MATERIALS AND METHODS

The study population from both trials comprised 577 patients who were randomly assigned to one of four dose groups (0.05, 0.1, 0.2, or 0.3 mmol/kg) before undergoing DE-MRI. Safety evaluations included physical and electrocardiographic (ECG) examinations. Vital signs, laboratory values, adverse events (AE), and serious adverse events (SAE) were monitored before and after contrast administration.

RESULTS

Of the 577 patients who received gadoversetamide, 124 (21.5%) reported a total of 164 AEs; most were mild (139 AEs; 84.8%) or moderate (25 AEs; 15.2%). ECG-related changes were the most frequent AE. Site investigators judged only eight AEs as likely related to gadoversetamide and only two of the eight as clinically relevant. Further evaluation suggested neither AE was related to gadoversetamide. Two SAEs were reported, but none was judged related to gadoversetamide by the site investigators.

CONCLUSION

Gadoversetamide is safe for use in patients with acute or chronic MI up to a dose of 0.3 mmol/kg.

Pharmacokinetics of gadoversetamide injection, a gadolinium-based contrast agent, in pediatric patients

OBJECTIVE

The pharmacokinetics of gadoversetamide were examined in pediatric patients scheduled to undergo contrast-enhanced MRI of the central nervous system.

MATERIALS AND METHODS

One hundred patients received an intravenous injection of gadoversetamide at a dose of 0.1 mmol/kg for a contrast-enhanced MRI procedure. A subpopulation of 30 patients were enrolled to evaluate the pharmacokinetics of gadoversetamide in patients 2-11 and 12-18 years of age. Serial blood and urine samples were collected before and after the administration of gadoversetamide.

RESULTS

The terminal half-life, initial concentration and area under the curve assessments for gadoversetamide showed no significant (P>.05) differences between the age groups or the sexes. Although no sex-related differences occurred in the volume of distribution or clearance, significant (P<.05) age-related differences were found, but once corrected for body mass or surface area the differences were no longer significant.

CONCLUSIONS

The pharmacokinetic behavior of gadoversetamide was not significantly altered by differences in age or sex in pediatric patients from 2 to 18 years of age. Although significant differences in volumes of distribution, and clearance occurred between the age groups, these differences appeared to depend on body size rather than on age in pediatric patients between 2 and 18 years of age.

Extracellular gadolinium-based contrast media: differences in diagnostic efficacy

Since the introduction of the first gadolinium-based contrast agent (Gd-CA) in 1988 it has become clear that these agents significantly improve the diagnostic efficacy of MRI. Studies on single agents have shown that, in comparison to unenhanced sequences, all agents help to improve the detection and delineation of lesions which can alter diagnosis in up to 40% of patients. Doubling or tripling the standard dose of 0.1 mmol/kg body weight may be beneficial for selected indications (e.g. brain perfusion, equivocal single dose study in MRI for brain metastasis, small vessel MR angiography). A more limited number of studies have compared the various agents. These studies do not show clinically significant differences in diagnostic efficacy between the various extracellular Gd-CA. Agents with higher concentration or protein binding may be relatively better suitable for selected applications (e.g. perfusion MRI). The higher relaxivity agents may be used in somewhat lower doses than the extracellular agents.

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.

Evaluation of intraaxial enhancing brain tumors on magnetic resonance imaging: intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine for visualization and assessment, and implications for surgical intervention

Object

The goal in this article was to compare 0.1 mmol/kg doses of gadobenate dimeglumine (Gd-BOPTA) and gadopentetate dimeglumine, also known as gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA), for enhanced magnetic resonance (MR) imaging of intraaxial brain tumors.

Methods

Eighty-four patients with either intraaxial glioma (47 patients) or metastasis (37 patients) underwent two MR imaging examinations at 1.5 tesla, one with Gd-BOPTA as the contrast agent and the other with Gd-DTPA. The interval between fully randomized contrast medium administrations was 2 to 7 days. The T1-weighted spin echo and T2-weighted fast spin echo images were acquired before administration of contrast agents and T1-weighted spin echo images were obtained after the agents were administered. Acquisition parameters and postinjection acquisition times were identical for the two examinations in each patient. Three experienced readers working in a fully blinded fashion independently evaluated all images for degree and quality of available information (lesion contrast enhancement, lesion border delineation, definition of disease extent, visualization of the lesion's internal structures, global diagnostic preference) and quantitative enhancement (that is, the extent of lesion enhancement after contrast agent administration compared with that seen before its administration [hereafter referred to as percent enhancement], lesion/brain ratio, and contrast/noise ratio). Differences were tested with the Wilcoxon signed-rank test. Reader agreement was assessed using kappa statistics.

