Is Magnetic Resonance Image Guidance the Key to Opening Chronic Total Occlusions?
2006; Lippincott Williams & Wilkins; Volume: 113; Issue: 8 Linguagem: Inglês
10.1161/circulationaha.105.609263
ISSN1524-4539
AutoresDonald S. Baim, Raymond Y. Kwong,
Tópico(s)Cardiac Imaging and Diagnostics
ResumoHomeCirculationVol. 113, No. 8Is Magnetic Resonance Image Guidance the Key to Opening Chronic Total Occlusions? Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBIs Magnetic Resonance Image Guidance the Key to Opening Chronic Total Occlusions? Donald S. Baim and Raymond Y. Kwong Donald S. BaimDonald S. Baim From the Cardiovascular Division, Center for Integration of Medicine and Innovative Technology (D.S.B.) and Cardiac Magnetic Resonance Imaging (R.Y.K.), Brigham and Women's Hospital, Boston, Mass. and Raymond Y. KwongRaymond Y. Kwong From the Cardiovascular Division, Center for Integration of Medicine and Innovative Technology (D.S.B.) and Cardiac Magnetic Resonance Imaging (R.Y.K.), Brigham and Women's Hospital, Boston, Mass. Originally published28 Feb 2006https://doi.org/10.1161/CIRCULATIONAHA.105.609263Circulation. 2006;113:1053–1055Through progressive plaque growth or fibrotic organization of occlusive thrombus, atherosclerosis may result in chronic total occlusion (CTO) of a major arterial conduit. If CTO develops slowly, collateral pathways may supply sufficient perfusion to retain tissue viability despite occlusion of the major inflow conduit. However, such collateral-mediated perfusion rarely matches that provided by an open main conduit, particularly during the peak demand of regional muscular activity. Although strategies to limit regional oxygen demand (eg, β-blockers for the treatment of angina pectoris) or to enhance collateral function (eg, a walking program for superficial femoral occlusion, experimental angiogenesis) may be of some benefit, these approaches generally offer less complete return of normal physiology and relief of ischemic symptoms than does direct revascularization of the occluded vessel. With surgical bypass, the nature of the occlusion (its length, duration, tortuosity, calcification) is less important than the presence of a suitable distal anastomotic target. On the other hand, with catheter-based techniques, success depends heavily on these lesion characteristics. In fact, crossing such occluded segments with a guidewire remains the dominant barrier to catheter-based treatments of occluded arterial segments. Once the guidewire has been passed successfully into the distal true lumen, the process of dilating and stenting the segment is usually straightforward and durable, at least with the use of drug-eluting stents in coronary CTOs.1,2Article p 1101Devices designed to cross CTOs should have 3 key features: an ability to distinguish a true luminal path from one created within (dissection) or through (perforation) the vessel wall of the occluded segment, an ability to change direction (steer) to correct deviations from the desired path through the occlusion, and an ability to penetrate the frequently fibrotic and focally calcific substance of the occlusion through the use of either mechanical stiffness or an alternative energy modality (laser, radiofrequency, ultrasound, blunt microdissection).Despite these seemingly simple requirements, devices that have emphasized only the third feature—penetrating power—have generally failed to deliver significant enhancements in their ability to cross the occluded segment and reenter the distal true lumen, because they can easily enter a vessel wall dissection plane (the path of least resistance) within the occlusion and then remain next to (rather than within) the distal true lumen.3 Fluoroscopic or intravascular ultrasound–guided devices can then be used to attempt puncture back into the distal true lumen to augment the success of such devices. Secondary success for crossing