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Abdominal and Iliac Arterial Stenoses: Comparative Double-blinded Randomized Study of Diagnostic Accuracy of 3D MR Angiography with Gadodiamide or Gadopentetate Dimeglumine¹

¹ From the Department of Diagnostic Radiology, University Hospital of Schleswig-Holstein Campus Kiel, Arnold-Heller-Strasse 9, 24105 Kiel, Germany (P.J.S.). A complete list of centers that participated in this study and author affiliations appears in the Acknowledgment at the end of this article. Received October 14, 2004; revision requested December 22; revision received January 27, 2005; accepted February 28; final version accepted May 11. Supported by a grant from Amersham Health. Address correspondence to P.J.S. (e-mail: jp.schaefer{at}rad.uni-kiel.de).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
Purpose: To prospectively evaluate accuracy of gadolinium-enhanced three-dimensional (3D) magnetic resonance (MR) angiography with gadodiamide and gadopentetate dimeglumine (0.1 mmol/kg), with intraarterial DSA as reference standard, for imaging abdominal and iliac arterial stenoses.

Materials and Methods: The study was approved by all institutional review boards; informed consent was obtained from each subject before procedures. Two hundred forty-seven subjects were included; 240 received either contrast agent and were available for safety analysis; 222 were available for accuracy analysis. Enhanced 3D MR angiography and DSA were performed; image data were evaluated in a double-blinded randomized study. Stenoses were classified as not relevant (<50% stenosis) or relevant (50%). For detection of main stenosis, accuracy with enhanced 3D MR angiography compared with that with DSA was determined.

Results: The difference in accuracy for imaging with gadodiamide and gadopentetate was 3.6%. Noninferiority was inferred because the lower bound of the exact two-sided 95% confidence interval was –10.1 and was above the noninferiority margin (–15%). Accuracy for detection of the main stenosis was low, 56.4% for gadodiamide and 52.8% for gadopentetate group. Subgroup analysis with exclusion of inferior mesenteric artery and internal iliac arteries and the most false-positive stenosis classifications yielded better results: 76.6% and 71.6%, respectively. Sensitivity, specificity, and negative and positive predictive values did not differ substantially between study groups. In the main analysis, values were 44%, 96%, 35%, and 97% for gadodiamide and 44%, 83%, 30%, and 90% for gadopentetate, respectively. In the subgroup analysis, values were 66%, 95%, 61%, and 96% for gadodiamide and 63%, 86%, 58%, and 88% for gadopentetate, respectively.

Conclusion: Noninferiority of gadodiamide versus gadopentetate was verified based on the primary end point, which was accuracy for detection of the main stenosis with enhanced 3D MR angiography compared with DSA.

© RSNA, 2006

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
In patients with arterial occlusive disease, it is essential that the anatomic vascular tree is imaged precisely for exact planning of revascularization procedures. Intraarterial digital subtraction angiography (DSA) is deemed the reference standard for the investigation of abdominal, iliac, and peripheral arteries (1). Generally, a stenosis of more than 50% in arteries of the abdomen, pelvis, and lower extremity is considered hemodynamically relevant and to require endovascular or vascular surgical procedures (2–7).

Because DSA is an invasive method that involves exposure to ionizing radiation and nephrotoxic iodinated contrast agents, there has been a demand for a noninvasive examination that is less risky and that can be performed quickly on an outpatient basis. In addition to duplex ultrasonography (US) and spiral computed tomography (CT), techniques of magnetic resonance (MR) angiography for the evaluation of arterial stenoses have been tested. Three-dimensional (3D) contrast material–enhanced MR angiography has emerged as a powerful modality for noninvasive arterial imaging. Its value has been proved in studies, and several articles about the studies (8–13) have appeared. Gadolinium-based contrast agents act by shortening the T1 relaxation of the blood and thus increase the signal intensity of the blood. In the abdominal and iliac regions, 3D contrast-enhanced MR angiography can be performed within one breath hold, and breathing artifacts can be avoided (14).

Gadodiamide (Omniscan; Amersham Health, Munich, Germany) is a nonionic paramagnetic contrast agent with a concentration of 0.5 mol/L. The safety, tolerance, and pharmacokinetic profiles of gadodiamide have been verified with doses of up to 1.5 mmol per kilogram of body weight in healthy volunteers and have been documented in clinical investigations worldwide (Europe, Japan, United States of America) at doses of both 0.1 and 0.3 mmol/kg (15,16). Findings indicate that nonionic gadodiamide is superior to gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany), hereafter referred to as gadopentetate, in regard to acute lethal toxic reactions (16), although gadodiamide currently is not approved for use with contrast-enhanced MR angiography in Germany. Thus, the purpose of our study was to prospectively evaluate the diagnostic accuracy of 3D contrast-enhanced MR angiography with gadodiamide versus the accuracy of that with gadopentetate at a dose of 0.1 mmol/kg, with intraarterial DSA as the reference standard, for evaluation of abdominal and iliac arterial stenoses.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
Study Design and Subjects
This study was designed as a parallel, double-blinded, randomized multicenter study. It was a phase IIIb study for Germany and a phase IV study for other participating countries, including 18 study centers altogether, and it was supported by Amersham Health, Munich, Germany, which provided contrast agents, equipment for laboratory tests, and financial assistance for performance of contrast-enhanced MR angiography. All authors were responsible for and had control of the data and information submitted for publication of this prospective study. The accuracy for detection of hemodynamically relevant stenoses was chosen as the primary end point. For noninferiority of gadodiamide, the difference in accuracy had to be above the lower bound (–15%) of the 95% confidence interval (CI).

From October 2000 to May 2002, a total of 247 subjects were included (Fig 1); mean age and percentages of men and women were calculated. Two hundred forty subjects received either of the contrast agents and were therefore available for safety analysis; 222 subjects were available for analysis of accuracy. The reasons that partial or complete data for some subjects were not included in the analysis were that the subjects had withdrawn before study drug application (n = 7) or that they had dropped out because of protocol deviations after administration of the study drug (n = 18).

