UNASSIGNED: Frameless Gamma Knife stereotactic radiosurgery (GKSRS) has become an effective supplement to frame-based, which is however sensitive to patient\'s involuntary motions and prone to prolonged treatment duration. Such delays during treatment inevitably result in patient discomfort and the inability to complete intended treatment. The purpose of this study is to investigate whether active coaching during frameless GKSRS can reduce actual treatment duration.
UNASSIGNED: Patients treated at a single institution with frameless GKSRS from 2017 to 2020 were retrospectively identified. Beginning in 2019, all patients treated with frameless GKSRS were actively coached to prevent treatment interruptions. Patient characteristics and treatment plans were compared between the cohorts of patients treated with and without active coaching. Linear regressions between the planned and actual treatment duration of treatment sessions were performed on either cohort. ANOVA and Wilcoxon tests were used for statistical analyses with a p-value less than 0.05 considered as significant.
UNASSIGNED: Of the total 43 patients and 105 treatment sessions identified, 27 patients underwent 51 treatment sessions of frameless GKSRS with active coaching. There was no significant difference in patient characteristics and treatment plans between the two cohorts. Patients treated with active coaching underwent significantly fewer CBCTs during treatment. The median planned and actual treatment durations were 31.4 and 51.7 min for the non-coached cohort, and 38.6 and 49.8 min for the coached cohort. The results of linear regressions showed that the actual treatment duration was 1.29 and 1.56 times longer with and without active coaching, respectively, which indicated a significant reduction in the actual treatment duration with active coaching.
UNASSIGNED: Our results suggest that active coaching was associated with significant reductions of actual treatment duration. This simple intervention can be clinically implemented to prevent unnecessary treatment interruptions, improve patient comfort and ensure completion of treatment as prescribed during frameless GKSRS.

UNASSIGNED: Early identification of patients who will experience delayed-onset pain relief after GKRS for trigeminal neuralgia (TN) will allow optimal patient management, and avoidance of unnecessary procedures. A non-invasive tool to identify late responders to GKRS is currently unavailable. We sought to evaluate MRI based diffusivity metrics obtained at the 3-month post-GKRS time point as predictors of treatment response.
UNASSIGNED: Pre-procedural and 3-month post-procedural 3T MRI examinations were obtained in 43 patients with TN. Diffusion tensor metrics including axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) were extracted from the bilateral trigeminal nerve intra-pontine fibers, cisternal radiosurgical targets (or corresponding contralateral nerve segments), and non-targeted cisternal nerve segments. A favorable treatment response was defined as pain intensity on the Barrow Neurological Institute (BNI) scale of I-II at last follow-up. Pain relief and treatment response at last follow-up were examined for correlation with the 3-month post-GKRS diffusivity metrics.
UNASSIGNED: At a median clinical follow-up of 5 months (range 0.5 to 24.5 months), all patients who did not experience pain relief at last follow-up had significantly reduced cisternal AD values (p=0.04) at the 3-month brain Diffusion Tensor image. In patients with classic TN, reduced mean cisternal AD (p=0.032), RD (p=0.026), and FA (p=0.042) values at the 3-month DTI follow-up were associated with BNI >2 at last follow-up. In addition, decreased mean cisternal AD (p=0.036), RD (p=0.029), and FA (p=0.037) were noted in patients with classic TN that failed to achieve a decrease of 2 points on the BNI scale at last follow-up.
UNASSIGNED: Alterations of diffusivity metrics on the treated trigeminal nerve 3 months after GKRS for classic TN significantly correlated with no response to GKRS at last follow-up. Further studies to clarify the value of DTI as a non-invasive tool to predict response to treatment in patients with TN managed with GKRS are warranted.

