safity of magnetic resonance in patients

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9/23/2009 YASSER ABD EL RAOUF 1 بسم الله العلى العظيم

WARD 5 PRESENTATIONSafety of Magnetic Resonance Imaging in Patients With Cardiovascular DevicesAHA Scientific Statement : 

9/23/2009 YASSER ABD EL RAOUF 2 WARD 5 PRESENTATIONSafety of Magnetic Resonance Imaging in Patients With Cardiovascular DevicesAHA Scientific Statement DR. YASSER ABD EL RAOUF (Circulation. 2007;116:2878-2891.)

RETIONAL : 

9/23/2009 YASSER ABD EL RAOUF 3 RETIONAL Advances in magnetic resonance (MR) imaging and MR angiography over the last 2 decades have led to MR becoming an increasingly attractive imaging modality. . MR imaging has thus developed into a broadly applied diagnostic tool for patients with cardiovascular and other disease states

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9/23/2009 YASSER ABD EL RAOUF 4 An increasing number of patients exposed to MRI are being treated with permanently or temporarily implanted cardiovascular devices. confusion and controversy still present regarding patients with cardiovascular devices and MRI.

General Safety Considerations : 

9/23/2009 YASSER ABD EL RAOUF 5 General Safety Considerations (1) the static main magnetic field (2) RF energy. (3) gradient magnetic fields

Patient Screening : 

9/23/2009 YASSER ABD EL RAOUF 6 Patient Screening All patients should undergo a thorough screening procedure for cardiovascular and other implants and devices, including an interview with a healthcare worker specifically trained in MR safety and completion of a standardized screening form. Any implanted devices should be identified via wallet-sized cards.

Safety Terminology for Implants and Devices (old) : 

9/23/2009 YASSER ABD EL RAOUF 7 Safety Terminology for Implants and Devices (old) "MR safe" -magnetic field interactions- heating -in some cases, induced electrical currents "MR compatible" -As above-plus characterization of artifacts.

New safety terminology : 

9/23/2009 YASSER ABD EL RAOUF 8 New safety terminology 1-MR safe, an item that poses no known hazards in any MR environment. Using the new terminology, "MR safe" items include nonconducting, nonmetallic, nonmagnetic items, such as a plastic Petri dish. 2-MR conditional , an item that has been demonstrated to pose no known hazards in a specified MR imaging environment with specified conditions of use.  3-MR unsafe, an item that is known to pose hazards in all MR environments.

MR Imaging After Device Implantation (GENERAL) : 

9/23/2009 YASSER ABD EL RAOUF 9 MR Imaging After Device Implantation (GENERAL) Nonferromagnetic "passive" implant (eg, titanium, titanium alloy, or nitinol ) , and if there are no concerns associated with MR-related heating, the patient with the device may undergo MR imaging immediately after implantation. The issue of when patients who have been treated with weakly ferromagnetic devices may undergo MR examination has not been established definitively for every device and thus remains controversial

MR Imaging After Device Implantation (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 10 MR Imaging After Device Implantation (cont..) For weakly ferromagnetic devices, it is theoretically possible that the forces present during an MR examination could move or dislodge such a device. it has been advocated by some to wait 6 weeks before MR imaging of certain devices.

MR Imaging After Device Implantation (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 11 MR Imaging After Device Implantation (cont..) For some weakly ferromagnetic devices, there are currently sufficient data and consensus that it can be recommended that patients with such devices can undergo MR examination any time . For weakly ferromagnetic devices for which there are not currently enough data and consensus to make the recommendation that scanning can be performed safely any time after implantation, here individulize decision:

MR Imaging After Device Implantation (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 12 MR Imaging After Device Implantation (cont..) For cases that occur in the days to weeks after device implantation in which there is a clear potential clinical benefit of scanning the patient at that time →DO. . For patients in whom it makes little difference whether the scan is performed at a given time or weeks later →WAIT 6 WEEKS.

