Editorial Slides VP Watch, February 20, 2002, Volume 2, Issue 7

MRI Guided Angioplasty and Stenting; How Far Away Are We?

Currently, x-ray coronary angiography is used both for the detection of the coronary artery disease and for guidance of treatment (angioplasty and stent deployment).

Cardiac MRI and coronary MRA are very close to become the standard of care for diagnosis of ischemic heart disease. However the role of MRI in guidance of treatment and interventional cardiology has not received much attention.

In 1997, Buecker and others successfully placed a catheter into the left or right sacral artery in pigs with use of an open 1.5-T magnetic resonance (MR) imager and a tracking catheter. 1

Manke, and colleagues showed that MR imaging–guided stent placement in iliac arteries is feasible in select patients. 2

In another study Buecker and his colleagues determined that real-time radial MR scanning is able to show correct position of the stent in iliac arteries of pigs.3

As highlighted in VP Watch of this week, Spuentrup, Manning, Buecker, and colleagues

presented the first MR-guided coronary artery stent placement in pigs. 4

They showed that real-time MR imaging allows for high-quality coronary MR fluoroscopy without motion artifacts. 4

Spuentrup and his colleagues performed MR-guided stent placement using a newly-developed interactive real-time radial steady-state free precession (rSSFP) imaging sequence during free breathing and without cardiac triggering. 4

Using guidewire in 3D SSFP coronary MRA images displayed a small artifact whereas, the mounted stent resulted in a larger artifact allowing for stent localization. 4

In this study, Spuentrup and colleagues placed 10 of 11 coronary stents correctly in pigs under MR guidance. 4

They could detect one case of stent dislocation during real-time MR imaging. 4

SSFP MR fluoroscopy shows a high contrast of the coronary artery lumen without injection of an exogenous contrast agent. 4

MR-guided coronary stent imaging has following advantages against x-ray angiography:

Can measure myocardial viability 5

Shows coronary artery vessel wall/plaque morphology 6,7

Does not need ionizing radiation No heavy metal contrast agent needed Superior 3D anatomical image Allows continuous visualization of coronary

artery and surrounding tissues without additional guiding catheters.

…

Technical challenges of MR-guided coronary stent are as following:

a. Substantial motion artifacts originating from respiratory and cardiac cycles. 8

b. Small size and the tortuous anatomy of coronary arteries. 9

Conclusion:

I. Real-time MR-guided stent placement is now feasible in coronary artery of pigs.

II. The presented real-time MR imaging sequence reliably allows for high-quality coronary MR fluoroscopy without cardiac motion artifacts.

III. Passive visualization of the guidewire and stent suffices for real-time monitoring of the procedure.

Questions:

I. What are the major barriers in the way of MRI to replace X-ray angiography for interventional cardiologists?

II. If MR can be of grade added value to the current cat labs, would marriage of X-ray and MR (X-MR) be meaningful? Can this marriage survive through cost effectiveness challenge?

Suggestion:

VP.org Editorial Suggestion:

- Please email your thoughts to:

Discussion-Group@VP.org or DG@VP.org

1) Bakker CJ, Smits HF, Bos C et al. MR-guided balloon angioplasty: in vitro demonstration of the potential of MRI for guiding, monitoring, and evaluating endovascular interventions. J Magn Reson Imaging 1998; 8: 245-250.

2) Manke C, Nitz WR, Djavidani B, et al. MR imaging-guided stent placement in iliac arterial stenoses: a feasibility study. Radiology. 2001; 219: 527–534.

3) Buecker A, Neuerburg JM, Adam GB, et al. Real-time MR fluoroscopy for MR-guided iliac artery stent placement. J Magn Reson Imaging. 2000; 12: 616–622. Elmar

4) Spuentrup, Alexander Ruebben, Tobias Schaeffter, Warren J. Manning, Rolf W. Günther, and Arno Buecker ; Magnetic Resonance–Guided Coronary Artery Stent Placement in a Swine Model;Circulation 2002 105: 874 - 879; published online before print January 14 2002, 10.1161/hc0702.104165.

5) Kim RJ, Wu E, Rafael A, et al. The use of contrast-enhanced magnetic resonance imaging to identify reversible myocardial dysfunction. N Engl J Med. 2000; 343: 1445–1453

6) a Fayad ZA, Fuster V, Fallon JT, et al. Noninvasive in vivo human coronary artery lumen and wall imaging using black-blood magnetic resonance imaging. Circulation. 2000; 102: 506–510

7) aBotnar RM, Stuber M, Kissinger KV, et al. Noninvasive coronary vessel wall and plaque imaging with magnetic resonance imaging. Circulation. 2000; 102: 2582–2587

8) Lardo AC, McVeigh ER, Jumrussirikul P, et al. Visualization and temporal/spatial characterization of cardiac radiofrequency ablation lesions using magnetic resonance imaging. Circulation. 2000; 102: 698–705

9) Dodge JT Jr, Brown BG, Bolson EL, et al. Lumen diameter of normal human coronary arteries: influence of age, sex, anatomic variation, and left ventricular hypertrophy or dilation. Circulation. 1992; 86: 232–246

References