Clinical evaluation of resection of functional area gliomas guided by intraoperative 3.0 T MRI combined with functional MRI navigation.

BACKGROUND: In assessing the clinical utility and safety of 3.0 T intraoperative magnetic resonance imaging (iMRI) combined with multimodality functional MRI (fMRI) guidance in the resection of functional area gliomas, we conducted a study. METHOD: Among 120 patients with newly diagnosed functional area gliomas who underwent surgical treatment, 60 were included in each group: the integrated group with iMRI and fMRI and the conventional navigation group. Between-group comparisons were made for the extent of resection (EOR), preoperative and postoperative activities of daily living based on the Karnofsky performance status, surgery duration, and postoperative intracranial infection rate. RESULTS: Compared to the conventional navigation group, the integrated navigation group with iMRI and fMRI exhibited significant improvements in tumor resection (complete resection rate: 85.0% vs. 60.0%, P = 0.006) and postoperative life self-care ability scores (Karnofsky score) (median ± interquartile range: 90 ± 25 vs. 80 ± 30, P = 0.013). Additionally, although the integrated navigation group with iMRI and fMRI required significantly longer surgeries than the conventional navigation group (mean ± standard deviation: 411.42 ± 126.4 min vs. 295.97 ± 96.48 min, P<0.0001), there was no significant between-group difference in the overall incidence of postoperative intracranial infection (16.7% vs. 18.3%, P = 0.624). CONCLUSION: The combination of 3.0 T iMRI with multimodal fMRI guidance enables effective tumor resection with minimal neurological damage.

Intraoperative magnetic resonance imaging in glioma surgery: a single-center experience.

PURPOSE: To investigate the effect of intraoperative magnetic resonance imaging (Io MRI) on overall and progression-free survival (OS and PFS), on the extent of resection (EOR) in patients with glioma, and impact of the radiological diagnosis on the decision to continue the surgery when a residual mass was detected on Io MRI. METHODS: The study comprised 153 glioma patients who received surgical treatment between 2013 and 2023. One-hundred twenty-five of them had Io MRI guidance during surgery. The remainder 28 patients constituted the control group who did not undergo Io MRI. All patients' age at surgery, gender, initial radiological diagnosis, primary tumor localization, EOR, last histopathological diagnosis, and the follow-up periods were recorded. RESULTS: The rate of tumor recurrence in Io MRI cases was significantly lower compared to the cases in the control group (p < .0001). It was decided to continue the operation in 45 Io MRI applied cases. This raised the gross total resection (GTR) rate from 33.6% to 49.6% in the Io MRI group. The frequency of GTR was significantly higher in patients with an initial radiological diagnosis of low grade glioma than those with high grade glioma. The shortest OS was seen in occipital gliomas. CONCLUSION: In this study, the convenience provided by the high-field MRI device was explored and proven both in reducing the tumor burden, increasing the PFS, and providing the surgeon with a maximal resection in the first operation.

Appearance of intracranial cottonoids on intraoperative magnetic resonance imaging.

To our knowledge, this is a unique report of intraoperative magnetic resonance imaging (iMRI) of an intracranial cottonoid. The current literature describes images of cottonoids as a post-operative finding in the setting of an unintentionally retained foreign body; however, the iMRI images we present are important as the use of iMRI in the resection of complex tumors and epilepsy foci increases. This series of images was obtained during a craniotomy for tumor resection of a patient with dysembryoplastic neuroepithelial tumor. To determine both the degree of tumor resection and the amount of residual tumor, cottonoids were left in our patient's resection cavity and underwent iMRI. The ability to distinguish cottonoids in these images is important for intraoperative localization of resection margins and to prevent the retention of cottonoids.

Transoperative Magnetic Resonance Imaging in Awake Glioma Surgery: Experience in a Latin American Tertiary-Level Center.

