Intraoperative Magnetic Resonance Imaging Research Articles

V03-07 THE USE OF INTRAOPERATIVE MRI (IMRI) AT THE TIME OF CYSTOVAGINOSCOPY FOR PATIENT WITH CLOACAL ANOMALY

You have accessJournal of UrologyPediatrics (V03)1 Sep 2021V03-07 THE USE OF INTRAOPERATIVE MRI (IMRI) AT THE TIME OF CYSTOVAGINOSCOPY FOR PATIENT WITH CLOACAL ANOMALY Poone Shoureshi, Christopher Austin, and Casey Seideman Poone ShoureshiPoone Shoureshi More articles by this author , Christopher AustinChristopher Austin More articles by this author , and Casey SeidemanCasey Seideman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001991.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Patients born with cloacal anomalies pose a significant reconstructive challenge to pediatric urologists. Preoperative workup with endoscopy and imaging to assess the length of the confluence is vital to determining the proper surgical approach for treatment. MRI is increasingly being used to assess anorectal malformations as it provides a clear image without radiation exposure. We present a unique case of an exam under anesthesia with simultaneous multiparametric intraoperative MRI (iMRI) for preoperative assessment of cloacal anomaly. METHODS: Our patient is a 7-month-old female with cloacal anomaly, bilateral ectopic ureters, grade 5 vesicoureteral reflux bilaterally, caudal dysgenesis, left lower extremity abnormalities, and imperforate anus s/p colostomy. She was scheduled for cystoscopy, vaginoscopy and exam under anesthesia for preoperative evaluate. We elected to perform simultaneous, intraoperative pelvic and abdominal MRI to avoid multiple sedation procedures. RESULTS: Cystovaginoscopy demonstrated a normal appearing bladder, an incompetent bladder neck, bilateral ectopic ureters entering just distal to bladder neck, and two vaginal openings. Prior to performing the iMRI, a Foley catheter was placed in the right hemivagina, the bladder, and a pollack catheter in the left hemivagina. We instilled a total of 10cc gadolinium and performed the iMRI. The common channel measured 3.3 cm and the urethra 1.3 cm. CONCLUSIONS: The novel use of iMRI simultaneously with cystovaginoscopy can further enhance the preoperative workup in patients with complex anomalies such as cloacal malformation, and avoids multiple sedation procedures. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e224-e224 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Poone Shoureshi More articles by this author Christopher Austin More articles by this author Casey Seideman More articles by this author Expand All Advertisement Loading ...

Evaluation and outcomes of paediatric epilepsy surgery in Singapore: A single-centre audit

Background: Paediatric epilepsy surgery reduces seizure burden in drug-refractory epilepsy reducing long-term neurocognitive damage. Methods: Single-centre retrospective audit of pre-surgical evaluations and outcomes of the paediatric epilepsy and epilepsy surgery programme over eleven years at KK Women’s and Children’s Hospital, Singapore. Data were collected based on National Institute of Neurological Disorders and Stroke Common Data Elements guidelines. Outcome was categorized using Engel classification scale, and favourable outcome defined as greater than 50% decrease in seizure frequency or drop attacks. Results: Thirty-three children underwent epilepsy surgery, with mean follow-up 3.8±3.1 years. Median age at surgery was 10.9 years. Twenty-four children with focal epilepsy underwent resection of the epileptogenic focus, including lesionectomy (n=8), anterior temporal lobectomy (n=7), extratemporal lobectomy (n=7) and hemispherectomy (n=2). Nine children underwent corpus callosotomy for Lennox Gastaut Syndrome (n=8) and West Syndrome (n=1). Median hospital stay duration was ten days. All twenty-three focal epilepsy patients with minimum three-month follow-up achieved greater than 50% seizure reduction. Fifteen (65%) focal epilepsy patients achieved seizure-freedom (Engel Class IA) after first surgeries. Four patients required second surgeries, with two achieving seizure-freedom. Intraoperative MRI (iMRI) is beneficial. All nine corpus callosotomy patients (100%) achieved greater than 50% decrease in drop attacks. Number of antiepileptic drugs was weaned for 21/32 (66%) patients. Post-operative complications were low and some patients had anticipated neurological deficits. Outcomes were comparable to current literature. Conclusions: In well-selected candidates with tailored evaluation, paediatric epilepsy surgery is a safe therapeutic option with favourable outcomes and can be performed across the entire paediatric age range.