Significantly better diagnostic information/imaging performance (p < 0.0001, all readers) was obtained with Gd-BOPTA for all visualization end points. Global preference for images obtained with Gd-BOPTA was expressed for 42 (50%), 52 (61.9%), and 56 (66.7%) of 84 patients (readers 1, 2, and 3, respectively) compared with images obtained with Gd-DTPA contrast in four (4.8%), six (7.1%), and three (3.6%) of 84 patients. Similar differences were noted for all other visualization end points. Significantly greater quantitative contrast enhancement (p < 0.04) was noted after administration of Gd-BOPTA. Reader agreement was good (κ > 0.4).

Conclusions

Lesion visualization, delineation, definition, and contrast enhancement are significantly better after administration of 0.1 mmol/kg Gd-BOPTA, potentially allowing better surgical planning and follow up and improved disease management.

Contrast-enhanced magnetic resonance imaging of central nervous system tumors: agents, mechanisms, and applications

Brain tumors are one of the most common neoplasms in young adults and are associated with a high mortality and disability rate. Magnetic resonance imaging (MRI) is widely accepted to be the most sensitive imaging modality in the assessment of cerebral neoplasms. Because the detection, characterization, and exact delineation of brain tumors require a high lesion contrast that depends on the signal of the lesion in relation to the surrounding tissue, contrast media is given routinely. Anatomical and functional, contrast agent-based MRI techniques allow for a better differential diagnosis, grading, and especially therapy decision, planing, and follow-up. In this article, the basics of contrast enhancement of brain tumors will be reviewed. The underlying pathology of a disrupted blood-brain barrier and drug influences will be discussed. An overview of the currently available contrast media and the influences of dosage, field strength, and application on the tumor tissue contrast will be given. Challenging, contrast-enhanced, functional imaging techniques, such as perfusion MRI and dynamic contrast-enhanced MRI, are presented both from the technical side and the clinical experience in the assessment of brain tumors. The advantages over conventional, anatomical MRI techniques will be discussed as well as possible pitfalls and drawbacks.

The safety and efficacy of neuroimaging with gadoversetamide injection in pediatric patients

OBJECTIVE

The safety and efficacy of gadoversetamide injection (OptiMARK) was examined in pediatric patients referred for magnetic resonance imaging (MRI) of the central nervous system (CNS).

RESEARCH AND DESIGN METHODS

This was an open-label, multicenter study in patients aged between 2 and 18 years scheduled for a contrast-enhanced MRI study. Patients received a single injection of gadoversetamide (0.1 mmol/kg). Safety of gadoversetamide was evaluated by physical examinations and monitoring of adverse events, laboratory values, vital signs, and electrocardiogram readings before and after drug administration. Efficacy was assessed by three independent, blinded readers for confidence in diagnosis and level of conspicuity for lesion visualization on precontrast and postcontrast images. The diagnostic accuracy, sensitivity, and specificity of lesion detection were determined for the precontrast images, the postcontrast images, and the precontrast and postcontrast images read together.

RESULTS

No drug-related moderate or serious adverse events were observed in this study, according to site investigators. A total of four adverse events in four of 100 patients (4%) were deemed likely related to gadoversetamide injection by the site investigators. All were mild in severity and not clinically significant. The most common adverse events, regardless of relationship to study drug, were injection-site reactions and a small prolongation of the QT interval. The administration of gadoversetamide significantly increased the level of lesion conspicuity and diagnostic confidence (p < 0.05). Compared with the nonenhanced image, gadoversetamide significantly increased the accuracy and sensitivity of lesion detection (p < 0.05). Limitations of the study included a lack of physiological measurements after sedation and prior to contrast administration, a single dose of gadoversetamide administered (0.1 mmol/kg) and patients younger than 2 years of age were excluded.

