Gadopentetate dimeglumine-enhanced three-dimensional MR-angiography: dosing, safety, and efficacy

Evaluation of the Contrast Enhancement Performance of Gadopiclenol for Magnetic Resonance Angiography in Healthy Rabbits and Pigs

OBJECTIVES

Unexpected accumulations of gadolinium in various organs were reported after the administration of gadolinium-based contrast agents, making desirable to reduce the dose while maintaining equivalent diagnostic performance. The aim of this study was to evaluate the contrast enhancement performance of high relaxivity gadopiclenol compared with gadoterate meglumine in abdominal contrast-enhanced magnetic resonance angiography (CE-MRA).

MATERIALS AND METHODS

In a first study in healthy rabbits, axial 3D gradient echo sequences were applied at 4.7 T to study arterial enhancement as a function of gadopiclenol dose (0.025, 0.05, 0.075, and 0.1 mmol Gd/kg) or gadoterate meglumine at 0.1 mmol Gd/kg (n = 5-6/group). The increase in signal-to-noise ratio (ΔSNR) in the aorta at the first pass was measured and compared. In a second, crossover study in 6 healthy pigs, abdominal CE-MRA sequences were acquired at 3 T with gadopiclenol at 0.05 mmol Gd/kg or gadoterate meglumine at 0.1 mmol Gd/kg at a 1-week interval. Quantitatively on the maximum intensity projection (MIP) images, the mean MIP SNR within the aorta of both groups was compared. Qualitatively, a blinded comparison of the angiograms was performed by an experienced radiologist to determine the preferred contrast agent.

RESULTS

In the rabbit, ∆SNR is linearly correlated with the gadopiclenol dose (P = 0.0010). Compared with gadoterate meglumine 0.1 mmol Gd/kg, an increase in the ∆SNR is observed after 0.05, 0.075, and 0.1 mmol Gd/kg of gadopiclenol (+63% P = 0.0731, +78% P = 0.0081, and +72% P = 0.0773, respectively), whereas at 0.025 mmol Gd/kg, ∆SNR is in the same range as with gadoterate meglumine 0.1 mmol Gd/kg (+15% P > 0.9999). In pigs, contrast enhancement after gadopiclenol at 0.05 mmol/kg is +22% superior to MIP SNR after gadoterate meglumine at 0.1 mmol Gd/kg (P = 0.3095). Qualitatively, a preference was shown for gadopiclenol images (3/6) over the gadoterate meglumine examinations (1/6), with no preference being shown for the remainder (2/6).

CONCLUSIONS

First-pass CE-MRA is feasible with gadopiclenol at 0.05 mmol Gd/kg with at least the same arterial signal enhancement and image quality as gadoterate meglumine at 0.1 mmol Gd/kg.

“Contrast nephropathy” in renal transplantation: Is it real?

The risk of contrast-induced nephropathy (CIN) in renal transplant recipients is increased in diabetics, patients with impaired basal kidney function, patients in shock, patients presenting with acute emergency and in old age recipients. Approximately one-third of all hospitalized patients with acute kidney injury is attributed to CIN. In the United States, it is the third leading cause of hospital-acquired renal failure. Therefore, efforts should be directed to minimize CIN-related morbidity and mortality as well as to shorten hospital stay. While the role of peri-procedural prophylactic hydration with saline is unequivocal; the use of acetyl cysteine is not based on robust evidence. The utility of theophylline, aminophylline, calcium channel blockers, natriuretic peptide, and diuretics does not have proven role in attenuating CIN incidence. We aim to analyze the evidence for using various protocols in published literature to limit CIN-associated morbidity and mortality, particularly during surveillance of the renal allograft survival.

Magnetic Resonance Angiography of the Upper Extremity

The magnetic resonance angiography (MRA) toolbox includes a wide array of versatile methods for diagnosis and therapy planning in patients with a variety of upper extremity vascular pathologies. MRA can provide excellent image quality with high spatial and high temporal resolution without the disadvantages of ionizing radiation, iodinated contrast, and operator dependency. Contrast-enhanced techniques are preferred for their robustness, image quality, and shorter scan times. This article provides an overview of the available MRA techniques and a description of the clinical entities that are well suited for evaluation with contrast-enhanced MRA.

Gadofosveset trisodium: abdominal and peripheral vascular applications

OBJECTIVE

The purpose of this review is to illustrate various applications of gadofosveset trisodium in evaluating abdominal and peripheral vascular disease. The basic properties, technical considerations, and clinical and potential future applications of gadofosveset are described.

