Implementation of a mobile 0.15-T intraoperative MR system in pediatric neuro-oncological surgery: feasibility and correlation with early postoperative high-field strength MRI

INTRODUCTION: We analyze our preliminary experience using the PoleStar N20 mobile intraoperative MR (iMR) system as an adjunct for pediatric brain tumor resection. METHODS: We analyzed 11 resections in nine children between 1 month and 17 years old. After resection, we acquired iMR scans to detect residual tumor and update neuronavigation. We compared final iMR interpretation by the neurosurgeon with early postoperative MR interpretation by a neuroradiologist. RESULTS: Patient positioning was straightforward, and image quality (T1 7-min 4-mm sequences) sufficient in all cases. In five cases, contrast enhancement suspect for residual tumor was noted on initial postresection iMR images. In one case, a slight discrepancy with postoperative imaging after 3 months was no longer visible after 1 year. No serious perioperative adverse events related to the PoleStar N20 were encountered, except for transient shoulder pain in two. CONCLUSIONS: Using the PoleStar N20 iMR system is technically feasible and safe for both supra- and infratentorial tumor resections in children of all ages. Their small head and shoulders favor positioning in the magnet bore and allow the field of view to cover more than the area of primary interest, e.g., the ventricles in an infratentorial case. Standard surgical equipment may be used without significant limitations. In this series, the use of iMR leads to an increased extent of tumor resection in 45 % of cases. Correlation between iMR and early postoperative MR is excellent, provided image quality is optimal and interpretation is carefully done by someone sufficiently familiar with the system

Patient-Specific Implants Compared With Stored Bone Grafts for Patients With Interval Cranioplasty

Interval cranioplasty after craniectomy carries the risk of infection and failure. There is no consensus regarding the choice of reconstruction technique. In addition to the replacement of the stored autogenous bone graft, the use of patient-specific implants (PSIs) has become popular. We conducted a retrospective study comparing 17 patients who underwent reconstruction with PSIs (titanium and polyether ether ketone) (follow-up, 43 months [range, 3-93]) with 16 control subjects who had their stored bone grafts reimplanted (follow-up, 32 months [range, 5-92]) based on success rate, complication rate, operative time, and duration of hospitalization. Complication rate and the rate of necessary reoperation were significantly lower, and the hospital stay was shorter in the PSI group. We did not find any significant differences concerning operative time. In our patient groups, interval reconstruction after craniectomy with a PSI was a safer procedure based on complication and success rates than reconstruction with stored autogenous bone grafts. In patients with interval cranioplasty who have a higher risk for complication or failure, the use of PSIs should be the treatment of choice