Intraoperative 3T MRI is more correlative to residual disease extent than early postoperative MRI.

Extent of resection of low grade glioma (LGG) is an important prognostic variable, and may influence decisions regarding adjuvant therapy in certain patient populations. Immediate postoperative magnetic resonance image (MRI) is the mainstay for assessing residual tumor. However, previous studies have suggested that early postoperative MRI fluid-attenuated inversion recovery (FLAIR) (within 48h) may overestimate residual tumor volume in LGG. Intraoperative magnetic resonance imaging (iMRI) without subsequent resection may more accurately assess residual tumor. Consistency in MRI techniques and utilization of higher magnet strengths may further improve both comparisons between MRI studies performed at different time points as well as the specificity of MRI findings to identify residual tumor. To evaluate the utility of 3T iMRI in the imaging of LGG, we volumetrically analyzed intraoperative, early, and late (~ 3months after surgery) postoperative MRIs after resection of LGG. A total of 32 patients with LGG were assessed retrospectively. Residual tumor was defined as hyperintense T2 signal on FLAIR. Volumetric assessment was performed with intraoperative, early, and late postoperative FLAIR via TeraRecon iNtuition. Perilesional FLAIR parenchymal abnormality volumes were significantly different comparing intraoperative and early postoperative MRI (2.17 ± 0.45 cm3 vs. 5.47 ± 1.07 cm3, respectively (p = 0.0002)). A significant difference of perilesional FLAIR parenchymal abnormality volumes was also found comparing early and late postoperative MRI (5.47 ± 1.07 cm3 vs. 3.22 ± 0.64 cm3, respectively (p = 0.0001)). There was no significant difference between intraoperative and late postoperative Perilesional FLAIR parenchymal abnormality volumes. Intraoperative 3T MRI without further resection appears to better reflect the volume of residual tumor in LGG compared with early postoperative 3T MRI. Early postoperative MRI may overestimate residual tumor. As such, intraoperative MRI performed after completion of tumor resection may be more useful for making decisions regarding adjuvant therapy.

Ultrasound guided brain abscess aspiration

A brain abscess is a neurosurgical emergency and frequently requires drainage to relieve intracranial pressure and identify the offending organism. Surgical adjuncts including neuronavigation and intra-operative CT and MRI facilitate surgery, but have limitations, including cost and not offering real time intracranial views. Intra-operative ultrasound is a fast and relatively cheap tool which offers live, real time imaging and visualisation of an abscess being aspirated, but is less frequently used. We describe our technique of ultrasound guidance as an adjunct with neuronavigation for brain abscess aspiration, review the literature on surgical adjuncts and remind the neurosurgical community of its value in this and other cranial procedures. We summarise our recent experience in its use in six patients with a brain abscess. There is a learning curve to using intra-operative ultrasound, but we recommend its routine use in abscess drainage surgery.

Failure of diffusion-weighted imaging in intraoperative 3\xa0Tesla MRI to identify hyperacute strokes during glioma surgery

