Pharmacokinetics of gadodiamide injection in patients with severe renal insufficiency and patients undergoing hemodialysis or continuous ambulatory peritoneal dialysis

[Nephrogenic systemic fibrosis]

A scleromyxedema-like disease was recognized in 1997. In 2000 this disorder was first published and termed nephrogenic fibrosing dermopathy because all patients had advanced renal failure. In 2006 it was discovered that the patients had a history of a preceding contrast-enhanced magnetic resonance imaging (MRI). All patients had acute or chronic severe renal insufficiency with a glomerular filtration rate (GFR) <30 ml/min per 1.73 m(2). So far a total of about 215 patients with this new skin disorder have been reported to international registries. The skin thickening has a typical histology and begins in the peripheral extremities and progresses proximally, including also the abdominal wall and the head in some patients. NSF involves not only the skin, but also the muscles and other organs (e.g., lungs, heart, eyes) in some patients. Therefore the term nephrogenic systemic fibrosis (NSF) was introduced. Skin fibrosis and sclerosis are usually progressive with disabling contractures of involved joints (knees, hands, feet). NSF may be lethal in up to 28% of patients. Spontaneous remissions are rare. No generally accepted treatment is available. So far, the pathogenesis is not well understood. One hypothesis supposes a role of gadolinium liberated from the contrast agents. As patients with acute or chronic advanced renal failure (GFR <30 ml/min per 1.73 m(2)) including those with hepatorenal dysfunctions are at high risk to develop NSF after exposure to gadolinium-based contrast agents, contrast-enhanced MRI should be avoided in this group and alternative diagnostic procedures should be used whenever possible.

Patient characteristics and risk factors for nephrogenic systemic fibrosis following gadolinium exposure

Nephrogenic systemic fibrosis (NSF) is a systemic illness, which only affects patients with kidney failure. NSF risk increases with progressively lower levels of kidney function. It is characterized by red skin areas or plaques that develop over several weeks to painful thickened skin with a "woody" texture, resembling "peau d'orange." It may ultimately cause flexion contractures of joints. Skin biopsy reveals thickened collagen bundles, mucin deposition, proliferation of fibroblasts and elastic fibers, without inflammation. Originally described as nephrogenic fibrosing dermopathy (NFD), because of its primarily cutaneous manifestation, it was renamed NSF because of the involvement of various organs like the lungs, myocardium, or striated muscles. The pathogenesis of the disease is not known yet, but recently we suggested a strong association between development of NSF and exposure to gadolinium-based contrast (GBC) agents, thereafter confirmed by other authors. As a consequence of our recent observations, medical authorities imposed restrictions that exclude patients with advanced levels of renal insufficiency from potentially important magnetic resonance imaging studies with gadolinium. Unfortunately, the only alternatives in many situations (examination of brain, lungs, vasculature) are imaging modalities using iodinated radiocontrast agents. Thus, clinicians are faced with weighing the potential risk of NSF from GBC exposure against the risk of acute kidney injury-associated with radiocontrast media. In this dilemma, clinicians must identify patients at high-risk to develop NSF. Known risk factors critical for the development of NSF after exposure to GBC agents (certain chelates and higher doses) are end-stage renal disease requiring dialysis, especially those with little or no residual renal function, and advanced kidney disease not on dialysis. Other potential risk factors include metabolic acidosis, iron overload/intravenous iron, divalent ion disturbances, endothelial/vascular injury, and high erythropoietin doses. Further studies are required.

Gadolinium and nephrogenic systemic fibrosis: association or causation

With widespread availability of magnetic resonance imaging (MRI), it has become standard practice for patients with severe renal impairment or previous severe reactions to iodine-containing contrast media to receive gadolinium-based MRI contrast agents instead of traditional radiographic contrast agents, particularly for magnetic resonance angiography. However, there is growing concern about the use of gadolinium contrast agents in the presence of severe renal insufficiency, because of increasing reports of nephrogenic fibrosing dermopathy (NFD)/nephrogenic systemic fibrosis (NSF), associated with the exposure to certain gadolinium-containing contrast agents. In this review we explore the causal link between gadolinium exposure and NSF, using an established system of epidemiological criteria proposed by Bradford Hill. Though the current evidence makes gadolinium a strong suspect as an aetiologic agent for NSF in the presence of severe renal failure, the die is not cast yet. At this stage there needs to be cautious approach to the use of gadolinium-containing contrast agents in the presence of severe renal failure (glomerular filtration rate <30 mL/min per 1.73 m(2)).

Biochemical safety profiles of gadolinium-based extracellular contrast agents and nephrogenic systemic fibrosis

Gadolinium (Gd)-based paramagnetic contrast agents are relatively safe when used in clinically recommended doses. However, with the rapidly expanding body of literature linking Gd-based paramagnetic contrast agents and nephrogenic systemic fibrosis (NSF), awareness of the potential side effects and adverse reactions from Gd is now an important requirement for practicing radiologists. In addition to the ongoing accumulation and analyses of clinical NSF data, it is also essential for the practicing radiologist to understand the biochemical characteristics of the extracellular Gd-chelates. The purpose of this review is to consolidate and update the available information on known side effects, adverse reactions, and toxicity of the Gd chelates, with particular emphasis on the potential mechanisms of NSF.