CONCLUSION

Gadofosveset trisodium facilitates comprehensive high-resolution arterial and venous MR angiography. Because of its prolonged intravascular residence time, gadofosveset trisodium is particularly useful for evaluating venous, dynamic, and functional vascular disease with a single low-dose contrast injection.

Safety of cardiac magnetic resonance and contrast angiography for neonates and small infants: a 10-year single-institution experience

BACKGROUND

With increasing applications of cardiac magnetic resonance (CMR) and magnetic resonance angiography (MRA) for evaluation of congenital heart disease (CHD), safety of this technology in the very young is of particular interest.

OBJECTIVE

We report our 10-year experience with CMR in neonates and small infants with particular focus on the safety profile and incidence of adverse events (AEs).

MATERIALS AND METHODS

We reviewed clinical, anesthesia and nursing records of all children ≤120 days of age who underwent CMR. We recorded variables including cardiac diagnosis, study duration, anesthesia type and agents, prostaglandin E1 (PGE1) dependence and gadolinium (Gd) use. Serially recorded temperature, systemic saturation (SpO(2)) and cardiac rhythm were analyzed. Primary outcome measure was any AE during or <24 h after the procedure, including minor AEs such as hypothermia (axillary temperature ≤95 °F), desaturation (SpO(2) drop ≥10% below baseline) and bradycardia (heart rate ≤100 bpm). Secondary outcome measure was unplanned overnight hospitalization of outpatients.

RESULTS

Children (n = 143; 74 boys, 69 girls) had a median age of 6 days (1-117), and 98 were ≤30 days at the time of CMR. The median weight was 3.4 kg (1.4-6 kg) and body surface area 0.22 m(2) (0.13-0.32 m(2)). There were 118 (83%) inpatients (108 receiving intensive care) and 25 (17%) outpatients. Indications for CMR were assessment of aortic arch (n = 57), complex CHD (n = 41), pulmonary veins (n = 15), vascular ring (n = 8), intracardiac mass (n = 8), pulmonary artery (n = 7), ventricular volume (n = 4), and systemic veins (n = 3). CMR was performed using a 1.5-T scanner and a commercially available coil. CMR utilized general anesthesia (GA) in 86 children, deep sedation (DS) in 50 and comforting methods in seven. MRA was performed in 136 children. Fifty-nine children were PGE1-dependent and 39 had single-ventricle circulation. Among children on PGE1, 43 (73%) had GA and 10 (17%) had DS. Twelve children (9%) had adverse events (AEs)-one major and 11 minor. Of those 12, nine children had GA (10%) and three had DS (6%). The single major AE was respiratory arrest after DS in a neonate (resuscitated without sequelae). Minor AEs included desaturations (n = 2), hypothermia (n = 5), bradycardia (n = 2), and bradycardia with hypoxemia (n = 2). Incidence of minor AEs was 9% for inpatients (vs. 4% for outpatients), and 8% for neonates (vs. 9% for age ≥30 days). Incidence of minor AEs was similar between PGE1-dependent infants and the non-PGE1 group. There were no adverse events related to MRA. Of 25 outpatients, 5 (20%) were admitted for overnight observation due to desaturations.

CONCLUSION

CMR and MRA can be accomplished safely in neonates and infants ≤120 days old for a wide range of pre-surgical cardiac indications. Adverse events were unrelated to patient age, complexity of heart disease, type of anesthesia or PGE1 dependence.

Signal quality of single dose gadobenate dimeglumine pulmonary MRA examinations exceeds quality of MRA performed with double dose gadopentetate dimeglumine

During a recent multi-center trial assessing gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) for diagnosis of acute pulmonary embolism (PE), the Food and Drug Administration announced a risk of nephrogenic sclerosing fibrosis in patients with renal insufficiency who had received intravenous Gd-based MR contrast agents. Although no patients in this trial had renal insufficiency, in cautious response to this announcement, the trial protocol was changed from an intravenous administration of 0.2 mmol/Kg of a conventional Gd-based MR contrast agent to 0.1 mmol/Kg of gadobenate dimeglumine. The study described herein compares the signal quality of pulmonary MRA performed with double dose conventional agent to single dose gadobenate dimeglumine. This study is a retrospective analysis of data from a prospective, multicenter study in men and women ≥18 years with documented presence or absence of PE. The study was approved by the Institutional Review Board at all participating centers, and all patients provided written indication of informed consent. We performed both objective and subjective analysis of pulmonary artery image quality. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the main pulmonary artery were assessed in single and double dose protocols and compared. SNR and CNR of the main PA were correlated with subjective quality assessment of main/lobar, segmental and subsegmental pulmonary arteries. Although there were individual outliers, both SNR (P = 0.01) and CNR (P = 0.008) were higher in all quartiles for examinations using gadobenate dimeglumine than with gadopentetate dimeglumine. Subjective quality of vascular signal intensity at each vessel order was significantly better for gadobenate dimeglumine (P < 0.0001), and correlated well with SNR and CNR at each order (<0.001). Because of agent high relaxivity, a single dose of gadobenate dimeglumine provides better pulmonary MRA signal quality than double dose of a conventional Gd-based MR contrast agent.