View larger version (43K): [in this window] [in a new window] [Download PPT slide]   Figure 1: Flow diagram of study population. The term "trade product" refers to the power injector filled with gadopentetate rather than gadodiamide.

Subjects who were considered for inclusion in this study were referred for DSA because they were suspected of having abdominal or iliac arterial stenosis. Exclusion criteria were as follows: (a) The subject was a woman who had child-bearing potential and was not using adequate contraception or who was pregnant or lactating. (b) The subject had had a known severe adverse drug reaction or had a contraindication to one of the investigational products. (c) The subject had received a contrast medium for MR angiography within 48 hours prior to or after administration of the investigational product. (d) The subject had received a contrast medium for radiography within 12 hours prior to or after administration of the investigational product. (e) The subject had active, serious, life-threatening disease and a life expectancy of less than 1 month. (f) The subject had a serum creatinine value that would not allow DSA assessment. (g) The subject previously had been included in this study. (h) The subject had a contraindication to MR angiography according to clinical guidelines and/or had undergone percutaneous transluminal angioplasty of the abdominal and/or iliac region within 4 weeks prior to administration of the investigational product.

The subjects underwent contrast-enhanced MR angiography within 14 days (mean, 4.5 days ± 5.2 [standard deviation]) either before or after DSA. Contrast-enhanced MR angiography was performed after an initial safety evaluation with physical examination, documentation of medical and surgical history, assessment of vital signs, and collection of blood samples for laboratory analysis. A subject's enrollment in the study was completed after a 48-hour follow-up examination, and all the safety assessments were performed again. The performance and quality of contrast-enhanced MR angiography and DSA were initially adjusted and afterward monitored by means of regular visits to the study centers during the entire study. The quality of contrast-enhanced MR angiography and of DSA was ensured by the study team leader and an independent review center, Image Review Center, Oslo, Norway, where the data sets for the blinded reading were processed.

Investigational Product Administration and Contrast-enhanced MR Angiography
To assign the study subjects to the group who received gadodiamide or the group who received gadopentetate (hereafter, the groups will be referred to as the gadodiamide group and the gadopentetate group), a randomization scheme that had been prepared by Amersham Health was used. The contrast agents were presented in indistinguishably labeled vials so that the double-blinded character of the study was maintained. Neither the investigator nor the subject knew which contrast agent was administered. Both study drugs, gadodiamide and gadopentetate, are paramagnetic contrast agents for contrast-enhanced MR imaging with a concentration of 0.5 mol/L. Gadodiamide has an osmolality of 0.780 mOsm/kg H₂O and a viscosity of 1.9 mPa · sec at 37°C body temperature. Gadopentetate has an osmolality of 1.960 mOsm/kg H₂O and a viscosity of 2.9 mPa · sec at 37°C body temperature. Because results of a previously performed study (17) indicated that contrast-enhanced MR angiography with gadodiamide at a dose of 0.1 mmol/kg offers sufficient image data for the detection of hemodynamically relevant stenoses (50%) in the abdominal and the iliac arteries (including the renal arteries), the standard dose of 0.1 mmol/kg was chosen for our study. The study drug was injected intravenously. All solutions were to be injected with sterile syringes, aseptic techniques, and a power injector (Spectris; Medrad, Pittsburgh, Pa).

First, a coronal scout sequence was performed for exact planning of contrast-enhanced MR angiography. The bolus transit time had to be determined with administration of a test bolus of 1–2 mL; the test bolus volume was subtracted from the total volume that had to be applied. Then, the contrast agent for contrast-enhanced MR angiography was injected without dilution at a flow rate of 2–4 mL/sec; the mean volume was 13.2 mL ± 2.7 (range, 6.8–20.0 mL) for gadodiamide and 13.4 mL ± 2.8 (range, 7.0–22.0 mL) for gadopentetate. After the test bolus and the main volume had been injected for contrast-enhanced MR angiography, a saline flush was administered at a flow rate of 2–4 mL/sec to ensure that the complete contrast agent bolus was transported into the blood vessels; the mean volume was 25.3 mL ± 8.6 (range, 10.0–50.0 mL) for gadodiamide and 25.1 mL ± 8.6 (range, 15.0–50.0 mL) for gadopentetate. The fast 3D sequence was started with a delay that was calculated by using the test bolus transit time.

Imaging was performed with the breath-hold technique. Commercially available MR imaging units (Expert [1.0 T], Harmony [1.0 T], Sonata [1.5 T], Symphony [1.5 T], Magnetom Vision [1.5 T], Siemens, Erlangen, Germany; HiSpeed LX [1.0 T], Signa MR/i [1.5 T], Signa CVMR [1.5 T], Signa Horizon [1.5 T], GE Healthcare, Milwaukee, Wis; Gyroscan [1.0 and 1.5 T], Philips, Eindhoven, the Netherlands) were used. One hundred eighty-four subjects were imaged with 1.5-T imagers, and 56 subjects were imaged with 1.0-T imagers. Machine settings were as follows: for 1.5-T MR imagers, 3.3–6.0/1.0–2.0 (repetition time msec/echo time msec), with a mean repetition time of 4.35 msec ± 0.80 and a mean echo time of 1.41 msec ± 0.24, and for 1.0-T MR imagers, 5.2–7.2/1.5–2.4, with a mean repetitition time of 6.28 msec ± 0.82 and a mean echo time of 1.92 msec ± 0.38. The total study time for MR angiography was 1.0–67.0 minutes (mean, 3.3 minutes ± 7.6) for gadodiamide and 1.0–33.0 minutes (mean, 3.1 minutes ± 5.6) for gadopentetate, including all subjects who were connected to the power injector, and documenting all MR angiographic performance from withdrawals because of claustrophobia (1.0 minute each for gadodiamide and gadopentetate) to breakdowns of the MR imager (67.0 minutes for gadodiamide and 33.0 minutes for gadopentetate, respectively). Maximum intensity projections were reconstructed from the data and electronically stored.