lesions that are uncrossable with conventional guidewire, however, is only 50% to 60%. On the other hand, if the energy source leads to frank perforation of the vessel wall, safe conclusion of the procedure may be difficult (except in the superficial femoral, where it may be possible to negotiate along side the occluded segment and then reenter the distal true lumen, salvaging success by stenting the path with covered stents).4It thus appears that any successful device for crossing CTOs must also incorporate strong performance in the second feature—steering—to continually readjust direction of the device toward the desired true lumen path. The recent introduction of specialized guidewires for crossing CTOs has demonstrated that coupling exceptional tip stiffness (the ability to deliver up to 12 g of force with the distal 1 cm of the wire compared with 0.5 to 1.0 g for conventional angioplasty wires), precise tip shaping, and steering with partial coverage by lubricious coatings can increase the success of crossing CTOs to 85% to 90% in the most skilled hands.1,2Still, the availability of devices with precise steering and potent advancement capability do not make up for the lack of the first feature—guidance—to allow the operator to understand the instantaneous device trajectory relative to both the occluded lumen and the distal reconstituted true lumen. In clinical practice, operators rely on a combination of x-ray fluoroscopy and tactile feel of the guidewire. One major advance has been the use of simultaneous contrast injection into both the occluded vessel and a contralateral (collateral-supplying) vessel to allow estimation of the position of the guidewire relative to the interpolated missing segment in between. Using such double injections in different projections frequently requires very high contrast and x-ray doses for procedural success. Attempts to use forward-looking ultrasound have been unsuccessful, but a recent device (the Safe-Cross-RF Guidewire, Intraluminal Therapeutics) has used optical coherence reflectometry via a 0.014-in intermediate-stiffness steerable guidewire to determine whether amorphous plaque or organized vessel wall layers lie immediately ahead of the guidewire tip.5 The penetrating power of the wire can then be enhanced by delivering a train of radiofrequency energy pulses to the wire tip.Against this backdrop, the development of an imaging modality that can visualize the position of the guidewire relative to the proximal and distal true lumen and relative to the vessel walls within the occluded segment would constitute a major advance. If this could be combined with technologies that allow precise wire steering and effective wire advancement, the triad of capabilities required to elevate the success of crossing CTOs (coronary and peripheral) to the 95% to 98% success rate now achieved for subtotal stenosis would be in place. In this issue of Circulation, Raval et al6 from the cardiovascular branch of the National Heart, Lung, and Blood Institute share a provocative preliminary animal study suggesting that magnetic resonance imaging (MRI) fluoroscopy, coupled with catheters and guidewires equipped to serve as active antennas within the MRI system, may be able to fulfill that goal.MR-guided vascular intervention is appealing for its freedom from ionizing radiation, superior soft tissue contrast that allows it to display the vascular lumen (with or without the use of gadolinium-based rather than more toxic iodine-based contrast materials), and tomographic capability that permits 3-dimensional display of the vascular path. If these are combined with methods to visualize catheters and guidewires under MR, real-time navigation of those devices relative to the vascular true lumen, including the latent true lumen within the occluded segment, would be enabled. But many technical challenges exist. MR-guided intervention