Stereotactic radiosurgery (SRS) is an established modality of treatment for vestibular schwannomas (VS). We aim to summarize the evidence-based use of SRS in VSs and address the specific considerations pertaining to the same, along with our own clinical experiences. A thorough review of the literature was done to gather evidence regarding the safety and efficacy of SRS in VSs. Additionally, we have reviewed the senior author\'s experience in treating VSs (N = 294) between 2009 and 2021 and our experiences with microsurgery in post-SRS patients. Available scientific evidence upholds the role of SRS in VSs, in small-to-medium-sized tumors (5-year local tumor control >95%). The risk of adverse radiation effects remains minimal, while the hearing preservation rates are variable. Our center\'s post-GammaKnife VS follow-up cohort (sporadic - 157, neurofibromatosis-2 - 14) showed excellent tumor control rates at the last follow-up of 95.5% (sporadic) and 93.8% (neurofibromatosis-2), with a median margin dose of 13 Gy and mean follow-up periods of 3.6 (sporadic) and 5.2 (neurofibromatosis-2) years. Microsurgery in post-SRS VSs poses a formidable challenge due to the resulting thickened arachnoid and adhesions to critical neurovascular structures. Near-total excision is the key to better functional outcomes in such cases. SRS is here to stay as a trusted alternative in the management of VSs. Further studies are required to propose means of accurate prediction of hearing preservation rates and also to compare the relative efficacies of various SRS modalities.

UNASSIGNED: To determine factors associated with increased risk of finding new and/or enlarged brain metastases (BM) on GammaKnife™ (GK) MRI and their impact on patient outcomes.
UNASSIGNED: 43.9% of patients showed BM growth, 32.9% had additional brain metastases (aBM), and 18.1 % had both. Initial brain metastasis velocity (iBMV) was associated with finding aBM. Time between diagnostic MRI (dMRI) and GK MRI was associated with interval growth and each day increased this risk by 2%. Prior brain metastasectomy and greater time between either dMRI or latest extracranial RT and GK MRI predicted both aBM and BM growth. aBM and/or BM growth led to management change in 1.8% of cases and were not associated with OS or incidence of distant intracranial failure.
UNASSIGNED: Number of metastases seen on dMRI and iBMV predicted both aBM and/or BM growth, however, these factors did not significantly affect survival or incidence of distant intracranial failure.

This study investigated the impact of patient motion on the dosimetric quality of treatment plans for metastatic patients undergoing frameless GammaKnife® Icon™ treatments. By quantifying dosimetric robustness at increasing high definition motion management (HDMM) gating tolerances, this study investigated the possibility of increasing the HDMM threshold for patients treated at our centre from our current standard of 1 mm.
UNASSIGNED: Motion was retrospectively simulated by shifting the stereotactic co-ordinates of shots in treatment plans using three motion models. Dosimetric quality indicators of original and shifted plans were compared. Influence of target location and size was determined.
UNASSIGNED: Motion models showed median (p-value) absolute changes in target coverage of up to -0.133% (<0.0001), -0.267% (<0.0001) and -0.667% (<0.0001) for HDMM tolerances of 1mm, 1.5mm and 3mm. The greatest median (p-value) absolute changes in Paddick Conformity Index (PCI) and Gradient Index (GI) were -0.008 (0.0032) and 0.017 (0.6893). A reduction in target size correlated weakly with greater changes in target coverage for all models and HDMM tolerances (r2 =0.040-0.309). No location dependence was observed.
UNASSIGNED: HDMM tolerances up to and including 3mm all resulted in negligible changes in PCI and GI. Target coverage exhibited greater sensitivity to motion, but only at 3mm was the target coverage reduced below local planning aims. Our HDMM tolerance could therefore potentially be increased to 1.5mm, with likely benefits to treatment delivery efficiency.

We evaluated the effect of lesion number and volume for brain metastasis treated with SRS using GammaKnife® ICON™ (GK) and CyberKnife® M6™ (CK). Four sets of lesion sizes (<5 mm, 5-10 mm, >10-15 mm, and >15 mm) were contoured and prescribed a dose of 20 Gy/1 fraction. The number of lesions was increased until a threshold mean brain dose of 8 Gy was reached; then individually optimized to achieve maximum conformity. Across GK plans, mean brain dose was linearly proportional to the number of lesions and total GTV for all sizes. The numbers of lesions needed to reach this threshold for GK were 177, 57, 29, and 10 for each size group, respectively; corresponding total GTVs were 3.62 cc, 20.37 cc, 30.25 cc, and 57.96 cc, respectively. For CK, the threshold numbers of lesions were 135, 35, 18, and 8, with corresponding total GTVs of 2.32 cc, 12.09 cc, 18.24 cc, and 41.52 cc respectively. Mean brain dose increased linearly with number of lesions and total GTV while V8 Gy, V10 Gy, and V12 Gy showed quadratic correlations to the number of lesions and total GTV. Modern dedicated intracranial SRS systems allow for treatment of numerous brain metastases especially for ≤10 mm; clinical evidence to support this practice is critical to expansion in the clinic.