Intraarterial DSA
The contrast-enhanced MR angiographic examination had to be performed for each subject within 2 weeks before or after intraarterial DSA. The radiologists who performed DSA in the centers had to be senior radiologists with DSA experience of at least 5 years. The machine settings for routine DSA in each study center were not allowed to be changed during the entire study to ensure consistency across study groups. With a nonionic contrast agent, DSA was performed with 5- or 6-F catheters. The field of view had to include the abdominal and iliac regions for the blinded image evaluation of the target blood vessels. At least two projections in the anteroposterior plane and the right anterior oblique plane (30°) or the left anterior oblique plane (30°) had to be obtained to collect valid data for the evaluation of the renal and the pelvic arteries. The image frequency was set at two per second. According to the study protocol, pressure gradients did not necessarily have to be measured across stenoses.

Image Evaluation
The blinded image evaluation of the DSA images and the MR angiographic data sets was conducted by a global provider of centralized imaging analysis services in the fields of cardiovascular, pulmonary, and orthopedic clinical research (Heart Core B.V., Leiden, the Netherlands). For analysis of the DSA images, three readers, who had 10, 11, and 13 years of experience, were appointed by the global provider of imaging analysis services. For the analysis of the MR angiographic data sets, three independent readers (readers A, B, and C), who had 11, 12, and 13 years of experience, respectively, were chosen by the global clinical project director and the study team leader. One additional reader with 13 years of experience who was responsible for the confirmation of stenosis location between the corresponding DSA images and the MR angiographic images was appointed by the global provider of imaging analysis services. All readers were experienced in the evaluation of images obtained at abdominal and iliac arterial MR angiography. After subject identification information was removed from all DSA and MR angiographic image sets, the sets were randomized and then presented to the readers. The DSA images were read by the three radiologists in consensus to obtain and ensure a consistent and valid evaluation of stenosis. This was important for the evaluation of the noninferiority of gadodiamide versus gadopentetate in the analysis of diagnostic accuracy of MR angiography compared with that of DSA. The MR angiographic images were presented to each of the three readers of the MR angiographic data set separately. None of them had access to the evaluations of stenosis performed by the fellow readers. Afterward, a majority decision was concluded, meaning that at least two readers had to give a corresponding classification of the same stenosis. The MR angiographic data were presented as source images, with the option of postprocessing the data, and as maximum intensity projection reconstructions.

The arterial blood vessel tree in the abdominal and iliac regions was subdivided into 14 vessel segments: the supraceliac abdominal aorta, the celiac trunk, the superior mesenteric artery, the left and the right renal arteries, the infrarenal aorta, the inferior mesenteric artery, the aortic bifurcation, the left and the right common iliac arteries, the left and the right external iliac arteries, and the left and the right internal iliac arteries.

For the primary end point of the study, the stenosis had to be evaluated. Stenosis was classified as nonrelevant (<50%) stenosis, which included no stenosis, and relevant (50%) stenosis, which included occlusion. The main stenosis was defined as the most severe and proximal reduction in diameter in the abdominal and iliac arteries seen with DSA. If a subject had more than one stenosis, the total number was limited to four. Vessel segments that the readers of MR angiographic images believed could not be evaluated because of severe subject motion, metallic artifact distortion, or inadequate enhancement were included in the accuracy analysis, because the study drug might have been the reason for the inability to evaluate the images. If a stenosis was seen with DSA and the corresponding vessel segment observed at MR angiography could not be evaluated for reasons other than image corruption or incorrect field of view, the vessel segment was classified as a mismatch when the MR angiographic image was compared with the DSA image: If the stenosis was estimated to be less than 50% at DSA, the MR angiographic image was classified as false-positive, and if the stenosis was estimated to be more than 50% at DSA, the MR angiographic image was classified as false-negative.

For each diagnosis, the examiners suggested one of the following therapeutic options: (a) no intervention, (b) percutaneous transluminal angioplasty and/or stent implantation, or (c) bypass graft surgery. Finally, a confirmation of stenosis location was performed to compare the DSA and MR angiographic results and to determine whether the identified stenoses corresponded to those identified with each modality.

Safety Variables
As safety variables, the serious adverse events, several clinical laboratory parameters, vital signs, and the results of physical examination were documented. An adverse event was defined as any unfavorable symptom that occurred within the 48-hour follow-up. Only symptoms that began or worsened in severity after the administration of an investigational product were recorded as adverse events. The severity of an adverse event was assigned a classification of mild when the symptom was tolerable; of moderate, when the symptom interfered with normal activity; or of severe, when the symptom was incapacitating or caused inability to perform usual activity or work.

From the serum of the blood samples that were obtained immediately before and 48 hours after the administration of the study drug, the following laboratory parameters were assessed: alkaline phosphatase level (reference range, 60–160 U/L), aspartate aminotransferase level (reference range, 1–18 U/L), alanine aminotransferase level (reference range, 1–22 U/L), -glutamyl transpeptidase level (reference range, 4–28 U/L), iron level (reference range, 7–29 µmol/L), transferrin level (reference range, 2.0–3.6 g/L), total iron binding capacity (reference range, 45–72 µmol/L), direct (reference range, 0–5 µmol/L) and total (reference range, 0–22 µmol/L) bilirubin levels, creatinine level (reference range, 44–106 µmol/L), phosphorus level (reference range, 0.8–1.6 mmol/L), and ionized calcium level (reference range, 2.0–2.7 mmol/L). All serum samples were sent to a central laboratory for testing to maintain consistency among the evaluated measurements.

As vital signs, the following parameters were evaluated: systolic (reference range, 85–139 mm Hg) and diastolic (reference range, 60–89 mm Hg) blood pressure, heart rate (reference range, 60–100 beats per minute), oral or tympanic body temperature (reference range, 36.4°–37.7°C), and respiratory rate (reference range, 12–22 breaths per minute). All measurements and examinations were performed immediately before and 48 hours after administration of the study drug.