What nephrologists need to know about gadolinium

Gadolinium chelates are commonly used to improve tissue contrast in MRI. Until recently the use of gadolinium was thought to be risk-free compared with alternative contrast agents. Recent studies, however, have raised serious concerns regarding the safety of gadolinium chelates. Although safe in patients with normal kidney function, administration of these agents in people with renal dysfunction can result in up to three clinical problems that the nephrologist should be familiar with. The first is nephrogenic systemic fibrosis (NSF), which was initially observed in 1997. Although manifesting primarily in skin, NSF can also cause systemic fibrosis, leading to disabling contractures and even death. Gadodiamide is the agent that has been most frequently associated with NSF, but other chelates might also pose a risk. The second clinical problem is that gadolinium chelates cause acute kidney injury, especially at high doses required for angiography. The third problem is that several laboratory artifacts are associated with gadolinium administration, with pseudohypocalcemia being the most important. The risk of a patient experiencing all three of these complications increases as renal function declines. In light of these problems, nephrologists need to re-evaluate the risks and benefits of gadolinium administration in patients with chronic kidney disease stage 3 or greater, as well as in those with acute kidney injury.

Nephrogenic systemic fibrosis: a nephrologist's perspective

Nephrogenic systemic fibrosis (NSF) is a debilitating disorder that affects patients with renal insufficiency. Recent evidence suggests that the development of NSF may be related to the administration of gadolinium-based contrast media (GBCM) in the setting of magnetic resonance imaging. As no treatment has consistently been effective in the management of NSF, strategies to prevent the development of this condition appear to be the best therapy. Identification of patients at greatest risk for developing NSF after exposure to GBCM is crucial. Risk factors include advanced chronic kidney disease (stages 4 and 5) and acute or chronic inflammatory events. The United States Food and Drug Administration has updated its public health advisory to include patients with moderate renal insufficiency (chronic kidney disease stage 3) as being at risk for developing NSF. However, these data require further verification and the vast majority of affected patients are already on renal replacement therapy. Another strategy in prevention may include consultation with a radiologist for imaging alternatives. If GBCM must be administered, immediate hemodialysis may be protective in patients already on hemodialysis; however, given the lack of data to support this, we do not recommend routine dialysis for patients not yet on dialysis or who are currently being treated with peritoneal dialysis. Decisions such as this should be made on a case by case basis after evaluating additional risk factors.

Increased signal in the subarachnoid space on fluid-attenuated inversion recovery imaging associated with the clearance dynamics of gadolinium chelate: a potential diagnostic pitfall

BACKGROUND AND PURPOSE

Hyperintense CSF in the subarachnoid space (SAS) on fluid-attenuated inversion recovery (FLAIR) imaging has been reported in numerous pathologic conditions, including subarachnoid hemorrhage, meningitis, meningeal carcinomatosis, superior sagittal thrombosis, adjacent tumors, status epilepticus, and stroke. It has also been reported in otherwise healthy patients undergoing anesthesia with supplemental oxygen. We present a series of 11 patients with hyperintense CSF signal intensity in the SAS on FLAIR imaging after previous administration of gadolinium chelate.

MATERIALS AND METHODS

Head MR images of patients who had a prior gadolinium-enhanced body, spine, or brain MR imaging and who had increased signal intensity in the SAS on FLAIR images were prospectively and retrospectively reviewed. Correlation was made with the clinical and laboratory findings.

RESULTS

Eight of the 11 patients had negative findings on lumbar punctures. Seven patients had either chronic renal insufficiency or acute renal failure, but the remaining 4 had normal renal function. Nine patients had no other significant intracranial abnormalities, and 2 patients had acute infarcts remote from the CSF hyperintensity. One patient had follow-up studies at 24 and 48 hours, documenting resolution of the CSF hyperintensities.

CONCLUSION

Given the sharp rise in volume of contrast-enhanced MR imaging studies, it is inevitable that some patients will have undergone a contrast-enhanced MR imaging 24-48 hours before an MR imaging of the brain. The neuroradiologist should be aware that previous administration of gadolinium chelate can cause increased signal intensity in the SAS on FLAIR imaging in patients with or without a history of renal insufficiency and without abnormalities known to disrupt the blood-brain barrier.

[Nephrogenic systemic fibrosis]

The nephrogenic systemic fibrosis - referred to in the literature earlier as nephrogenic fibrotizing dermopathy - is a rare clinical entity that develops in patients with renal disease. Its development has been described mainly after the usage of a gadolinium-based MRI contrast medium in patients with impaired renal function, mainly in dialysed patients. The nephrogenic systemic fibrosis is characterized by fibrosis evolving in the distal part of the extremities, and in more severe cases involving the lung, the liver, heart and skeletal muscles. The disease may have a fast progression and fatal outcome if it involves multiple organ systems, in approximately 5% of the cases. Until now, no evidence-based therapy of nephrogenic systemic fibrosis is known, however, in single cases an amelioration has been described after renal transplantation and plasmapheresis, and remission has been described after extracorporal photopheresis.

