Deep-seated Brain Research Articles

Basal ganglia tuberculoma mimicking a brain tumor: Minimally invasive resection using tubular retractor system

ObjectiveTo report an uncommon case of a patient with an isolated deep-seated brain tuberculoma. MethodsCase illustration and discussion on the pathogenesis and current clinical and surgical management of this condition. ResultsGross total resection was achieved through a left frontal craniotomy and a trans-sulcal approach using a tubular retractor system for access. The patient presented with an isolated brain lesion without any primary foci in the lung parenchyma or any other organ. Antifimic treatment began as soon as the diagnosis was confirmed by PCR. ConclusionsTB continues to be a public health burden in developing countries and is still considered among the most lethal infectious diseases in the world. The main objective of minimally invasive surgery of deep-seated lesions is to reduce damage caused by prolonged brain retraction required to access these lesions. Tubular retractors could be advantageous for tumor resection in deep regions.

Brain Delivery of Curcumin Through Low-Intensity Ultrasound-Induced Blood-Brain Barrier Opening via Lipid-PLGA Nanobubbles.

BackgroundParkinson’s disease (PD) is a progressive neurodegenerative disorder. Owing to the presence of blood–brain barrier (BBB), conventional pharmaceutical agents are difficult to the diseased nuclei and exert their action to inhibit or delay the progress of PD. Recent literatures have demonstrated that curcumin shows the great potential to treat PD. However, its applications are still difficult in vivo due to its poor druggability and low bioavailability through the BBB.MethodsMelt-crystallization methods were used to improve the solubility of curcumin, and curcumin-loaded lipid-PLGA nanobubbles (Cur-NBs) were fabricated through encapsulating the curcumin into the cavity of lipid-PLGA nanobubbles. The bubble size, zeta potentials, ultrasound imaging capability and drug encapsulation efficiency of the Cur-NBs were characterized by a series of analytical methods. Low-intensity focused ultrasound (LIFU) combined with Cur-NB was used to open the BBB to facilitate curcumin delivery into the deep brain of PD mice, followed by behavioral evaluation for the treatment efficacy.ResultsThe solubility of curcumin was improved by melt-crystallization methods, with 2627-fold higher than pure curcumin. The resulting Cur-NBs have a nanoscale size about 400 nm and show excellent contrast imaging performance. Curcumin drugs encapsulated into Cur-NBs could be effectively released when Cur-NBs were irradiated by LIFU at the optimized acoustic pressure, achieving 30% cumulative release rate within 6 h. Importantly, Cur-NBs combined with LIFU can open the BBB and locally deliver the curcumin into the deep-seated brain nuclei, significantly enhancing efficacy of curcumin in the Parkinson C57BL/6J mice model in comparison with only Cur-NBs and LIFU groups.ConclusionIn this work, we greatly improved the solubility of curcumin and developed Cur-NBs for brain delivery of curcumin against PD through combining with LIFU-mediating BBB. Cur-NBs provide a platform for these potential drugs which are difficult to cross the BBB to treat PD disease or other central nervous system (CNS) diseases.

Precise Ultrasound Neuromodulation in a Deep Brain Region Using Nano Gas Vesicles as Actuators.

Ultrasound is a promising new modality for non‐invasive neuromodulation. Applied transcranially, it can be focused down to the millimeter or centimeter range. The ability to improve the treatment's spatial resolution to a targeted brain region could help to improve its effectiveness, depending upon the application. The present paper details a neurostimulation scheme using gas‐filled nanostructures, gas vesicles (GVs), as actuators for improving the efficacy and precision of ultrasound stimuli. Sonicated primary neurons display dose‐dependent, repeatable Ca2+ responses, closely synced to stimuli, and increased nuclear expression of the activation marker c‐Fos in the presence of GVs. GV‐mediated ultrasound triggered rapid and reversible Ca2+ responses in vivo and could selectively evoke neuronal activation in a deep‐seated brain region. Further investigation indicate that mechanosensitive ion channels are important mediators of this effect. GVs themselves and the treatment scheme are also found not to induce significant cytotoxicity, apoptosis, or membrane poration in treated cells. Altogether, this study demonstrates a simple and effective method to achieve enhanced and better‐targeted neurostimulation with non‐invasive low‐intensity ultrasound.

