Utilization of MRI-Based Synthetic CTs for Pedicle Screw Navigation in Children: A Feasibility Study

Résumé fourni par la source

Introduction Pedicle screw instrumentation using a fluoroscopy-assisted freehand technique (FAFT) or using navigation based on a preoperative traditional computed tomography (tCT) scan is a common practice. However, concerns remain regarding the long-term effects of repeated ionizing radiation exposure. In 2025, the first pediatric patients in the U.S. underwent navigated PSFs using MRI imaging converted to CT scan-like quality, known as synthetic CTs (sCT). The purpose of this study is to report on the clinical, radiographic, and complication outcomes of this cohort and compare radiation exposure between sCT, tCT, and FAFT modalities. Methods Twenty patients received PSFs using sCT imaging and MvIGS navigation. Fluoroscopy was used in sCT cases to confirm the location of T12 and for small adjustments in alignment after rod insertion. To compare radiation exposure, the sCT patients were compared to a matched cohort of 135 patients receiving PSFs using the FAFT, and 27 patients receiving PSFs using tCT imaging paired with Machine-vision image-guided surgical (MvIGS) navigation. Radiation exposure was measured in mGy. Pedicle morphologies were measured and classified according to Sarawahi et. al. Results Twelve sCT patients (63%) had an idiopathic diagnosis. Mean age at surgery was 13.6 ± 4 years. Across 335 pedicles instrumented, 13% were Type C or D in morphology. The mean radiation exposure to the 27 patients receiving a preoperative tCT scan combined with routine intraoperative fluoroscopy was 5.44 mGy. For the 20 sCT cases, the mean radiation exposure was 0.90 mGy, reflecting an 83.5% reduction in radiation (p=0.001). In comparison, 3 surgeons utilized FAFT during PSFs, producing a mean radiation exposure of 7 mGy. Thus, navigated sCT cases resulted in an 87.1% reduction in radiation exposure in comparison to FAFT cases (p<0.001). Within the sCT cohort, there were no IONM changes, CSF leaks, or postoperative neurologic deficits. Conclusions Navigated PSFs utilizing sCTs paired with MvIGS navigation allow for instrumentation of small pedicles with an 83.5% reduction in radiation compared to tCTs and an 87.1% reduction in radiation compared to FAFT cases. Level of Evidence III (Retrospective Cohort Study)