UNASSIGNED: The evolution of cavernous sinus meningiomas (CSMs) might be unpredictable and the efficacy of their treatments is challenging due to their indolent evolution, variations and fluctuations of symptoms, heterogeneity of classifications and lack of randomized controlled trials. Here, a dedicated task force provides a consensus statement on the overall management of CSMs.
UNASSIGNED: To determine the best overall management of CSMs, depending on their clinical presentation, size, and evolution as well as patient characteristics.
UNASSIGNED: Using the PRISMA 2020 guidelines, we included literature from January 2000 to December 2020. A total of 400 abstracts and 77 titles were kept for full-paper screening.
UNASSIGNED: The task force formulated 8 recommendations (Level C evidence). CSMs should be managed by a highly specialized multidisciplinary team. The initial evaluation of patients includes clinical, ophthalmological, endocrinological and radiological assessment. Treatment of CSM should involve experienced skull-base neurosurgeons or neuro-radiosurgeons, radiation oncologists, radiologists, ophthalmologists, and endocrinologists.
UNASSIGNED: Radiosurgery is preferred as first-line treatment in small, enclosed, pauci-symptomatic lesions/in elderly patients, while large CSMs not amenable to resection or WHO grade II-III are candidates for radiotherapy. Microsurgery is an option in aggressive/rapidly progressing lesions in young patients presenting with oculomotor/visual/endocrinological impairment. Whenever surgery is offered, open cranial approaches are the current standard. There is limited experience reported about endoscopic endonasal approach for CSMs and the main indication is decompression of the cavernous sinus to improve symptoms. Whenever surgery is indicated, the current trend is to offer decompression followed by radiosurgery.

OBJECTIVE: Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases.
METHODS: Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors.
RESULTS: Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7 months (range 0.5-47.6). The median total dose and prescription isodose was 27.5 Gy (range, 20-27.5) in 5 daily fractions and 52% (range, 45-93), respectively. The median overall survival (OS) was 12.7 months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5 Gy vs. ≤ 25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5 cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE.
CONCLUSIONS: Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE.

OBJECTIVE: According to A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) conservative treatment seems to be superior to any intervention for unruptured brain arteriovenous malformations (AVM). This study aims to evaluate safety and efficacy of upfront and repeated Gamma-Knife Radiosurgery (GKRS) in patients harbouring small AVM fulfilling the inclusion criteria of ARUBA.
METHODS: A retrospective study was conducted to evaluate outcomes of unruptured naive brain AVM with a volume ⩽ 5cc eligible to ARUBA treated by GKRS with at least 3 years of follow-up.
RESULTS: From 1992 to 2014, 249 patients were fulfilling the inclusion criteria of this study. The median age was 36 years [18-78]. The median treated volume of the nidus was 1.3 cc [0.4-5] and 63% of the AVM were in eloquent areas. Radiosurgery Based AVM score was 1-1.8 (76%), the Spetzler-Martin grade was II-III (73%), and the Virginia Radiosurgery AVM scale was ≤1point (75%). The overall AVM obliteration rate was 77.1% after up to 3 GKRS sessions. The median dose at the margin was 24 Gy [15-25] and the median follow-up was 45 months [36-205]. Eight patients (3.2%) experienced hemorrhage after GKRS, corresponding to a post-GKRS hemorrhage annual rate of 1.03%. Permanent symptomatic radio-induced changes rate was 2% (4 increased seizures, 1 neurological deficit).
CONCLUSIONS: The very low toxicity rate and the high occlusion rate are preaching in favor of upfront and repeated GKRS for unruptured small AVM (≤5cc).

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