New insights into nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis is a new disorder reported almost exclusively in patients who have renal insufficiency and are exposed to contrast media formulated with gadolinium. High morbidity and mortality are associated with this severely disabling and painful condition. The acute phase begins upon exposure to gadolinium contrast media, characterized by a systemic inflammatory response involving iron mobilization, and then as a progressive, chronic phase in which fibrosis develops. Proposed is a unifying model of cumulative risk factors in which the interplay of systemic inflammation and stimulated hematopoietic environment associated with hyperparathyroidism and erythropoietin may tie to a common pathogenic mechanism of fibrogenesis. Because there are no uniformly effective interventions to treat nephrogenic systemic fibrosis other than successful renal transplantation, prevention by avoiding gadolinium contrast media in patients with chronic kidney disease is vital. On the basis of suspected pathogenesis, it is also reasonable to limit erythropoietin and iron therapy to dosages ensuring recommended targets and adequately control hyperparathyroidism. Herein is reviewed what is currently known about this subject.

Gadolinium-enhanced MR imaging and nephrogenic systemic fibrosis: retrospective study of a renal replacement therapy cohort

PURPOSE

To retrospectively compare the frequency of administration and cumulative dose of gadolinium-based contrast agent in dialysis-dependent patients who did and those who did not develop nephrogenic systemic fibrosis.

MATERIALS AND METHODS

The ethics committees granted exempt status for this study and also waived the need for informed consent. A retrospective analysis was performed of all adult patients undergoing dialysis in the west of Scotland between January 1, 2000, and July 1, 2006. Diagnoses of nephrogenic systemic fibrosis, episodes of gadolinium-enhanced magnetic resonance (MR) imaging, and cumulative doses of gadolinium-based contrast agent were recorded. Outcomes were analyzed by means of parametric and nonparametric testing.

RESULTS

Fourteen of 1826 patients had a diagnosis of nephrogenic systemic fibrosis. Mortality was similar for affected and nonaffected patients. Thirteen (93%) of 14 patients with nephrogenic systemic fibrosis had undergone gadolinium-enhanced MR imaging compared with 408 (22.5%) of 1812 nonaffected patients (P<.001). Patients with nephrogenic systemic fibrosis received a higher median cumulative dose of gadodiamide (0.39 vs 0.23 mmol per kilogram of body weight, P=.008) and underwent more gadolinium-enhanced MR imaging than their nonaffected gadolinium-exposed counterparts.

CONCLUSION

The data support a positive association between gadolinium-based contrast agent administration and development of nephrogenic systemic fibrosis in the established renal failure population; in addition, there is a positive association between cumulative dose of gadodiamide used and dosing events.

Nephrogenic systemic fibrosis: A clinicopathologic study of six cases

BACKGROUND

Nephrogenic systemic fibrosis is a rare fibrosing condition that occurs in patients with renal insufficiency. While its histologic characteristics have been well described, the etiology and pathogenesis have not been fully characterized. Several recent studies support the theory that gadolinium-based contrast agents play a causative role in the development of the disease. Erythropoietin therapy and endothelial damage from surgical procedures have also been suggested as potential contributing factors.

OBJECTIVE

This study attempts to help contribute to the understanding of this novel disorder.

METHODS

We performed a retrospective chart review of 6 patients diagnosed with nephrogenic systemic fibrosis at our institution. Emphasis was placed on identification of potential putative etiologic agents including gadolinium, erythropoietin therapy, and previous surgical procedures.

RESULTS

All patients had documented exposure to gadolinium-based contrast agents. Three of the 6 patients were treated with erythropoietin, and all patients underwent a previous surgical procedure.

LIMITATIONS

This study is limited by its small size; therefore, the findings and results may not be applicable to all patients with this disorder.

CONCLUSION

Our data suggest that gadolinium plays a primary role in nephrogenic systemic fibrosis and that prior surgery may be a contributory factor.

[Nephrogenic systemic fibrosis and gadolinium-based contrast media]

Nephrogenic systemic fibrosis (NSF) is a recently characterized systemic fibrosing disorder occurring in patients with underlying renal disease. This condition principally leads to skin thickening and hardening and may induce joint immobility and inability to walk. In 2006, clusters of NSF were associated to an exposure to gadolinium containing contrast agents during magnetic resonance imaging. Gadolinium has been detected in skin tissue of patients with NSF. Gadodiamide, a linear gadolinium chelate appears to be particularly at risk. During renal failure, gadodiamide accumulation may explain the development of NSF. Regulatory decisions have been taken to contraindicate gadodiamide in patients with severe renal impairment.

Effectiveness and renal tolerance of multidetector helical CT with gadobutrol: results of a comparative porcine study

PURPOSE

To prospectively evaluate the safety and effectiveness of high doses of 1 mol/L gadobutrol as a contrast agent for computed tomography (CT).

MATERIALS AND METHODS

Experiments were performed according to guidelines for care of laboratory animals. The local animal care committee approved the study protocol. Unenhanced and contrast material-enhanced CT images of the chest and abdomen were obtained randomly in nine domestic pigs. Gadobutrol was injected (1, 2, or 3 mL per kilogram of body weight; three pigs for each dose). Attenuation was measured in different vascular and parenchymal structures. Changes in blood chemistry and hematologic parameters were monitored before and 1, 2, 3, and 7 days after gadobutrol administration. Urine samples were evaluated before and 7 days after gadobutrol administration. Technetium 99m mertiatide renal scintigraphy was performed before and 7 days after contrast medium injection. Animals were sacrificed 7 days after contrast medium administration, and one kidney was removed from each animal for examination with light microscopy. No serious adverse events occurred. A mixed-model nested analysis of variance was used for statistical evaluation.