Intraoperatively acquired diffusion-weighted imaging (DWI) sequences in cranial tumor surgery are used for early detection of ischemic brain injuries, which could result in impaired neurological outcome and their presence might thus influence the neurosurgeon’s decision on further resection. The phenomenon of false-negative DWI findings in intraoperative magnetic resonance imaging (ioMRI) has only been reported in single cases and therefore yet needs to be further analyzed. This retrospective single-center study’s objective was the identification and characterization of false-negative DWI findings in ioMRI with new or enlarged ischemic areas on postoperative MRI (poMRI). Out of 225 cranial tumor surgeries with intraoperative DWI sequences, 16 cases with no additional resection after ioMRI and available in-time poMRI (< 14 days) were identified. Of these, a total of 12 cases showed false-negative DWI in ioMRI (75%). The most frequent tumor types were oligodendrogliomas and glioblastomas (4 each). In 5/12 cases (41.7%), an ischemic area was already present in ioMRI, however, volumetrically increased in poMRI (mean infarct growth + 2.1 cm3; 0.48–3.6), whereas 7 cases (58.3%) harbored totally new infarcts on poMRI (mean infarct volume 0.77 cm3; 0.05–1.93). With this study we provide the most comprehensive series of false-negative DWI findings in ioMRI that were not followed by additional resection. Our study underlines the limitations of intraoperative DWI sequences for the detection and size-estimation of hyperacute infarction. The awareness of this phenomenon is crucial for any neurosurgeon utilizing ioMRI.

Simulation of surgery for supratentorial gliomas in virtual reality using a 3D volume rendering technique: a poor man's neuronavigation.

Different techniques of performing image-guided neurosurgery exist, namely, neuronavigation systems, intraoperative ultrasound, and intraoperative MRI, each with its limitations. Except for ultrasound, other methods are expensive. Three-dimensional virtual reconstruction and surgical simulation using 3D volume rendering (VR) is an economical and excellent technique for preoperative surgical planning and image-guided neurosurgery. In this article, the authors discuss several nuances of the 3D VR technique that have not yet been described. The authors included 6 patients with supratentorial gliomas who underwent surgery between January 2019 and March 2021. Preoperative clinical data, including patient demographics, preoperative planning details (done using the VR technique), and intraoperative details, including relevant photos and videos, were collected. RadiAnt software was used for generating virtual 3D images using the VR technique on a computer running Microsoft Windows. The 3D VR technique assists in glioma surgery with a preoperative simulation of the skin incision and craniotomy, virtual cortical surface marking and navigation for deep-seated gliomas, preoperative visualization of morbid cortical surface and venous anatomy in surfacing gliomas, identifying the intervenous surgical corridor in both surfacing and deep-seated gliomas, and pre- and postoperative virtual 3D images highlighting the exact spatial geometric residual tumor location and extent of resection for low-grade gliomas (LGGs). Image-guided neurosurgery with the 3D VR technique using RadiAnt software is an economical, easy-to-learn, and user-friendly method of simulating glioma surgery, especially in resource-constrained countries where expensive neuronavigation systems are not readily available. Apart from cortical sulci/gyri anatomy, FLAIR sequences are ideal for the 3D visualization of nonenhancing diffuse LGGs using the VR technique. In addition to cortical vessels (especially veins), contrast MRI sequences are perfect for the 3D visualization of contrast-enhancing high-grade gliomas.

Case of multifocal glioblastoma with four fusion transcripts of ALK, FGFR2, NTRK2, and NTRK3 genes stresses the need for tumor tissue multisampling for transcriptomic analysis

Glioblastoma multiforme (GBM) is the most malignant brain tumor with patient mortality rate close to 100%, 5-yr survival rate of ∼5%, and a median survival of 14 mo. GBMs have notorious histomorphologic and molecular heterogeneities thus giving hope for development of future personalized therapies. We describe here a case of a 48-yr-old male patient with three-nodular GBM. To address the question of intratumoral molecular heterogeneity, a comparative analysis of gene expression was performed by using multiple samples collected from different tumor sites with the aid of intraoperative magnetic resonance imaging (MRI). Sixteen GBM biosamples from parietal, temporal, and temporo-polar localizations were collected from primary, recurrent, and second recurrent tumors and were obtained and investigated by RNA sequencing. Our investigations revealed that biosamples derived from different tumor sites differ in their gene expression profiles with classical or mesenchymal signatures associated with clinically distinct molecular subtypes of GBM found within the same tumor. The results also showed significant differences in the expression of genes specific for targeted therapeutics. Our investigations have enabled the identification of four novel fusion transcripts—KIF5C-NTRK3, AC016907.2-ALK, CNTNAP3-NTRK2, and ZNF135-FGFR2—each present in only one sample. We found no differences between untreated and recurrent stages in the expression levels of genes involved in fusion transcripts, suggesting the lack of association between fusion transcript and treatment response. In contrast, longitudinal changes in the expression of VEGF and MGMT genes were concordant with the tumor response to bevacizumab and temozolomide. Our study underscores the importance of integrating a multisampling approach and RNA sequencing and demonstrates the predictive merit of an integrated approach for differentiating genomic aberrations associated with untreated or post-treatment recurrent GBMs.