CONCLUSION

The administration of gadoversetamide injection (0.1 mmol/kg) was safe, well tolerated and produced clinically appropriate contrast enhancement for MRI of the CNS in the pediatric population.

Contrast Enhancement of Central Nervous System Lesions: Multicenter Intraindividual Crossover Comparative Study of Two MR Contrast Agents

PURPOSE

To prospectively compare gadobenate dimeglumine with gadopentetate dimeglumine (0.1 mmol per kilogram body weight) for enhanced magnetic resonance (MR) imaging of central nervous system (CNS) lesions.

MATERIALS AND METHODS

This study was HIPAA-compliant at U.S. centers and was conducted at all centers according to the Good Clinical Practice standard. Institutional review board and regulatory approval were granted; written informed consent was obtained. Seventy-nine men and 78 women (mean age, 50.5 years +/- 14.4 [standard deviation]) were randomized to group A (n = 78) or B (n = 79). Patients underwent two temporally separated 1.5-T MR imaging examinations. In randomized order, gadobenate followed by gadopentetate was administered in group A; order of administration was reversed in group B. Contrast agent administration (volume, speed of injection), imaging parameters before and after injection, and time between injections and postinjection acquisitions were identical for both examinations. Three blinded neuroradiologists evaluated images by using objective image interpretation criteria for diagnostic information end points (lesion border delineation, definition of disease extent, visualization of internal morphologic features of the lesion, enhancement of the lesion) and quantitative parameters (percentage of lesion enhancement, contrast-to-noise ratio [CNR]). Overall diagnostic preference in terms of lesion conspicuity, detectability, and diagnostic confidence was assessed. Between-group comparisons were performed with Wilcoxon signed rank test.

RESULTS

Readers 1, 2, and 3 demonstrated overall preference for gadobenate in 75, 89, and 103 patients, compared with that for gadopentetate in seven, 10, and six patients, respectively (P < .0001). Significant (P < .0001) preference for gadobenate was demonstrated for diagnostic information end points, percentage of lesion enhancement, and CNR. Superiority of gadobenate was significant (P < .001) in patients with intraaxial and extraaxial lesions.

CONCLUSION

Gadobenate compared with gadopentetate at an equivalent dose provides significantly better enhancement and diagnostic information for CNS MR imaging.

Safety of Gadobenate Dimeglumine (MultiHance)

OBJECTIVES

Prospective studies and retrospective analyses were undertaken to evaluate the clinical safety of gadobenate dimeglumine (MultiHance) and to assess tolerability in special populations.

MATERIALS AND METHODS

A total of 3092 subjects received MultiHance in 79 clinical trials. Data from comparisons with other contrast agents and studies in children, subjects with hepatic or renal impairment, or subjects with coronary artery disease were reviewed. Postmarketing safety surveillance data after more than 1.5 million applications were also evaluated.

RESULTS

In total, 413 of 2982 (14%) adult subjects receiving MultiHance reported at least one adverse event (AE) definitely or potentially related to MultiHance, an incidence that was similar to that observed with placebo (21/127, 17%) or active controls (59/723, 8%). In crossover studies, 23 of 287 (8%) subjects receiving MultiHance experienced AE compared with 25 of 295 (9%) receiving gadopentetate dimeglumine (Magnevist). No increased AE rate was observed in children and no worsening of renal or liver function was observed in subjects with hepatic or renal impairment. No detrimental effect on cardiac electrophysiology could be observed from a retrospective analysis of ECG parameters in more than 1000 patients and healthy volunteers. The AE reporting rate from postmarketing safety surveillance of MultiHance was 0.05%. Serious AEs were rarely reported and included dyspnea, nausea, urticaria, hypotension, and anaphylactoid reactions.

CONCLUSIONS

MultiHance appears to be well tolerated in adults and children and in subjects with impaired liver or kidney function or coronary artery disease. In controlled trials, MultiHance demonstrated a similar safety profile to that of Magnevist.