demands rapid acquisition of real-time imaging data to track the motion of the interventional devices. Needed pulse sequences such as the steady-state free precession (also known as TrueFisp, Fiesta, or balanced FFE) may deposit enough radiofrequency energy to heat commercial ferromagnetic materials (eg, stainless steel guidewires) significantly. In addition, any ferromagnetic metal elements embedded in catheters may distort the magnetic field and obscure adjacent structures.7 Active catheters with embedded signal pickup coils can interface with the coil inputs of the MR scanner, allowing the catheters to be displayed on the MR image in faux colors, but this requires dedicated multiple receiver channels and MR-imaging pulse sequences.Despite these considerable challenges, Raval et al6 have demonstrated feasibility of using MRI guidance to recanalize carotid artery CTO in a swine model. Several technical developments were required: Nonmagnetic materials (MP35N, nitinol) were used to build custom guidewires, loopless and microcoil active antennas were created on the guidewires and catheters to allow real-time detection of these devices, and the microcoils and their associated circuitry were detuned and decoupled to prevent device heating during real-time MRI. Similar to other reports, echo-sharing data acquisition was used to improve temporal resolution, allowing capture of device motion during manipulation, whereas an interactive flat-panel display inside the scanner room allowed superimposed multiplanar display of real-time images from the active devices combined with anatomic images acquired from the surface coils. For higher resolution before and after intervention, subtraction MR angiography of the carotid artery was achieved at an in-plane resolution of 0.3×0.5 mm. In this particular model, MR-guided intervention actually had a higher success rate than conventional fluoroscopic techniques.The authors should be commended for the latest in their ongoing efforts at developing MR-guided intervention and for their encouraging preclinical results. But, significant hurdles remain in implementing MR-guided vascular intervention clinically. High-field (≥1.5 T) MRI systems are required to achieve adequate signal-to-noise ratio and speed for real-time data acquisition and display. Conventional x-ray fluoroscopy may be required as an adjunct to facilitate initial catheter placement, to verify procedural success, and to manage emergency bailout situations. In some applications, this may require the construction of combined MRI/x-ray fluoroscopy interventional units with intermodality patient-table transfer capability. Other challenges include claustrophobia and limited patient access within closed-bored magnets, although major vendors have designed newer short-bore or more spacious MRI systems that may partially overcome this problem. Cathode-ray tubes (x-ray image intensifiers or even conventional monitors) do not function adequately within the high-magnetic-field MRI environment, and the vibration of the image coils during pulse sequencing creates relatively high levels of acoustic noise, making custom-built interactive flat-panel display systems and special communication equipment a requirement to move MRI-guided intervention beyond specialized research centers such as the NIH facility.Although improved real-time "passive" visualization of conventional catheters can be achieved by filling the catheters with gadolinium8,9 or CO2 contrast,10 the various active designs11–15 that incorporate MRI receiver coils provide better device positioning and motion tracking. To reduce heating risk, detuning or decoupling the conductive wire16 or replacing metal circuitry with fiberoptic connections is required. Although vascular stents made of nonmagnetic or weakly ferromagnetic materials (eg, nitinol, titanium, titanium alloy) are considered safe in the MRI