BJR
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
British Journal of Radiology (2006) 79, 298-302
© 2006 British Institute of Radiology
doi: 10.1259/bjr/19491401
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Paetzel, C
Right arrow Articles by Herold, T
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Paetzel, C
Right arrow Articles by Herold, T

Full Paper

Intra-arterial MR angiography in the iliac system: initial clinical experience with 25 patients

C Paetzel, MD N Zorger, MD O W Hamer, MD J Seitz, MD T Schleicher, MD S Feuerbach, MD W R Nitz, PhD M Lenhart, MD and T Herold, MD

Department of Diagnostic Radiology, University of Regensburg, Hospital, 93042 Regensburg, Germany


   Abstract
Top
 Abstract
Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
 References
 
The aim of this study was to evaluate intra-arterial magnetic resonance angiography (MRA) of the iliac arteries. Therefore, 25 consecutive patients (17 male, 8 female) suffering from symptomatic occlusive disease of the lower limbs were investigated prospectively. Catheter angiography was performed before MRA and served as the standard of reference. Contrast-enhanced intra-arterial MRA was performed using a 1.5 Tesla MRI system. Contrast agent (gadodiamide) was injected by a conventional pigtail-shaped angiography catheter placed in the abdominal aorta. Vascular lesions were assessed by four investigators. The degree of stenosis was compared with the findings of conventional catheter angiography. Additionally, the diagnostic quality of the MR angiograms was assessed by the investigators using a semi quantitative five-point scale. All lesions shown by catheter angiography were detected and correctly localized by intra-arterial MRA. MR angiograms exhibit a specificity of 95% and a sensitivity of 96% for stenoses of 50% or more. The diagnostic quality of the images was judged from good to excellent, on average. Intra-arterial MRA exhibits a specificity and sensitivity comparable with intravenous angiography. The image quality appears to be adequate for supporting MR-guided vascular intervention.


   Introduction
Top
 Abstract
 Introduction
Materials and methods
 Results
 Discussion
 Conclusion
 References
 
Fluoroscopy-guided percutaneous interventional procedures like transluminal angioplasty are well established methods for the treatment of peripheral arterial occlusive disease of the lower limbs. Although MR guidance of manoeuvres for vascular intervention provides several advantages, such as the absence of ionizing radiation, avoidance of potential hazards from iodinated contrast material and superior soft tissue contrast, it has not yet gained acceptance in the clinical routine. Specific problems with MR-guided intervention are the lack of availability of MR compatible materials (e.g. stents, guidewires), their visibility and the associated high costs. Furthermore, the precise localization of stenosis and post-interventional workup may cause difficulties. Manke et al [1] showed the feasibility of MRI-guided stent placement in iliac artery stenoses in 14 cases using intravenous magnetic resonance angiography (MRA) for pre- and post-interventional imaging. Due to the restricted total amount of applicable MR contrast agent, recurrent control examinations cannot be performed. Manke reported one stent misplacement due to patient motion during the procedure while relying on a previously acquired MRA roadmap. A newer report describes MR-guided angioplasty using intra-arterial MRA [2]. Intra-arterial MRA with a catheter positioned in the infrarenal abdominal aorta allows a reduction in the amount of contrast material applied. Based on this approach, the correct intraluminal site of the catheter can be identified, and repeated control examinations due to patient motion can be performed. There are reports regarding this technique in the literature, but sensitivity and specificity have not yet been systematically assessed [3, 4].

The aim of this study was to investigate the sensitivity, specificity and the image quality of intra-arterial MR angiograms of the iliac arteries using conventional catheter angiography as the standard of reference.GoGo


Figure 1
View larger version (88K):
[in this window]
[in a new window]
  		Figure 1. Examination of a 53-year-old man suffering from symptomatic arterial occlusive disease of the lower limbs with rest pain.(a) Maximum intensity projection of the intra-arterial magnetic resonance angiography showing an occlusion of the left common iliac artery. The artefact of the angiography catheter is indicated by an arrow. (b,c) Corresponding conventional catheter angiography confirms the finding of the MR angiogram.