Coronary Artery and Peripheral Vascular Stents : 

9/23/2009 YASSER ABD EL RAOUF 13 Coronary Artery and Peripheral Vascular Stents Most coronary artery and peripheral vascular stents are composed of either 316L stainless steel or nitinol. Less commonly, stents may be composed of or contain variable amounts of platinum, cobalt alloy, gold, tantalum, MP35N, Most coronary and peripheral vascular stents exhibit nonferromagnetic or weakly ferromagnetic characteristics.

Coronary Artery and Peripheral Vascular Stents (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 14 Coronary Artery and Peripheral Vascular Stents (cont..) Most of the stents currently used for carotid procedures are made of nitinol and are nonferromagnetic or only weakly ferromagnetic. Implantation of the stent against the vessel wall provides for immediate anchoring of the stent.

Coronary Artery and Peripheral Vascular Stents (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 15 Coronary Artery and Peripheral Vascular Stents (cont..) Most coronary and peripheral vascular stents that have been tested have been labeled as "MR safe“. the remainder have been labeled as "MR conditional." Tested coronary artery stents (including tested drug-eluting coronary stents) that are nonferromagnetic (all currently used coronary stents) can be safely scanned at 3 T or less any time after implantation.

Coronary Artery and Peripheral Vascular Stents (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 16 Coronary Artery and Peripheral Vascular Stents (cont..) MR examination at 3 T in patients with peripheral stents that are nonferromagnetic can be performed immediately after implantation. The timing of MR examination at 3 T in patients with peripheral stents that are weakly ferromagnetic should be determined on a case-by-case basis.

Aortic Stent Grafts : 

9/23/2009 YASSER ABD EL RAOUF 17 Aortic Stent Grafts The majority of endovascular aortic stent grafts, but not all, are made from nonferromagnetic or weakly ferromagnetic materials. Most aortic stent grafts that have been tested have been labeled as "MR safe" .

Aortic Stent Grafts (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 18 Aortic Stent Grafts (cont..) The Zenith AAA endovascular graft stent has been labeled as "MR unsafe. Patients with stent grafts made from nonferromagnetic materials may be scanned immediately after implantation at 3 T or less. The timing of MR examination at 3 T or less in patients with aortic stent grafts that are weakly ferromagnetic should be weighed on a case-by-case basis.

Aortic Stent Grafts (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 19 Aortic Stent Grafts (cont..) Although patients with the Endologix AAA or Lifepath AAA stents may undergo MR imaging, because of the artifacts created by these stents, MR examination is not recommended as the modality of choice for examinations specifically targeted toward evaluation of the stent grafts.

Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires : 

9/23/2009 YASSER ABD EL RAOUF 20 Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires Bioprosthetic heart valves are composed primarily of nonmetallic materials (usually porcine tissue or bovine pericardium) but may contain small amounts of metal (used for scaffolding rings). Mechanical heart valves are composed of a variety of metals, including titanium alloy, MP35N, pyrolytic carbon, Elgiloy, chromium cobalt alloy, nitinol, 316L stainless steel, and 316LVM stainless steel

Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) : 

9/23/2009 YASSER ABD EL RAOUF 21 Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) Some annuloplasty rings contain no metal, whereas others may be composed in part of titanium, chromium cobalt, and other metallic materials. Sternal wires are most commonly composed of stainless steel or similar alloys.

Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) : 

9/23/2009 YASSER ABD EL RAOUF 22 Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) The majority of prosthetic heart valves and annuloplasty rings that have been tested have been labeled as "MR safe“. The remainder of heart valves and rings that have been tested have been labeled as "MR conditional.

Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) : 

9/23/2009 YASSER ABD EL RAOUF 23 Prosthetic Heart Valves, Annuloplasty Rings, and Sternal Suture Wires (CONT..) prosthetic heart valve or annuloplasty ring that has been formally evaluated for MR safety should not be considered a contraindication to an MR examination at 3 T or less (and possibly even 4.7 T in some cases) any time after implantation. MR examination of patients with sternal wires is generally considered to be safe.