environment,17 the clinical safety of deploying vascular stents made from ferromagnetic materials (eg, stainless steel) under MR guidance requires further evaluation.Beyond the challenges of the imaging system, moving to the MR environment also requires adapting or modifying many of the existing clinical systems and devices. Although the patient's ECG can be reliably monitored for rhythm and gated image acquisition, it is not possible to monitor ST-segment changes inside the scanner room because of artifacts generated by aortic blood flow in the magnetic field. A designated area outside the scanner room should always be available in case of patient emergency, because resuscitative equipment such as the defibrillator cart may be pulled violently into the magnet if brought inside the scanner room.It is also important to appreciate how hard it may be to move from the relatively static carotid artery studied by Raval et al6 to cardiac or coronary intervention. Several groups have demonstrated preclinical success in MRI-guided cardiac interventions, including left and right heart catheterization,18 targeted injections of intramyocardial contrast19,20 and stem cells,21 catheter-based closure of atrial septal defect,22,23 atrial septal puncture,24 abdominal aortic aneurysm repair,25 and even transcatheter aortic valve replacement.26 MRI is also useful in assessing myocardial perfusion, tomographic visualization of coronary anatomy, and potentially even coronary plaque morphology. Although preliminary human experience in MR-guided cardiac intervention also exists,10 to be competitive with current x-ray–guided coronary procedures, a 3- to 4-fold improvement in spatial and temporal resolution is needed. Second, the operator needs to work in a single (although selectable) MR imaging plane that contains the catheter, so real-time 3-dimensional data acquisition and multiplanar or "stacked" layered display of the local coronary anatomy may be required. Third, it is unlikely that the device industry will undertake the development of a whole suite of MR-enabled and MR-compatible devices without a demonstration of strong clinical demand (driven by improved outcomes or equal outcomes with elimination of x-ray exposure) and the potential growth of a critical mass of suitably equipped interventional MR or MR/x-ray fluoroscopy suites.The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.DisclosuresDr Baim receives research support from IntraLuminal Therapeutics. Dr Kwong reports no conflicts.FootnotesCorrespondence to Donald S. Baim MD, Cardiovascular Division, Center for Integration of Medicine and Innovative Technology, Brigham and Women's Hospital, 1620 Tremont St, Boston MA 02120. E-mail [email protected] References 1 Stone GW, Kandzari DE, Mehran R, Colombo A, Schwarts RS, Bailey S, Moussa I, Teirstein PS, Dangas G, Baim DS, Selmon M, Strauss BH, Tamai H, Suzuki T, Mitsudo K, Katoh O, Cox DA, Hoye A, Mintz GS, Grube E, Cannon LA, Reifart NJ, Reisman M, Abizaid A, Moses JW, Leon MB, Serruys PW. Percutaneous recanalization of chronically occluded coronary arteries: a consensus document part I. Circulation. 2005; 112: 2364–2372.LinkGoogle Scholar2 Stone GW, Reifard NJ, Moussa, Hoye A, Cox DA, Colombo A, Baim DS, Teirstein PS, Strauss BH, Selmon M, Mintz GS, Katoh O, Mitsudo K, Suzuki T, Tamai H, Grube E, Cannon LA, Kandzari DE, Reisman M, Schwartz RS, Bailey SA, Dangas G, Abizaid A, Moses JW, Leon MB, Serruys PW. Percutaneous recanalization of chronically occluded coronary arteries: a consensus document part II. Circulation. 2005; 112: 2530–2537.LinkGoogle Scholar3 Whitbourn RJ, Vincotta M, Mossop P, Selmon M. Intraluminal blunt microdissection for angioplasty of chronic total occlusions. Catheter Cardiovasc Interv. 