Mobile intraoperative CT-assisted frameless stereotactic biopsies achieved single-millimeter trajectory accuracy for deep-seated brain lesions in a sample of 7 patients

BackgroundBrain biopsies are crucial diagnostic interventions, providing valuable information for treatment and prognosis, but largely depend on a high accuracy and precision. We hypothesized that through the combination of neuronavigation-based frameless stereotaxy and MRI-guided trajectory planning with intraoperative CT examination using a mobile unit, one can achieve a seamlessly integrated approach yielding optimal target accuracy.MethodsWe analyzed a total of 7 stereotactic biopsy trajectories for a variety of deep-seated locations and different patient positions. After rigid head fixation, an intraoperative pre-procedural scan using a mobile CT unit was performed for automatic image fusion with the planning MRI images and a peri-procedural scan with the biopsy cannula in situ for verification of the definite target position. We then evaluated the radial trajectory error.ResultsIntraoperative scanning, surgery, computerized merging of MRI and CT images as well as trajectory planning were feasible without difficulties and safe in all cases. We achieved a radial trajectory deviation of 0.97 ± 0.39 mm at a trajectory length of 60 ± 12.3 mm (mean ± standard deviation). Repositioning of the biopsy cannula due to inaccurate targeting was not required.ConclusionIntraoperative verification using a mobile CT unit in combination with frameless neuronavigation-guided stereotaxy and pre-operative MRI-based trajectory planning was feasible, safe and highly accurate. The setting enabled single-millimeter accuracy for deep-seated brain lesions and direct detection of intraoperative complications, did not depend on a dedicated operating room and was seamlessly integrated into common stereotactic procedures.

A new simple and free tubular device for microscopic transcortical approach to deep-seated lesions: technical note and case example.

Surgery for deep-seated brain tumors remains challenging. Transcortical approaches often require brain retraction to ensure an adequate surgical corridor, thus possibly leading to brain damage. Various techniques have been developed to minimize brain retraction such as self-retaining retractors, endoscopic approaches, or tubular retractor systems. Even if they evenly distribute the mechanical pressure over the parenchyma, rigid retractors can also cause some degree of brain damage and have significant disadvantages. We propose here a soft cottonoid retractor for microscopic resection of deep-seated and ventricular lesions. Through a small corticectomy, a channel route with a blunt cannula is developed until the lesion is reached. Then, a "balloon-like system" made with a surgical glove is progressively inflated, dilatating the surgical corridor. A mini-tubular device, handmade by suturing a surgical cottonoid, is positioned into the corridor, unfolded, and sutured to the edge of the dura, to prevent it from being progressively expelled from the working channel. This allows a good visualization of the lesion and surrounding structures under the microscope. Advantages of this technique are the softness of the tube walls, the absence of rigid arm to hold the tube, and the possibility for the tube to follow the movements of the instruments and to modify its orientation according to the working area. This simple and inexpensive tubular working channel for microscopic transcortical approach is a valuable alternative technique to traditional self-retaining retractor and rigid tube for the microsurgical resection of deep-seated brain tumors.

Endoscope-controlled Access to Thalamic Tumors using Tubular Brain Retractor: An Alternative Approach to Microscopic Excision.

Surgery for thalamic lesions has been considered challenging due to their deep-seated location. Endoscopic excision of deep-seated brain tumors using tubular retractor has been shown to be safe and effective in prior studies; however, there are limited reports regarding its use for thalamic tumors. We present our experience of endoscope-controlled resection of thalamic tumors using a tubular retractor. This was a prospective observational case series done at a tertiary center specialized for endoscopic neurosurgery during the period from 2010 to 2019. Surgeries were performed under the endoscopic control using a silicon tubular retractor. Lesions were approached transcortically or trans-sulcally. Data were collected for the extent of resection, amount of blood loss, operative time, need for conversion to microscopy, and complications. Twenty-one patients of thalamic masses of 14- to 60-year age underwent the surgeries. Pathologies ranged from grade I to IV gliomas. Gross total and near-total resection could be done in 42.85% of cases for each group. The average blood loss and operative time were164.04 ± 83.63 mL and 157.14 ± 28.70 minutes, respectively. Complications included a small brain contusion, two transient hemipareses, and one transient speech deficit. Endoscopic excision of thalamic tumors using a tubular retractor was found to be a safe and effective alternative to microscopic resection.

