Increased incidence of indeterminate pancreatic cysts and changes of management pattern: Evidence from nationwide data.

BACKGROUND: Pancreatic cysts are common. However, most studies are based on data collected from individual centers. The present study aimed to evaluate the changes of management patterns for pancreatic cystic lesions (PCLs) by analyzing large epidemiologic data. METHODS: Between January 2007 and December 2018, information regarding pancreatic cystic lesions was acquired from the nationwide Health Insurance Review and Assessment Service database in Korea. RESULTS: The final number of patients with pancreatic cysts was 165 277 among the total claims for reimbursement of 855 983 associated with PCLs over 12 years. The total number of claims were increased from 19 453 in 2007 to 155 842 in 2018 and the prevalence increased from 0.04% to 0.23%. For 12 years, 2874 (1.7%) had pancreatic cancer and 8212 (5.0%) underwent surgery, and 36 had surgery for twice (total 8248 pancreatectomy). After ruling out claims from the first 3 years of washout period, the incidence increased from 9891 to 24 651 and the crude incidence rate of PCLs expanded from 19.96 per 100 000 to 47.77 per 100 000. Compared to specific neoplasm codes (D136 or D377), the use of pancreatic cyst code (K862) has been remarkably increased and the most common since 2010. The annual number of pancreatectomies increased from 518 to 861 between 2007 and 2012, and decreased to 596 until 2018. The percentage of pancreatic cancer in patients who received pancreatectomy increased from 5.6% in 2007 to 11.7% in 2018. CONCLUSIONS: The incidence of PCLs is rapidly increasing. Among PCLs, indeterminate cyst is increasing outstandingly. A trend of decreasing in the number of resections and increasing cancer rates among resected cysts may be attributed to the updated international guidelines.

Factors Associated With Abducens Nerve Palsy in Patients Undergoing Surgery for Petroclival Meningiomas.

BACKGROUND: During the surgical resection of petroclival meningiomas, preserving the cranial nerves is crucial. The abducens nerve is particularly vulnerable during surgery. However, the preoperative risk factors and postoperative prognosis of abducens nerve palsy (ANP) are poorly understood. METHODS: We retrospectively analyzed 70 patients who underwent surgery for petroclival meningiomas between May 2010 and December 2019, divided into gross-total resection (GTR) and subtotal resection (STR) groups. The relationship of preoperative clinical factors with the incidence and recovery of postoperative ANP was analyzed. RESULTS: Postoperative ANP was observed in 23 patients (32.9%). Multivariable logistic regression revealed that the tumor-to-cerebellar peduncle T2 imaging intensity index (TCTI) (P < 0.001) and internal auditory canal invasion (P = 0.033) contributed to postoperative ANP. GTR was achieved in 37 patients (52.9%), and 10 (27.0%) of them showed ANP. STR was achieved in 33 patients (47.1%), and 13 (39.4%) of them showed ANP. Recovery from ANP took a median of 6.6 months (range, 4.5-20.3 months). At 6 months after the operation, recovery of the abducens nerve function was observed in 16 patients (69.0%); of whom, 4 (40.0%) were in the GTR group and 12 (92.3%) were in the STR group (P = 0.025). CONCLUSIONS: TCTI and internal auditory canal invasion were the risk factors for postoperative ANP. Although intentional STR did not prevent ANP immediately after the operation, recovery of the abducens nerve function after surgery was observed more frequently in the STR group than in the GTR group.

Differences in surgical outcome between petroclival meningioma and anterior petrous meningioma.

BACKGROUND: Petroclival meningiomas (PC MNGs) and anterior petrous meningiomas (AP MNGs) have similar locations. However, these are different tumors clearly divided by the trigeminal nerve. There has never been a study on the comparison of the surgical outcomes of these two meningiomas. In this study, we compared and analyzed the surgical outcome of PC MNGs and AP MNGs. METHODS: The charts of 85 patients diagnosed with PC MNGs of AP MNGs who underwent surgical treatment were retrospectively reviewed. And we analyzed the characteristics of 49 PC MNGs (57.6%) and compared them with those of 36 AP MNGs. RESULTS: Preoperative brainstem edema was observed in 11 patients (22.4%) of the PC MNG group and 1 patient (2.8%) of the AP MNG group (p = 0.024). Total tumor removal was achieved in 21 patients (58.3%) of the AP MNG group, but only 17 patients (34.7%) of the PC MNG group were able to completely (p = 0.047). In addition, sixth cranial nerve palsy occurred in 17 patients (34.7%) of the PC MNG group and 4 patients (11.1%) of the AP MNG group (p = 0.025). CONCLUSIONS: In this study, we found that PC MNGs has a worse surgical outcome than AP MNGs, because PC MNGs were difficult to completely remove and were more likely to damage abducens nerve.