2003; 58: 194–198.CrossrefMedlineGoogle Scholar4 Treiman GS, Whiting JH, Treiman RL, McNamara RM, Ashrafi A. Treatment of limb-threatening ischemia with percutaneous intentional extraluminal recanalization: a preliminary evaluation. J Vasc Surg. 2003; 38: 29–35.CrossrefMedlineGoogle Scholar5 Baim DS, Braden G, Heuser R, Popma JJ, Cutlip DE, Massaro JM, Marulkar S, Arvay LJ, Kuntz RE, for the Guided Radio Frequency Energy Ablation of Total Occlusions Registry Study. Utility of the Safe-Cross-guided radiofrequency total occlusion crossing system in chronic coronary total occlusions (results from the Guided Radio Frequency Energy Ablation of Total Occlusions Registry Study). Am J Cardiol. 2004; 94: 853–858.CrossrefMedlineGoogle Scholar6 Raval AN, Karmarkar PV, Guttman MA, Ozturk C, Sampath S, DeSilva R, Aviles RJ, Xu M, Wright VJ, Schenke WH, Kocaturk O, Dick AJ, Raman VK, Atalar E, McVeigh ER, Lederman R. Real-time magnetic resonance imaging–guided endovascular recanalization of chronic total arterial occlusion in a swine model. Circulation. 2006; 113: 1101–1107.LinkGoogle Scholar7 Buecker A, Spuentrup E, Schmitz-Rode T, Kintzel S, Pfeffer J, Hohl C, van Vaals JJ. Gunther RW. Use of a nonmetallic guide wire for magnetic resonance-guided coronary artery catheterization. Invest Radiol. 2004; 39: 656–660.CrossrefMedlineGoogle Scholar8 Omary RA, Unal O, Koscielski DS, Frayne R, Korosec FR, Mistretta CA, Snother CM, Grist TM. Real-time MR imaging-guided passive catheter tracking with use of gadolinium-filled catheters. J Vasc Interv Radiol. 2000; 11: 1079–1085.CrossrefMedlineGoogle Scholar9 Omary RA, Green JD, Schirf BE, Li Y, Finn JP, Li D. Real-time magnetic resonance imaging-guided coronary catheterization in swine. Circulation. 2003; 107: 2656–2659.LinkGoogle Scholar10 Razavi R, Hill DL, Keevil SF, Miquel ME, Muthurangu V, Hegde S, Rhode K, Barnett M, van Vaals J, Hawkes DJ, Baker E. Cardiac catheterisation guided by MRI in children and adults with congenital heart disease. Lancet. 2003; 362: 1877–1882.CrossrefMedlineGoogle Scholar11 Quick HH, Zenge MO, Kuehl H, Kaiser G, Aker S, Massing S, Bosk S, Ladd ME. Interventional magnetic resonance angiography with no strings attached: wireless active catheter visualization. Magn Reson Med. 2005; 53: 446–455.CrossrefMedlineGoogle Scholar12 Atalar E, Bottomley PA, Ocali O, Correia LC, Kelemen MD, Lima JA, Zerhouni EA. High resolution intravascular MRI and MRS by using a catheter receiver coil. Magn Reson Med. 1996; 36: 596–605.CrossrefMedlineGoogle Scholar13 Atalar E, Kraitchman DL, Carkhuff B, Lesho J, Ocali O, Solaiyappan M, Guttman MA, Charles HK Jr. Catheter-tracking FOV MR fluoroscopy. Magn Reson Med. 1998; 40: 865–872.CrossrefMedlineGoogle Scholar14 Ocali O, Atalar E. Intravascular magnetic resonance imaging using a loopless catheter antenna. Magn Reson Med. 1997; 37: 112–118.CrossrefMedlineGoogle Scholar15 Lederman RJ. Cardiovascular interventional magnetic resonance imaging. Circulation. 2005; 112: 3009–3017.LinkGoogle Scholar16 Ladd ME, Quick HH. Reduction of resonant RF heating in intravascular catheters using coaxial chokes. Magn Reson Med. 2000; 43: 615–619.CrossrefMedlineGoogle Scholar17 Gerber TC, Fasseas P, Lennon RJ, Valeti VU, Wood CP, Breen JF, Berger PB. Clinical safety of magnetic resonance imaging early after coronary artery stent placement. J Am Coll Cardiol. 2003; 42: 1295–1298.CrossrefMedlineGoogle Scholar18 Schalla S, Saeed M, Higgins CB, Martin A, Weber O, Moore P. Magnetic resonance–guided cardiac catheterization in a swine model of atrial septal defect. Circulation. 2003; 108: 1865–1870.LinkGoogle Scholar19 Lederman RJ, Guttman MA, Peters DC, Thompson RB, Sorger JM, Dick AJ, Raman VK, McVeigh ER. Catheter-based endomyocardial injection with real-time magnetic resonance imaging. Circulation. 2002; 105: 1282–1284.LinkGoogle Scholar20 Krombach GA, Pfeffer JG, Kinzel S, Katoh M, Gunther RW, Buecker AM. R-guided percutaneous intramyocardial injection with an MR-compatible catheter: feasibility and changes in T1 values after injection of extracellular contrast medium in pigs. Radiology. 