OBJECTIVE: Analyze the usefulness, efficacy, and safety of transoperative magnetic resonance imaging (tMRI) in glioma surgery in awake patients. METHODS: Retrospective, single-center, analytical study of a cohort of patients who underwent awake surgery for gliomas by the same surgeon in a third-level Argentine center, in the period between 2012 and 2022. Only patients with pathology-confirmed gliomas, with 6-month follow-up, who had preoperative and postoperative volumetric magnetic resonance imaging, were included in this sample. Subsequently, we analyzed which patients received surgery with the tMRI protocol and the results using multivariate regression analysis. RESULTS: A total of 71 patients were included. A tMRI study was performed on 22 (31%) of these patients. The use of tMRI increased the percentage of resection by 20% (P = 0.03), thereby increasing the possibility of gross total resection. However, using tMRI significantly extended surgical time by 84 minutes (P < 0.001). In 55% of the patients in whom tMRI was performed, the resection was continued after it. The use of tMRI did not increase the rate of infections or the development of surgically associated neurological deficits in the long term, despite the fact that 47% of the patients showed the development of a new deficit or worsening of a previous one during the intraoperative period. CONCLUSIONS: The use of tMRI in awake glioma surgery proved to be a safe tool that contributes to increasing the degree of tumor resection, compared to the use of neurophysiological mapping and neuronavigation, at the expense of increased surgical times and costs. We consider tMRI in awake glioma surgery should be used in properly selected cases.

Effect of high-field iMRI guided resection in cerebral glioma surgery: A randomized clinical trial.

BACKGROUND: Extent of resection (EOR) in glioma contributes to longer survival. The purpose of NCT01479686 was to prove whether intraoperative magnetic resonance imaging (iMRI) increases EOR in glioma surgery and benefit survival. METHODS: Patients were randomized (1:1) to receive the iMRI (n = 161) or the conventional neuronavigation (n = 160). The primary endpoint was gross total resection (GTR); secondary outcomes reported were progression-free survival (PFS), overall survival (OS), and safety. RESULTS: 188 high-grade gliomas (HGGs) and 133 low-grade gliomas (LGGs) were enrolled. GTR was 83.85% in the iMRI group vs. 50.00% in the control group (P < 0.0001). In 321 patients, the median PFS (mPFS) was 65.12 months in the iMRI group and 61.01 months in the control group (P = 0.0202). For HGGs, mPFS was improved in the iMRI group (19.32 vs. 13.34 months, P = 0.0015), and a trend of superior OS compared with control was observed (29.73 vs. 25.33 months, P = 0.1233). In the predefined eloquent area HGG subgroup, mPFS, and mOS were 20.47 months and 33.58 months in the iMRI vs. 12.21 months and 21.16 months in the control group (P = 0.0098; P = 0.0375, respectively). From the exploratory analyses of HGGs, residual tumor volume (TV) < 1.0 cm3 decreased the risk of survival (mPFS: 18.99 vs. 9.43 months, P = 0.0055; mOS: 29.77 vs. 18.10 months, P = 0.0042). LGGs with preoperative (pre-OP) TV > 43.1 cm3 and postoperative (post-OP) TV > 4.6 cm3 showed worse OS (P= 0.0117) CONCLUSIONS: It showed that iMRI significantly increased EOR and indicated survival benefits for HGGs, particularly eloquent HGGs. Residual TV in either HGGs or LGGs is a prognostic factor for survival.

Magnetic Resonance Imaging-Aided SmartFlow Convection Delivery of DNX-2401: A Pilot, Prospective Case Series.