RESULTS

Mean attenuations for the 1, 2, and 3 mL/kg gadobutrol doses, respectively, were 148 HU +/- 20 (standard deviation), 282 HU +/- 18, and 289 HU +/- 20 in the thoracic aorta; 99 HU +/- 11, 166 HU +/- 9, and 153 HU +/- 18 in the kidneys; and 106 HU +/- 7, 186 HU +/- 18, and 224 HU +/- 24 in the inferior vena cava. No clinically relevant changes in hematologic, blood chemistry, or urine analysis results were detected. Markers for glomerular filtration and tubular function were unaffected in all groups. Scintigraphy revealed no differences between unenhanced and contrast-enhanced results. No morphologic changes of the renal parenchyma were found at histologic analysis.

CONCLUSION

Contrast-enhanced CT with a 2 or 3 mmol/kg dose of 1 mol/L gadobutrol resulted in excellent vascular and parenchymal enhancement. A gadobutrol dose of up to 3 mL/kg did not affect renal function.

Gadolinium and nephrogenic systemic fibrosis

Nephrogenic systemic fibrosis (NSF) is characterized by red skin areas or plaques that over several weeks successively develop to painful thickened skin with a 'woody' texture, resembling 'peau d'orange'. Starting at the extremities, it may spread to the trunk, and may progressively inhibit flexion of adjacent joints. In skin biopsies of affected areas, thickened collagen bundles, mucin deposition, and proliferation of fibroblasts and elastic fibers are seen. Originally described as nephrogenic fibrosing dermopathy (NFD) because of its primarily cutaneous manifestation, this entity was then named NSF because of systemic involvement of other organs like lungs, myocardium, or striated muscles. The pathogenesis of the disease is not yet known, but our observations suggest a close association between development of NSF and exposure to gadolinium-containing contrast agents, thereafter confirmed by other authors. Recently, gadolinium was demonstrated to be detectable in skin tissue samples of affected patients. In this short review, the development of NSF and its sequential association with the exposure to gadolinium-containing contrast agents is presented. The mechanisms likely to cause NFD/NSF are discussed.

Imaging in the time of NFD/NSF: do we have to change our routines concerning renal insufficiency?

To date there are potential chronology-based but not conclusive reasons to believe that at least some of the gadolinium complexes play a causative role in the pathophysiology of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). Still, the exact pathogenesis and the risk for patients is unclear beside the obvious connection to moderate to severe renal insufficiency. So far, MR imaging with Gd-enhancement was regarded as the safest imaging modality in these patients--the recent development creates tremendous uncertainty in the MR-community. Nevertheless, one should remember that, despite the over 200 cases of NSF and about 100 with proven involvement of Gd(3+), the vast majority of over 200 million patients exposed to gadolinium since the 1980s have tolerated these agents well. Importantly, NSF is a rare disease and does not appear to occur in patients without renal impairment. Many patients and researchers have undergone MR investigations with Gd exposure in the past. For those, it is essential to know about the safety of the agents at normal renal function. We can hope that pharmacoepidemiological and preclinical studies will allow us to better understand the pathophysiology and role of the various MR contrast agents in the near future.

Clinical and biological consequences of transmetallation induced by contrast agents for magnetic resonance imaging: a review

Gadolinium-based contrast agents (CAs) are widely used to enhance the contrast of images in magnetic resonance imaging procedures. Two categories of gadolinium chelates exist: the macrocyclic molecules where Gd3+ is caged in the pre-organized cavity of the ligand and the linear molecules. Gadolinium chelates differ in their thermodynamic stability constants and in their kinetic stability. In general, macrocyclic chelates such as Gd-DOTA or Gd-HP-DO3A are more stable than linear molecules. Even among linear agents, differences can be found. There is increasing evidence that transmetallation can be found in vivo, in the case of certain CAs (especially linear chelates), with body cations such as zinc, calcium or iron. Furthermore, analytical interference with colorimetric determination of calcium has been clinically evidenced with two linear chelates, Gd-DTPA-BMA and Gd-DTPA-BMEA. Clinical cases of spurious hypocalcaemia have been reported with these molecules. Such interference with some colorimetric assays for calcium is clinically relevant in that it can lead to unnecessary and potentially harmful treatment for hypocalcaemia.

Gadolinium-based Contrast Media and the Development of Nephrogenic Systemic Fibrosis in Patients with Renal Insufficiency

Gadolinium-based contrast media are important tools in diagnostic and interventional radiology that are particularly useful in patients with renal insufficiency. Recent reports in which exposure to gadolinium compounds has been linked to the development of nephrogenic systemic fibrosis in this patient population, however, are quite concerning. It is of great importance that radiologists be aware of this serious disease and exercise caution when considering the use of gadolinium-based contrast media in patients with moderate (glomerular filtration rate, <60 mL/min/1.73 m(2)) to severe (glomerular filtration rate, <15 mL/min/1.73 m(2)) renal disease.