THE DESIGN AND USE OF A MINIMALLY-INVASIVE, EXPANDABLE RETRACTOR FOR DEEP-SEATED BRAIN LESIONS.

Access to deep-seated brain lesions (e.g., tumors, aneurysms, hematomas, and other malformations) is challenging due to the potential for retraction-induced injury. Traditionally, neurosurgeons use dissection and blade retractors to push apart tissue to visualize and operate on target lesions. These blades apply focal pressure onto the brain, resulting in ischemia, edema, and parenchymal trauma, leading to complications in up to 29% of cases. Tubular retractors were introduced to distribute forces radially and have led to improved safety and clinical outcomes. However, reports indicate that tubular retractors still led to complications in up to 9.1% of cases. Other concerns include significant pressure in the direction of insertion and the displacement of anatomic landmarks leading to inaccurate stereotaxis. We present a novel, minimally-invasive brain retractor that utilizes an expandable soft balloon to further reduce retraction-induced injury and increase stereotactic accuracy with a minimal port of entry. The device consists of a balloon catheter system, a clear sheath, and integration with neuronavigation stylets. This approach can reduce the rate of iatrogenic injury and improve clinical outcomes for brain lesion operations. Furthermore, we illustrate the efficacy of this device in use compared to those of conventional tubular and blade retractors in a pig cadaver.

Navigated Endoport in the Purely Endoscopic Microsurgery of Intraventricular and Other Deep-Seated Brain Lesions: A Case Report

<p><strong>Objective. </strong>Brain parenchyma retraction is often necessary to reach various deep brain lesions during surgery. In order to minimise the incidence of the brain retraction injury, an endoport system may be employed. We present a report of a navigated endoport system in conjunction with an purely endoscopic microsurgery that was used in a patient with a deep-seated subependymoma.</p><p><strong>Case Report. </strong>A navigated endoport with purely endoscopic microsurgery were used in a patient with a tumour</p><p>located in the frontal horn of the left lateral ventricle. The endoport channel was made of a polyvinyl sheet that was cut into a 7 cm square, rolled into a tubular structure that was wrapped around the neuronavigational probe, and inserted in the access trajectory to the tumour. The endoport tube was then expanded with a balloon to a diameter of 7 mm and a surgical corridor was thus formed. During the purely endoscopic microsurgical lesionectomy, the tumour was completely removed from the frontal horn. The foramen of Monro was released and the septum pellucidum was perforated for better cerebrospinal fluid circulation. Histopathological examination confirmed the tumour as subependymoma. The recovery of the patient was unremarkable.</p><p><strong>Conclusion. </strong>The expandable endoport system supplemented with neuronavigation is a safe and efficient option for deep-seated tumour removal. The tubular shape of the retractor enables standard microsurgical techniques through minimally invasive approaches and offers an excellent visualization of the underlying lesion.</p>

Fluorescein Sodium-Guided Neuroendoscopic Resection of Deep-Seated Malignant Brain Tumors: Preliminary Results of 18 Patients.