BACKGROUND: The Combination Adenovirus + Pembrolizumab to Trigger Immune Virus Effects (CAPTIVE) study is a phase II clinical trial testing the efficacy of a recombinant adenovirus DNX-2401 combined with the immune checkpoint inhibitor pembrolizumab. Here, we report the first patients in this study who underwent viral delivery through real-time magnetic resonance imaging (MRI) stereotaxis-guided SmartFlow convection delivery of DNX-2401. METHODS: Patients who underwent real-time MRI-guided DNX-2401 delivery through the SmartFlow convection catheter were prospectively followed. RESULTS: Precise catheter placement was achieved in all patients treated, and no adverse events were noted. Average radial error from target was 0.9 mm. Average procedural time was 3 hours 16 minutes and was comparable to other convection-enhanced delivery techniques. In 2 patients, delivery of DNX-2401 was visualized as >1 cm maximal diameter of T1 hypointensity infusate on MRI obtained immediately after completion of viral infusion. These patients exhibited partial response based on Response Assessment in Neuro-Oncology assessment. The remaining patient showed <1 cm maximal diameter of infusate on immediate postinfusion MRI and showed disease progression on subsequent MRI. CONCLUSIONS: Our pilot case series supports compatibility of the SmartFlow system with oncolytic adenovirus delivery and provides the basis for future validation studies.

Critical Assessment of Cancer Characterization and Margin Evaluation Techniques in Brain Malignancies: From Fast Biopsy to Intraoperative Flow Cytometry.

Brain malignancies, given their intricate nature and location, present significant challenges in both diagnosis and treatment. This review critically assesses a range of diagnostic and surgical techniques that have emerged as transformative tools in brain malignancy management. Fast biopsy techniques, prioritizing rapid and minimally invasive tissue sampling, have revolutionized initial diagnostic stages. Intraoperative flow cytometry (iFC) offers real-time cellular analysis during surgeries, ensuring optimal tumor resection. The advent of intraoperative MRI (iMRI) has seamlessly integrated imaging into surgical procedures, providing dynamic feedback and preserving critical brain structures. Additionally, 5-aminolevulinic acid (5-ALA) has enhanced surgical precision by inducing fluorescence in tumor cells, aiding in their complete resection. Several other techniques have been developed in recent years, including intraoperative mass spectrometry methodologies. While each technique boasts unique strengths, they also present potential limitations. As technology and research continue to evolve, these methods are set to undergo further refinement. Collaborative global efforts will be pivotal in driving these advancements, promising a future of improved patient outcomes in brain malignancy management.

Acute cerebral hemorrhage mimicking glioblastoma on intraoperative magnetic resonance imaging: A case report.

Intraoperative magnetic resonance imaging (iMRI) is important in neurosurgical practice, especially for glioma surgery. However, the well-reported possibility to mistake lesions for brain tumors (tumor mimics) with MRI also exists for iMRI. Here, we first report a case of glioblastoma with acute cerebral hemorrhage that mimicked a newly emerged brain tumor on iMRI. A 53-year-old man underwent a second surgery for recurrent glioblastoma. Intraoperatively, iMRI revealed a new, enhanced lesion near the resected area that was absent on preoperative MRI and difficult to differentiate from newly emerged tumors. Here, a recent preoperative MRI was helpful and the new lesion was actually a hematoma. Neurosurgeons must understand that, as acute intracerebral hemorrhaging can mimic brain tumors on iMRI, preoperative MRI should be conducted just before surgery to place iMRI findings in proper context and avoid unnecessary resections.

Evaluating the use of intraoperative magnetic resonance imaging in paediatric brain tumour resection surgeries: a literature review.

Brain tumours are the most common solid neoplasm in children, posing a significant challenge in oncology due to the limited range of treatment. Intraoperative magnetic resonance imaging (iMRI) has recently emerged to aid surgical intervention in neurosurgery resection with the potential to delineate tumour boundaries. This narrative literature review aimed to provide an updated evaluation of the clinical implementation of iMRI in paediatric neurosurgical resection, with an emphasis on the extent of brain tumour resection, patient outcomes and its drawbacks. Databases including MEDLINE, PubMed, Scopus and Web of Science were used to investigate this topic with key terms: paediatric, brain tumour, and iMRI. Exclusion criteria included literature comprised of adult populations and the use of iMRI in neurosurgery in the absence of brain tumours. The limited body of research evaluating the clinical implementation of iMRI in paediatric cohorts has been predominantly positive. Current evidence demonstrates the potential for iMRI use to increase rates of gross total resection (GTR), assess the extent of resection, and improve patient outcomes, such as progression-free survival. Limitations regarding the use of iMRI include prolonged operation times and complications associated with head immobilisation devices. iMRI has the potential to aid in the achievement of maximal brain tumour resection in paediatric patients. Future prospective randomised controlled trials are necessary to determine the clinical significance and benefits of using iMRI during neurosurgical resection for clinical management of brain neoplasms in children.