Nephrogenic systemic fibrosis: a mysterious disease in patients with renal failure--role of gadolinium-based contrast media in causation and the beneficial effect of intravenous sodium thiosulfate

Nephrogenic fibrosing dermopathy/nephrogenic systemic fibrosis (NSF) is an emerging scleromyxedema-like cutaneous disorder of unknown cause that is seen in patients with renal failure, and the number of reported cases has grown significantly since its first recognition. Recent case reports associated the use of gadolinium (Gd3+)-based contrast agents with the development of NSF. Herein is reported an additional patient who had NSF and had multiple previous exposures to Gd3+-based magnetic resonance imaging studies and had marked improvement in pain and skin changes after a trial of intravenous sodium thiosulfate. Discussed are the possible association of Gd3+-based contrast media with the development of NSF and potential for the use of sodium thiosulfate in the treatment of NSF.

Nephrogenic Systemic Fibrosis

OBJECTIVES

Nephrogenic systemic fibrosis (NSF) is a rare acquired disorder that was first recognized in 1997. Presented is a retrospective review of 6 cases of NSF diagnosed by skin biopsy in our institution during the past 4 years and their relationship to gadodiamide exposure.

METHODS AND RESULTS

Patient age ranged from 23 to 71 years. The onset of symptoms consistent with NSF was between 19 days and 2 months after gadodiamide exposure. Five patients had severe renal impairment and started dialysis around the period of gadodiamide exposure (1 day before the 37 days after contrast administration). The sixth patient had a clotted access at the time of a contrast-enhanced magnetic resonance venogram and was hence not being adequately dialyzed. The dose of gadodiamide ranged from 16 to 40 mL (0.11 to 0.36 mmol/kg). Despite having normal serum bicarbonate, 5 of the 6 patients had an elevated anion gap metabolic acidosis.

CONCLUSIONS

In our 6 patients, all had either failing native or transplant kidneys at the time of gadodiamide exposure. The development of NSF was temporally related to gadodiamide injection, suggesting as the etiology dechelation of the agent and thus emphasizing the need for change in clinical practice.

Gadodiamide-Associated Nephrogenic Systemic Fibrosis: Why Radiologists Should Be Concerned

OBJECTIVE

Nephrogenic systemic fibrosis (NSF) is a rare multisystemic fibrosing disorder that principally affects the skin but may affect other organs of patients with renal insufficiency. The purpose of our study was to identify any common risk factors and determine whether i.v. gadodiamide is associated with the development of NSF.

MATERIALS AND METHODS

A retrospective chart review was performed for all 12 patients diagnosed with NSF at our institution between 2000 and 2006 to identify the clinical manifestations, timing, and dose of gadodiamide administration; dialysis records; concurrent medications; comorbid conditions and surgeries; laboratory findings; imaging findings; and clinical outcome. A review of the dialysis and MR records between 2000 and 2006 showed 559 MRI examinations on 168 dialysis patients (including 301 contrast-enhanced examinations).

RESULTS

NSF was diagnosed by clinical findings and tissue diagnosis. All 12 patients had renal insufficiency--eight with dialysis-dependent chronic renal insufficiency and four with acute hepatorenal syndrome. All 12 patients developed skin fibrosis within 2-11 weeks after gadodiamide administration. The odds ratio for development of NSF after gadodiamide exposure was 22.3. No other common event or exposure could be found. Four patients had abnormal scintigraphic bone scans with skin and muscle uptake and lower-extremity MRI finding of edema in the muscles, intermuscular fascia, and skin. Despite the fact that 10 patients were dialyzed within 2 days of gadodiamide administration, this did not prevent the development of NSF.

CONCLUSION

Development of NSF was strongly associated with gadodiamide administration in the setting of either acute hepatorenal syndrome or dialysis-dependent chronic renal insufficiency.

Cytotoxicity of iodinated and gadolinium-based contrast agents in renal tubular cells at angiographic concentrations: in vitro study

PURPOSE

To test in vitro whether gadolinium-based contrast agents induce fewer toxic effects on renal tubular cells than does an iodinated contrast medium at concentrations used for angiography.

MATERIALS AND METHODS

LLC-PK1 cells were incubated with iomeprol, gadopentetate dimeglumine, gadobenate dimeglumine, gadoterate meglumine, gadodiamide, and corresponding mannitol solutions for 24 hours at 37 degrees C in two experimental settings: measurements with equally attenuating solutions and measurements with equimolar solutions. Cytotoxicity was assessed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, trypan blue testing, and an assay to detect apoptosis and necrosis. Data were analyzed with analyses of variance and post hoc tests.