Deep-seated intracranial lesions are challenging to resect completely and safely. Fluorescence-guided surgery (FGS) promotes the resection of malignant brain tumors (MBTs). Classically, FGS is performed using microscope equipped with a special filter. Fluorescence-guided neuroendoscopic resection of deep-seated brain tumors has not been reported yet. To evaluate the feasibility, safety, and effectiveness of the fluorescence-guided neuroendoscopic surgery in deep-seated MBTs. A total of 18 patients with high-grade glioma (HGG) and metastatic tumor (MT) underwent fluorescein sodium (FS)-guided neuroendoscopic surgery. Tumor removal was carried out using bimanual microsurgical techniques under endoscopic view. The degree of fluorescence staining was classified as "helpful" and "unhelpful" based on surgical observation. Extent of resection was determined using magnetic resonance imaging (MRI). Karnofsky Performance Status (KPS) score was used for evaluation of general physical performances of patients. A total of 11 patients had HGG, and 7 had MT. No technical difficulty was encountered regarding the use of endoscopic technique. "Helpful" fluorescence staining was observed in 16 patients and fluorescent tissue was completely removed. Postoperative MRI confirmed gross total resection (88.9%). In 2 patients, FS enhancement was not helpful enough for tumor demarcation and postoperative MRI revealed near total resection (11.1%). No complication, adverse events, or side effects were encountered regarding the use of FS. KPS score of patients was improved at 3-mo follow-up. FS-guided endoscopic resection is a feasible technique for deep-seated MBTs. It is safe, effective, and allows for a high rate of resection. Future prospective randomized studies are needed to confirm these preliminary data.

SURG-20. USE OF NICO MYRIAD NOVUS DEVICE WITH LIGHT SOURCE AND REAL-TIME STEREOTACTIC NAVIGATION TO OPTIMIZE SURGICAL RESECTION OF DEEP-SEATED TUMORS

Abstract Maximal and safe surgical resection remains a critical component of the standard of care for patients with brain tumors. Stereotactic navigation tools are often incorporated into the surgical planning and implementation. The NICO Myriad NOVUS device couples a light source with the resecting tip to allow enhanced visualization of the surgical cavity and surrounding anatomical structures. At the Cleveland Clinic, we were the first group in the U.S. to start utilizing this augmented technology to maximize the resection of particularly deep-seated brain tumors, using the xenon light and real-time stereotactic navigation of the tool tip with the BrainLAB cranial setting. The navigated tip allows us to reach the deep corners of tumors with or without a tubular retracting device by sparing large corticotomies. Furthermore, the light source within the handheld device is easier to handle and manipulate than a large microscope to illuminate the surgical cavity. In addition, this new tool allows for automated tumor and peri-tumoral tissue harvesting, annotating each sample by location intraoperatively, as well as biological preservation of the harvested tissue for post-surgical molecular analysis. We describe the techniques and advantages of using this novel technology in patients while following and preliminarily reporting their surgical outcomes. With the emergence of novel technological advances, we must adapt as neurosurgeons and develop innovative methods to optimize the surgical resection of brain tumors.

A bi-tapered and air-gapped beam shaping assembly used for AB-BNCT

The 7Li(p,n)7Be reaction, which leads to a soft neutron field, is often chosen as the neutron producing reaction used for accelerator-based boron neutron capture therapy (AB-BNCT). This study aims to design a compact beam shaping assembly (BSA) and auxiliary system for a 7Li(p,n)7Be reaction-based neutron source and to evaluate the relationship between the BSA design and the consequent neutron beam quality for further optimization.In this study, five types of moderator shapes for the BSA model were designed. Both the in-air and in-phantom figures of merit were considered to evaluate the performance of the BSA designs. It was found that the BSA with a bi-tapered and air-gapped design could generate a high-intensity epithermal neutron beam, which could be used to treat deep-seated brain tumors within a reasonable time.

Use of a novel navigable tubular retractor system in 1826 minimally invasive parafascicular surgery (MIPS) cases involving deep-seated brain tumors, hemorrhages and malformations