Review of Clinical and Technological Consideration for MRI-Guided Robotic Prostate Brachytherapy

Low Dose Rate Brachytherapy (LDR-BT) is a technique for treating localized prostate cancer by implanting radioactive seeds. In conventional practice, the delivery of seeds is performed using transrectal ultrasonography (TRUS) imaging for implant guidance and checked using computed-tomography for post-implant dosimetry. In the case of TRUS, accuracy can be compromised due to sub-optimal imaging. Magnetic Resonance Imaging (MRI), however, is known to provide better soft-tissue contrast, therefore, increasing the ability to detect small lesions; for that reason, the integration of intraoperative MRI in BT workflows has been investigated over the last two decades. The fusion of preoperative MR-images during TRUS-brachytherapy is possible. However, the image registration process introduces a source of uncertainty. Manual, real-time intra-operative LDR-BT is challenging under MRI due to confined space and procedural workflows. This motivates the development of MRI-compatible robots for prostate BT, with potential advantages of improved source placement accuracy and final dosimetry. In this paper, the state-of-art of technological components in MRI compatible robots, especially for LDR-BT, has been presented. This systematic review helps us to position an ongoing Cooperative Brachytherapy project, developing a real-time MRI-guided robot for adaptive LDR-BT. The design approach includes integrating separate modules: imaging, dose planning, needles, and robot.

Surgically Induced Contrast Enhancements on Intraoperative and Early Postoperative MRI Following High-Grade Glioma Surgery: A Systematic Review

For the radiological assessment of resection of high-grade gliomas, a 72-h diagnostic window is recommended to limit surgically induced contrast enhancements. However, such enhancements may occur earlier than 72 h post-surgery. This systematic review aimed to assess the evidence on the timing of the postsurgical MRI. PubMed, Embase, Web of Science and Cochrane were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only original research articles describing surgically induced contrast enhancements on MRI after resection for high-grade gliomas were included and analysed. The frequency of different contrast enhancement patterns on intraoperative MRI (iMRI) and early postoperative MRI (epMRI) was recorded. The search resulted in 1443 studies after removing duplicates, and a total of 12 studies were chosen for final review. Surgically induced contrast enhancements were reported at all time points after surgery, including on iMRI, but their type and frequency vary. Thin linear contrast enhancements were commonly found to be surgically induced and were less frequently recorded on postoperative days 1 and 2. This suggests that the optimal time to scan may be at or before this time. However, the evidence is limited, and higher-quality studies using larger and consecutively sampled populations are needed.

Anesthesia for deep brain stimulation: an update.

Deep brain stimulation (DBS) is a rapidly expanding surgical modality for the treatment of patients with movement disorders. Its ability to be adjusted, titrated, and optimized over time has given it a significant advantage over traditional more invasive surgical procedures. Therefore, the success and popularity of this procedure have led to the discovery of new indications and therapeutic targets as well as advances in surgical techniques. The aim of this review is to highlight the important updates in DBS surgery and to exam the anesthesiologist's role in providing optimal clinical management. New therapeutic indications have a significant implication on perioperative anesthesia management. In addition, new technologies like frameless stereotaxy and intraoperative magnetic resonance imaging to guide electrode placement have altered the need for intraoperative neurophysiological monitoring and hence increased the use of general anesthesia. With an expanding number of patients undergoing DBS implantation, patients with preexisting DBS increasingly require anesthesia for unrelated surgery and the anesthesiologist must be aware of the considerations for perioperative management of these devices and potential complications. DBS will continue to grow and evolve requiring adaptation and modification to the anesthetic management of these patients.

