Contraindications to MRI

Study Purpose

1. CONTRAINDICATIONS TO M.R.I SCAN PRESENTED BY MUHAMMED SWALI HM BSc RADIOLOGY FINAL YEAR GANGA INSTITUTE OF HEALTHSCIENCES COIMBATORE

2. Magnetic resonance imaging (MRI) is a method that has evolved continuously during the past 20 years, yielding MR systems with stronger static magnetic fields, faster and stronger gradient magnetic fields, and more powerful radiofrequency transmission coils To evaluate the contraindications to MRI is equivalent to understanding the safety issues surrounding the use MRI.

3. Risks associated with MRI may be attributed to one or to a combination of the three main mechanisms of the system Strong static magnetic fields As a result of ferromagnetic interactions, an object or device may be moved, rotated, dislodged, or accelerated toward the magnet. The ‘‘projectile effect’’ means that, depending on the type of magnet and the intensity of the generated field, to varying extent, objects are attracted to the centre of the magnet For example, helium or oxygen cylinders, ventilators, wheelchair, etc ),

4. Pulsed gradient magnetic fields Gradients are time-varying magnetic fields used to encode for various aspects of the image acquisition. They are much weaker than the main magnetic field. As they are repeatedly and rapidly turned on and off the rapid changing magnetic fields can induce electrical currents in electrically conductive devices and may directly cause neuromuscular stimulation.

5. Pulsed radiofrequency fields The main biological effects of radiofrequency fields is their thermogenic effect. Some of the applied energy will be absorbed by the body and converted into heat. Radiofrequency energy can also induce electrical currents in wires and leads which might induce arrhythmias.

6. The following conditions are often contraindications to MRI scanning. Implanted pacemaker or defibrillator : Until recently, MRI was contraindicated for all patients with implantable cardiac devices because the fields generated have the potential to damage components and interfere with functioning. New MRI-conditional pacemakers are now available, but MRI for patients with even these new devices should be undertaken only when deemed medically necessary and under strict guidelines

7. Ferromagnetic aneurysm clips May move or become dislodged under the force of the magnetic field A cochlear implant It can be damaged or create tissue damage in the presence of an MRI system. Metallic foreign bodies Shrapnel or other metallic objects in the body can be heated and/or moved by the magnetic field. This includes any minute metal chips or fragments that may have lodged in the eye as a result of welding, grinding, or any type of accident

8. Some varieties of ocular implants It pose a risk of damage to the eye due to metallic components. A Swan-Ganz catheter may malfunction during MRI scanning. Prosthetic heart valves: Although prosthetic heart valves and annuloplasty rings are made from a variety of materials, numerous studies have demonstrated that MRI examinations are safe

9. OTHER POTENTIAL CONTRAINDICATIONS Tattoos and Cosmetics Claustrophobia Permanent Contraceptive Devices Aneurysm clip(s) Any metallic fragment or foreign body Coronary and peripheral artery stents Aortic stent graft Prosthetic heart valves and annuloplasty rings Cardiac occluder devices Vena cava filters and embolisation coils pregnancy or breast feeding

10. Haemodynamic monitoring and temporary pacing devices, Eg , Swan–Ganz catheter Haemodynamic support devices Cardiac pacemaker Implanted cardioverter-defibrillator (ICD) Retained transvenous pacemaker and defibrillator leads Electronic implant or device, eg , insulin pump or other infusion pump Permanent contraceptive devices, diaphragm, or pessary Cochlear, otologic, or other ear implant Neurostimulation system Shunt (spinal or intraventricular)

11. Vascular access port and/or catheter Tissue expander ( eg , breast) Joint replacement ( eg , hip, knee, etc ) Any type of prosthesis ( eg , eye, penile, etc ) Body piercing jewellery Hearing aid Renal insufficiency Known/possible

12. MRI COMPATIBLE METALS ARE . titanium Aluminum Brass

13. Usually MRI compatible Cardiac Sternal wires Heart valves & annuloplasty rings Coronary stents Epicardial wires (cut short and taped) Other vascular stents, coils and filters Other Orthopaedic implants Contraceptive devices Dental implants

14. OXYGEN SUPPLY IN MRI SUITE Two types of Supply 1- Pipe Line Supply Branch From Central Oxygen Supply Usually Mounted on the wall of the MRI Room ( S h o u l d B e M R C o m p a t i a b l e

15. 2- Cylinder Supply Cylinder made up of Aluminum Uses MR Compatible Oxygen regulator Oxygen supplying mask have a metallic- hook usually MR compatible