MRI-Compatible C-Arm Imaging for Cardiac Intervention
Minimally invasive interventions limit visual access to the anatomy under treatment requiring the use of imaging technologies for guidance. Organs and vessels located deep within the body can be visualized with imaging modalities having good tissue penetration such as X-ray or magnetic resonance imaging (MRI). X-ray guidance via fluoroscopy provides real-time images of large anatomical territories with a spatial resolution of ~0.2 mm usually with the aid of contrast agents. X-ray guidance also provides excellent percutaneous device visualization. MRI provides superior soft tissue differentiation and three-dimensional (3D) localization. However, intravascular MRI guidance is still in its clinical infancy, and concerns remain over exclusive reliance on this modality (Bock M and Wacker FK, J Magn Reson Imaging 27:326–38, 2008; Hushek SG et al., J Magn Reson Imaging 27:253–66; Ratnayaka K et al., J Cardiovasc Magn Reson 10:62, 2008). MRI and X-ray catheterization imaging exhibit complementary strengths that may potentially improve percutaneous therapies. Efforts to combine these two modalities into a fully hybrid X-ray-MR (XMR) system were first proposed by Fahrig et al. (J Magn Reson Imaging 13:294–300, 2001; Acta Neurochir 145:995–7, 2003). Current approaches include (1) the use of conventional X-ray catheterization and MRI systems in adjacent rooms with the addition of a dual-modality compatible patient table and transport system, (2) “combined” or “hybrid” systems, whereby both modalities can image overlapping volumes of interest with no or minimal patient relocation. Examples of interventions that may benefit from XMR are presented, as well as the imaging requirements associated with these procedures. We describe a novel hybrid cone-beam XMR system built by introducing a rotating anode X-ray catheterization system within 140 cm of a closed-bore 1.5 T MRI. The system is used to acquire images of an MRI-compatible catheter moving inside an aorta phantom.
KeywordsAortic Valve Magn Reson Image Chronic Total Occlusion Percutaneous Coronary Intervention Aortic Annulus
Financial support from the CFI (Canadian Foundation for Innovation) and the ORF (Ontario Research Fund), and CIHR (Canadian Institute for Health Research) is gratefully acknowledged.
- 6.Owell SJOC, Ewby DAEN, Oon NIAB, Lder ANTE. Calcific aortic stenosis: same old story? Society. 2004;33(6):538–44.Google Scholar
- 10.Foster GP, Weissman NJ, Picard MH, Fitzpatrick PJ, Shubrooks SJ, Zarich SW. Determination of aortic valve area in valvular aortic stenosis by direct measurement using intracardiac echocardiography: a comparison with the Gorlin and continuity equations. J Am Coll Cardiol. 1996;27(2):392–8.PubMedCrossRefGoogle Scholar
- 39.Srinivas VS. Contemporary percutaneous coronary intervention versus balloon angioplasty for multivessel coronary artery disease: a comparison of the National Heart, Lung and Blood Institute Dynamic Registry and the Bypass Angioplasty Revascularization Investigation (BARI) study. Circulation. 2002;106(13):1627–33.PubMedCrossRefGoogle Scholar
- 40.Morice MC, Serruys PW, Sousa JE, Fajadet J, Ban Hayashi E, Perin M, Colombo A, Schuler G, Barragan P, Guagliumi G, Molnàr F, Falotico R, RAVEL Study Group. Randomized Study with the Sirolimus-Coated Bx Velocity Balloon-Expandable Stent in the Treatment of Patients with de Novo Native Coronary Artery Lesions. A randomized comparison of a sirolimus-eluting stent with a standard stent for coronary revascularization. N Engl J Med. 2002;346(23):1773–80.PubMedCrossRefGoogle Scholar
- 53.Dick AJ, et al. Invasive human magnetic resonance imaging: feasibility during revascularization in a combined XMR suite. 2005. doi: 10.1002/ccd.20302.