Cardiac Closure and Occluder Devices : 

9/23/2009 YASSER ABD EL RAOUF 24 Cardiac Closure and Occluder Devices Cardiac closure and left atrial appendage occluder devices are typically made from metals that include nitinol, titanium, titanium alloy, MP35N, 316L stainless steel, and 304V stainless steel. In tests for magnetic field interactions conducted at 1.5 T, devices made from 304V stainless steel displayed weakly ferromagnetic qualities, whereas those made from nitinol, titanium, titanium alloy, and MP35N were nonferromagnetic

Cardiac Closure and Occluder Devices (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 25 Cardiac Closure and Occluder Devices (cont..) The majority of cardiac closure and occluder devices that have been tested have been labeled as "MR safe“. several that have been tested are labeled as "MR conditional“. Patients with nonferromagnetic cardiac closure and occluder devices may undergo MR procedures at any time after implantation.

Cardiac Closure and Occluder Devices (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 26 Cardiac Closure and Occluder Devices (cont..) The timing of MR examination at 3 T or less in patients with cardiac closure or occluder devices that are weakly ferromagnetic should be weighed on a case-by-case basis.

Inferior Vena Cava Filters : 

9/23/2009 YASSER ABD EL RAOUF 27 Inferior Vena Cava Filters Many inferior vena cava (IVC) filters are made of nonferromagnetic materials, whereas some others are composed of weakly ferromagnetic materials. Most IVC filters that have been tested have been labeled as "MR safe“. the remainder of IVC filters that have been tested are classified as "MR conditional”.

Inferior Vena Cava Filters (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 28 Inferior Vena Cava Filters (cont..) Patients who have been treated with nonferromagnetic IVC filters can undergo MR examination any time after filter implantation. stainless steel Greenfield vena cava filter [Boston Scientific]), it is advised that the patient wait at least 6 weeks before undergoing an MR examination (because these older devices initially may not be anchored as firmly in place)

Embolization Coils : 

9/23/2009 YASSER ABD EL RAOUF 29 Embolization Coils The earliest embolization coils were stainless steel; more recently developed coils are often made from platinum or other alloys. Commonly used embolization coils are either nonferromagnetic or weakly ferromagnetic. Because of the shape of certain coils, the theoretical potential of coil heating during an MR examination exists.

Embolization Coils (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 30 Embolization Coils (cont..) Most embolization coils that have been tested have been labeled as "MR safe“. The remainder that have been tested have been labeled as "MR conditional“. Patients who have been treated with nonferromagnetic embolization coils can undergo MR examination any time after coil implantation.

Embolization Coils (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 31 Embolization Coils (cont..) The timing of MR examination at 3 T or less in patients with embolization coils that are weakly ferromagnetic should be weighed on a case-by-case basis.

Hemodynamic Monitoring and Temporary Pacing Devices : 

9/23/2009 YASSER ABD EL RAOUF 32 Hemodynamic Monitoring and Temporary Pacing Devices Cardiovascular catheters, such as pulmonary artery hemodynamic monitoring/thermodilution catheters]), and temporary transvenous cardiac pacing devices generally contain no ferromagnetic components but may incorporate nonferromagnetic, electrically conductive materials.

Hemodynamic Monitoring and Temporary Pacing Devices (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 33 Hemodynamic Monitoring and Temporary Pacing Devices (cont..) The MR examination may induce sufficient voltages and currents in electrically conductive material so as to result in thermal injuries and burns to adjacent tissue (including myocardial tissue). Those few catheters that contain conducting wires and those few temporary transvenous pacing wires that have been tested have been labeled as "MR unsafe

Hemodynamic Monitoring and Temporary Pacing Devices (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 34 Hemodynamic Monitoring and Temporary Pacing Devices (cont..) Patients with pulmonary artery hemodynamic monitoring/thermodilution catheters (such as the Swan-Ganz catheter) and similar catheters that have conductive wires or similar components should not undergo MR examinations because of the possible associated risks.

