Intraoperative Magnetic Resonance Imaging Assisted Endoscopic Endonasal Resection of Clival Chordomas

BackgroundCranial base chordomas are typically indolent and usually appear as encapsulated tumors. They slowly grow by infiltrating the bone, along with the lines of least resistance. Due to its relationship with important neurovascular structures, skull base chordoma surgery is challenging.ObjectiveThe usefulness of intraoperative magnetic resonance imaging (IO-MRI) in achieving the goal of surgery, is evaluated in this study.MethodsBetween March 2018 and March 2020, 42 patients were operated on for resection of skull base chordomas in our institution. All of them were operated on under IO-MRI. Patients were analyzed retrospectively for identifying common residue locations, complications and early post-operative outcomes.ResultsIn 22 patients (52,4%) gross total resection was achieved according to the final IO-MRI. In 20 patients (47,6%) complete tumor removal was not possible because of extension to the petrous bone (8 patients), pontocerebellar angle (6 patients), prepontine cistern (4 patients), temporobasal (1 patient), cervical axis (1 patient). In 13 patients, the surgery was continued after the first IO-MRI control was performed, which showed a resectable residual tumor. 7 of these patients achieved total resection according to the second IO-MRI, in the other 6 patients all efforts were made to ensure maximal resection of the tumor as much as possible without morbidity. Repeated IO-MRI helped achieve gross total resection in 7 patients (53.8%).ConclusionsOur study proves that the use of IO-MRI is a safe method that provides the opportunity to show the degree of resection in skull base chordomas and to evaluate the volume and location of the residual tumor intraoperatively. Hence IO-MRI can improve the life expectancy of patients because it provides an opportunity for both gross total resection and maximal safe resection in cases where total resection is not possible.

Integration of Microanatomy, Neuronavigation, Dynamic Neurophysiologic Monitoring, and Intraoperative Multimodality Imaging for the Safe Removal of an Insular Glioma: 2-Dimensional Operative Video

Insular gliomas are located amongst myriad critical neurovascular structures, including lenticulostriate vessels, long insular perforators, putamen, internal capsule, frontal and temporal opercula, and key fasciculi.1-6 Each of these critical structures engenders key function of the brain, which must be preserved. Although anatomic knowledge remains the cornerstone of insular glioma surgery, novel tools have been developed to aid the surgeon in identifying and preserving these essential structures. Modern surgery of the insular glioma calls for seamless integration of these techniques to maximize the safety and totality of insular glioma resection, which has been shown to improve length of survival and seizure control, while reducing risk of tumor transformation.7-10 Neuronavigation can be used to help plan the craniotomy to achieve adequate exposure and assist during tumor resection. Brain “shift” can be corrected by re-registration following intraoperative magnetic resonance imaging (MRI). Interval ultrasound imaging reflects real-time progressive tumor resection. Dynamic neurophysiologic monitoring using thresholding techniques guides the surgeon as he resects tumor at its depth and posterior pole—close to the internal capsule. Intraoperative magnetic resonance imaging depicts residual infiltrative tumor that may require additional resection. The patient is a 33-yr-old woman with progressive growth of a right insular tumor and has consented to surgery, photography, and video recording. Figure at 1:57, © Ossama Al-Mefty, used with permission.

Utility of intraoperative magnetic resonance imaging for giant cell tumor of bone after denosumab treatment: a pilot study

Background Giant cell tumor of bone (GCTB) is an intermediate but locally aggressive neoplasm. Current treatment of high-risk GCTB involves administration of denosumab, which inhibits bone destruction and promotes osteosclerosis. However, denosumab monotherapy is not a curative treatment for GCTB and surgical treatment remains required. Denosumab treatment complicates surgery, and the recurrence rate of GCTB is high (20%–30%). Purpose To examine the utility of intraoperative magnetic resonance imaging (iMRI) for detection and reduction of residual tumor after denosumab treatment and to investigate the utility of iMRI, which is not yet widely used. Material and Methods We enrolled five patients who received denosumab for a median period of eight months (range 6–12 months). Surgery was performed when the degree of osteosclerosis around the articular surface was deemed appropriate. We performed iMRI using a modified operation table to identify residual tumor after initial curettage and evaluated the rate of detection of residual tumor by iMRI, intraoperative and postoperative complications, exposure time of iMRI, and operation time. Results Suspected residual tumor tissue was identified in all five cases and was confirmed by histopathology after additional curettage. The rate of detection of residual tumor by iMRI was 100%. Residual tumor was located in sites which were difficult to remove due to osteosclerosis. The iMRI was performed safely and without trouble. During the median follow-up period of 10 months (range 6–24 months), no adverse events or recurrences occurred. Conclusion Intraoperative MRI could contribute to the reduction of residual tumor tissue and it may prevent recurrence of GCTB after denosumab therapy.

Asleep Deep Brain Stimulator Placement in the Intraoperative Magnetic Resonance Imaging System Hybrid Operating Suite: 2-Dimensional Operative Video

Asleep, image-guided deep brain stimulation (DBS) placement is rapidly gaining popularity because it offers greater patient comfort and comparable accuracy with frame-based methods using microelectrode recording.1 In this video, we demonstrate our protocol to use the frameless, stereotactic ClearPoint system (MRI Interventions Inc, Irvine, California) to place DBS electrodes within an intraoperative magnetic resonance imaging hybrid operating suite (IMRIS; Deerfield Imaging Inc, Minnetonka, Minnesota).1-4 This system uses a skull-mounted aiming device coupled with sequential, intraoperative magnetic resonance imaging guidance to direct DBS lead placement to subcortical targets.2,5 Importantly, this method allows the patient to remain asleep during the operation and does not require medication holidays or additional microelectrode recording equipment. The literature indicates it has comparable accuracy1,6 and outcomes2 with the awake method. We demonstrate this technique with the case of a patient with Parkinson disease who required lead placement in the bilateral subthalamic nuclei.7-9 The patient consented to the procedure and publication. Patient positioning, draping nuances, initial indirect targeting, and final direct targeting are demonstrated. Risks of the operation include a risk of hemorrhage, hardware failure, and infection.10 DBS is currently an underutilized treatment option for patients with Parkinson disease.11 Offering the asleep option may be more tolerable for many patients who are wary of awake surgery.