The Ameliorating Effects of Bee Pollen on Scopolamine-Induced Cognitive Impairment in Mice.

Bee pollen consists of floral pollen mixed with bee secretions and nectar. It has been considered as a functional food and has different kinds of biologically active ingredients, such as flavonoids, polyphenols, phytosterols and minerals. However, its function in cognition has yet been investigated. In the present study, we investigated the ameliorating effect of bee pollen against scopolamine-caused cognitive impairment through the passive avoidance test, the Y-maze test and the Morris water maze test. In addition, Western blotting was employed to verify the effects of bee pollen on memory-related signaling molecules in the hippocampus. Bee pollen extract (100 or 300 mg/kg, per os (p.o.)) obviously reversed scopolamine-caused cognitive impairment in the passive avoidance test, ameliorated spontaneous alternation versus the scopolamine-treated group in the Y-maze test and prolonged swimming time in the target zone in the Morris water maze test. In addition, the phosphorylation levels of extracellular signal-regulated kinase (ERK), cAMP response element-binding protein (CREB), protein kinase B (Akt) and glycogen synthase kinase-3ß (GSK-3ß), and the expression levels of brain-derived neurotrophic factor (BDNF) and tissue plasminogen activator (tPA) in the hippocampi, were increased in response to the treatment with bee pollen extract (100 or 300 mg/kg, p.o.). These results indicated that bee pollen ameliorates cognitive impairment induced by cholinergic blockade through the enhancing conversion of proBDNF to mature BDNF by tPA, probably, through the ERK-CREB pathway or Akt-GSK-3ß signaling pathway and would be a useful agent for the treatment of cognitive dysfunction.

The Seed of Zizyphus jujuba var. spinosa Attenuates Alzheimer's Disease-Associated Hippocampal Synaptic Deficits through BDNF/TrkB Signaling.

Ziziphus jujuba is a plant, which bears fruits and seeds that are used for medicinal purposes in Traditional oriental medicine. The seed of Zizyphus jujuba var. spinosa (EZJ) has been also traditionally used for psychiatric disorders in Chinese and Korean medicines. Recent findings have indicated that EZJ improves memory impairment, a common symptom of various neurological diseases. However, the effects of EZJ on amyloid ß (Aß) toxicity, which is a main cause of Alzheimer's disease (AD), remain to be elucidated. To illuminate the potential anti-AD effect and mechanism in the mouse hippocampal tissue, we examined the effect of standardized EZJ on Aß-induced synaptic long-term potentiation (LTP) deficit in the hippocampal tissue. EZJ blocked Aß-induced LTP deficits in a concentration-dependent manner. Moreover, EZJ increased brain-derived neurotrophic factor (BDNF) level in naïve hippocampal slices. The finding that the blockade of BDNF receptor reduced the effect of EZJ suggests that EZJ ameliorates the Aß-induced LTP deficit through BDNF/topomyosin receptor kinase B (TrkB) signaling. However, transcription or translation inhibitors failed to block the effect of EZJ, suggesting that BDNF synthesis is not required for the action of EZJ on LTP. Finally, we found that EZJ stimulates plasmin activity. In contrast, plasmin inhibitor blocked the effect of EZJ on the Aß-induced LTP deficit. Our findings indicate that EZJ ameliorates Aß-induced LTP deficits through BDNF/TrkB signaling. This phenomenon is induced by a regulatory effect of EZJ on the post-translation modification of BDNF.

Cognitive Ameliorating Effect of Acanthopanax koreanum Against Scopolamine-Induced Memory Impairment in Mice.