RESULTS

Yielding the same x-ray attenuation, iomeprol-300 and iomeprol-150 at concentrations of 2.34-18.75 mg of iodine per milliliter induced significantly (P < .001) lower inhibition of MTT conversion (74%-102% of undamaged control cells) compared with 15.63-125.00 mmol/L concentrations of the gadolinium-based agents (mean percentages of undamaged control cells: 48%-80%, 50%-87%, 60%-95%, and 56%-92% with gadopentetate dimeglumine, gadobenate dimeglumine, gadoterate meglumine, and gadodiamide, respectively). At equimolar concentrations (62.5 mmol/L), iomeprol-190 induced a mean extent of inhibition of MTT conversion (69% of undamaged control cells) similar to that induced by gadoterate meglumine (71%) and gadodiamide (70%), whereas gadopentetate dimeglumine and gadobenate dimeglumine induced stronger effects (63% and 64%, respectively; P < .001). At trypan blue testing, there were more dead cells after incubation with 125 mmol/L gadopentetate dimeglumine than after incubation with iomeprol-190 (57% vs 19%, P < .001). The 125 mmol/L gadopentetate and gadobenate formulations induced more necrosis and apoptosis than did gadoterate meglumine, gadodiamide, and iomeprol (mean percentage difference between treated and untreated control cells: for necrosis, +124%, +95%, +17%, -6%, and +3%, respectively; for apoptosis, +34%, +35%, +13%, +4%, and +5%, respectively; P < .001).

CONCLUSION

At angiographic concentrations, gadolinium-based contrast agents do not induce fewer cytotoxic effects on cultured renal tubular cells than does iomeprol.

Nephrogenic systemic fibrosis: suspected causative role of gadodiamide used for contrast-enhanced magnetic resonance imaging

Nephrogenic systemic fibrosis is a new, rare disease of unknown cause that affects patients with renal failure. Single cases led to the suspicion of a causative role of gadodiamide that is used for magnetic resonance imaging. This study therefore reviewed all of the authors' confirmed cases of nephrogenic systemic fibrosis (n = 13) with respect to clinical characteristics, gadodiamide exposure, and subsequent clinical course. It was found that all had been exposed to gadodiamide before the development of nephrogenic systemic fibrosis. The delay from exposure to first sign of the disease was 2 to 75 d (median 25 d). Odds ratio for acquiring the disease when gadodiamide exposed was 32.5 (95% confidence interval 1.9 to 549.2; P < 0.0001). Seven (54%) patients became severely disabled, and one died 21 mo after exposure. No other exposure/event than gadodiamide that was common to more than a minority of the patients could be identified. These findings indicate that gadodiamide plays a causative role in nephrogenic systemic fibrosis.

Noninvasive gadolinium-enhanced three dimensional computed tomography coronary angiography

RATIONALE AND OBJECTIVES

Although the use of gadolinium (Gd)-based contrast agents for angiographic studies of abdominal aorta, renal vasculature, and digital subtraction angiography has been reported, no studies have shown their diagnostic efficacy and image quality in coronary computed tomography angiography (CTA). The aim of this study is to evaluate the image quality of Gd-based contrast agents during coronary CTA.

MATERIALS AND METHODS

A phantom study was done to evaluate the attenuation of serial dilutions of Gd and iodinated agents. This study was done on a 64-slice multirow detector CT (MDCT) scanner and e-speed scanner and CT attenuation Hounsfield units (CTHU) were compared. We evaluated 35 consecutive patients who underwent Gd-enhanced CTA. CTHU of aorta was measured at first, mid, and lowest slice levels with and without contrast administration. The image quality was graded on the basis of visualization of the coronary arteries (scale I-III; III demonstrating diagnostic image quality of the distal-most vessels). In a substudy, four patients with borderline renal insufficiency underwent CTA using Gd and iodinated contrast agents admixed in a 50:50 ratio.

RESULTS

The phantom study showed that enhancement of various dilutions of Gd and iodine resulted in near identical CTHU with both e-speed and 64-slice scanners (r(2) > or = 0.997). Mean CTHU with contrast at the top slice was 116 HU, at middle slice was 125 HU, and at the lower slice was 93 (111.14 +/- 22). Quality evaluation showed 2 grade III, 9 grade II, and 24 grade I images (average quality of images 1.35). Mean CTHU was 222.

CONCLUSION

Gd-enhanced contrast medium provides adequate enhancement of coronary vasculature, allowing for diagnostic evaluation of coronary arteries with new CT systems. Use of newer generations of multirow detector CT scanners should further enhance the quality of images.

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.

Safety of gadodiamide mixed with a small quantity of iohexol in patients with impaired renal function undergoing coronary angiography

Gadolinium-based contrast agents can be used in diagnostic and interventional angiography, and are safe in recommended doses in patients with impaired renal function, but the image quality is usually unsatisfactory. The objective of the present study is to evaluate the safety of gadolinium mixed with a small quantity of iodine-based contrast agent and the image quality of this mixture in patients with renal insufficiency undergoing diagnostic coronary angiography. Forty-two patients with baseline creatinine level>1.5 mg/dl were randomized into gadolinium or iodine groups. In the gadolinium group gadodiamide was mixed with 1:3 iohexole and in the iodine group only this agent was used as contrast material. Peak creatinine levels 48-72 h after the procedure were measured. The primary end point was the development of contrast-induced nephropathy (CIN), defined as >25% increase of baseline creatinine levels, and the secondary end points were absolute and relative changes in baseline creatinine levels. Total contrast volumes used were not different between groups (57+/-11 ml in gadolinium and 55+/-10 ml in iodine; P=0.68). Mean creatinine level did not increase significantly in the gadolinium group (from 1.9+/-0.3 to 1.9+/-0.4 mg/dl; P=0.06), but did in the iodine group (from 2.0+/-0.4 to 2.3+/-0.5 mg/dl; P=0.001). No patient had CIN in the gadolinium group whereas 5 (23%) patients had this phenomenon in the iodine group (P=0.048). Contrast regimen was very well tolerated in the gadolinium group, with only transient headache in two patients. Gadodiamide mixed with a small quantity of iohexol is safe in patients with azotemia undergoing diagnostic coronary angiography. The image qualities obtained with this combination are also satisfactory in all of the cases. Further evaluation of the safety of this technique is warranted, especially in other types of diagnostic and interventional procedures in which a higher amount of contrast dye is needed.