Detection of lymph node metastases by gadolinium-enhanced magnetic resonance imaging: systematic review and meta-analysis

BACKGROUND

Gadolinium-based contrast agents are used with magnetic resonance imaging (MRI) to highlight tumor vascularity in organs. They are also widely used for primary tumor visualization. We conducted a systematic review and meta-analysis of the existing evidence of the accuracy of gadolinium-enhanced MRI for staging lymph node metastases.

METHODS

We systematically searched the MEDLINE, Cochrane, CANCERLIT, and EMBASE databases for studies published in English or German from January 1, 1988, to January 1, 2008, that assessed the diagnostic accuracy of gadolinium-enhanced MRI in the evaluation of lymphatic metastases compared with histopathologic examination as the reference test. Based on a priori-defined clinical considerations, we studied three subgroups of studies: those that used a single malignancy criterion and those that used multiple malignancy criteria with or without contrast highlighting. Summaries of MRI sensitivity and specificity for detecting lymph node metastases were calculated using a bivariate regression model. All statistical tests were two-sided.

RESULTS

The literature search yielded 43 full-text papers that were considered for inclusion in the meta-analysis. We performed quantitative pooled analyses on the 32 studies that provided data on patient-level diagnosis. The weighted estimates of sensitivity and specificity for all studies combined were 0.72 (95% confidence interval [CI] = 0.66 to 0.79) and 0.87 (95% CI = 0.82 to 0.91). Estimates of sensitivity and specificity were essentially unchanged for studies that used a single malignancy criterion (0.71 [95% CI = 0.61 to 0.79] and 0.88 [95% CI = 0.80 to 0.93], respectively; n = 11 studies) or multiple malignancy criteria without contrast enhancement (0.70 [95% CI = 0.58 to 0.79] and 0.86 [95% CI = 0.68 to 0.94], respectively; n = 6 studies). The sensitivity increased to 0.84 (95% CI = 0.70 to 0.92), with a specificity of 0.82 (95% CI = 0.72 to 0.89) for the nine studies that incorporated contrast enhancement in their multiple malignancy criteria. Six studies did not define the malignancy criteria they used.

CONCLUSIONS

The overall accuracy of gadolinium-enhanced magnetic resonance imaging for the detection of nodal metastases is moderate. Incorporating contrast enhancement in the malignancy criteria substantially improves the accuracy of this diagnostic test.

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.

Variable echo time imaging: signal characteristics of 1-M gadobutrol contrast agent at 1.5 and 3T

Gadobutrol (Gd-Bt; Gadovist(R), Schering AG) is a 1-M Gadolinium (Gd)-based contrast agent. Its higher Gd concentration allows for reduction of injection volumes in first pass contrast-enhanced MR angiography (CE-MRA) and should increase bolus sharpness and image quality. However, ambivalent results were reported. In order to explore the performance of 1-M contrast agents such as Gd-Bt and its dependence on molecular environment and temperature, signal characteristics were analyzed for a series of increasing Gd-Bt concentrations for different temperature-controlled samples in water and human blood plasma. Relaxation times, relaxivities, and signal-concentration curves were assessed for several Gd-Bt concentrations in water at 20 degrees C and 37 degrees C and in plasma at 37 degrees C for 1.5T and 3T. Gd-Bt concentration influence on signal intensity (SI) could be effectively simulated and compared with experimental measurements as well as simulations with other contrast agents at realistic in vivo concentrations. Particular attention was given to T(2)- and T(*) (2)-induced losses at high concentrations, which annihilate benefits from T(1) shortening. Based on these findings, variable echo time (VTE) approaches with readout bandwidth varying with k-space position were explored in order to enhance the signal to noise performance of gradient echo imaging at high contrast agent concentrations. Results indicate the potential of VTE for imaging with increased SNR at high contrast agent concentrations.

A Summary of Safety of Gadofosveset (MS-325) at 0.03 mmol/kg Body Weight Dose

OBJECTIVE

We sought to summarize the Phase II and Phase III clinical trials safety data for gadofosveset (Vasovist, MS-325), a new magnetic resonance angiography contrast agent.