Statistical Analysis
The results of 3D contrast-enhanced MR angiography for each independent blinded reader of MR angiographic images and of the concluded majority decision were compared with the results of DSA for the three readers of DSA images in consensus. Interobserver agreement was documented, and concordance among the readers of MR angiographic images was calculated by using the Cohen coefficient. The primary end point, however, was determined by the majority decision of the three readers of MR angiographic images.

The statistical analysis of the main parameter was based on the use of an exact two-sided 95% CI for the difference in accuracy (calculated by subtracting the accuracy value of the gadopentetate group from the accuracy value of the gadodiamide group). Noninferiority was inferred if the lower bound of the 95% CI decreased above the noninferiority margin (greater than –15%). Accuracy was determined for each vessel segment for the majority decision. In addition to the planned analysis of the 14 vessel segments, an exploratory subgroup analysis in which the inferior mesenteric artery and the left and right internal iliac arteries were excluded was performed. This exploratory analysis was performed because the most false-positive assessments for stenosis occurred among the blood vessels that were excluded.

As secondary end points, sensitivity, specificity, and positive and negative predictive values for the detection of hemodynamically relevant main stenoses were calculated for the majority decision. Corresponding to the analysis of the main stenosis, the statistical data for all (maximum of four) hemodynamically relevant stenoses were also assessed. Another end point was the treatment in each subject with the suggested therapies, whereas the Cohen coefficient was calculated for each reader of MR angiographic images and the majority decision concerning the main stenosis and all stenoses that were detected with DSA and MR angiography. In addition, logistic regression models were evaluated to investigate the effect of supplementary explanatory variables, such as sex, age, and interaction between study groups, in regard to the relationship between DSA and MR angiography. Both ordinary logistic regression models and generalized estimating equations were analyzed.

Statistical software (SAS 8.2 and SAS 6.12 combined with Proc-StatXact 4.0 and Proc-Genmod; Cytel Software, Cambridge, Mass) was used for analyses.

	RESULTS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
General Findings
A total of 247 subjects were enrolled in this study. Two hundred forty subjects received the contrast agents (119 [49.6%] subjects were in the gadodiamide group and 121 [50.4%] were in the gadopentetate group); these subjects were evaluated for the safety assessment (Fig 1). In the gadodiamide group, the mean age was 63.3 years ± 11.1, and 73.1% (87 of 119) of the subjects were men and 26.9% (32 of 119) were women. In the gadopentetate group, the mean age was 62.6 years ± 11.9, and 77.7% (94 of 121) of the subjects were men and 22.3% (27 of 121) were women (Table 1). Two hundred twenty-two subjects were available for the analysis of accuracy; 113 (50.9%) subjects were in the gadodiamide group and 109 (49.1%) were in the gadopentetate group.

View larger version (126K): [in this window] [in a new window] [Download PPT slide]   Figure 2a: Bilateral renal artery stenosis in 69-year-old man. Anteroposterior projections of (a) intraarterial DSA image and (b) coronal gadopentetate-enhanced maximum intensity projection obtained with 3D fast low-angle shot 1.5-T MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil reveal clearly relevant (50%) stenoses in right and left renal arteries (arrows) and stenoses less than 50% in infrarenal aorta and left common iliac artery.

View larger version (95K): [in this window] [in a new window] [Download PPT slide]   Figure 2b: Bilateral renal artery stenosis in 69-year-old man. Anteroposterior projections of (a) intraarterial DSA image and (b) coronal gadopentetate-enhanced maximum intensity projection obtained with 3D fast low-angle shot 1.5-T MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil reveal clearly relevant (50%) stenoses in right and left renal arteries (arrows) and stenoses less than 50% in infrarenal aorta and left common iliac artery.

View larger version (115K): [in this window] [in a new window] [Download PPT slide]   Figure 3a: Multiple stenoses in 58-year-old woman. (a) Left anterior oblique and (b) right anterior oblique intraarterial DSA projections reveal eccentric plaque (<50%) in left common iliac artery (arrow) and nonrelevant (<50%) stenoses in both external iliac arteries. Coronal gadodiamide-enhanced (c) anteroposterior and (d) left anterior oblique projections obtained with 3D 1.5-T fast low-angle shot MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil show relevant (50%) stenosis in left common iliac artery (arrow), nonrelevant (<50%) stenosis in left external iliac artery, and subtotal occlusion in right external iliac artery.

View larger version (124K): [in this window] [in a new window] [Download PPT slide]   Figure 3b: Multiple stenoses in 58-year-old woman. (a) Left anterior oblique and (b) right anterior oblique intraarterial DSA projections reveal eccentric plaque (<50%) in left common iliac artery (arrow) and nonrelevant (<50%) stenoses in both external iliac arteries. Coronal gadodiamide-enhanced (c) anteroposterior and (d) left anterior oblique projections obtained with 3D 1.5-T fast low-angle shot MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil show relevant (50%) stenosis in left common iliac artery (arrow), nonrelevant (<50%) stenosis in left external iliac artery, and subtotal occlusion in right external iliac artery.

View larger version (85K): [in this window] [in a new window] [Download PPT slide]   Figure 3c: Multiple stenoses in 58-year-old woman. (a) Left anterior oblique and (b) right anterior oblique intraarterial DSA projections reveal eccentric plaque (<50%) in left common iliac artery (arrow) and nonrelevant (<50%) stenoses in both external iliac arteries. Coronal gadodiamide-enhanced (c) anteroposterior and (d) left anterior oblique projections obtained with 3D 1.5-T fast low-angle shot MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil show relevant (50%) stenosis in left common iliac artery (arrow), nonrelevant (<50%) stenosis in left external iliac artery, and subtotal occlusion in right external iliac artery.