 

Figure 2
View larger version (76K):
[in this window]
[in a new window]
  		Figure 2. 62-year-old man with ischaemic ulcer of the right foot.(a) Intra-arterial MR angiography detects a high grade stenosis of the right external and an arteriosclerotic dilation of the left common iliac artery as effectively (b) as conventional angiography. The arrow marks the artefact of the angiography catheter.

 

   Materials and methods
Top
 Abstract
 Introduction
 Materials and methods
Results
 Discussion
 Conclusion
 References
 
Patient population
Over a time period of 5 months, 25 consecutive patients (17 men, 8 women; mean age 61.4 years, range 33–82 years, standard deviation ±8.5) suffering from peripheral arterial occlusive disease of the lower limbs underwent intra-arterial conventional catheter angiography and intra-arterial MRA of the iliac arteries. The grading of the disease according to the classification of Fontaine is presented in Table 1Go. Written informed consent was obtained from all patients in advance. The study protocol was approved by the institutional review board.


View this table:
[in this window]
[in a new window]
  		Table 1. Patient population: Fontaine's classification of peripheral arterial occlusive disease

 
Protocol of conventional angiography and intra-arterial MRA
Digital subtraction angiography (DSA) was the standard of reference in all patients. Femoral access with a 5 F sheath was performed in the angiography suite. To avoid thromembolic complications due to the extended investigation time, all patients received 2500 IE heparin intravenously and 40 mg butylscopolamin. A pigtail catheter was placed in the infrarenal aorta at the level of the second lumbar vertebral body. Non-ionic contrast material with 320 mgI ml–1 was injected intra-arterially (volume 20 ml; injection rate 10 ml s–1; frame rate 2 s–1). Imaging was performed using the 35° left and right anterior oblique position. The degree of stenosis was assessed using the commercially available software on the Polytron T.O.P. (Siemens, Erlangen, Germany). Using this software to analyse the angiographic findings, the degree of stenosis was calculated automatically by comparing the geometry and density of a lesion.

After conventional DSA the patients were taken to the MR-scanner with a permanently flushed pigtail-catheter.

MRA images were acquired on a 1.5 T scanner (Sonata; Siemens Medical Solutions) with a gradient strength of 40 mT m–1 and a slew rate of 200 T m–1 s–1 using a phased array receiver coil and breath-hold acquisitions (22 s). A fast-low-angle-shot (FLASH) sequence was utilized with elliptical scanning encoding, 40 partitions (75% partial Fourier), 280 mm x 263 mm field of view, 1.5 mm partition thickness, 25° excitation angle, 266 x 512 matrix size (75% partial Fourier) with an echo time of 1.92 ms and a repetition time of 5.87 ms for a bandwidth of 200 Hz/pixel. 10 ml of gadodiamide (Omniscan; Amersham Buchler, Braunschweig, Germany) was applied via the arterial catheter with a concentration of 0.5 mmol l–1, which was diluted with 50 ml of 0.9% of saline solution at an injection rate of 3.5 ml s–1. The injection was followed by 20 ml of 0.9% saline solution with an injection rate of 3.5 ml s–1 [4]. The application of the contrast agent was performed with an MR injection system (Spectris; Medrad, Indianola, Iowa).

A maximum intensity projection (MIP) algorithm was applied to all contrast-enhanced MR angiography studies after subtraction of the unenhanced measurement by using the commercially available software on the MRI system (Magnetom Symphony, software Numaris 3.5, version VA11A; Siemens). MIPs were reconstructed in steps of 9° (range of 180°).

Image analysis
Four radiologists experienced in cardiovascular imaging assessed the MR angiograms independently in a randomized order for stenoses of the common and external iliac arteries and image quality of MRA. Observers were not aware of DSA findings when analysing contrast enhanced MRA, and vice versa.

Image analysis was based on original contrast-enhanced data sets, MIPs and digital subtraction angiograms. None of the observers were aware of the clinical history or the interpretations of the other observers. The degree of stenosis was defined as the ratio of the narrowest diameter (A) within the stenosis and the diameter of the nearest downstream uninvolved segment of the artery (B): 100 x (1–A/B). The stenoses were classified into occlusions, high grade stenoses (75–99%), moderate stenoses (50–74%), mild stenoses (25–49%) and non-stenoses (0–24%).