MATERIALS AND METHODS

Subjects with known or suspected vascular disease were administered 0.03 mmol/kg gadofosveset (767 subjects) or placebo (49 subjects) in phase II and phase III studies. Overall safety data were pooled from 8 studies and included adverse event monitoring, clinical laboratory assays, vital signs, oxygen saturation, physical examination, and electrocardiography. The safety was monitored for 72 to 96 hours postinjection (PI), and safety comparison with x-ray angiography using iodinated contrast media also was performed in 318 subjects. In the phase II trial, 5 doses of gadofosveset and placebo were evaluated. In this study, 38 patients were administered placebo and 39 patients received 0.03 mmol/kg gadofosveset.

RESULTS

In pooled data, treatment related adverse events were reported by 176 (22.9%) patients receiving gadofosveset and by 16 (32.7%) patients receiving placebo. In phase II trial, treatment-related adverse events were reported by 13 of the 39 (33.3%) patients receiving gadofosveset and 9 of the 38 (23.7%) patients receiving placebo. No severe or serious adverse events were reported in either gadofosveset or placebo groups in this phase II trial. Pooled data revealed no clinically significant trends in adverse events, laboratory assays, vital signs, or oxygen saturation. A QTc prolongation of 2.8 milliseconds was observed at 45 minutes after MS-325 injection; however, this trend was similar to that of the placebo group at the same time point (3.2 milliseconds).

CONCLUSION

Gadofosveset has exhibited a good safety profile and can be safely administered as an intravenous bolus injection. The overall rate and experience of adverse events was similar to that of placebo. The safety profile of gadofosveset is comparable with that of other gadolinium contrast agents as reported in the literature.

Evaluation of CH3-DTPA-Gd (NMS60) as a new MR contrast agent: early phase II study in brain tumors and dual dynamic contrast-enhanced imaging

PURPOSE

A newly developed contrast material, CH3-DTPA-Gd (NMS60), a trimer containing 3 Gd(3+) atoms per molecule, has been shown to offer greater enhancement and longer vascular retention than gadopentetate dimeglumine (Gd-DTPA) in animals. We report on our early phase II study on NMS60 in brain tumor patients together with supplementary investigations.

METHODS AND MATERIALS

The longitudinal relaxation rate (R(1)=1/T(1)) and the transverse relaxation rate (R(2)*=1/T(2)*) of NMS60 and Gd-DTPA were determined at 20 degrees C in water at 1.5 T. An NMS60 dose of 0.1 or 0.2 mmol (Gd)/kg was randomly assigned and administered to 10 patients (five women, five men; mean age: 49 years) with brain tumors. Safety and contrast-enhancing ability of NMS60 were evaluated. Dual dynamic contrast-enhanced T(1) and R(2)* studies (DUCE imaging) were also carried out in two patients.

RESULTS

Regarding the relaxivity per Gd, R(1) and R(2)* of NMS60 were 9.5 and 11.0 (mmol/L x s)(-1), respectively, compared to 4.8 and 7.2 (mmol/L x s)(-1) for Gd-DTPA. Although a transient slight increase of alanine aminotransferase was observed in one case, no other adverse reactions were observed after administration of NMS60. Contrast enhancement by NMS60 was excellent at both concentrations, and when tumor detectability was assessed with a five-point scale, the diagnostic usefulness was 4 or higher in all cases. In DUCE imaging, NMS60 appeared to show high signal intensity, when compared with the data obtained separately for Gd-DTPA.

CONCLUSION

NMS60 had a high contrasting effect and little toxicity, and is expected to be clinically useful.

Stroke Imaging at 3.0 T

Stroke is a devastating disease with a complex pathophysiology. It is a major cause of death and disability in North America. To fully characterize its extent and effects, one requires numerous specialized anatomical and functional MR techniques, specifically diffusion-weighted imaging, MR angiography, and perfusion-weighted imaging. The advent of 3.0 T clinical scanners has the potential to provide higher quality information in potentially less time compared with 1.5 T stroke-specific MR imaging protocols. This article gives a brief overview of stroke, presents the principles and clinical applications of the relevant MR techniques required for diagnostic stroke imaging at high field, and discusses the advantages, challenges, and limitations of 3.0 T imaging as they relate to stroke.

Contrast-enhanced magnetic resonance angiography of the great arteries in patients with congenital heart disease: an accurate tool for planning catheter-guided interventions

BACKGROUND

Catheter-guided interventions are increasingly used for relief of lesions in patients with congenital heart disease. Exact anatomical imaging with measurement of the vascular structures is crucial in the planning of such interventions. This can be provided non-invasively and without radiation by contrast-enhanced MR angiography (CE-MRA).