Enhancing lesions of the brain: intraindividual crossover comparison of contrast enhancement after gadobenate dimeglumine versus established gadolinium comparators

RATIONALE AND OBJECTIVES

Gadobenate dimeglumine (Gd-BOPTA) possesses a two-fold higher T1 relaxivity compared to other available gadolinium contrast agents. The study was conducted to evaluate the benefits of this increased relaxivity for MR imaging of intracranial enhancing brain lesions.

MATERIALS AND METHODS

Forty-five patients (31 males, 14 females) with suspected glioma or cerebral metastases were evaluated. Patients received Gd-BOPTA and either Gd-DTPA (n = 23) or Gd-DOTA (n = 22) in fully randomized order at 0.1 mmol/kg body weight and at a flow rate of 2 ml/s. The second agent was administered 1-14 days after the first agent. Images were acquired precontrast (T1wSE, T2wFSE sequences) and at sequential postcontrast time-points (T1wSE sequences at 0, 2, 4, 6, and 8 and 15 min and a T1wSE-MT sequence at 12 min) at 1.0 or 1.5 T using a head coil. Determination of contrast enhancement was performed quantitatively (lesion-to-brain ratio, contrast-to-noise ratio, and percent enhancement) and qualitatively (border delineation, internal morphology, contrast enhancement, and diagnostic preference) by two independent, fully blinded readers.

RESULTS

Images from 43/45 patients were available for quantitative assessment. After correction for precontrast values, significantly greater lesion-to-brain ratio (P < .003), contrast-to-noise ratio (P < .03), and percent enhancement (P < .0001) was noted by both readers for Gd-BOPTA-enhanced images at all time-points from 2 min postcontrast. Qualitative assessment of all patients similarly revealed significant preference for Gd-BOPTA for lesion border delineation (P < .004), lesion internal morphology (P < .008), contrast enhancement (P < .0001), and diagnostic preference (P < .0005).

CONCLUSIONS

The greater T1 relaxivity of Gd-BOPTA permits improved visualization of intracranial enhancing lesions compared to conventional gadolinium agents.

Comparison of gadobenate dimeglumine (Gd-BOPTA) with gadopentetate dimeglumine (Gd-DTPA) for enhanced MR imaging of brain and spine tumours in children

BACKGROUND

Gadobenate dimeglumine (Gd-BOPTA) demonstrates superior enhancement of brain tumours in adult patients than Gd-DTPA.

OBJECTIVE

To determine whether Gd-BOPTA has advantages over Gd-DTPA for enhanced MR imaging of paediatric brain and spine tumours.

MATERIALS AND METHODS

Sixty-three subjects, aged 6 months to 16 years, who were enrolled in a prospective, fully blinded, randomized parallel-group phase III clinical trial, received 0.1 mmol/kg doses of either Gd-BOPTA (n=29) or Gd-DTPA (n=34). The MR images were acquired before and within 10 min of contrast agent injection. The primary objective was to compare the difference from pre-dose to post-dose lesion visualization between Gd-BOPTA and Gd-DTPA. Lesion visualization was determined as the sum of individual scores for three criteria of lesion morphological characteristics (lesion border delineation, internal morphology, and contrast enhancement), each assessed qualitatively using 4-point scales. Quantitative evaluation compared changes in lesion-to-background (LBR) and contrast-to-noise (CNR) ratios and per cent enhancement. Monitoring for adverse events and evaluation of vital signs and laboratory values was performed.

RESULTS

Pre-dose to post-dose changes in lesion visualization were significantly better for Gd-BOPTA for both lesion level (2.68+/-2.17 vs. 1.05+/-1.90, P=0.0106) and patient level (2.55+/-2.18 vs. 1.14+/-1.68, P=0.0079) comparisons. The mean pre-dose to post-dose change in CNR was greater for Gd-BOPTA (9.13+/-15.36) than Gd-DTPA (2.18+/-9.90), but the difference was only marginally significant (P=0.0779; 95% CI: -0.553, 14.454) because of wide variations of signal intensity between lesions. Similar findings were obtained for LBR and per cent enhancement. No differences between the agents were noted in terms of safety parameters.

CONCLUSIONS

At an equivalent dose Gd-BOPTA is significantly better than Gd-DTPA for visualization of enhancing CNS tumours in paediatric patients.

