Use of Magnetic Resonance Imaging for Postoperative Radiation Therapy Planning in Patients with Carbon Fiber-Reinforced Polyetheretherketone Instrumentation.

Purpose: Carbon fiber-reinforced polyetheretherketone (CFR-PEEK) instrumentation is being used more frequently in the spinal oncology landscape. Better visualization with this material allows for more precise postoperative stereotactic body radiation therapy (SBRT) planning using either computed tomography (CT)-myelography or magnetic resonance imaging (MRI) studies. We compared the dosimetric planning equivalencies and outcomes.

Methods and materials: Thirty-six consecutively treated patients were reviewed who underwent spinal fusion using CFR-PEEK instrumentation for spine metastases followed by postoperative SBRT between January 1, 2022, and April 3, 2023. Patients were divided into 2 cohorts based on the imaging modality, MRI versus CT-myelogram, used for postoperative SBRT planning. Surgical, demographic, postoperative radiation dosimetry, complication, and survival data were collected. Statistical analysis was performed in SPSS (v29.0.1.0).

Results: Eleven patients underwent CT-myelograms, and 25 patients underwent MR-spine imaging for SBRT planning. The median follow-up was 145.5 days (13-530). There were no significant differences between baseline demographic, surgical characteristics, or SBRT dosimetry between the MRI spine and CT-myelogram groups. There was no significant difference between the cohorts for survival (P = .402).

Conclusions: MR scans are an effective choice for postoperative SBRT contouring patients using CFR-PEEK instrumentation for oncologic spinal fusions. Avoidance of CT-myelography reduces the need for an invasive procedure and potential risks including cerebrospinal fluid (CSF) leak, nerve root injury, and increased procedural burden.