Intraoperative use of ultra-low-field, portable magnetic resonance imaging - first report.

Background: Intraoperative use of portable magnetic resonance imaging (pMRI) has become a valuable tool in a surgeon's arsenal since its inception. It allows intraoperative localization of tumor extent and identification of residual disease, hence maximizing tumor resection. Its utility has been widespread in high-income countries for the past 20 years, but in lower-middle-income countries (LMIC), it is still not widely available due to several reasons, including cost constraints. The use of intraoperative pMRI may be a cost-effective and efficient substitute for conventional MRI machines. The authors present a case where a pMRI device was used intraoperatively in an LMIC setting. Case Description: The authors performed a microscopic transsphenoidal resection of a sellar lesion with intraoperative imaging using the pMRI system on a 45-year-old man with a nonfunctioning pituitary macroadenoma. Without the need for an MRI suite or other MRI-compatible equipment, the scan was conducted within the confinements of a standard operating room. Low-field MRI showed some residual disease and postsurgical changes, comparable to postoperative high-field MRI. Conclusion: To the best of our knowledge, our report provides the first documented successful intraoperative transsphenoidal resection of a pituitary adenoma using an ultra-low-field pMRI device. The device can potentially enhance neurosurgical capacity in resource-constrained settings and improve patient outcomes in developing country.

Role of 1p/19q Codeletion in Diffuse Low-grade Glioma Tumour Prognosis.

BACKGROUND/AIM: In the latest 2021 WHO classification of central nervous system tumours (CNS), gliomas that present isocitrate dehydrogenase (IDH) mutations are defined as diffuse low-grade gliomas (DLGGs). IDH mutations are commonly observed in this tumour type. The Extent of Resection (EOR) positively influence survival; however, it is still debated whether the predictive value of EOR is independent of the 1p/19q co-deletion. We carried out a retrospective analysis on patients operated on for DLGG at the Sant'Andrea University Hospital Sapienza University of Rome, correlating the outcome with the presence of 1p/19q co-deletion and EOR. PATIENTS AND METHODS: The study examined 66 patients with DLGG who had undergone surgery for tumour resection between 2008 and 2018. Patients with DLGG were divided into two groups; diffuse astrocytoma (DA) in which 1p/19q codeletion is absent and oligodendroglioma (OG) in which 1p/19q codeletion is present. According to EOR, both groups were divided into two subgroups: subtotal resection (STR) and gross total resection (GTR). Three end-point variables were considered: overall survival (OS), progression-free survival (PFS) and time to malignant transformation (TMT). RESULTS: In the DA group, the GTR subgroup had an average OS of 81.6 months, an average PFS of 45.9 months and an average TMT of 63.6 months. After surgery, these patients had an average Karnofsky Performance Score (KPS) of 83.4. The STR subgroup had an average OS of 60.4 months, PFS was 38.7 months, and TMT was 46.4 months, post-operative KPS was 83.4. In contrast, in the OG group, the GTR averagely had 101.7 months of OS, 64.9 months of PFS, 80.3 months of TMT and an average post-operative KPS of 84.2, and the STR subgroup had an average of OS of 73.3 months, PFS of 48.2 months, TMT of 57.3 and an average postoperative KPS of 96.2. CONCLUSION: In patients affected by DLGGs, 1p/19q codeletion is significantly associated with prolonged survival and longer time-to-malignant transformation (TMT) compared to the absence of 1p/19q codeletion. Also, the extent of surgical resection (EOR) in DLGG patients has been confirmed as one of the main prognostic factors. However, its predictive value is substantially influenced by the presence of the 1p/19q codeletion.

Surgical Treatment of Glioblastoma: State-of-the-Art and Future Trends.

