Use of MRI for postoperative RT planning in patients with CFR-PEEK instrumentation

Abstract

Carbon-fiber reinforced PEEK instrumentation is being utilized more frequently in the spinal oncology landscape. Better visualization with this material allows for more precise post-operative stereotactic body radiation therapy (SBRT) planning using either CT-myelography or MRI imaging studies. We compared the dosimetric planning equivalencies and outcomes. Thirty-six consecutively treated patients were reviewed who underwent spinal fusion using CFR-PEEK instrumentation for spine metastases followed by post-operative SBRT between 1/1/2022 and 4/3/2023. Patients were divided into two cohorts based on the imaging modality, MRI vs CT-myelogram, used for post-operative SBRT planning. Surgical, demographic, post-operative radiation dosimetry, complication, and survival data were collected. Statistical analysis was performed in SPSS (v29.0.1.0). Eleven patients underwent CT-myelograms, and twenty-five 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=0.402). MR scans are an effective choice for post-operative SBRT contouring patients utilizing CFR-PEEK instrumentation for oncologic spinal fusions. Avoidance of CT myelography reduces the need for an invasive procedure and potential risks including CSF leak, nerve root injury, and increased procedural burden.