Preliminary experience with contrast-enhanced MR angiography in patients with end-stage renal failure

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate our preliminary experience with routine contrast-enhanced magnetic resonance angiography (CE-MRA) of the lower limb arteries in patients with end-stage renal failure.

MATERIALS AND METHODS

A retrospective analysis was performed on clinical, physiological, and imaging data for 104 patients with end-stage renal failure. Patients were considered to be in end-stage renal failure if they were on renal replacement therapy (peritoneal or hemodialysis) or were being evaluated as part of a pretransplant workup. CE-MRA was carried out on a 1.5-T scanner using a single-injection, three-station moving table technique.

RESULTS

Eleven percent of asymptomatic patients with normal ankle/brachial pressure indexes (ABPI) were found to have severe arterial disease on CE-MRA, and in 30% of asymptomatic patients with abnormal ABPI, CE-MRA showed mild or no disease. Moreover two of three symptomatic patients with normal ABPI were shown to have severe disease. Two patients on peritoneal dialysis had to be switched to hemodialysis. No other adverse events were revealed.

CONCLUSION

CE-MRA is a useful adjunct to clinical and physiological examination for the evaluation of the lower limb arteries in a group of patients who have a higher-than-average incidence of peripheral vascular disease, yet have previously been severely restricted from traditional angiography because of contrast-medium-induced nephrotoxicity.

Clinical perspectives in perfusion: neuroradiologic applications

Imaging of cerebral perfusion, particularly by the dynamic tracking of a bolus of gadolinium-based contrast agent, has emerged from the experimental laboratory and become a routine aspect of neuroradiologic practice. This article discusses the practical implementation of "perfusion" protocols into neuroradiologic examinations, as well as discussing the role of postprocessing and quantitative interpretation in terms of vascular physiology and function. Several key clinical indications are introduced, such as acute cerebral ischemia, chronic vascular disease, and tumors.

Pseudohypocalcemia after magnetic resonance imaging with gadolinium in patients with cirrhosis

Hypocalcemia in patients with cirrhosis may be due to a number of causes. We noted a relationship between injection with gadodiamide, a particular gadolinium chelate, during magnetic resonance imaging of the liver and the development of a falsely low serum total calcium level in a patient with cirrhosis. A cross-reference and retrospective chart review identified 10 additional patients in whom this phenomenon was noted. We describe the temporal relationship and clinical characteristics of these patients. Pseudohypocalcemia following magnetic resonance imaging with gadodiamide contrast should be considered in the differential diagnosis of hypocalcemia in patients with cirrhosis.

Iron-mobilizing properties of the gadolinium-DTPA complex: clinical and experimental observations

BACKGROUND

Gadolinium (Gd) magnetic resonance imaging (MRI) contrast agents are considered to be safe in patients with impaired renal function. Our study investigates a mechanism of severe iron intoxication with life-threatening serum iron levels in a haemodialysis patient following MRI with Gd-diethylenetriaminepentaacetic acid (Gd-DTPA) administration. His previous history was remarkable for multiple blood transfusions and biochemical evidence of iron overload. We hypothesized that Gd-DTPA may have an iron-mobilizing effect in specific conditions of iron overload combined with prolonged exposure to the agent.

METHODS

For the in vitro study, Gd-DTPA was added to mice liver homogenate and iron metabolism parameters were measured after incubation in comparison with the same samples incubated with saline only. For the in vivo study, an experimental model of acute renal failure in iron-overloaded rats was designed. Previously iron-overloaded and normally fed rats underwent bilateral nephrectomy by renal pedicle ligation, followed by Gd-DTPA or saline injection. Iron and iron saturation levels were checked before and 24 h after Gd-DTPA or vehicle administration.

RESULTS

Significant mobilization of iron from mice liver tissue homogenate in mixtures with Gd in vitro was seen in the control (saline) and in the experimental (Gd) groups (513+/-99.1 vs 1117.8+/-360.8 microg/dl, respectively; P<0.05). Administration of Gd-DTPA to iron-overloaded rats after renal pedicle ligation caused marked elevation of serum iron from baseline 143+/-3.4 to 570+/-8 microg/dl (P<0.0001). There were no changes of the named parameter, either in iron-overloaded anuric rats after saline injection or in normal diet uraemic animals, following Gd-DTPA administration.