Glioblastoma (GBM) is a highly aggressive disease and is associated with poor prognosis despite treatment advances in recent years. Surgical resection of tumor remains the main therapeutic option when approaching these patients, especially when combined with adjuvant radiochemotherapy. In the present study, we conducted a comprehensive literature review on the state-of-the-art and future trends of the surgical treatment of GBM, emphasizing topics that have been the object of recent study.

Impact of Intraoperative Magnetic Resonance Imaging on Short-Term and Long-Term Outcomes After Transsphenoidal Resection of Pituitary Adenoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Intraoperative magnetic resonance imaging (iMRI) allows for greater tumor visualization and extent of resection. It is increasingly used in transsphenoidal surgeries but its role is not yet established. OBJECTIVE: We aimed to clarify the usefulness of iMRI in transsphenoidal surgery using direct statistical comparisons, with additional subgroup and regression analyses to investigate which patients benefit the most from iMRI use. METHODS: Systematic searches of PubMed, Embase, and Cochrane Central were undertaken from database inception to May 2020 for published studies reporting the outcomes of iMRI use in transsphenoidal resection of pituitary adenoma. RESULTS: Thirty-three studies reporting 2106 transsphenoidal surgeries in 2099 patients were included. Of these surgeries, 1487 (70.6%) were for nonfunctioning pituitary adenomas, whereas 619 (29.4%) were for functioning adenomas. Pooled gross total resection (GTR) was 47.6% without iMRI and 66.8% with iMRI (risk ratio [RR], 1.32; P < 0.001). Subgroup and meta-regression analyses demonstrated comparable increases in GTR between microscopic (RR, 1.35; P < 0.001) and endoscopic (RR, 1.31; P < 0.001) approaches as well as functioning and nonfunctioning adenomas (P = 0.584). The pooled rate of hypersecretion normalization was 73.0% within 3 months and 51.7% beyond 3 months postoperatively. The pooled rate of short-term and long-term improvement in visual symptoms was 96.5% and 84.9%, respectively. The incidence of postoperative surgical complications was low. The pooled reoperation rate was 3.8% across 1106 patients. CONCLUSIONS: The use of iMRI as an adjunct significantly increases GTR for both microscopic and endoscopic resection of pituitary adenomas, with comparable benefits for both functioning and nonfunctioning adenomas. Satisfactory endocrinologic and visual outcomes were achieved.

Single-stage resection of bottom-of-a-sulcus dysplasia involving eloquent cortex using navigated transcranial magnetic stimulation and intraoperative modalities.

BACKGROUND: Focal cortical dysplasia (FCD) is a common etiology of refractory epilepsy, particularly in children. Surgical management is potentially curative, but poses the challenge of distinguishing the border between ictogenic regions of dysplasia and functionally critical brain tissue. Bottom-of-a-sulcus dysplasia (BOSD) amplifies this challenge, due to difficulties in physiologic mapping of the deep tissue. METHODS: We report a one-stage resection of a dysplasia-associated seizure focus abutting and involving the hand and face primary motor cortex. In doing so, we describe our surgical planning integrating neuronavigated transcranial magnetic stimulation (nTMS) for functional motor mapping, combined with intraoperative ultrasonography, intracranial electroencephalography, and magnetic resonance imaging (MRI). A 5-year-old girl with intractable focal epilepsy was referred to our comprehensive epilepsy program. Despite attentive pharmacotherapy, she experienced status epilepticus and up to 70 seizures per day, accompanied by multiple side effects from her antiseizure medication. A right frontal BOSD in close proximity to the hand motor area of the precentral gyrus was identified on MRI. Postoperatively, she is seizure-free for over 1 year with no hand deficit. CONCLUSION: Although technically complex, single-stage resection taking advantage of comprehensive surgical planning with optimized fusion of functional mapping and intraoperative modalities merits consideration given the invasiveness of a two-stage approach for limited added value. Integrated pre-surgical nTMS allowed for mapping of eloquent cortex without invasive electrocortical stimulation.