View larger version (102K): [in this window] [in a new window] [Download PPT slide]   Figure 3d: Multiple stenoses in 58-year-old woman. (a) Left anterior oblique and (b) right anterior oblique intraarterial DSA projections reveal eccentric plaque (<50%) in left common iliac artery (arrow) and nonrelevant (<50%) stenoses in both external iliac arteries. Coronal gadodiamide-enhanced (c) anteroposterior and (d) left anterior oblique projections obtained with 3D 1.5-T fast low-angle shot MR imaging (4.6/1.8; matrix, 200 [frequency]x 512 [phase]; flip angle, 30°; field of view, 420 mm; acquisition time, 23 seconds) and phased-array coil show relevant (50%) stenosis in left common iliac artery (arrow), nonrelevant (<50%) stenosis in left external iliac artery, and subtotal occlusion in right external iliac artery.

The observed similarity between the gadodiamide and the gadopentetate groups for estimation of the diagnostic accuracy of contrast-enhanced MR angiography was confirmed with results of logistic regression analyses that incorporated sex and age. Corresponding results were obtained by using generalized estimating equations to incorporate the three readers of MR angiographic images simultaneously. With a repeated-measures model, a high correlation between each pair of readers of MR angiographic images was estimated, and correlation coefficients were larger than 0.99. In these analyses, differences were not significant for the effect of any exploratory variable, with P > .4 for reader effect, P = .484 for MR angiographic result effect, P = .837 for study group effect, and P = .593 for study group interaction effect.

Safety Evaluation
Data from 240 subjects were available for the safety analysis; these data were from 119 subjects for the gadodiamide group and from 121 subjects for the gadopentetate group. Four adverse events, two in the gadodiamide group and two in the gadopentetate group, were reported. The adverse events for the gadodiamide group were diarrhea (moderate) and an increase in alanine aminotransferase level (mild), and the investigators in the study centers did not consider them to be related to the study drug. The adverse event for the gadopentetate group was a rash (mild) that the investigators considered to be related to the study drug. No serious adverse events occurred in this study.

Results of laboratory analysis for serum samples obtained at baseline and at 48-hour follow-up revealed no differences among mean values for all parameters. Also, mean changes from baseline were similar between the study groups. The mean values of -glutamyl transpeptidase and creatinine were above the reference range at baseline and at 48-hour follow-up. For the gadodiamide group, values were 32.2 and 29.7 U/L, respectively, for -glutamyl transpeptidase and 109.5 and 107.8 µmol/L, respectively, for creatinine. For the gadopentetate group, values were 29.5 and 30.2 U/L, respectively, for -glutamyl transpeptidase and 102.6 and 101.9 µmol/L, respectively, for creatinine. At 48-hour follow-up, all mean values for ALP, alanine aminotransferase, aspartate aminotransferase, direct bilirubin, and iron decreased slightly from the levels at baseline, but they remained within the reference range. At 48-hour follow-up, the number and percentage of subjects with values outside the reference range were similar in both study groups: For alkaline phosphatase, 17 (14.3%) of 119 subjects in the gadodiamide group and 17 (14.0%) of 121 subjects in the gadopentetate group had such values; for alanine aminotransferase, 14 (11.8%) of 119 subjects in the gadodiamide group and 14 (11.6%) of 121 subjects in the gadopentetate group had such values; and for aspartate aminotransferase, 10 (8.4%) of 119 subjects in the gadodiamide group and eight (6.6%) of 121 subjects in the gadopentetate group had such values. From levels at baseline to those at 48-hour follow-up, all mean values of transferrin, total iron binding capacity, calcium, and phosphorus remained within the levels in the reference range.

In either study group, changes in the vital signs in regard to mean values of systolic blood pressure, diastolic blood pressure, heart rate, body temperature, and respiration rate from baseline to 48-hour follow-up were not significant. The mean values of systolic blood pressure were outside the reference range at baseline and at 48-hour follow-up in both groups: The mean value was 144.5 and 145.4 mm Hg, respectively, at baseline and at 48-hour follow-up in the gadodiamide group, and the mean value was 143.1 and 143.0 mm Hg, respectively, at those times in the gadopentetate group. The mean values of diastolic blood pressure, body temperature, and heart and respiratory rates were within the reference ranges at baseline and at 48-hour follow-up in both groups. No noteworthy changes in any physical examination parameters were detectable from baseline to 48-hour follow-up.

	DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 
Because of advances in MR technology and contrast-enhanced MR angiographic protocols, including the use of bolus-tracking techniques, and the use of programmable moving tables and dedicated surface coils, 3D contrast-enhanced MR angiography has developed beyond expectation in the past years (11,19–22). To obtain the best possible image quality by using 3D contrast-enhanced MR angiography, it is very important to set exact technical parameters of the MR imager with precise bolus tracking for the contrast agent. An overdose of contrast agent may preclude sufficient evaluation of the arteries because of diffusion into extravascular tissue and venous overlay (23). According to the results of an evaluation by Thurnher et al (17), the standard dose of 0.1 mmol/kg was chosen for our study; results of the study of Thurnher et al indicated that contrast-enhanced MR angiography with a dose of 0.1 mmol/kg offers sufficient image quality for the detection of hemodynamically relevant stenoses (50%) in abdominal and iliac arteries, including the renal arteries.

For the majority decision, the overall difference in accuracy was 3.6% in favor of gadodiamide. The noninferiority of gadodiamide versus gadopentetate was inferred from the lower bound of the 95% CI (–10.1), which remained above the predetermined noninferiority margin of –15%. Similar results were obtained for each reader. For both contrast agents, the differences among the study groups in regard to the 95% CIs, all of which included zero, were not significant. Furthermore, there were no statistically significant differences between the two study groups with regard to sensitivity, specificity, positive predictive value, and negative predictive value; in most cases, the lower bound of the 95% CI was above the predefined margin of –15% for these parameters. The results of the secondary analysis also provided additional confirmation of the noninferiority of gadodiamide. The differences between the study groups with regard to accuracy, sensitivity, specificity, and positive and negative predictive values were not significant. Results of logistic regression analysis and generalized estimating equation analysis confirmed the similarity of gadodiamide and gadopentetate.

