Quantification of MRI Artifacts in Carbon Fiber Reinforced Polyetheretherketone Thoracolumbar Pedicle Screw Constructs prior to Spinal Stereotactic Radiosurgery

Carbon fiber reinforced polyetheretherketone (CFRP) is a non-metallic material gaining interest in the manufacture of spinal instrumentation. The radiolucency and low magnetic susceptibility of CFRP has potential to create less interference with diagnostic imaging compared to titanium (Ti) implants.  However, an objective comparison of the image artifact produced by titanium and CFRP implants has not been described. Spinal oncology, particularly after resection of spinal tumors and at the time of spinal stereotactic radiosurgery (SSRS) planning, relies heavily on imaging interpretation for evaluating resection, adjuvant treatment planning, and surveillance. We present a study comparing measurements of post-operative MRI artifacts between titanium and CFRP pedicle screw constructs in the setting of separation surgery for metastatic disease. The diameter of the signal drop around the screws (Pedicle Screw Artifact, PSA) and the diameter of the spinal canal free from artifacts (Canal Visualization, CV) were measured in consecutive patients who had spinal instrumentation followed by SSRS in the June 2019 - May 2022 timeframe. The spinal cord presented a shift at the screw level in sagittal images which was also measured (Sagittal Distortion, SagD). Fifty patients, corresponding to 356 screws and 183 vertebral levels, were evaluated overall. CFRP produced less artifacts in all the three parameters when compared to titanium: mean PSA (CFRP=5.8mm, Ti=13.2mm), CV (CFRP=19.2mm, Ti=15.5mm), and SagD (CFRP=0.5mm, Ti=1.9mm), all p<0.001. In practice, these findings translate into better-quality MRI. The initial perceived advantages are easier evaluation of post-operative imaging, facilitating radiation treatment planning, recurrence detection, and avoidance in repeating a suboptimal computed tomography myelogram. Further clinical studies analyzing long-term outcomes of patients treated with CFRP implants are necessary.