Maximum resection and immunotherapy improve glioblastoma patient survival: a retrospective single-institution prognostic analysis

Glioblastoma (GBM) is a refractory disease with a poor prognosis and various methods, including maximum resection and immunotherapy, have been tested to improve outcomes. In this retrospective study we analyzed the prognostic factors of 277 newly diagnosed GBM patients over 11 years of consecutive cases at our institution to evaluate the effect of these methods on prognosis. Various data, including the extent of removal (EOR) and type of adjuvant therapy, were examined and prognostic relationships were analyzed. The median overall survival (OS) of the entire 277-case cohort, 200 non-biopsy cases, and 77 biopsy cases was 16.6 months, 19.7 months, and 9.7 months, respectively. Gross total removal (GTR; 100% of EOR) was achieved in 32.9% of the cases. Univariate analysis revealed younger age, right side, higher Karnofsky performance status, GTR, intraoperative magnetic resonance imaging (MRI) use for removal, proton therapy, combination immunotherapy, and discharge to home as good prognostic factors. Intraoperative MRI use and EOR were closely related. In the multivariate analysis, GTR, proton therapy, and a combination of immunotherapies, including autologous formalin-fixed tumor vaccine, were the significant prognostic factors. A multivariate analysis of 91 GTR cases showed that immunotherapy contributed to prognostic improvements. The median OS and 5-year OS % values were 36.9 months and 43.3% in GTR cases receiving immunotherapy. In conclusion, GTR, proton therapy, and immunotherapy were good prognostic factors in single-center GBM cases. Tumor vaccine therapy for GTR cases achieved a notably high median survival time and long-term survival ratio, indicating its usefulness in GTR cases.

Practical Anatomy of the Basal Ganglia

Anatomical knowledge of target structures is essential in stereotactic functional neurosurgery. Thus, we created a three-dimensional(3D)atlas comprising frozen sections and histologically stained slides prepared from cadaveric brains. Herein, we describe the anatomical information of stereotactic functional neurosurgery targets gained from our atlas. The subthalamic nucleus(STN)was found to be clearly enclosed by neural fibers with high neuronal density. Based on our 3D models, the mean penetration length of deep brain stimulation leading into the STN was 6.6 mm. The globus pallidus was found to be clearly divided into the grobus pallidus externus(GPe)and internus(GPi)by its neural fibers, and the optic tract was located below the GPi. Although the thalamic lateral nuclear group(ventrooralis, ventrontermedius, and ventrocaudalis)could not be identified from either macroscopic frozen sections or MR images, these structures were clearly discernible from each other based on cell architecture(cell size and cell density)when viewed under a microscope. In contrast, distinguishing ventral and dorsal nuclei in humans is difficult. In addition to the main targets of the basal ganglia, we also investigated the anatomy of other targets in detail(posterior subthalamic area, pedunclopontine nucleus, nucleus accumbens, and nucleus basalis of Meynert). Overall, this anatomical knowledge from the atlas helps functional neurosurgeons interpret intraoperative microelectrode recording and MRI more precisely, helping facilitate more accurate surgeries.

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.

Evolution of surgical attitudes to paediatric thalamic tumours: the alder hey experience.