Measurement of Serum Calcium Concentration after Administration of Gadoversetamide in Dogs

PURPOSE

To measure serum calcium concentration with three different analytic methods after administration of gadoversetamide and three other gadolinium chelates in dogs.

MATERIALS AND METHODS

Six dogs were injected with 0.1-, 0.3-, 1.0-, and 3.0-mmol/kg doses of gadoversetamide; 1.0-mmol/kg doses of gadodiamide, gadopentetate, and gadoteridol; and a 6-mL/kg dose of saline. Baseline blood samples were collected before injection; 5, 15, 30, and 60 minutes after each treatment; and 2, 4, 6, 12, and 24 hours after each treatment. Serum calcium levels were measured with inductively coupled plasma mass spectrometry, an arzenazo III dye assay, and an orthocresolphalthalin (OCP) complexone system. Analysis of variance coupled with the Dunnett procedure was used to compare serum calcium concentrations at different time points after injection with baseline values.

RESULTS

Administration of gadoversetamide caused no decrease in serum calcium levels, as measured with inductively coupled plasma mass spectrometry or arzenazo III analytic techniques. In contrast, OCP assays showed a significant (P <.05) decrease in serum calcium values after administration of gadoversetamide. The decrease in serum calcium values peaked immediately after injection, and serum calcium values quickly returned to baseline. Injection of gadodiamide caused a significant (P <.05) decrease in the value of serum calcium when analyzed with the OCP technique but not when analyzed with inductively coupled plasma mass spectrometry or arzenazo III assays. In contrast, administration of gadopentetate or gadoteridol produced no significant change in serum calcium values, regardless of analytic method.

CONCLUSION

Gadoversetamide and gadodiamide caused a transient artifact in measurement of serum calcium levels with an OCP assay but not with an arzenazo III technique or inductively coupled plasma mass spectrometry. The presence of gadopentetate or gadoteridol in the blood did not affect measurement of serum calcium levels.

Primary and Secondary Brain Tumors at MR Imaging: Bicentric Intraindividual Crossover Comparison of Gadobenate Dimeglumine and Gadopentetate Dimeglumine

PURPOSE

To evaluate the safety of and compare the enhancement characteristics of gadobenate dimeglumine (MultiHance; Bracco Imaging, Milan, Italy) with those of a standard gadolinium chelate (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) in primary and secondary brain tumors on the basis of qualitative and quantitative parameters, on an intraindiviual basis.

MATERIALS AND METHODS

Twenty-seven patients with either high-grade glioma or metastases were enrolled in a bicentric intraindividual crossover study to compare lesion enhancement with doses of 0.1 mmol per kilogram of body weight of 0.5 mol/L gadopentetate dimeglumine and 0.5 mol/L gadobenate dimeglumine. MR imaging was performed before injection (T1-weighted spin-echo [SE] and T2-weighted fast SE acquisitions) and at 1, 3, 5, 7, 9, and 16 minutes after injection (T1-weighted SE acquisitions). Qualitative assessment was performed by blinded off-site readers (for 22 patients) and on-site investigators (for 24 patients) in terms of global contrast enhancement, lesion-to-brain contrast, lesion delineation, internal lesion morphology and structure, tumor vascularization, and global image preference. Additional quantitative assessment with region-of-interest analysis was performed by off-site readers alone. Statistical analysis of qualitative data was performed with the Wilcoxon signed rank test, whereas a nonparametric approach was adopted for analysis of quantitative data.

RESULTS

Significant (P <.05) preference for gadobenate dimeglumine over gadopentetate dimeglumine was noted both off-site and on-site for the global assessment of contrast enhancement. For off-site readers 1 and 2 and the on-site investigators, respectively, gadobenate dimeglumine was preferred in 13, 17, and 16 patients; gadopentetate dimeglumine was preferred in four, four, and four patients; and equality was found in five, one, and four patients). Similar preference for gadobenate dimeglumine was noted by off-site readers and on-site investigators for lesion-to-brain contrast and all other qualitative parameters. Off-site quantitative evaluation revealed significantly (P <.05) superior enhancement for gadobenate dimeglumine compared with that for gadopentetate dimeglumine at all time points from 3 minutes after injection.