Although the mentioned results indicate the noninferiority of gadodiamide when it is compared with gadopentetate for abdominal and iliac angiography, the accuracy and the sensitivity and specificity of 3D contrast-enhanced MR angiography for the detection of stenoses were considerably lower for both study groups when they were compared with the results reported in the literature. In a study of Ruehm et al (12), sensitivity and specificity of 3D contrast-enhanced MR angiography ranged between 92% and 96.6%; however, Meaney et al (8) reported results between 81% and 95%. Factors that might explain the present results could be the predetermined choice of a fairly low dose of 0.1 mmol/kg, the inclusion criteria for MR imaging, the prolonged duration of our multicenter study, and the image evaluation with a reading of DSA images in consensus versus that with an independent blinded reading of MR angiographic images.

The dose of 0.1 mmol/kg offers sufficient contrast enhancement for the evaluation of the aorta and its major branches at 1.0-T field strength with a repetition time of 7.3 msec and an echo time of 2.8 msec (24). Lentschig et al (24) refer to a decrease in the signal-to-noise ratio with reduction of the repetition and echo times that would require a higher dose. Thus, in our study, with a mean repetition time of 4.35 msec ± 0.80 and a mean echo time of 1.41 msec ± 0.24 at 1.5-T imaging and with a mean repetition time of 6.28 msec ± 0.82 and a mean echo time of 1.92 msec ± 0.38 at 1.0-T imaging, a higher dose should have been used, and a dose of at least 0.15–0.20 mmol/kg should have been used for sufficient evaluation of the smaller branches of the aorta or the pelvic arteries, such as the inferior mesenteric artery or the internal iliac arteries (25). For all three readers of MR angiographic images, these blood vessels generally appeared to be the most difficult to evaluate, and the accuracy for detection of stenoses was very low.

The investigators in other clinical studies injected contrast agents at doses between 0.2 and 0.3 mmol/kg for abdominal and iliac angiography (26–28), whereas Prince (29) showed that there is no improvement in image quality with doses higher than 0.2 mmol/kg. Thus, the dose depends on what blood vessels are to be visualized and on the individual preference of the radiologist in terms of what he or she considers to be adequate. Furthermore, the image resolution of contrast-enhanced MR angiography is too low for the reliable assessment of the inferior mesenteric artery (30). However, the effect in our study was not an overestimation as it is reported in several other studies mainly of peripheral arteries (8,12,31), but the data from the MR angiographic evaluation tend to be false-negative values compared with those from the DSA evaluation. Corresponding to this effect, Vosshenrich and Fischer (30) believe that overestimation is no longer an issue, for the arterial contrast is not flow dependent with contrast-enhanced MR angiography. With the exclusion of the three mentioned blood vessels—inferior mesenteric artery and right and left internal iliac arteries, for which the proportion of false-negative results was highest—the subgroup analysis yielded markedly better numbers. These results more closely reflected those reported in the literature (1,21,22).

When we compared the results obtained in our study with those found in the literature, we found that one also has to consider the strict evaluation criteria with contrast-enhanced MR angiography. We found several vessel segments that, in our judgment, could not be evaluated because of severe subject motion, metallic artifact distortion, or inadequate enhancement, although the fact that they could not be evaluated was not necessarily caused by the study drug. Stenoses depicted with DSA and not with MR angiography—because they could not be evaluated for reasons mentioned previously—were classified as mismatched, and this classification resulted in a false-negative classification for stenoses of more than 50% evaluated with DSA and in a false-positive classification for stenoses of less than 50% evaluated with DSA. In addition, the prolonged duration of the study at 18 centers certainly caused decreases in the statistical results. Many studies of a comparison of stenosis classification between DSA and contrast-enhanced MR angiography are limited to one center because the technical equipment may be different in more than one center, and, therefore, it is especially not easy to reproduce the contrast-enhanced MR angiographic techniques at other institutions (32). Consequently, in our study, the criteria for image evaluation had to be strict to obtain similar data at each study center.

DSA was set as the reference standard, and the decision in regard to the classification of stenosis on DSA images was based on a reading of three experienced radiologists in consensus. This part of the process was necessary for evaluation of the noninferiority of gadodiamide versus gadopentetate in regard to the analysis of the diagnostic accuracy of MR angiography compared with that of DSA. Because this part was predetermined in the study protocol, it was not possible to compare interobserver differences between MR angiography and DSA. In opposition, the MR angiographic examinations were evaluated separately by three independent experienced radiologists who were as well experienced as the DSA readers. Consequently, there was variation among the readers of MR angiographic images themselves, with a moderate concordance among them, and this variation had a considerable effect on the majority decision. These circumstances, however, were predetermined and required to compare the accuracy of gadodiamide versus that of gadopentetate for angiography of abdominal and iliac arteries.

In reference to the suggested further treatment strategies based on DSA versus MR angiographic evaluation, the strength of agreement varied between moderate (for all stenoses with Cohen values of 0.60 and 0.46 for the gadodiamide group and the gadopentetate group, respectively) and substantial (for the main stenosis with Cohen values of 0.78 and 0.65 for the gadodiamide group and the gadopentetate group, respectively). In this study, the comparison was between a consensus therapeutic decision with DSA and an individual therapeutic decision with MR angiography. Among the two study groups, however, the results were similar, and the differences between them were not significant, findings that also support the comparability of gadodiamide and gadopentetate.