Hemodynamic Monitoring and Temporary Pacing Devices (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 35 Hemodynamic Monitoring and Temporary Pacing Devices (cont..) Patients with nonferromagnetic pulmonary artery catheters that contain no electrically conductive pathways in the catheter may undergo MR examination; however, it must be emphasized that such conditions must be verified before such patients undergo MR examination.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators : 

9/23/2009 YASSER ABD EL RAOUF 36 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators significant proportion of patients who would ideally be referred for MR examinations will have permanent cardiac pacemakers or implantable cardioverter defibrillators (ICDs). It has been estimated that a patient with a pacemaker or implanted defibrillator has a 50% to 75% likelihood of having a clinical indication for MR imaging over the lifetime of their device.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 37 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) These devices contain metal with variable ferromagnetic qualities, as well as complex electrical systems, and additionally consist of 1 or several leads implanted into the myocardium.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 38 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) The potential for movement of the device, programming changes, asynchronous pacing, activation of tachyarrhythmia therapies, inhibition of pacing output, and induced lead currents that could lead to heating and cardiac stimulation has led to concerns regarding the performance of MR examinations in patients with permanent pacemakers and ICDs.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 39 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) Patients who have a pacemaker or ICD should not undergo an MR study if an alternative diagnostic test is available. and MR imaging should only be considered in cases in which the potential benefit to the patient clearly outweighs the risks to the patient.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 40 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) Risks to the patient are likely increased in centers without highly experienced personnel in both function and programming of the device and operations/pulse sequences of the MR scanner.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 41 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) MR scanning should be discussed specifically and clearly with the patient, and the written informed consent should specifically list risks, including. (1) pacemaker/ICD dysfunction (2) pacemaker/ICD damage (3) arrhythmia, and (4) death.

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 42 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) Those pacemakers that have been tested have been labeled as "MR unsafe“. MR examination of non–pacemaker-dependent patients is discouraged and should only be considered in cases in which there is a strong clinical indication. MR examination of pacemaker-dependent patients should not be performed unless there are highly compelling circumstances in which the benefits clearly outweigh the risks

Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) : 

9/23/2009 YASSER ABD EL RAOUF 43 Permanent Cardiac Pacemakers and Implantable Cardioverter Defibrillators (cont..) MR examination of patients with ICDs should not be performed unless there are highly compelling circumstances in which the benefits clearly outweigh the risks.

Retained Transvenous Pacemaker and Defibrillator Leads : 

9/23/2009 YASSER ABD EL RAOUF 44 Retained Transvenous Pacemaker and Defibrillator Leads Retained transvenous pacemaker and defibrillator leads (leads left in the body after explantation of the permanent pacemaker or ICD generator) pose significant theoretical risks, including heating and cardiac excitation.

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9/23/2009 YASSER ABD EL RAOUF 45 patients with retained transvenous pacemakers or ICD leads be approached similarly to those with pacemakers or ICDs, as outlined above. MR examination of patients with retained transvenous leads is discouraged, and MR examination should only be considered in centers with expertise in MR and electrophysiology, and only in cases in which there is a strong clinical indication. MR examination should not be performed in patients with known retained transvenous leads that have fractures.

Hemodynamic Support Devices : 

9/23/2009 YASSER ABD EL RAOUF 46 Hemodynamic Support Devices Hemodynamic support devices, including intra-aortic balloon pumps, right ventricular assist devices, and left ventricular assist devices, are complex devices with variable degrees of ferromagnetic materials, moving parts, and electrical components. It is believed that these devices should be considered absolute contraindications to MR examination,

Slide 47: 

9/23/2009 YASSER ABD EL RAOUF 47 THANK YOU