CONCLUSION

Significantly superior contrast enhancement of intraaxial enhancing brain tumors was achieved with 0.1 mmol/kg gadobenate dimeglumine compared with that with 0.1 mmol/kg gadopentetate dimeglumine.

Safety assessment of gadoversetamide (OptiMARK®) administered by power injector

PURPOSE

To evaluate the safety of OptiMARK (gadoversetamide injection) administered via power injector.

MATERIALS AND METHODS

The study population included 144 healthy volunteers aged 18 years or older randomly assigned to one of seven treatment groups (N = 20/group). The safety assessment was based on changes in physical examination, vital signs, electrocardiograms (ECGs), standard clinical laboratory tests, and adverse events (AEs) through a 24-hour postinjection period.

RESULTS

OptiMARK caused no serious AEs or unexpected changes in physical examinations or laboratory parameters. The changes observed in vital signs and ECG intervals did not vary with changes in injection rate and were not significantly (P < 0.05) different from those elicited by saline administration at the same rates.

CONCLUSION

This study demonstrated the safety of OptiMARK when administered via a power injector at rates of 2, 4, and 6 mL/second.

Contrast agents for magnetic resonance imaging: safety update

Magnetic resonance contrast agents, particularly the gadolinium-based agents, are extremely safe and lack the nephrotoxicity associated with iodinated contrast media. Currently, seven gadolinium agents are available in one or more countries of the world, of which only four are available for clinical use in the United States. Minor adverse effects associated with each of these agents occur infrequently and include nausea, headache, and taste perversion. Whereas the gadolinium agents cannot be differentiated on the basis of these mild adverse effects, recent studies have brought to light the issue of chelate stability, and in particular, clinical observations associated with the least stable of these agents. This review briefly discusses the most recent safety issues concerning the gadolinium agents. A brief review of safety issues concerning the non-gadolinium agents is also provided.

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.

Safety of magnetic resonance contrast media

Intravenous contrast media, specifically the gadolinium chelates, are well accepted for use in the clinical practice of magnetic resonance imaging. The gadolinium chelates are considered to be very safe and lack (in intravenous use) the nephrotoxicity found with iodinated contrast media. Minor adverse reactions, including nausea and hives, occur in a low percentage of cases. The four agents currently available in the United States cannot be differentiated on the basis of these adverse reactions. Severe anaphylactoid reactions are also known to occur with all agents, although these are uncommon. This review discusses the safety issues involved with intravenous administration of the gadolinium chelates and off-label use. The latter is common in clinical practice and permits broader application of these agents.

Central nervous system: review of clinical use of contrast media

The clinical utility of intravenous contrast administration for magnetic resonance imaging in neoplastic disease of the brain, non-neoplastic disease of the brain, and in disease of the spine is reviewed. Magnetic resonance imaging (MRI) is the modality of choice for the evaluation of most suspected intracranial and spinal pathology. Contrast use substantially improves lesion detection and differential diagnosis. Applications are discussed in neoplastic disease, infection, vascular disorders, demyelinating disease, and trauma (specifically including in the spine disk herniation). Gadolinium chelates play as important a role in magnetic resonance imaging as do iodinated agents in computed tomography. Contrast administration facilitates time-efficient and cost-effective diagnosis.

Toxicological assessment of gadoversetamide injection (OptiMARK), a new contrast-enhancement agent for use in magnetic resonance imaging

RATIONALE AND OBJECTIVES

A series of preclinical tests were undertaken during the developmental process to determine the safety profile of gadoversetamide injection (OptiMARK).

METHODS

Acute intravenous, acute intracisternal, and repeated-dose toxicities; cardiovascular effects; and genetic and reproductive toxicology characteristics were assessed in several animal species.