AIM

To evaluate the accuracy of the measurements of the vessels obtained by CE-MRA in comparison to those obtained by conventional X-ray angiography (XRA).

METHODS

Measurements of the diameters of aorta and pulmonary arteries were performed retrospectively and blinded on the CE-MRA and XRA images, in comparable locations. The limits of agreement between the two methods were calculated.

RESULTS

Twenty-one CE-MRA and XRA were performed in 20 children with congenital heart disease, median age 4 years (1 day-13 years), weight 18 kg (3.2-74 kg). The time interval between CE-MRA and XRA was 2.6 +/- 2.3 months. A total of 98 measurements, 38 of the aorta and 60 of the pulmonary arteries were performed on the images obtained by each technique. The correlation between CE-MRA and XRA measurements was excellent, r = 0.97, p < 0.0001. The mean difference between the two techniques was 0.018 +/- 1.1 mm; the limits of agreement -2.14 and + 2.18 mm. Similar agreement was found for measures of the aorta (r = 0.97, mean difference 0.20 +/- 1.08 mm) and of the pulmonary arteries (r = 0.97, mean difference 0.048 +/- 0.89 mm).

CONCLUSIONS

CE-MRA provides accurate quantitative anatomical information, which highly agrees with XRA data, and can therefore be used for planning catheter-guided procedures.

Contrast-enhanced magnetic resonance angiography of the great arteries in patients with congenital heart disease: an accurate tool for planning catheter-guided interventions

BACKGROUND

Catheter-guided interventions are increasingly used for relief of lesions in patients with congenital heart disease. Exact anatomical imaging with measurement of the vascular structures is crucial in the planning of such interventions. This can be provided non-invasively and without radiation by contrast-enhanced MR angiography (CE-MRA).

AIM

To evaluate the accuracy of the measurements of the vessels obtained by CE-MRA in comparison to those obtained by conventional X-ray angiography (XRA).

METHODS

Measurements of the diameters of aorta and pulmonary arteries were performed retrospectively and blinded on the CE-MRA and XRA images, in comparable locations. The limits of agreement between the two methods were calculated.

RESULTS

Twenty-one CE-MRA and XRA were performed in 20 children with congenital heart disease, median age 4 years (1 day-13 years), weight 18 kg (3.2-74 kg). The time interval between CE-MRA and XRA was 2.6 +/- 2.3 months. A total of 98 measurements, 38 of the aorta and 60 of the pulmonary arteries were performed on the images obtained by each technique. The correlation between CE-MRA and XRA measurements was excellent, r = 0.97, p < 0.0001. The mean difference between the two techniques was 0.018 +/- 1.1 mm; the limits of agreement -2.14 and + 2.18 mm. Similar agreement was found for measures of the aorta (r = 0.97, mean difference 0.20 +/- 1.08 mm) and of the pulmonary arteries (r = 0.97, mean difference 0.048 +/- 0.89 mm).

CONCLUSIONS

CE-MRA provides accurate quantitative anatomical information, which highly agrees with XRA data, and can therefore be used for planning catheter-guided procedures.

Lower Extremity: Low-Dose Contrast Agent Intraarterial MR Angiography in Patients—Initial Results

Institutional review board approval and patient consent were obtained. A low-dose injection protocol for intraarterial three-dimensional (3D) gadolinium-enhanced magnetic resonance (MR) angiography was derived from femoral flow phantom studies and prospectively evaluated in patients with peripheral arterial occlusive disease (PAOD). All MR angiograms were obtained at 1.5 T with a T1-weighted gradient-echo sequence. MR angiograms of a gadolinium dilution series (0.8-200.0 mmol/L) were acquired in a femoral phantom at different flow rates. Signal-to-noise ratios (SNRs) above the 75% threshold of the measured maximum were considered optimal. The lowest optimal concentration was injected intraarterially in nine patients to obtain 3D MR angiograms of the thigh and calf station. Contrast-to-noise ratios (CNRs) were calculated for four arterial segments. The low optimal concentration of 50 mmol/L (20-mL bolus volume), about 5% of the total permissible dose, showed SNRs larger than the 75% threshold in the phantom study. In patients, this concentration led to high-spatial-resolution angiograms with mean CNRs of 70.0 +/- 14.5 (+/- standard deviation) for the superficial femoral artery and 47.5 +/- 13.4 at the infrapopliteal level. Low-dose contrast agent intraarterial 3D MR angiography showed high arterial enhancement, enabling assessment of lower extremity arteries in patients with PAOD and multiple injections--a crucial precondition for MR-guided endovascular interventions.