Anterior Cervical Discectomy and Fusion (ACDF) is a common spinal procedure used to treat neck issues, such as a herniated disc or spinal canal narrowing. The surgery involves removing the problematic disc and inserting a spacer, often along with a metal plate and screws, to stabilize the cervical spine and promote bone fusion. Because the procedure places materials into the body, patients commonly ask whether a Magnetic Resonance Imaging (MRI) scan can be safely performed afterward. Generally, an MRI is safe after ACDF, but this depends entirely on the materials used and requires specific precautions.
The Hardware Used in ACDF
The concern about MRI safety stems from the presence of hardware, which is a necessary component to ensure the spinal segment fuses correctly. The implants used in modern ACDF are composed of materials chosen specifically for their biocompatibility and favorable magnetic properties. Historically, certain spinal implants contained strongly ferromagnetic stainless steel, which posed a risk in a powerful magnetic field.
Today, standard materials include titanium or titanium alloys for the plates and screws that stabilize the vertebrae. The interbody cage, which replaces the removed disc, is often made from titanium or Polyetheretherketone (PEEK). PEEK is a medical-grade plastic that is non-metallic and non-conductive, making it highly advantageous for imaging.
MRI Safety and Compatibility
Spinal hardware safety in an MRI environment is assessed based on two primary risks: the possibility of the device moving and the potential for the device to heat up. Modern ACDF hardware, particularly those made from titanium and PEEK, are classified as either “MR Safe” or “MR Conditional.” MR Safe devices are entirely non-metallic and pose no known hazard.
MR Conditional devices, such as titanium implants, contain materials that are weakly or non-ferromagnetic. This means the strong magnetic field of the MRI will not cause them to displace or migrate once they are firmly fixed in the bone. Heating of these fixed implants during a scan is minimal and generally insignificant, posing no threat to the surrounding tissue. The key factor is that the hardware is firmly anchored and made from these specialized, non-ferromagnetic materials.
Image Distortion from Spinal Hardware
While modern ACDF hardware is safe in the MRI scanner, its presence can still affect the quality of the resulting images. The interaction between metallic components and the MRI’s magnetic field creates a phenomenon called magnetic susceptibility artifact. This artifact appears as a dark area or distortion around the implant, which can obscure the anatomy the doctor is trying to evaluate.
The extent of this distortion varies depending on the hardware material. PEEK cages cause virtually no artifact, while titanium components create some degree of distortion. This artifact is a practical limitation, not a safety risk, as it may make it difficult for the radiologist to clearly see the spinal cord or nerve roots directly adjacent to the fusion site. Radiologists can minimize this distortion by using specialized techniques, such as metal artifact reduction sequences, which adjust the MRI’s pulse sequences to produce clearer images near the implant.
Necessary Steps Before the MRI
Before undergoing an MRI after ACDF, the patient must take several necessary and proactive steps to ensure the scan is performed safely and effectively. It is mandatory to inform the ordering physician and the MRI technologist about the presence of the spinal hardware. This disclosure allows the facility to verify the specific implant’s safety classification.
The most important step is providing documentation, such as the operative report from the surgeon or an implant card, which specifies the exact manufacturer, model, and material of the hardware used. The MRI facility staff must cross-reference this information with safety guidelines to confirm the hardware is MR Conditional under the specific conditions of their scanner. This includes verifying the magnetic field strength (e.g., 1.5 Tesla or 3 Tesla). This verification process is the final safeguard before the patient enters the magnetic environment.