Attitudes to surgery for paediatric thalamic tumours have evolved due to improved preoperative imaging modalities and the advent of intraoperative MRI (iMRI) as well as enhanced understanding of tumour biology. We review the developments in our local practice over the last three decades with particular attention to the impact of iMRI. We identified all paediatric patients from a prospectively maintained neuro-oncology database who received surgery for a thalamic tumour (n = 30). All children were treated in a single UK tertiary paediatric neurosurgery centre between January 1991 and June 2020. Twenty patients underwent surgical resection, the remainder (10) undergoing biopsy only. Pre-operative surgical intent (biopsy versus debulking, near-total resection, or complete resection) as well as the use of iMRI were prospectively recorded. Complications recorded in clinical documentation between postoperative days 0 and 30 were retrospectively graded using a modified version of the Clavien Dindo scale. The extent of resection with respect to the pre-determined surgical aim was also recorded. Data on patient survival and disease progression status were obtained retrospectively. In our series, there were 42 procedures (25 craniotomies, 17 biopsies) performed on 30 patients (17 male, with a median age of 8 at surgery). Of the 25 surgical resections performed, complete resection was achieved in 9 (36%), near-total resection in 10 (40%), and limited debulking in 6 (24%). The predetermined surgical aim was achieved or exceeded in 91.3% of cases. The proportion of craniotomies for which substantial resection was achieved, increased from 37.5 to 94.2% with use of iMRI (p = 0.014). Surgical morbidity was not associated with greater extent of surgical resection. High-grade histology is identified as the only independent significant factor influencing overall survival as calculated by Cox proportional hazards model (p = 0.006). We note a significant change in the rate and extent of attempted resection of paediatric thalamic tumours that has developed over the last 3 decades. Use of iMRI is associated with a significant increase in substantial tumour resection surgeries. This is not associated with any significant level of surgical morbidity. Improvements in pre- and intra-operative imaging alongside better understanding of tumour biology facilitate patient selection and a surgically more aggressive approach in selected cases whilst maintaining safety and avoiding operative morbidity.

Can Preoperative Mapping with Functional MRI Reduce Morbidity in Brain Tumor Resection? A Systematic Review and Meta-Analysis of 68 Observational Studies.

Background Preoperative functional MRI (fMRI) is one of several techniques developed to localize critical brain structures and brain tumors. However, the usefulness of fMRI for preoperative surgical planning and its potential effect on neurologic outcomes remain unclear. Purpose To assess the overall postoperative morbidity among patients with brain tumors by using preoperative fMRI versus surgery without this tool or with use of standard (nonfunctional) neuronavigation. Materials and Methods A systematic review and meta-analysis of studies across major databases from 1946 to June 20, 2020, were conducted. Inclusion criteria were original studies that (a) included patients with brain tumors, (b) performed preoperative neuroimaging workup with fMRI, (c) investigated the usefulness of a preoperative or intraoperative functional neuroimaging technique and used that technique to resect cerebral tumors, and (d) reported postoperative clinical measures. Pooled estimates for adverse event rate (ER) effect size (log ER, log odds ratio, or Hedges g) with 95% CIs were computed by using a random-effects model. Results Sixty-eight studies met eligibility criteria (3280 participants; 58.9% men [1555 of 2641]; mean age, 46 years ± 8 [standard deviation]). Functional deterioration after surgical procedure was less likely to occur when fMRI mapping was performed before the operation (odds ratio, 0.25; 95% CI: 0.12, 0.53; P < .001]), and postsurgical Karnofsky performance status scores were higher in patients who underwent fMRI mapping (Hedges g, 0.66; 95% CI: 0.21, 1.11; P = .004]). Craniotomies for tumor resection performed with preoperative fMRI were associated with a pooled adverse ER of 11% (95% CI: 8.4, 13.1), compared with a 21.0% ER (95% CI: 12.2, 33.5) in patients who did not undergo fMRI mapping. Conclusion From the currently available data, the benefit of preoperative functional MRI planning for the resection of brain tumors appears to reduce postsurgical morbidity, especially when used with other advanced imaging techniques, such as diffusion-tensor imaging, intraoperative MRI, or cortical stimulation. © RSNA, 2021 Online supplemental material is available for this article.