2005; 235: 487–494.CrossrefMedlineGoogle Scholar21 Dick AJ, Guttman MA, Raman VK, Peters DC, Pessanha BS, Hill JM, Smith S, Scott G, McVeigh ER, Lederman RJ. Magnetic resonance fluoroscopy allows targeted delivery of mesenchymal stem cells to infarct borders in swine. Circulation. 2003; 108: 2899–2904.LinkGoogle Scholar22 Buecker A, Spuentrup E, Grabitz R, Freudenthal F, Muehler EG, Schaeffter T, van Vaals JJ, Gunther RW. Magnetic resonance–guided placement of atrial septal closure device in animal model of patent foramen ovale. Circulation. 2002; 106: 511–515.LinkGoogle Scholar23 Rickers C, Jerosch-Herold M, Hu X, Murthy N, Wang X, Kong H, Seethamraju RT, Weil J, Wilke NM. Magnetic resonance image–guided transcatheter closure of atrial septal defects. Circulation. 2003; 107: 132–138.LinkGoogle Scholar24 Arepally A, Karmarkar PV, Weiss C, Rodriguez ER, Lederman RJ, Atalar E. Magnetic resonance image-guided trans-septal puncture in a swine heart. J Magn Reson Imaging. 2005; 21: 463–467.CrossrefMedlineGoogle Scholar25 Raman VK, Karmarkar PV, Guttman MA, Dick AJ, Peters DC, Ozturk C, Pessanha BS, Thompson RB, Raval AN, De Silva R, Aviles RJ, Atalar E, McVeigh ER, Lederman RJ. Real-time magnetic resonance-guided endovascular repair of experimental abdominal aortic aneurysm in swine. J Am Coll Cardiol. 2005; 45: 2069–2077.CrossrefMedlineGoogle Scholar26 Kuehne T, Yilmaz S, Meinus C, Moore P, Saeed M, Weber O, Higgins CB, Blank T, Elsaesser E, Schnackenburg B, Ewert P, Lange PE, Nagel E. Magnetic resonance imaging-guided transcatheter implantation of a prosthetic valve in aortic valve position: feasibility study in swine. J Am Coll Cardiol. 2004; 44: 2247–2249.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Pica S, Di Giovine G, Bollati M, Testa L, Bedogni F, Camporeale A, Pontone G, Andreini D, Monti L, Gasparini G, Grancini L, Secco G, Maestroni A, Ambrogi F, Milani V and Lombardi M (2018) Cardiac magnetic resonance for ischaemia and viability detection. Guiding patient selection to revascularization in coronary chronic total occlusions: The CARISMA_CTO study design, International Journal of Cardiology, 10.1016/j.ijcard.2018.08.061, 272, (356-362), Online publication date: 1-Dec-2018. Qian D and Bottomley P (2012) High-resolution intravascular magnetic resonance quantification of atherosclerotic plaque at 3T, Journal of Cardiovascular Magnetic Resonance, 10.1186/1532-429X-14-20, 14:1, Online publication date: 1-Dec-2012. Liu G, Qi X, Robert N, Dick A and Wright G (2012) Ultrasound-guided identification of cardiac imaging windows, Medical Physics, 10.1118/1.4711757, 39:6Part1, (3009-3018), Online publication date: 10-May-2012. Sathyanarayana S and Bottomley P (2009) MRI endoscopy using intrinsically localized probes, Medical Physics, 10.1118/1.3077125, 36:3, (908-919), Online publication date: 23-Feb-2009. Chamié D, Abizaid A, Júnior J, Feres F, Abizaid A, Staico R, Costa R, Mattos L, Sousa A and Sousa J (2008) The revascular active percutaneous interventional device for coronary total occlusions study, Catheterization and Cardiovascular Interventions, 10.1002/ccd.21560, 72:2, (156-163), Online publication date: 1-Aug-2008. Sampath S, Raval A, Lederman R and McVeigh E (2006) High-resolution 3D arteriography of chronic total peripheral occlusions using aT1-W turbo spin-echo sequence with inner-volume imaging, Magnetic Resonance in Medicine, 10.1002/mrm.21098, 57:1, (40-49), Online publication date: 1-Jan-2007. February 28, 2006Vol 113, Issue 8 Advertisement Article InformationMetrics https://doi.org/10.1161/CIRCULATIONAHA.105.609263PMID: 16505189 Originally publishedFebruary 28, 2006 KeywordsEditorialsocclusionmagnetic resonance imagingangioplastyimagingPDF download Advertisement SubjectsCatheter-Based Coronary and Valvular InterventionsComputerized Tomography (CT)Stent
Referência(s)