For the safety analysis of the 240 subjects, only four adverse events—two in each study group—were reported. In the gadodiamide group, both adverse events were not related to the contrast agent. The two adverse events (rashes classified as mild) in the gadopentetate group were related to the contrast agent. Differences at baseline and 48-hour follow-up between both study groups were not significant for all laboratory, clinical, and physical parameters. Nearly identical and decreasing and increasing in a parallel manner, the values of both study groups are population specific; there was no evident dependence of the values on either contrast agent. Both gadodiamide and gadopentetate are well tolerated contrast agents, and they are comparable in regard to their effects in an organism.

There were limitations in our study that should be addressed: First, the predetermined dose of 0.1 mmol/kg for 3D contrast-enhanced MR angiography yielded insufficient contrast enhancement, especially of the internal iliac arteries and the inferior mesenteric artery. Second, the reading of DSA images in consensus versus the independent blinded reading of MR angiographic images created a bias toward the reference standard in the comparison between MR angiography and DSA. Third, the strict inclusion and evaluation criteria for MR angiography in our randomized multicenter study were in regard to the classification of the MR angiographic evaluation as a mismatch, as mentioned previously.

In summary, the accuracy values achieved for classification of stenosis with findings at MR angiography compared with those for classification with findings at DSA were fairly low in our study, with a value of 56.4% for the gadodiamide group and 52.8% for the gadopentetate group, because a single dose of 0.1 mmol/kg was too low to obtain sufficient contrast enhancement of smaller abdominal and iliac arteries. Furthermore, the degree of procedural standardization among the study centers and the overall duration of the study considerably influenced the results. Nevertheless, the study design with an independent blinded reading of the MR angiographic images versus a reading of the DSA images in consensus offered reliable and consistent outcomes for our study. We believe the main hypothesis of noninferiority of gadodiamide versus gadopentetate was verified on the basis of the primary end point, which was the accuracy for the detection of the main stenosis with 3D contrast-enhanced MR angiography compared with that for detection with the reference standard of intraarterial DSA.

	ACKNOWLEDGMENTS

 
The centers that participated in this study and affiliations of authors are as follows: Department of Diagnostic Radiology, University Hospital of Schleswig-Holstein Campus Kiel, Kiel, Germany (P.J.S., T.J.); Department of Radiology, Hospital Tenon, Paris, France (F.P.B.); Department of Radiology, University of Ulm, Ulm, Germany (H.J.B.); Department of Radiology, University Hospital La Paz, Madrid, Spain (M.B.); Department of Radiology, University Hospital La Princesa, Madrid, Spain (J.L.C.); Department of Radiology, Hospital Papworth, Cambridge, England (R.A.C.); Department of Radiology, University Hospital of Schleswig-Holstein Campus Luebeck, Luebeck, Germany (H.B.G.); Department of Radiology, University Hospital Frankfurt/Main, Frankfurt/Main, Germany (R.H.); Department of Radiology, University Hospital Grosshadern, Munich, Germany (A.H.); Department of Radiology, Hospital Clinico San Carlos, Madrid, Spain (R.J.M.); Department of Radiology, Hospital De La Cavale Blanche, Brest, France (M.N.); Department of Radiology, University Hospital Charite, Berlin, Germany (J.W.O.); Department of Radiology, University Hospital Pamplona, Pamplona, Spain (J.C.P.); Department of Radiology, AKH Vienna, Vienna, Austria (S.T.); Department of Radiology, University Hospital Zuerich, Zuerich, Switzerland (D.W.); Department of Radiology, University Hospital Halle, Halle, Germany; Department of Radiology, Centre Diagnostic Pedralbes, Barcelona, Spain; and Department of Radiology, Hospital Nord, St Étienne, France.

	FOOTNOTES

 

Abbreviations: CI = confidence interval • DSA = digital subtraction angiography • 3D = three-dimensional

See Materials and Methods for pertinent disclosures.

Author contributions: Guarantors of integrity of entire study, all authors; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, P.J.S.; clinical studies, all authors; statistical analysis, P.J.S.; and manuscript editing, P.J.S., T.J.

	References

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION References

 