Acanthopanax koreanum Nakai (Araliaceae) is one of the most widely cultivated medicinal plants in Jeju Island, Korea, and the roots and stem bark of A. koreanum have been traditionally used as a tonic agent for general weakness. However, the use of A. koreanum for general weakness observed in the elderly, including those with declined cognitive function, has not been intensively investigated. This study was performed to investigate the effect of the ethanol extract of A. koreanum (EEAK) on cholinergic blockade-induced memory impairment in mice. To evaluate the ameliorating effects of EEAK against scopolamine-induced memory impairment, mice were orally administered EEAK (25, 50, 100, or 200 mg/kg), and several behavioral tasks, including a passive avoidance task, the Y-maze, and a novel object recognition task, were employed. Besides, western blot analysis was conducted to examine whether EEAK affected memory-associated signaling molecules, such as protein kinase B (Akt), Ca2+ /calmodulin-dependent protein kinase II (CaMKII), and cAMP response element-binding protein (CREB). The administration of EEAK (100 or 200 mg/kg, p.o.) significantly ameliorated the scopolamine-induced cognitive impairment in the passive avoidance task, the Y-maze, and the novel object recognition task. The phosphorylation levels of both Akt and CaMKII were significantly increased by approximately two-fold compared with the control group because of the administration of EEAK (100 or 200 mg/kg) (p < 0.05). Moreover, the phosphorylation level of CREB was also significantly increased compared with the control group by the administration of EEAK (200 mg/kg) (p < 0.05). The present study suggests that EEAK ameliorates the cognitive dysfunction induced by the cholinergic blockade, in part, via several memory-associated signaling molecules and may hold therapeutic potential against cognitive dysfunction, such as that presented in neurodegenerative diseases, for example, Alzheimer's disease. Copyright © 2017 John Wiley & Sons, Ltd.

The Efficacy of Traumatic Brain Injury Treatment by Neurotrauma Specialists.

Objective: Since the establishment of Regional Trauma Centers (RTCs) in Korea, significant efforts have been made to improve the quality of care for patients with trauma. Simultaneously, the Department of Neurosurgery assigned neurotrauma specialists to RTCs to provide specialized care to patients with traumatic brain injury (TBI). In this study, we sought to determine whether neurotrauma specialists, compared to general neurosurgeons, could make a significant difference in treatment outcomes of patients with TBI. Methods: In total, 156 patients with acute TBI who required decompression were included. We reviewed their records and compared the characteristics, outcomes, and prognosis of those who received surgical treatment from either neurotrauma specialists or general neurosurgeons at our institution. Results: A significant difference was observed between treatment by trauma neurosurgery specialists and general neurosurgeons in time to surgery, with trauma specialists experiencing shorter surgical delays. However, no significant differences existed in mortality rates or Extended Glasgow Outcome Scale scores. Univariate and multivariable regression analyses revealed that lower Glasgow Coma Scale scores, an abnormal pupil reflex, larger transfusion volume, and prolonged time from emergency room admission to surgery were associated with high mortality rates. Conclusion: Neurotrauma specialists can provide prompt surgical treatment to patients with TBI compared to general neurosurgeons. Our study did not reveal a significant difference in outcomes between the two groups. However, it is clear that rapid decompression is effective in patients with impending brain herniation. Therefore, the effectiveness of neurotrauma specialists needs to be confirmed through further systematic studies.

Development of Magnetic Resonance-Compatible Head Immobilization Device and Initial Experience of Magnetic Resonance-Guided Radiation Therapy for Central Nervous System Tumors.

PURPOSE: We aimed to develop and investigate positional reproducibility using a fixation device (Unity Brain tumor Immobilization Device [UBID]) in patients with brain tumor undergoing magnetic resonance (MR)-guided radiation therapy (RT) with a 1.5 Tesla (T) MR-linear accelerator (MR-LINAC) to evaluate its feasibility in clinical practice and report representative cases of patients with central nervous system (CNS) tumor. MATERIALS AND METHODS: Quantitative analysis was performed by comparing images obtained by placing only the MR phantom on the couch with those obtained by placing UBID next to the MR phantom. Twenty patients who underwent RT for CNS tumors using 1.5T MR-LINAC between June and October 2022 were retrospectively analyzed. Among them, 5 did not use UBID, whereas 15 used UBID. The positional reproducibility of UBID was evaluated using the median interfractional and intrafractional errors in the first 10 fractions. RESULTS: Each MR quality factor of the MR phantom with UBID satisfied the criteria presented by Elekta. Median values of median shifts in the mediolateral, anteroposterior, and craniocaudal axes for interfractional errors were 2.98, 2.35, and 1.40 mm, respectively. For intrafractional errors, the median values were 0.05, 0.03, and 0.06 mm, respectively. The median values of the median rotations in pitch, roll, and yaw for both interfractional and intrafractional rotations were 0.00°. One patient diagnosed with an optic nerve sheath meningioma received RT with motion monitoring during irradiation. In 2 patients, changes in the tumor cavity and residual lesions were observed in the MRI obtained using 1.5T MR-LINAC on the day of the first treatment and immediately before the 21st fraction, respectively; therefore, offline/online adaptation was performed. CONCLUSIONS: The reproducible and immobile UBID is clinically feasible in patients with CNS tumors receiving RT with 1.5T MR-LINAC. Based on our initial experience, we developed a workflow for 1.5T MR-LINAC treatment of CNS tumors.