Initial Clinical Experience With ClearPoint SmartFrame Array-Aided Stereotactic Procedures.

BACKGROUND: The ClearPoint SmartFrame Array (ClearPoint Neuro, Inc., Solana Beach, CA) system consists of a magnetic resonance imaging compatible frame supported by a customized neuro navigation software. This system received U.S. Food and Drug Administrationclearance for clinical use in January 2021. Our objective was to report initial safety data and user experience of SmartFrame Array-supported stereotactic procedures. METHODS: We prospectively followed the first 10 consecutive patients who underwent stereotactic procedures supported by SmartFrame Array. Clinical and procedural data were recorded and compared to data obtained from prior cases with SmartFrame XG. RESULTS: Ten patients underwent stereotactic needle biopsy, stereotactic laser ablation (SLA), or combined biopsy/SLA procedures. For needle biopsies (n = 9), the average maximal diameter of the contrast-enhancing target lesion was 9.9 ± 2.8 mm. The radial error of stereotaxis was less than 2 mm. Definitive diagnosis was achieved in all cases. For procedures involving SLA (n = 5), 100% of the contrast-enhancing lesion was ablated. All patients were discharged home by postoperative day 2. There were no 30-day readmissions, morbidity, or mortality. The average stereotaxis time for the SmartFrame Array-aided single trajectory procedure was 80 ± 9.5 minutes, which compared favorably to that required for the earlier generation SmartFrame XG frame (111.5 ± 16.5 minutes; P < 0.01). The unique Array design supported stereotactic procedures that cannot be easily achieved with the previous SmartFrame XG frame. CONCLUSIONS: The SmartFrame Array system offers a more rigid and compact build to enhance procedural efficiency while maintaining accuracy and safety. The design supports multi-trajectory stereotaxis, allowing novel clinical applications.

Intraoperative MR Imaging during Glioma Resection.

One of the major issues in the surgical treatment of gliomas is the concern about maximizing the extent of resection while minimizing neurological impairment. Thus, surgical planning by carefully observing the relationship between the glioma infiltration area and eloquent area of the connecting fibers is crucial. Neurosurgeons usually detect an eloquent area by functional MRI and identify a connecting fiber by diffusion tensor imaging. However, during surgery, the accuracy of neuronavigation can be decreased due to brain shift, but the positional information may be updated by intraoperative MRI and the next steps can be planned accordingly. In addition, various intraoperative modalities may be used to guide surgery, including neurophysiological monitoring that provides real-time information (e.g., awake surgery, motor-evoked potentials, and sensory evoked potential); photodynamic diagnosis, which can identify high-grade glioma cells; and other imaging techniques that provide anatomical information during the surgery. In this review, we present the historical and current context of the intraoperative MRI and some related approaches for an audience active in the technical, clinical, and research areas of radiology, as well as mention important aspects regarding safety and types of devices.

The impact of 1.5-T intraoperative magnetic resonance imaging in pediatric tumor surgery: Safety, utility, and challenges.

Objective: In this study, we present our experience with 1.5-T high-field intraoperative magnetic resonance imaging (ioMRI) for different neuro-oncological procedures in a pediatric population, and we discuss the safety, utility, and challenges of this intraoperative imaging technology. Methods: A pediatric consecutive-case series of neuro-oncological surgeries performed between February 2020 and May 2022 was analyzed from a prospective ioMRI registry. Patients were divided into four groups according to the surgical procedure: intracranial tumors (group 1), intraspinal tumors (group 2), stereotactic biopsy for unresectable tumors (group 3), and catheter placement for cystic tumors (group 4). The goal of surgery, the volume of residual tumor, preoperative and discharge neurological status, and postoperative complications related to ioMRI were evaluated. Results: A total of 146 procedures with ioMRI were performed during this period. Of these, 62 were oncology surgeries: 45 in group 1, two in group 2, 10 in group 3, and five in group 4. The mean age of our patients was 8.91 years, with the youngest being 12 months. ioMRI identified residual tumors and prompted further resection in 14% of the cases. The mean time for intraoperative image processing was 54 ± 6 min. There were no intra- or postoperative security incidents related to the use of ioMRI. The reoperation rate in the early postoperative period was 0%. Conclusion: ioMRI in pediatric neuro-oncology surgery is a safe and reliable tool. Its routine use maximized the extent of tumor resection and did not result in increased neurological deficits or complications in our series. The main limitations included the need for strict safety protocols in a highly complex surgical environment as well as the inherent limitations on certain patient positions with available MR-compatible headrests.