Additionally, the four radiologists assessed MR angiograms independently for the following: diagnostic value of the infrarenal abdominal aorta; common iliac arteries; internal and external iliac arteries, and the overall impressions were rated on a subjective scale (1 = excellent, no limitations; 2 = good, minor limitations; 3 = moderate, moderate limitations; 4 = poor, major limitations but still of diagnostic quality; 5 = non-diagnostic). Intermediate scores at 0.5 intervals were not allowed.

The catheter angiograms were assessed by a consensus of two of the investigators. The degree of stenosis was quantified and the lesions were classified in the same manner as described for the MR angiograms. If there was no vascular lesion detected by either catheter angiography or intra-arterial MRA, it was scored as a patient with one lesion with a stenosis of 0%.


   Results
Top
 Abstract
 Introduction
 Materials and methods
 Results
Discussion
 Conclusion
 References
 
In total, 40 vascular lesions were assessed by catheter angiography. There were 10 patients with one lesion, nine patients with two, three patients with three and three patients with none.

The catheter angiography detected four occlusions (Figure 1)Go, three high grade (Figure 2)Go, 12 moderate and 10 mild stenoses (Table 2Go). All of the seven lesions with a degree of stenosis higher than 75% were correctly assessed by intra-arterial MRA. The moderate stenoses were overestimated by one of the investigators in two cases out of 48 (4.2%) and underestimated in three cases (6.3%). Mild stenoses were overestimated in 4 out of 40 (10%), no stenoses in 9 out of 44 (20.5%) cases. Mild stenoses were underestimated three times (7.5%). The lesions which were assessed incorrectly by at least one of the observers are outlined in Table 3Go. With respect to stenoses of more than 50%, the sensitivity and specificity were calculated at 96% and 95%, respectively.


View this table:
[in this window]
[in a new window]
  		Table 2. Classification of stenoses; results of intra-arterial MR angiography compared with conventional catheter angiograms

 

View this table:
[in this window]
[in a new window]
  		Table 3. Lesions scored incorrectly by at least one observer

 
The diagnostic value of all intra-arterial MR angiograms was judged to be 1.54 (range 1–4, median 1) on average by all investigators. The absolute and relative frequency of the scores for diagnostic quality is listed in Table 4Go.


View this table:
[in this window]
[in a new window]
  		Table 4. Estimation of image quality by four investigators in 25 patients

 

   Discussion
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
Conclusion
 References
 
MR-guided vascular interventions provide many advantages over fluoroscopy-guided techniques as mentioned above. Nevertheless, MR-guided procedures are not yet well established in the clinical routine. The reasons for this are the lack of availability of visible materials, real time imaging during the intervention and the peri-interventional check-up. Manke et al used commercially available catheters and guidewires [1] for the treatment of iliac artery stenoses by stent placement based on the safety precautions as described by Nitz et al [4]. Pre-interventional imaging was performed using intravenous MRA. Even though the usefulness of intravenous MRA for imaging the iliac arteries has been demonstrated by several authors [6–16], the restricted total amount of contrast medium of approximately 0.3 mmol kg–1 body weight prohibits the investigator from performing repeated angiograms, which can lead to stent misplacement due to patient motion. To avoid this, intra-arterial MRA was used in a recent study for peri-interventional imaging [2]. Thus, the contrast agent dose is reduced 50% compared with MRA with intravenous injection, allowing the investigator to perform repeated angiograms up to four times. The contrast agent dose chosen was based on a conservative level for a wide range of interindividual conditions. A further reduction in the total amount of contrast agent administered seems possible. Even if initial reports about intra-arterial MRA already exist in the literature [3, 4], there is no further experience with this method concerning its sensitivity and specificity.

In this study, all of the 40 lesions assessed by catheter angiography were detected and correctly localized by intra-arterial MRA. Thus, verification of lesions is possible using intra-arterial angiography with a sensitivity of 100% in this study.