Risk Factors for Postoperative Contralateral Hemorrhage in Patients With Traumatic Brain Injury who Underwent Surgical Treatment: A Multicenter Study.

Objective: Patients with a contralateral intracranial hemorrhage after decompressive craniectomy have a worse prognosis than those whose recovery is uneventful. Therefore, the objective of this study was to identify risk factors for postoperative contralateral hemorrhage (PCH) in patients who underwent unilateral craniectomy or craniotomy due to a traumatic brain injury (TBI). Methods: Data were obtained from the Korean Neuro-Trauma Data Bank System and retrospectively reviewed. Patients who had a unilateral craniectomy or craniotomy for acute TBI were included in this study. Clinical outcomes of a PCH group and an uneventful group were compared and the risk factors for PCH were identified using regression analysis. Results: A total of 326 patients were included in this study. PCH was observed in 25 (7.7%) patients. The Glasgow coma scale (GCS) and Glasgow outcome scale extended (GOSE) scores at discharge were significantly lower in the PCH group than those in the uneventful group (GCS: 3.6 vs. 6.2, p=0.043; GOSE: 2.1 vs. 3.2, p=0.032). In the multivariable regression analysis, when the time from injury to surgery was shorter than 150 minutes, the risk of PCH was increased by 4.481 times (p=0.005). When the intraoperative transfusion volume was more than 1.5 L, the risk of PCH was increased by 4.843 times (p=0.003). Conclusion: The risk of PCH is increased when the time from injury to surgery is shorter than 150 minutes and when the intraoperative transfusion volume is greater than 1.5 L. Neurosurgeons must predict and be prepared for the development of PCH in high-risk patients.

Fencing Knife-Induced Transorbital Penetrating Brain Injury: A Case Report.

Penetrating brain injury (PBI) is a rare type of traumatic brain injury, which accounts for 0.4% of all head trauma cases. In this study, we describe a 14-year-old male adolescent who sustained a transorbital penetrating injury caused by a fencing knife. Although the patient visited the hospital after the foreign body had been removed, we diagnosed a PBI based on identification of a linear injury trajectory extending from an orbital roof fracture to the contralateral parietal lobe, using three-dimensional reconstruction of the hemorrhage. The patient fully recovered after conservative treatment. We hope that sharing our experience will serve as a guideline for the clinical management of PBI.

Critical Evaluation and Thermodynamic Re-Optimization of the Si-P and Si-Fe-P Systems.

Thermodynamic modeling of the Si-P and Si-Fe-P systems was performed using the CALculation of PHAse Diagram (CALPHAD) method based on critical evaluation of available experimental data in the literature. The liquid and solid solutions were described using the Modified Quasichemical Model accounting for the short-range ordering and Compound Energy Formalism considering the crystallographic structure, respectively. In the present study, the phase boundaries for the liquidus and solid Si phases of the Si-P system were reoptimized. Furthermore, the Gibbs energies of the liquid solution, (Fe)3(P,Si)1, (Fe)2(P,Si)1, and (Fe)1(P,Si)1 solid solutions and FeSi4P4 compound were carefully determined to resolve the discrepancies in previously assessed vertical sections, isothermal sections of phase diagrams, and liquid surface projection of the Si-Fe-P system. These thermodynamic data are of great necessity for a sound description of the entire Si-Fe-P system. The optimized model parameters from the present study can be used to predict any unexplored phase diagrams and thermodynamic properties within the Si-Fe-P alloys.