ObjectivesThis retrospective, observational experiential study aimed to examine the utility of Minimally Invasive Parfasicular Surgery (MIPS) with Brainpath® and/or Myriad™ in a large, diverse patient cohort and to compare observational characteristics with those in the existing MIPS-BrainPath/Myriad medical literature. Patients and methodsDemographic and surgical data from June 2, 2012 to April 30, 2019 were retrospectively extracted from a secure MIPS case summary database. Descriptive statistics were performed. Results1826 cases were extracted for analysis: 668 vascular; 1109 tumor; 47 unclassified and 2 “other.” Predominate vascular locations were subcortical and intraventricular. The average age for the vascular and tumor groups were 57.1 and 53.3 years respectively with a greater number of pediatric patients in the tumor group. Mean operating times were 176.0 min (tumor group) and 120.6 (vascular group). Hemorrhages and malformations averaged 5.27 cm3 vs. 2.76 cm in the tumor cohort. There were more male patients. Of the vascular cases, most were intracranial hemorrhages (n = 563, 84.5%); most tumor cases were primary brain tumors (n = 522, 47.7%) with 335 secondary tumors or metastatic brain tumors. Thirty-four percent of the entire cohort experienced at least one presurgical deficit related to the brain defect; headaches were the most commonly observed symptom. Deaths or infections directly related to MIPS were not captured within the database. ConclusionThese data support current, yet limited, medical literature observations demonstrating the versatility and utility of MIPS-BrainPath and/or Myriad for reaching and removing tumors and vascular anomalies located in eloquent brain regions in a variety of patient types.

A systematic review of endovascular stent-electrode arrays, a minimally invasive approach to brain-machine interfaces.

The goal of this study was to systematically review the feasibility and safety of minimally invasive neurovascular approaches to brain-machine interfaces (BMIs). A systematic literature review was performed using the PubMed database for studies published between 1986 and 2019. All studies assessing endovascular neural interfaces were included. Additional studies were selected based on review of references of selected articles and review articles. Of the 53 total articles identified in the original literature search, 12 studies were ultimately selected. An additional 10 articles were included from other sources, resulting in a total of 22 studies included in this systematic review. This includes primarily preclinical studies comparing endovascular electrode recordings with subdural and epidural electrodes, as well as studies evaluating stent-electrode gauge and material type. In addition, several clinical studies are also included. Endovascular stent-electrode arrays provide a minimally invasive approach to BMIs. Stent-electrode placement has been shown to be both efficacious and safe, although further data are necessary to draw comparisons between subdural and epidural electrode measurements given the heterogeneity of the studies included. Greater access to deep-seated brain regions is now more feasible with stent-electrode arrays; however, further validation is needed in large clinical trials to optimize this neural interface. This includes the determination of ideal electrode material type, venous versus arterial approaches, the feasibility of deep brain stimulation, and more streamlined computational decoding techniques.

Minimally invasive therapeutic ultrasound: Ultrasound-guided ultrasound ablation in neuro-oncology

IntroductionTo improve patient outcomes (eg, reducing blood loss and infection), practitioners have gravitated toward noninvasive and minimally invasive surgeries (MIS), which demand specialized toolkits. Focused ultrasound, for example, facilitates thermal ablation from a distance, thereby reducing injury to surrounding tissue. Focused ultrasound can often be performed noninvasively; however, it is more difficult to carry out in neuro-oncological tumors, as ultrasound is dramatically attenuated while propagating through the skull. This shortcoming has prompted exploration of MIS options for intracranial placement of focused ultrasound probes, such as within the BrainPath™ (NICO Corporation, Indianapolis, IN). Herein, we present the design, development, and in vitro testing of an image-guided, focused ultrasound prototype designed for use in MIS procedures. This probe can ablate neuro-oncological lesions despite its small size. Materials & MethodsPreliminary prototypes were iteratively designed, built, and tested. The final prototype consisted of three 8-mm-diameter therapeutic elements guided by an imaging probe. Probe functionality was validated on a series of tissue-mimicking phantoms. ResultsLesions were created in tissue-mimicking phantoms with average dimensions of 2.5 × 1.2 × 6.5 mm and 3.4 × 3.25 × 9.36 mm after 10- and 30-second sonification, respectively. 30 s sonification with 118 W power at 50% duty cycle generated a peak temperature of 68 °C. Each ablation was visualized in real time by the built-in imaging probe. ConclusionWe developed and validated an ultrasound-guided focused ultrasound probe for use in MIS procedures. The dimensional constraints of the prototype were designed to reflect those of BrainPath trocars, which are MIS tools used to create atraumatic access to deep-seated brain pathologies.