The indication to treat a lesion depends on the degree of the stenosis and the clinical symptoms. The degree of stenosis was correctly classified in 86.9% (139/160); stenoses were overestimated in 9.4% (15/160) and underestimated in 3.8% (6/160) of the cases. Focusing on obstructions or stenosis of more than 50%, the sensitivity and specificity of approximately 95% is comparable with intravenous MRA [6, 10–15]. The value of contrast-enhanced intravenous MRA has been demonstrated in a study by Lenhart et al, showing that MRA can take the place of catheter angiography in the routine work-up of patients with peripheral arterial occlusive disease. Additional examinations are necessary in approximately 5% of the patients, mainly due to inadequate diagnostic quality of the vessels of the lower leg. Thus, with respect to the clinical symptoms, intravenous and intra-arterial MRA give us sufficient information for the treatment of iliac artery lesions in patients with symptomatic arterial occlusive disease of the lower limbs. The outcome of this study is comparable with the results of a recent study concerning the accuracy of intra-arterial MRA of the femorocrural arteries [16].

Using gadodiamide for intra-arterial injection represents an "off-label" use. There are some studies dealing with the intra-arterial application of gadolinium-complex in catheter angiography [17, 18]. The reasons for such application are allergic reactions to iodide contrast agents, renal insufficiency and hyperthyroidism. We used gadodiamide due to the low osmolality of 780 mmol kg–1 compared with the other available gadolinium complexes. Similar to reports in the literature, no adverse reactions where observed during this study.

The confidence of the radiologists in the diagnostic quality of the intra-arterial MR angiograms is demonstrated by their subjective assessment of the image quality. They judged 89% of the investigations as good or excellent using a five point scale. All MR angiograms were assessed as having diagnostic quality. This result indicates that no additional examinations would have been required by the readers to make decisions about further treatment.


   Conclusion
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
References
 
Lesions of the iliac arteries can be detected and localized by intra-arterial MRA. MR angiograms presented with a sensitivity and specificity comparable with intravenous MRA. Thus, intra-arterial MRA seems to support MR-guided interventional procedures.


   Footnotes
 
Current address for Christian Paetzel: Department of Diagnostic Radiology, Klinikum Weiden, Söllnerstraße 16, 92637 Weiden, Germany. Back

Received for publication March 29, 2005. Revision received June 10, 2005. Accepted for publication July 18, 2005.


   References
Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Conclusion
 References
 