Anticoagulation and Antiplatelet Agent Resumption Timing following Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major global health concern. Due to the increase in TBI incidence and the aging population, an increasing number of patients with TBI are taking antithrombotic agents for their underlying disease. When TBI occurs in patients with these diseases, there is a conflict between the disease, which requires an antithrombotic effect, and the neurosurgeon, who must minimize intracranial hemorrhage. Nevertheless, there are no clear guidelines for the reversal or resumption of antithrombotic agents when TBI occurs in patients taking antithrombotic agents. In this review article, we intend to classify antithrombotic agents and provide information on them. We also share previous studies on the reversal and resumption of antithrombotic agents in patients with TBI to help neurosurgeons in this dilemma.

Pharmacological Management of Germinal Matrix-Intraventricular Hemorrhage.

Germinal matrix-intraventricular hemorrhage (GM-IVH) is among the devastating neurological complications with mortality and neurodevelopmental disability rates ranging from 14.7% to 44.7% in preterm infants. The medical techniques have improved throughout the years, as the morbidity-free survival rate of very-low-birth-weight infants has increased; however, the neonatal and long-term morbidity rates have not significantly improved. To this date, there is no strong evidence on pharmacological management on GM-IVH, due to the limitation of well-designed randomized controlled studies. However, recombinant human erythropoietin administration in preterm infants seems to be the only effective pharmacological management in limited situations. Hence, further high-quality collaborative research studies are warranted in the future to ensure better outcomes among preterm infants with GM-IVH.

Complications After Deep Brain Stimulation: A 21-Year Experience in 426 Patients.

Background: Deep brain stimulation is an established treatment for movement disorders such as Parkinson's disease, essential tremor, and dystonia. However, various complications that occur after deep brain stimulation are a major concern for patients and neurosurgeons. Objective: This study aimed to analyze various complications that occur after deep brain stimulation. Methods: We reviewed the medical records of patients with a movement disorder who underwent bilateral deep brain stimulation between 2000 and 2020. Among them, patients requiring revision surgery were analyzed. Results: A total of 426 patients underwent bilateral deep brain stimulation for a movement disorder. The primary disease was Parkinson's disease in 315 patients, followed by dystonia in 71 patients and essential tremor in 40 patients. Twenty-six (6.1%) patients had complications requiring revision surgery; the most common complication was infection (12 patients, 2.8%). Conclusion: Various complications may occur after deep brain stimulation, and patient prognosis should be improved by reducing complications.

Pseudoprogression and peritumoral edema due to intratumoral necrosis after Gamma knife radiosurgery for meningioma.

Peritumoral cerebral edema is reported to be a side effect that can occur after stereotactic radiosurgery. We aimed to determine whether intratumoral necrosis (ITN) is a risk factor for peritumoral edema (PTE) when gamma knife radiosurgery (GKRS) is performed in patients with meningioma. In addition, we propose the concept of pseudoprogression: a temporary volume expansion that can occur after GKRS in the natural course of meningioma with ITN. This retrospective study included 127 patients who underwent GKRS for convexity meningioma between January 2019 and December 2020. Risk factors for PTE and ITN were investigated using logistic regression analysis. Analysis of variance was used to determine whether changes in tumor volume were statistically significant. After GKRS, ITN was observed in 34 (26.8%) patients, and PTE was observed in 10 (7.9%) patients. When postoperative ITN occurred after GKRS, the incidence of postoperative PTE was 18.970-fold (p = 0.009) greater. When a 70% dose volume ≥ 1 cc was used, the possibility of ITN was 5.892-fold (p < 0.001) higher. On average, meningiomas with ITN increased in volume by 128.5% at 6 months after GKRS and then decreased to 94.6% at 12 months. When performing GKRS in meningioma, a 70% dose volume ≥ 1 cc is a risk factor for ITN. At 6 months after GKRS, meningiomas with ITN may experience a transient volume expansion and PTE, which are characteristics of pseudoprogression. These characteristics typically improve at 12 months following GKRS.

Induction FOLFIRINOX followed by stereotactic body radiation therapy in locally advanced pancreatic cancer.