1. Nelemans PJ, Leiner T, de Vet HC, van Engelshoven JM. Peripheral arterial disease: meta-analysis of the diagnostic performance of MR angiography. Radiology 2000;217:105–114.[Abstract/Free Full Text]
2. Glickerman DJ, Obregon RG, Schmiedl UP, et al. Cardiac-gated MR angiography of the entire lower extremity: a prospective comparison with conventional angiography. AJR Am J Roentgenol 1996;167:445–451.[Abstract/Free Full Text]
3. Poon E, Yucel EK, Pagan-Marin H, Kayne H. Iliac artery stenosis measurements: comparison of two-dimensional time-of-flight and three-dimensional dynamic gadolinium-enhanced MR angiography. AJR Am J Roentgenol 1997;169:1139–1144.[Abstract/Free Full Text]
4. Quinn SF, Sheley RC, Szumowski J, Shimakawa A. Evaluation of the iliac arteries: comparison of two-dimensional time of flight magnetic resonance angiography with cardiac compensated fast gradient recalled echo and contrast-enhanced three-dimensional time of flight magnetic resonance angiography. J Magn Reson Imaging 1997;7:197–203.[Medline]
5. Snidow JJ, Harris VJ, Trerotola SO, et al. Interpretations and treatment decisions based on MR angiography versus conventional arteriography in symptomatic lower extremity ischemia. J Vasc Interv Radiol 1995;6:595–603.[Medline]
6. Snidow JJ, Johnson MS, Harris VJ, et al. Three-dimensional gadolinium-enhanced MR angiography for aortoiliac inflow assessment plus renal artery screening in a single breath hold. Radiology 1996;198:725–732.[Abstract/Free Full Text]
7. Steffens JC, Link J, Muller-Hulsbeck S, Freund M, Brinkmann G, Heller M. Cardiac-gated two-dimensional phase-contrast MR angiography of lower extremity occlusive disease. AJR Am J Roentgenol 1997;169:749–754.[Abstract/Free Full Text]
8. Meaney JF, Ridgway JP, Chakraverty S, et al. Stepping-table gadolinium-enhanced digital subtraction MR angiography of the aorta and lower extremity arteries: preliminary experience. Radiology 1999;211:59–67.[Abstract/Free Full Text]
9. Prince MR, Narasimham DL, Stanley JC, et al. Gadolinium-enhanced magnetic resonance angiography of abdominal aortic aneurysms. J Vasc Surg 1995;21:656–669.[CrossRef][Medline]
10. Prince MR. Peripheral vascular MR angiography: the time has come. Radiology 1998;206:592–593.[Free Full Text]
11. Ho KY, Leiner T, de Haan MW, Kessels AG, Kitslaar PJ, van Engelshoven JM. Peripheral vascular tree stenoses: evaluation with moving-bed infusion-tracking MR angiography. Radiology 1998;206:683–692.[Abstract/Free Full Text]
12. Ruehm SG, Hany TF, Pfammatter T, Schneider E, Ladd M, Debatin JF. Pelvic and lower extremity arterial imaging: diagnostic performance of three-dimensional contrast-enhanced MR angiography. AJR Am J Roentgenol 2000;174:1127–1135.[Abstract/Free Full Text]
13. Sueyoshi E, Sakamoto I, Matsuoka Y, et al. Aortoiliac and lower extremity arteries: comparison of three-dimensional dynamic contrast-enhanced subtraction MR angiography and conventional angiography. Radiology 1999;210:683–688.[Abstract/Free Full Text]
14. Alley MT, Shifrin RY, Pelc NJ, Herfkens RJ. Ultrafast contrast-enhanced three-dimensional MR angiography: state of the art. RadioGraphics 1998;18:273–285.[Abstract]
15. Aslanian V, Lemaignen H, Bunouf P, Svaland MG, Borseth A, Lundby B. Evaluation of the clinical safety of gadodiamide injection, a new nonionic MRI contrast medium for the central nervous system: a European perspective. Neuroradiology 1996;38:537–541.[Medline]
16. Harpur ES, Worah D, Hals PA, Holtz E, Furuhama K, Nomura H. Preclinical safety assessment and pharmacokinetics of gadodiamide injection, a new magnetic resonance imaging contrast agent. Invest Radiol 1993;28(suppl 1):S28–S43.
17. Thurnher SA, Capelastegui A, Del Olmo FH, et al. Safety and effectiveness of single- versus triple-dose gadodiamide injection-enhanced MR angiography of the abdomen: a phase III double-blind multicenter study. Radiology 2001;219:137–146.[Abstract/Free Full Text]
18. Landis JR, Koch GG. An application of hierarchical kappa-type statistics in the assessment of majority agreement among multiple observers. Biometrics 1977;33:363–374.[CrossRef][Medline]
19. Shetty AN, Shirkhoda A, Bis KG, Alcantara A. Contrast-enhanced three-dimensional MR angiography in a single breath-hold: a novel technique. AJR Am J Roentgenol 1995;165:1290–1292.[Free Full Text]
20. Vosshenrich R, Castillo E, Kopka L, Rodenwaldt J, Grabbe E. Contrast media-enhanced 3D MR angiography of the peripheral vessels using a "tracking technique": preliminary results. Rofo 1998;168:90–94.[Medline]
21. Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170–177.[CrossRef][Medline]
22. Schoenberg SO, Londy FJ, Licato P, Williams DM, Wakefield T, Chenevert TL. Multiphase-multistep gadolinium-enhanced MR angiography of the abdominal aorta and runoff vessels. Invest Radiol 2001;36:283–291.[CrossRef][Medline]
23. Kopka L, Vosshenrich R, Rodenwaldt J, Grabbe E. Differences in injection rates on contrast-enhanced breath-hold three-dimensional MR angiography. AJR Am J Roentgenol 1998;170:345–348.[Abstract/Free Full Text]
24. Lentschig MG, Reimer P, Rausch-Lentschig UL, Allkemper T, Oelerich M, Laub G. Breath-hold gadolinium-enhanced MR angiography of the major vessels at 1.0 T: dose-response findings and angiographic correlation. Radiology 1998;208:353–357.[Abstract/Free Full Text]
25. Laissy JP, Trillaud H, Douek P. MR angiography: noninvasive vascular imaging of the abdomen. Abdom Imaging 2002;27:488–506.[CrossRef][Medline]
26. Hany TF, Debatin JF, Leung DA, Pfammatter T. Evaluation of the aortoiliac and renal arteries: comparison of breath-hold, contrast-enhanced, three-dimensional MR angiography with conventional catheter angiography. Radiology 1997;204:357–362.[Abstract/Free Full Text]
27. Hany TF, Leung DA, Pfammatter T, Debatin JF. Contrast-enhanced magnetic resonance angiography of the renal arteries. Original investigation. Invest Radiol 1998;33:653–659.
28. Venkataraman S, Semelka RC, Weeks S, Braga L, Vaidean G. Assessment of aorto-iliac disease with magnetic resonance angiography using arterial phase 3-D gradient-echo and interstitial phase 2-D fat-suppressed spoiled gradient-echo sequences. J Magn Reson Imaging 2003;17:43–53.[CrossRef][Medline]
29. Prince MR. Contrast-enhanced MR angiography: theory and optimization. Magn Reson Imaging Clin N Am 1998;6:257–267.[Medline]
30. Vosshenrich R, Fischer U. Contrast-enhanced MR angiography of abdominal vessels: is there a role for angiography? Eur Radiol 2002;12:218–230.[CrossRef][Medline]
31. Rofsky NM, Adelman MA. MR angiography in the evaluation of atherosclerotic peripheral vascular disease. Radiology 2000;214:325–338.[Abstract/Free Full Text]
32. Schoenberg SO, Essig M, Hallscheidt P, et al. Multiphase magnetic resonance angiography of the abdominal and pelvic arteries: results of a bicenter multireader analysis. Invest Radiol 2002;37:20–28.[CrossRef][Medline]

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