  1. Manke C, Nitz WR, Djavidani B, Strotzer M, Lenhart M, Völk M, et al. MR imaging-guided stent placement in iliac arterial stenoses: a feasibility study. Radiology 2001;219:527–34.[Abstract/Free Full Text]
  2. Paetzel C, Zorger N, Bachthaler M, Völk M, Seitz J, Herold T, et al. Feasibility of MR guided angioplasty of femoral artery stenoses using real-time imaging and intraarterial contrast-enhanced MR-angiography. Rofo 2004;176:1232–6.[Medline]
  3. Tello R, Mitchel PJ, Melhem ER, Witte D, Thomson KR. Interventional catheter magnetic resonance angiography with a conventional 1.5-T magnet: work in progress. Australas Radiol 1999;43:435–9.[CrossRef][Medline]
  4. Paetzel C, Zorger N, Seitz J, Völk M, Nitz WR, Herold T, et al. Intraarterial contrast-enhanced magnetic resonance angiography of the aortoiliac system. J Vasc Interv Radiol 2004;15:981–4.[Medline]
  5. Nitz WR, Oppelt A, Renz W, Manke C, Lenhart M, Link J. On the heating of linear conducting structures as guidewires and catheter in interventional MR. J Magn Reson Imaging 2001;13:105–14.[CrossRef][Medline]
  6. Kai Yiu JAM, Leiner T, de Haan MW, Kessels AG, Kitslaar PJ, van Engelhoven J. Periphereal vascular tree stenoses: evaluation with moving-bed infusion-tracking MR angiography. Radiology 1998;206:683–92.[Abstract/Free Full Text]
  7. Quinn SF, Sheley RC, Semonsen KG, Leonardo VJ, Kryss K, Szumowski J. Aortic and lower-extremity arterial disease: evaluation with MR angiography versus conventional angiography. Radiology 1998;206:693–701.[Abstract/Free Full Text]
  8. Snidow JJ, Johnson MS, Harris VJ, Margosian PM, Aisen AM, Lalka SG, et al. Three-dimensional gadolinium-enhanced MR angiography for aortoiliac inflow assessment plus renal artery screening in a single breath hold. Radiology 1998;198:725–32.
  9. Lenhart M, Finkenzeller T, Paetzel C, Strotzer M, Mann S, Djavidani B, et al. Contrast-enhanced MR angiography in the routine work-up of the lower extremity arteries. Rofo 2002;174:1289–95.[Medline]
  10. Sueyoshi E, Sakamoto I, Matsuoka Y, Ogawa Y, Hayashi H, Hashmi R, et al. Aortoiliac and lower extremity arteries: comparison of three-dimensional dynamic contrast-enhanced subtraction MR angiography and conventional angiography. Radiology 1999;210:683–8.[Abstract/Free Full Text]
  11. Lenhart M, Herold T, Volk M, Seitz J, Manke C, Zorger N, et al. Contrast media-enhanced MR angiography of the lower extremity arteries using a dedicated peripheral vascular coil system. First clinical results. Rofo 2000;172:992–9.[Medline]
  12. Lenhart M, Djavidani B, Volk M, Strotzer M, Manke C, Requardt M, et al. Contrast medium-enhanced MR angiography of the pelvic and leg vessels with an automated table-feed technique. Rofo 1999;171:442–9.[Medline]
  13. Kreitner KF, Kalden P, Neufang A, Duber C, Krummenauer F, Kustner E, et al. Diabetes and peripheral arterial occlusive disease: prospective comparison of contrast-enhanced three-dimensional MR angiography with conventional digital subtraction angiography. AJR Am J Roentgenol 2000;174:171–9.[Abstract/Free Full Text]
  14. Huber A, Scheidler J, Wintersperger B, Baur A, Schmidt M, Requardt M, et al. Moving-table MR angiography of the peripheral runoff vessels: comparison of body coil and dedicated phased array coil systems. AJR Am J Roentgenol 2003;180:1365–73.[Abstract/Free Full Text]
  15. Douek PC, Revel D, Chazel S, Falise B, Villard J, Amiel M. Fast MR angiography of the aortoiliac arteries and arteries of the lower extremity: value of bolus-enhanced, whole-volume subtraction technique. AJR Am J Roentgenol 1995;165:431–7.[Abstract/Free Full Text]
  16. Zorger N, Völk M, Hamer OW, Lenhart M, Seitz J, Butz B, et al. Intraarterial gadolinium-enhanced MR angiography in humans: feasibility and accuracy for detection of infrainguinal arterial stenoses before and after percutaneous angioplasty. AJR Am J Roentgenol 2005;185:867–72.[Abstract/Free Full Text]
  17. Schild HH, Weber W, Boeck E, Mildenberger P, Strunk H, Duber C, et al. Gadolinium-DTPA (Magnevist) as a contrast medium for arterial DSA. Rofo 1994;160:218–21.[Medline]
  18. Hatrick AG, Jarosz JM, Irvine AT. Gadopetate dimeglumine as an alternative contrast agent for use in interventional procedures. Clin Radiol 1997;52:948–52.[CrossRef][Medline]



This article has been cited by other articles:


Home page
 Br. J. Radiol.Home page
F J DE ALBUQUERQUE, A C COUTINHO, E C CASTRO NETTO, R C DOMINGUES, and E L GASPARETTO
Infra-renal abdominal aorta agenesis: a case report with emphasis on MR angiography findings
Br. J. Radiol., July 1, 2008; 81(967): e179 - e183.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF)
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Paetzel, C
Right arrow Articles by Herold, T
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Paetzel, C
Right arrow Articles by Herold, T

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
BJR DMFR IMAGING  ALL BIR JOURNALS