Introduction: FOLFIRINOX (the combination of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin) is the preferred systemic regimen for locally advanced pancreatic cancer (LAPC). Furthermore, stereotactic body radiation therapy (SBRT) is a promising treatment option for achieving local control in these patients. However, clinical outcomes in patients with LAPC treated using FOLFIRINOX followed by SBRT have not been clarified. Therefore, we aimed to evaluate clinical outcomes of induction FOLFIRINOX treatment followed by SBRT in patients with LAPC. Methods: To this end, we retrospectively reviewed the medical records of patients with LAPC treated with induction FOLFIRINOX followed by SBRT in a single tertiary hospital. We evaluated overall survival (OS), progression-free survival (PFS), resection rate, SBRT-related adverse events, and prognostic factors affecting survival. Results: Fifty patients were treated with induction FOLFIRINOX for a median of 8 cycles (range: 3-28), which was followed by SBRT. The median OS and PFS were 26.4 (95% confidence interval [CI]: 22.4-30.3) and 16.7 months (95% CI: 13.0-20.3), respectively. Nine patients underwent conversion surgery (eight achieved R0) and showed better OS than those who did not (not reached vs. 24.1 months, p = 0.022). During a follow-up period of 23.6 months, three cases of grade 3 gastrointestinal bleeding at the pseudoaneurysm site were noted, which were managed successfully. Analysis of the factors affecting clinical outcomes revealed that a high radiation dose (≥ 35 Gy) resulted in a higher rate of conversion surgery (25% [8/32] vs. 5.6% [1/18], respectively) and was an independent favorable prognostic factor for OS in the adjusted analysis (hazard ratio: 2.024, 95% CI: 1.042-3.930, p = 0.037). Conclusion: Our findings suggest that induction FOLFIRINOX followed by SBRT in patients with LAPC results in better survival with manageable toxicities. A high total SBRT dose was associated with a high rate of conversion surgery and could afford better survival.

Endoscopic transorbital approach to the cavernous sinus: Cadaveric anatomy study and clinical application (‡SevEN-009).

Objective: Cavernous sinus (CS) invasion is frequently encountered in the management of skull base tumors. Surgical treatment of tumors in the CS is technically demanding, and selection of an optimal surgical approach is critical for maximal tumor removal and patient safety. We aimed to evaluate the feasibility of an endoscopic transorbital approach (ETOA) to the CS based on a cadaveric study. Methods: Five cadaveric heads were used for dissection under the ETOA in the comparison with the endoscopic endonasal approach (EEA) and the microscopic transcranial approach (TCA). The CS was exposed, accessed, and explored, first using the ETOA, followed by the EEA and TCA. A dedicated endoscopic system aided by neuronavigation guidance was used for the procedures. During the ETOA, neurovascular structures inside the CS were approached through different surgical triangles. Results: After completing the ETOA with interdural dissection, the lateral wall of the CS was fully exposed. The lateral and posterior compartments of the CS, of which accessibility is greatly limited under the EEA, were effectively approached and explored under the ETOA. The anteromedial triangle was the largest window via which most of the lateral compartment was freely approached. The internal carotid artery and abducens nerve were also observed through the anteromedial triangle and just behind V1. During the ETOA, the approaching view through the supratrochlear and infratrochlear triangles was more directed towards the posterior compartment. After validation of the feasibility and safety based on the cadaveric study, ETOA was successfully performed in a patient with a pituitary adenoma with extensive CS invasion. Conclusions: Based on the cadaveric study, we demonstrated that the lateral CS wall was reliably accessed under the ETOA. The lateral and posterior compartments of the CS were effectively explored via surgical triangles under the ETOA. ETOA provides a unique and valuable surgical route to the CS with a promising synergy when used with EEA and TCA. Our experience with a clinical case convinces us of the efficacy of the ETOA during surgical management of skull base tumors with CS-invasion.

Epidural grid, a new methodology of invasive intracranial EEG monitoring: A technical note and experience of a single center.