RESULTS

Gadoversetamide injection demonstrated an acute intravenous median lethal dose of 25 to 28 mmol/kg and a maximum nonlethal dose of 14 mmol/kg in mice. In the dog, acute administration of gadoversetamide injection showed a no observable effect level at 3 mmol/kg. Dosed daily for 4 weeks, gadoversetamide injection (0.1 mmol x kg(-1) x d(-1)) caused no serious irreversible changes in any organs in rats and dogs. At a dose of 0.1 mmol/kg, gadoversetamide injection caused no significant (P < 0.05) changes in cardiovascular function in anesthetized dogs. Gadoversetamide injection showed no mutagenic activity. Fertility, reproductive performance, and postnatal fetal development were not affected at doses up to 0.5 mmol x kg(-1) x d(-1) in the rat. No teratogenicity was observed at doses up to 4.2 mmol x kg(-1) x d(-1) in the rat and up to 1.6 mmol x kg(-1) x d(-1) in the rabbit.

CONCLUSIONS

Data from our toxicological assessment demonstrate the safety of gadoversetamide injection in a number of animal species at doses exceeding the intended human clinical dose.

Cardiovascular effects caused by rapid administration of gadoversetamide injection in anesthetized dogs

RATIONALE AND OBJECTIVES

This study assessed the cardiovascular effects of gadoversetamide and other gadolinium chelates administered at high rates of injection.

METHODS

Anesthetized beagles were instrumented to record the electrocardiogram and to measure arterial blood pressure. In part 1, each animal was injected with gadoversetamide at rates of 1.0, 3.0, and 10 mL/s. In part 2, each animal was injected with gadoversetamide, gadopentetate dimeglumine, gadodiamide, and gadoteridol at a dose of 0.6 mmol/kg delivered at a rate of 3.0 mL/s.

RESULTS

Intravenous administration of gadoversetamide caused transient decreases in both heart rate and blood pressure. The rate of injection did not affect the magnitude of the heart rate or blood pressure changes. Administration of gadoversetamide, gadopentetate dimeglumine, and gadodiamide elicited equivalent changes in cardiovascular function. Injection of gadoteridol caused a similar degree of hypotension, but the changes lasted longer.

CONCLUSIONS

Rapid administration of gadoversetamide caused no potentiation in cardiovascular changes. Our data support the initiation of a clinical trial to demonstrate the safety of rapidly administering gadoversetamide with the use of a power injector.

A review of contrast media research in 1999-2000

Contrast media research published during the years 1999 and 2000 is reviewed in this article, in terms of relevance to developments within the field of diagnostic radiology. The primary focus is on publications from the journal Investigative Radiology, which publishes much of the clinical and laboratory research performed in this field. The journals Radiology and the American Journal of Roentgenology are dominant in the field of diagnostic radiology and together publish more than 10 times the number of articles as appear each year in Investigative Radiology. However, in 1999 for example, these two journals together published fewer articles than did Investigative Radiology alone that concerned basic (animal) research with contrast media. Thirty-six percent of the articles in Investigative Radiology in 1999 had a primary focus on contrast media and 18% on basic (animal) research with contrast media. To make this review more complete, articles from other major journals are cited and discussed, as needed, to provide supplemental information in the few areas not well covered by articles in Investigative Radiology. The safety of contrast media is always an important topic and research continues to be performed in this area, both to explore fundamental issues regarding iodinated contrast media and also to establish the overall safety profile of new magnetic resonance (MR) and ultrasound agents. In regard to preclinical investigations, most of the work performed in the last 2 years has been with MR and ultrasound. In MR, research efforts continue to be focused on the development of targeted agents. In ultrasound, research efforts are split between studies looking at new imaging methods and early studies of targeted agents. In regard to the clinical application of contrast media, the published literature continues to be dominated by MR. Investigations include the study of disease in clinical trials and in animal models. A large number of studies continue to be published in regard to new techniques and applications within the field of contrast-enhanced magnetic resonance angiography. This field represents the single, largest new clinical application of contrast media in MR to emerge in the last decade. New clinical research continues to be published regarding the use of contrast media in computed tomography (CT), ultrasound, and x-ray angiography. The introduction of spiral CT (together with the multidetector scanners) has led to greater utilization of this modality, as well as intravenous iodinated contrast media. The number of publications regarding clinical applications of intravenously injected ultrasound contrast agents remains low, with the high expectations in regard to growth (in terms of number of exams using contrast) of the last decade yet to be fulfilled.