Anatomical relationships between medullary veins and three types of deep-seated malignant brain tumors as detected by susceptibility-weighted imaging.

Deep-seated brain tumors can be difficult to differentiate. Three tumor types (primary central nervous system lymphoma [PCNSL], high-grade glioma, and metastatic brain tumors), identified by susceptibility-weighted imaging, have different relationships with small medullary veins, and these relationships can be used to enhance diagnostic accuracy. Records of patients with pathology confirmed malignant brain tumors who received susceptibility-weighted imaging between 2009 and 2015 were reviewed. A total of 29 patients with deep-seated malignant brain tumors in the territory of small medullary veins were enrolled in this study. The sensitivity, specificity, and diagnostic accuracy of medullary vein blockage (MVB), defined as a small medullary vein terminating at the margin of the tumor, for indicating malignant brain tumors were analyzed. Of 11 patients with PCNSLs, 5 with high-grade gliomas, and 13 with metastases, only the latter presented MVBs. The sensitivity, specificity, and accuracy of using MVBs for diagnosing metastatic tumors were 76.9%, 100%, and 89.7%, respectively. An MVB is an accurate sign for differentiating metastatic brain tumors from two other common malignancies and thus provides a useful tool for preoperative planning.

An Awake Contralateral, Transcallosal Approach for Deep-Seated Gliomas of the Basal Ganglia

The basal ganglia and thalamus are uncommon locations for infiltrating gliomas. Tumors here are usually managed with biopsy and adjuvant therapy, with relatively poor results. Rarely do patients undergo extensive surgical intervention. It seems reasonable to suggest that successful cytoreduction may help these patients. However, this hypothesis has not been studied because of the general view that it is not possible to remove deep-seated brain tumors with acceptable outcomes. Through retrospective data collection, we describe a small case series of patients undergoing awake contralateral, transcallosal surgery for deep-seated brain tumors affecting the basal ganglia. We describe our patient cohort, report on patient outcomes, and describe our surgical technique. Four patients underwent awake contralateral, transcallosal surgery for glioblastoma invading the basal ganglia. All 4 patients demonstrated hemibody weakness contralateral to the side of their tumors, with 3 patients confined to wheelchairs at presentation. Their ages ranged from 25 to 64 years. Tumor volumes ranged from 14 to 93 cm3. More than 50% resection of each tumor was achieved during surgery. In 2 cases, approximately 90% resection was achieved. Motor strength improved in 1 patient who presented with hemiplegia. Two patients required ventriculoperitoneal shunting for complications related to hydrocephalus. At the writing of this article, 2 of our patients were still alive, functional, and free of tumor progression. We present the results of our attempts to resect large gliomas infiltrating the basal ganglia in 4 patients. Our technique combined a contralateral, transcallosal approach with awake neuromonitoring. Our results suggest it is possible to remove these tumors with reasonable outcomes.

What is the best therapeutic approach to a pediatric patient with a deep-seated brain AVM?

Although brain arteriovenous malformations (bAVMs) account for a very small proportion of cerebral pathologies in the pediatric population, they are the cause of roughly 50% of spontaneous intracranial hemorrhages. Pediatric bAVMs tend to rupture more frequently and seem to have higher recurrence rates than bAVMs in adults. Thus, the management of pediatric bAVMs is particularly challenging. In general, the treatment options are conservative treatment, microsurgery, endovascular therapy (EVT), gamma knife radiosurgery (GKRS), proton-beam stereotactic radiosurgery (PSRS), or a combination of the above. In order to identify the best approach to deep-seated pediatric bAVMs, we performed a systematic review, according to the PRISMA guidelines. None of the options seem to offer a clear advantage over the others when used alone. Microsurgery provides the highest obliteration rate, but has higher incidence of neurological complications. EVT may play a role when used as adjuvant therapy, but as a stand-alone therapy, the efficacy is low and the long-term side effects of radiation from the multiple sessions required in deep-seated pediatric bAVMs are still unknown. GKRS has a low risk of complication, but the obliteration rates still leave much to be desired. Finally, PSRS offers promising results with a more accurate radiation that avoids the surrounding tissue, but data is limited due to its recent introduction. Overall, a multi-modal approach, or even an active surveillance, might be the most suitable when facing deep-seated bAVM, considering the difficulty of their management and the high risk of complications in the pediatric population.