CONCLUSIONS

The combination of iron overload and lack of adequate clearance of Gd chelates may cause massive liberation of iron with dangerous elevation of free serum iron. It is highly recommended that after Gd contrast study, end-stage renal disease patients with probable iron overload should undergo prompt and intensive haemodialysis for prevention of this serious complication.

1-molar gadobutrol as a contrast agent for computed tomography: results from a comparative porcine study

RATIONALE AND OBJECTIVES

To evaluate prospectively the efficacy of gadobutrol as contrast agent for computed tomography (CT) compared with iodinated contrast media in a porcine animal model.

METHODS

In 8 domestic pigs (35 +/- 4 kg body weight [BW]), continuous spiral CTs of the chest and abdomen were performed using either 2 mmol/kg BW Gadovist 1.0 (1 mol/L gadobutrol) intravenously or Ultravist (300 mg I/mL iopromide) (slice 5 mm, table feed 7.5 mm, reconstruction increment 5 mm). One week later, the same animals were examined using the same protocol with the other contrast agent. In 2 additional animals, serial CTs were performed at the same level using gadobutrol or iopromide on day 1 and the alternate agent on day 8 inches order to determine contrast media kinetics, peak enhancement, and time enhancement-product in important vascular regions and parenchymal organs (abdominal aorta, inferior vena cava, liver, and renal parenchyma). Peak enhancement (net increase compared with nonenhanced baseline values) was measured in Hounsfield units (HU) in defined regions of interest.

RESULTS

In vivo, the mean peak enhancement 5, 15, 30, and 120 seconds in the abdominal aorta after injection of 2 mL/kg BW gadobutrol and iopromide was 200 +/- 11, 224 +/- 10, 261 +/- 13, and 95 +/- 9 HU versus 232 +/- 10, 298 +/- 10, 152 +/- 11, and 123 +/- 10 HU, respectively. Differences in enhancement of vascular structures was statistically significant (P < 0.05) in carotid arteries (235 +/- 20 HU for gadobutrol and 264 +/- 19 HU for iopromide) and the aortic arch (261 +/- 14 HU for gadobutrol and 279 HU +/- 13 HU for iopromide). No statistical significance was seen in all other measured vascular structures and parenchymal organs.

CONCLUSION

Contrast-enhanced CT with 1 mol/L gadobutrol in a dose of 2 mmol/kg BW resulted in an excellent vascular and parenchymal enhancement in most vascular regions and parenchymal organs similar to an equivalent volume of 300 mg/mL iodinated contrast media.

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.

X-ray digital subtraction angiography with 1 mol/L gadobutrol: results from a comparative porcine study With iodinated contrast agents

RATIONALE AND OBJECTIVES

To evaluate prospectively diagnostic accuracy of 1 mol/L gadobutrol as a contrast agent for intraarterial x-ray digital subtraction angiography (DSA) in comparison to iodinated, nonionic contrast media and 0.5 mol/L gadolinium-DTPA.

METHODS

Flush arteriograms (ascending, descending, abdominal aorta, iliac, and femoral arteries) and selective angiograms (carotid, renal, and visceral arteries) were obtained from bilateral femoral arterial access (5 F sheaths) in 10 domestic pigs (70 kg body weight). Digital subtracted angiograms were obtained during injection of undiluted 1 mol/L gadobutrol, 300 mg I/mL iopromide, or 0.5 mol/L gadopentetate. Injection parameters (volume and velocity) were similar for all three contrast agents. In paired arteries, two different contrast media were used during the same angiographic run. Diagnostic quality and accuracy of the angiograms were evaluated on a three-step scale by three independent blinded investigators.

RESULTS

Sufficient nonselective angiographic images were obtained in 90% of cases using iodinated contrast material. Gadobutrol achieved sufficient nonselective angiograms in 64%. Selective angiograms were sufficient in 98% using iodinated contrast material, 90% using 1 mol/L Gadobutrol and 48% using 0.5 mol/L Gd-DTPA. Adverse reactions to any of the used contrast agents were not noted.

CONCLUSION

One mol/L Gadobutrol solution allows x-ray digital subtraction angiography with a diagnostic accuracy equivalent to 300 mg/mL iodinated contrast media, if selective injections are performed. Flush aortograms are of inferior image quality to iodinated contrast material.

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.

The OptiMARK clinical development program: summary of safety data

PURPOSE

To describe and summarize the safety data from the OptiMARK clinical development program.

MATERIALS AND METHODS

In the 18 clinical studies comprising the clinical program, doses ranging from 0.1 to 0.7 mmol/kg were administered to healthy adult volunteers, patients with hepatic or renal impairment, and patients with confirmed or highly suspected central nervous system (CNS), liver, breast, vascular, bone, or soft tissue pathologies. A total of 2038 injections of OptiMARK, Magnevist, or placebo were administered to 1684 subjects. Safety assessments were performed at appropriate intervals during all Phase 1, 2, and 3 studies.

RESULTS

Of the 1684 subjects exposed to a study drug or placebo in the clinical development program, 646 subjects experienced 1293 adverse events. Thirty-one percent of the OptiMARK injections were associated with an adverse event. In comparison, 35% of Magnevist injections and 48% of placebo injections were associated with at least one adverse event.

CONCLUSIONS

OptiMARK was safe and well-tolerated with a safety profile similar to that of Magnevist.