The Magnetic Resonance Imaging (MRI)-Directed Implantable Guide Tube Technique: Accuracy and Applications in Deep Brain Stimulation

The magnetic resonance imaging (MRI)-directed implantable guide tube technique allows for direct targeting of deep brain structures without microelectrode recording or intraoperative clinical assessment. This study describes a 10-year institutional experience of this technique including nuances that enable performance of surgery using readily available equipment. Eighty-seven patients underwent deep brain stimulation surgery using the guide tube technique for Parkinson disease (n= 59), essential tremor (n= 16), and dystonia (n= 12). Preoperative and intraoperative MRI was analyzed to measure lead accuracy, volume of pneumocephalus, and the ability to safely plan a trajectory for multiple electrode contacts. Mean target error was measured to be 0.7 mm (95% confidence interval [CI] 0.6-0.8 mm) in the anteroposterior plane, 0.6 mm (95% CI 0.5-0.7 mm) in the mediolateral plane, and 0.8 mm (95% CI 0.7-0.9 mm) in the superoinferior plane. Net deviation (Euclidean error) from the planned target was 1.3 mm (95% CI 1.2-1.4 mm). Mean intracranial air volume per lead was 0.2 mL (95% CI 0.1-0.4 mL). In total, 52 patients had no intracranial air on postoperative imaging. In all patients, a safe trajectory could be planned to target for multiple electrode contacts without violating critical neural structures, the lateral ventricle, sulci, or cerebral blood vessels. The MRI-directed implantable guide tube technique is a highly accurate, low-cost, reliable method for introducing deep brain electrodes. This technique reduces brain shift secondary to pneumocephalus and allows for whole trajectory planning of multiple electrode contacts.

Intraoperative magnetic resonance imaging for cerebral cavernous malformations: When is it maybe worth it?

ObjectiveIntraoperative magnetic resonance imaging (iMRI) can be useful for cerebral cavernous malformations (CCM) surgery. However, literature on this topic is scarce. We aim to investigate its clinical utility and propose criteria for the selection of patients who may benefit the most from iMRI. MethodsFrom 2017 to 2019, all patients with CCMs who required surgery assisted with iMRI were included in the study. Clinical and radiological features were analyzed. Outcome measures included the need for an immediate second-look resection and clinical course in early post-surgery -Timepoint 1- (Tp1) and at the 6-to-12-month follow-up -Timepoint2- (Tp2). ResultsOut of 19 patients with 20 CCMs, 89% had bleeding in the past, and in 75% the CCM affected an eloquent area. According to the iMRI results, an immediate second-look resection was needed in 16% of them. In one patient, a remnant was not seen on iMRI. The mRS worsened in the immediate post-surgical exam (median, 1; IQR, 1) with improvements on the 6-month visit (median, 1; IQR, 2), (p = 0.018). When comparing the outcome of patients with and without symptoms at baseline, the latter fared better at Tp2 (p = 0.005). ConclusionsiMRI is an intraoperative imaging tool that seems safe for CCM surgery and might reduce the risk of lesion remnants. In our series, it allowed additional revision for further resection in 16% of the patients. In our experience, iMRI may be especially useful for lesions in eloquent areas, those with a significant risk of brain shift and for large CCMs.

Challenges and Opportunities of Intraoperative 3D Ultrasound With Neuronavigation in Relation to Intraoperative MRI.

