Guidelines for the Management of the Post-Operative Patient Referred for a Magnetic Resonance Procedure*
There is often confusion regarding the issue of performing a magnetic resonance (MR) procedure during the post-operative period in a patient with a metallic implant or device. Studies have supported that, if the metallic object is a “passive implant” (i.e. there is no electronically- or magnetically-activated component associated with the operation of the device) and it is made from nonferromagnetic material, the patient may undergo an MR procedure immediately after implantation using an MR system operating at 1.5-Tesla or less (or, the field strength that was used to test the device, including 3-Tesla). In fact, there are several reports that describe placement of vascular stents, coils, filters, and other implants using MR-guided procedures that include the use of high-field-strength (1.5- and 3-Tesla) MR systems. Additionally, a patient or individual with a nonferromagnetic, passive implant is allowed to enter the MR environment associated with a scanner operating at 1.5-Tesla (or, the field strength that was used to test the device, including 3-Tesla) or less immediately after its implantation.
For an implant or device that exhibits magnetic qualities, it may be necessary to wait a period of six weeks after implantation before performing an MR procedure or allowing the individual or patient to enter the MR environment. For example, certain intravascular and intracavitary coils, stents, and filters designated as magnetic become firmly incorporated into tissue a minimum of six weeks following placement. In these cases, retentive or counter-forces provided by tissue ingrowth, scarring, granulation, or other mechanisms serve to prevent these objects from presenting risks or hazards to patients or individuals in the MR environment with regard to movement or dislodgement.
However, patients with implants or devices that are “weakly magnetic” but rigidly fixed in the body (e.g., bone screws, other orthopedic implants, or other devices) may be studied immediately after implantation. Specific information pertaining to the recommended post-operative waiting period may be found in the labeling or product insert for an implant or device.
Of course, the information above pertains to magnetic field interactions and further consideration must be given to MRI-related heating for the implant or device under consideration.
Special Note: If there is any concern regarding the integrity of the tissue with respect to its ability to retain the implant or object in place or the implant cannot be properly identified, the patient or individual should not be exposed to the MR environment.
[*The document, Guidelines for the Management of the Post-Operative Patient Referred for a Magnetic Resonance Procedure, was developed by the Institute for Magnetic Resonance Safety, Education, and Research (www.IMRSER.org) and published with permission. Reviewed and updated 2016.]
Bueker A, et al. Real-time MR fluoroscopy for MR-guided iliac artery stent placement. J Magn Reson Imag 2000;12:616-622.
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.
Rutledge JM, et al. Safety of magnetic resonance immediately following Palmaz stent implant: A report of three cases. Catheter Cardiovasc Interv 2001;53:519-523.
Sawyer-Glover A, Shellock FG. Pre-MRI procedure screening: recommendations and safety considerations for biomedical implants and devices. J Magn Reson Imag 2000;12:92-106.
Shellock FG. Guidelines for the Management of the Post-Operative Patient Referred for a Magnetic Resonance Procedure. Signals, No. 47, Issue 3, pp. 14, 2003.
Shellock FG. Magnetic Resonance Procedures: Health Effects and Safety. CRC Press, LLC, Boca Raton, FL, 2001.
Shellock FG, Cosendai G, Park S-M, Nyenhuis JA. Implantable microstimulator: Magnetic resonance safety at 1.5-Tesla. Investigative Radiology 2004;39:591-594.
Shellock FG, Crues JV. MR procedures: Biologic effects, safety, and patient care. Radiology 2004;232:635-652.
Spuentrup E, et al. Magnetic resonance-guided coronary artery stent placement in a swine model. Circulation 2002;105:874-879.
Teitelbaum GP, et al. MR imaging artifacts, ferromagnetism, and magnetic torque of intravascular filters, stents, and coils. Radiology 1988;166:657-664.
Teitelbaum GP, et al. Ferromagnetism and MR imaging: Safety of cartoid vascular clamps. Am J Neuroradiol 1990;11:267-272.
Teitelbaum GP, Ortega HV, Vinitski S, et al. Low artifact intravascular devices: MR imaging evaluation. Radiology 1988;168:713-719.
Teitelbaum GP, et al. Evaluation of ferromagnetism and magnetic resonance imaging artifacts of the Strecker tantalum vascular stent. Cardiovasc Intervent Radiol 1989;12:125-127.