INTRODUCTION: Subdural grid monitoring (SDG) has the advantage to provide continuous coverage over a larger area of cortex, direct visualization of electrode location and functional mapping. However, SDG can cause direct irritation of the cortex or postoperative headaches due to cerebrospinal fluid (CSF) leakage. Epidural grid monitoring (EDG) without opening the dura is thought to reduce the possibility of these complications. We report our experience with EDG. METHODS: We described our surgical technique of EDG in invasive intracranial electroencephalography (iEEG) monitoring. A retrospective review of 30 patients who underwent grid placement of iEEG between March 2019 and December 2020 was performed to compare SDG and EDG. RESULTS: Of the 30 patients, 10 patients underwent SDG and 20 patients underwent EDG. There was no difference in age between SDG and EDG groups (p = 0.13). Also, there was no difference in the number of grid electrodes, craniotomy size, number of electrodes per craniotomy area and postoperative complication rate (p = 0.32, 0.84, 0.58 and 0.40). However, the maximum number of electrodes that have been undermined from the bone margin was much higher in SDG group (SDG 4.6 ± 2.2 vs. EDG 2.0 ± 0.9; p = 0.001). The demand for postoperative analgesics was significantly lower in EDG group (SDG 13.4 ± 9.1 vs. EDG 4.1 ± 4.3; p = 0.012); and the demand for postoperative antiemetics also tended to be low (SDG 4.6 ± 3.6 vs. EDG 1.8 ± 1.6; p = 0.078). CONCLUSIONS: There was no significant difference in craniotomy and electrode insertion between the two groups; however, the EDG group showed less postoperative headache and nausea. Though not in direct contact with the cortex, the quality of the electrophysiological signal received through the electrode in EDG is comparable to that of the SDG. The EDG enables to detect the onset of seizure and delineate the epileptogenic zone sufficiently. Moreover, functional mapping is possible with EDG. Therefore, EDG has the sufficient potential to replace SDG for monitoring of the lateral surface of brain.

Clinical application of deep learning-based synthetic CT from real MRI to improve dose planning accuracy in Gamma Knife radiosurgery: a proof of concept study.

Dose planning for Gamma Knife radiosurgery (GKRS) uses the magnetic resonance (MR)-based tissue maximum ratio (TMR) algorithm, which calculates radiation dose without considering heterogeneous radiation attenuation in the tissue. In order to plan the dose considering the radiation attenuation, the Convolution algorithm should be used, and additional radiation exposure for computed tomography (CT) and registration errors between MR and CT are entailed. This study investigated the clinical feasibility of synthetic CT (sCT) from GKRS planning MR using deep learning. The model was trained using frame-based contrast-enhanced T1-weighted MR images and corresponding CT slices from 54 training subjects acquired for GKRS planning. The model was applied prospectively to 60 lesions in 43 patients including benign tumor such as meningioma and pituitary adenoma, metastatic brain tumors, and vascular disease of various location for evaluating the model and its application. We evaluated the sCT and compared between treatment plans made with MR only (TMR 10 plan), MR and real CT (rCT; Convolution with rCT [Conv-rCT] plan), and MR and synthetic CT (Convolution with sCT [Conv-sCT] plan). The mean absolute error (MAE) of 43 sCT was 107.35 ± 16.47 Hounsfield units. The TMR 10 treatment plan differed significantly from plans made by Conv-sCT and Conv-rCT. However, the Conv-sCT and Conv-rCT plans were similar. This study showed the practical applicability of deep learning based on sCT in GKRS. Our results support the possibility of formulating GKRS treatment plans while considering radiation attenuation in the tissue using GKRS planning MR and no radiation exposure.

Robust Co alloy design for Co interconnects using a self-forming barrier layer.

With recent rapid increases in Cu resistivity, RC delay has become an important issue again. Co, which has a low electron mean free path, is being studied as beyond Cu metal and is expected to minimize this increase in resistivity. However, extrinsic time-dependent dielectric breakdown has been reported for Co interconnects. Therefore, it is necessary to apply a diffusion barrier, such as the Ta/TaN system, to increase interconnect lifetimes. In addition, an ultrathin diffusion barrier should be formed to occupy as little area as possible. This study provides a thermodynamic design for a self-forming barrier that provides reliability with Co interconnects. Since Cr, Mn, Sn, and Zn dopants exhibited surface diffusion or interfacial stable phases, the model constituted an effective alloy design. In the Co-Cr alloy, Cr diffused into the dielectric interface and reacted with oxygen to provide a self-forming diffusion barrier comprising Cr2O3. In a breakdown voltage test, the Co-Cr alloy showed a breakdown voltage more than 200% higher than that of pure Co. The 1.2 nm ultrathin Cr2O3 self-forming barrier will replace the current bilayer barrier system and contribute greatly to lowering the RC delay. It will realize high-performance Co interconnects with robust reliability in the future.