IntroductionNeuronavigation greatly improves the surgeons ability to approach, assess and operate on brain tumors, but tends to lose its accuracy as the surgery progresses and substantial brain shift and deformation occurs. Intraoperative MRI (iMRI) can partially address this problem but is resource intensive and workflow disruptive. Intraoperative ultrasound (iUS) provides real-time information that can be used to update neuronavigation and provide real-time information regarding the resection progress. We describe the intraoperative use of 3D iUS in relation to iMRI, and discuss the challenges and opportunities in its use in neurosurgical practice.MethodsWe performed a retrospective evaluation of patients who underwent image-guided brain tumor resection in which both 3D iUS and iMRI were used. The study was conducted between June 2020 and December 2020 when an extension of a commercially available navigation software was introduced in our practice enabling 3D iUS volumes to be reconstructed from tracked 2D iUS images. For each patient, three or more 3D iUS images were acquired during the procedure, and one iMRI was acquired towards the end. The iUS images included an extradural ultrasound sweep acquired before dural incision (iUS-1), a post-dural opening iUS (iUS-2), and a third iUS acquired immediately before the iMRI acquisition (iUS-3). iUS-1 and preoperative MRI were compared to evaluate the ability of iUS to visualize tumor boundaries and critical anatomic landmarks; iUS-3 and iMRI were compared to evaluate the ability of iUS for predicting residual tumor.ResultsTwenty-three patients were included in this study. Fifteen patients had tumors located in eloquent or near eloquent brain regions, the majority of patients had low grade gliomas (11), gross total resection was achieved in 12 patients, postoperative temporary deficits were observed in five patients. In twenty-two iUS was able to define tumor location, tumor margins, and was able to indicate relevant landmarks for orientation and guidance. In sixteen cases, white matter fiber tracts computed from preoperative dMRI were overlaid on the iUS images. In nineteen patients, the EOR (GTR or STR) was predicted by iUS and confirmed by iMRI. The remaining four patients where iUS was not able to evaluate the presence or absence of residual tumor were recurrent cases with a previous surgical cavity that hindered good contact between the US probe and the brainsurface.ConclusionThis recent experience at our institution illustrates the practical benefits, challenges, and opportunities of 3D iUS in relation to iMRI.

The Latest Glioma Surgical Support Devices and Intraoperative Applications of MRI

We previously proposed an information-guided surgery based on objective intraoperative information to achieve a high precision and maximum resection of gliomas. In 2000, an "intelligent operating room" was constructed and put into operation as a place to train new "eyes," "hands," and "brains" for surgeons. Based on the positive experience from this room, it was subsequently developed into the Smart Cyber Operating Theater (SCOT), and from October 2019, Hyper SCOT was introduced at Tokyo Women's Medical University Hospital. This report introduces the latest surgical support devices that we have implemented in glioma surgery with Hyper SCOT. As an intraoperative image information support device, intraoperative MRI can correct brain shift, visualize residual tumor, and aid in performing maximal tumor resection, thereby greatly contributing to surgical results. As an intraoperative histological information support device, intraoperative flow cytometry can evaluate the presence of tumor cells and malignancy based on the measurement of the amount of DNA in tumor cells, and also predict the prognosis intraoperatively. Photodynamic therapy has been shown to be effective in clinical trials as an intraoperative treatment support device, and it is covered by insurance. Therefore, it is expected to be established as a standard treatment method for primary glioblastoma patients.

Utility of the Polestar N30 low-field MRI system for resecting non-enhancing intra-axial brain lesions.

To determine the utility of an intraoperative magnetic resonance imaging (iMRI) system, the Polestar N30, for enhancing the resection control of non-enhancing intra-axial brain lesions. Seventy-three patients (60 males [83.3%], mean age 37 years) with intra-axial brain lesions underwent resection at Sheba Medical Centre using the Polestar between February 2012 and the end of August 2018. Demographic and imaging data were retrospectively analysed. Thirty-five patients had a non-enhancing lesion (48%). Complete resection was planned for 60/73 cases after preoperative imaging. Complete resection was achieved in 59/60 (98.3%) cases. After iMRI, additional resection was performed in 24/73 (32.8%) cases, and complete resection was performed in 17/60 (28.8%) cases in which a complete resection was intended. In 6/13 (46%) patients for whom incomplete resection was intended, further resection was performed. The extent of resection was extended mainly for non-enhancing lesions: 16/35 (46%) as opposed to only 8/38 (21%) for enhancing lesions. Further resection was not significantly associated with sex, age, intended resection, recurrence, or affected side. Univariate analysis revealed non-eloquent area, intended complete resection, and enhancing lesions to be predictive factors for complete resection, and non-enhancing lesions and scan time to be predictive factors for an extended resection. Non-enhancement was the only independent factor for extended resection. The Polestar N30 is useful for evaluating residual non-enhancing intra-axial brain lesions and achieving maximal resection.