Utility of Tubular Retractors Augmented with Intraoperative Ultrasound in the Resection of Deep-seated Brain Lesions: Technical Note.

Traditional brain retraction has been associated with significant damage to the healthy brain tissue particularly when attempting to expose a deep-seated lesion of the brain. Tubular retractors tend to provide a surgical corridor to treat these lesions while minimizing the extent of retraction on the brain. Intraoperative ultrasound can be used as a handy adjunct in maximizing the safe resection primarily by identifying the entry point, visualizing the lesion, and providing real-time feedback on the extent of resection. The authors provide a technical note with case illustrations on the use of tubular retractors augmented with intraoperative ultrasound to ensure a maximal safe resection of deep-seated brain lesions.

Stereotactic-Guided Dilatable Endoscopic Port Surgery for Deep-Seated Brain Tumors: Technical Report with Comparative Case Series Analysis

Deep-seated brain tumors are often best treated by primary surgical excision. Traditional microsurgical techniques can cause retraction injury and require extensive brain dissection. To mitigate this risk, stereotactic-guided tubular retractors were developed; however, the risk of shear injury remains. We created a stereotactic-guided dilatable port system to create a corridor for deep brain tumor surgery along the trajectory of a brain needle to minimize iatrogenic brain injury. Of the 8 included patients (6 colloid cysts, 1 metastasis, 1 intraventricular meningioma), 5 had undergone frameless and 3 frame-based stereotactic targeting. We used a tans-sulcal trajectory and a 2.6-mm stereotactic needle. At the target depth, the cannula was removed and the balloon inflated to 14 mm. The balloon was deflated and removed before placing the port. Pre- and 3-month postoperative magnetic resonance imaging scans were used to measure the T2-weighted signal change and residual cannulation defect. These patients were compared with a case-matched standard endoscopic port surgery cohort. All patients had undergone total lesional resection without new neurologic deficits. Patients undergoing dilatable endoscopic port surgery (DEPS) had significantly smaller residual cannulation defects (P < 0.05) but no significant differences in postoperative T2-weighted signal changes or diffusion restriction volumes at 3 months postoperatively (P > 0.05). DEPS might be a safe alternative to standard endoscopic port surgery or microsurgery for deep-seated brain tumors. The degree of iatrogenic injury using DEPS, as determined by magnetic resonance imaging analysis, might be equivalent to or less than that with standard port surgery techniques, although larger sample sizes are needed for validation.

Design and optimization of two-sided beam based on 7Li(p,n)7Be source using in BNCT for brain and liver tumors

Recent studies in BNCT have focused on investigating appropriate neutron sources based on accelerators. One of the common reactions based on accelerators for neutron production is7Li(p,n)7Be. In this paper we designed and optimized two-sided Beam Shaping Assembly composed of a moderator, a filter, a reflector and a collimator for the perpendicular neutrons with respect to the direction of the incident beam to provide an appropriate neutron beam in BNCT. Calculations for our design show, using a proton beam of 2.5 MeV with a current of 10 mA, will produce proper epithermal neutron flux in both sides of the system. The final optimized flux for the system was calculated to be 2.15×109n∕cm2.s for one side of BSA and the epithermal neutron flux on one of two sides has increased by about 32% with respect to the forward direction. All in-air licensed parameters proposed by the International Atomic Energy Agency (IAEA) have been established. The dose evaluation results and depth dose curves were presented for a simulated head phantom and a human phantom including the liver with a typical tumor. The results confirmed that the designed neutron source and BSAs, can potentially be used to treat deep-seated brain and liver tumors in BNCT.