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.

Intraoperative MRI in trans-sphenoidal surgery using frameless stereotaxis.

BACKGROUND: Intraoperative magnetic resonance imaging (iMRI) has been used for pituitary surgery for approximately 20 years. The introduction of frameless stereotaxis allows efficient navigation for both the ENT and neurosurgeon. This allows flexibility in placement of the patients head to facilitate resection, efficient use of theater time and improves the safety profile of the operation. This is the first study to describe and investigate the use of frameless stereotaxis in conjunction with iMRI. METHODS: Consecutive patients who underwent iMRI guided trans-sphenoidal debulking using frameless stereotaxis over a 3-year period, from January 2016 to June 2019, were included in this case series and reviewed retrospectively. The use of AxiEM (Medtronic, USA) tracker facilitated frameless stereotaxis in conjunction with iMRI for trans-sphenoidal debulking of sellar lesions based on the "twin-operating" model. RESULTS: The cohort of 47 patients had a mean age of 55 years with a slight female predilection. The average lesion size measured 20 mm (3-46 mm) in maximal diameter with objective evidence of visual deterioration being the most common indication to consider surgery. The use of iMRI identified two patients with suboptimal decompression facilitating further resection in the same anesthetic and one hemorrhagic complication requiring evacuation and hemostasis to reduce postoperative morbidity. CONCLUSION: This study describes the procedural nuances in the use of frameless stereotaxis for iMRI in transsphenoidal surgery to further reduce morbidity and improve outcomes, as well as improving theater utilization and reducing cost.

Impact of intraoperative magnetic resonance imaging on gross total resection, extent of resection, and residual tumor volume in pituitary surgery: systematic review and meta-analysis.

BACKGROUND: Residual tumor tissue after pituitary adenoma surgery, is linked with additional morbidity and mortality. Intraoperative magnetic resonance imaging (ioMRI) could improve resection. We aim to assess the improvement in gross total resection (GTR), extent of resection (EOR), and residual tumor volume (RV) achieved using ioMRI. METHODS: A systematic review was carried out on PubMed/MEDLINE to identify any studies reporting intra- and postoperative (1) GTR, (2) EOR, or (3) RV in patients who underwent resection of pituitary adenomas with ioMRI. Random effects meta-analysis of the rate of improvement after ioMRI for these three surgical outcomes was intended. RESULTS: Among 34 included studies (2130 patients), the proportion of patients with conversion to GTR (∆GTR) after ioMRI was 0.19 (95% CI 0.15-0.23). Mean ∆EOR was + 9.07% after ioMRI. Mean ∆RV was 0.784 cm3. For endoscopically treated patients, ∆GTR was 0.17 (95% CI 0.09-0.25), while microscopic ∆GTR was 0.19 (95% CI 0.15-0.23). Low-field ioMRI studies demonstrated a ∆GTR of 0.19 (95% CI 0.11-0.28), while high-field and ultra-high-field ioMRI demonstrated a ∆GTR of 0.19 (95% CI 0.15-0.24) and 0.20 (95% CI 0.13-0.28), respectively. CONCLUSIONS: Our meta-analysis demonstrates that around one fifth of patients undergoing pituitary adenoma resection convert from non-GTR to GTR after the use of ioMRI. EOR and RV can also be improved to a certain extent using ioMRI. Endoscopic versus microscopic technique or field strength does not appear to alter the impact of ioMRI. Statistical heterogeneity was high, indicating that the improvement in surgical results due to ioMRI varies considerably by center.