RT-1 Treatment results of salvage gamma knife stereotactic radiosurgery and bevacizumab (AVAgamma therapy) for recurrent malignant glioma

Purpose: We report the treatment results of AVAgamma therapy combining gamma knife (GK) and bevacizumab for recurrent malignant glioma. Subjects: From August 2013 to January 2021, 71 patients (Grade 2:8 patients, Grade3:16 patients, Grade 4:47 patients) with recurrent malignant glioma treated with AVAgamma therapy as salvage therapy at the time of relapse after initial treatment. The average age is 55.7 years, with 44 men and 27 women. The tumor volume is 150 ml or less, and KPS is 40% or more as the indication of AVAgamma therapy. When the irradiation volume of the gamma knife was 15 ml or less, the marginal dose was 20 to 26 Gy, and when the irradiation volume was 15 ml or more, the marginal dose was 12 to 15 Gy in two divided doses.The mean therapeutic borderline dose was 24 Gy. Bevacizumab was administered 10 mg / kg or 15 mg / kg 1 to 10 times after GK. Methods: Median progression-free survival (mPFS) from AVAgamma treatment, median survival (mOS), and mOS from initial treatment were examined and compared with mOS in the RPA classification of recurrent glioma. Results: In relapsing glioma RPA classification, NABTT CNC class 2 mOS is 17.2 months, class 3 mOS is 3.8 months, class 5 mOS is 5.6 months, class 6 mOS is 6.4 months, but mOS from AVAgamma therapy is 18 months in class 3, 11 months in class 5, 9 months in class 6. The survival time has been extended in class3, class5, class6. Discussion: By AVAgamma therapy, it was thought that recurrent lesions were locally controlled and life prognosis was prolonged. Conclusion: AVAgamma therapy is thought to prolong the survival of recurrent malignant glioma and play an important role as salvage treatment.

Segmentation of vestibular schwannoma from MRI, an open annotated dataset and baseline algorithm

Automatic segmentation of vestibular schwannomas (VS) from magnetic resonance imaging (MRI) could significantly improve clinical workflow and assist patient management. We have previously developed a novel artificial intelligence framework based on a 2.5D convolutional neural network achieving excellent results equivalent to those achieved by an independent human annotator. Here, we provide the first publicly-available annotated imaging dataset of VS by releasing the data and annotations used in our prior work. This collection contains a labelled dataset of 484 MR images collected on 242 consecutive patients with a VS undergoing Gamma Knife Stereotactic Radiosurgery at a single institution. Data includes all segmentations and contours used in treatment planning and details of the administered dose. Implementation of our automated segmentation algorithm uses MONAI, a freely-available open-source framework for deep learning in healthcare imaging. These data will facilitate the development and validation of automated segmentation frameworks for VS and may also be used to develop other multi-modal algorithmic models.

Mean Brain Dose Remains Uninfluenced by Lesion Number for Gamma Knife Stereotactic Radiosurgery for Ten+ Metastases

Purpose:Gamma Knife (GK) stereotactic radiosurgery (SRS) is increasingly used as an initial treatment for patients with ten or more brain metastases (BM). However, the clinical and dosimetric consequences of this practice are not well established.Methods: We performed a single institution, retrospective analysis of 30 patients who received GK SRS for ten or more BM in one session. We utilized MIM Software to contour the whole brain and accumulated the doses from all treated lesions to determine the mean dose delivered to the whole brain. Patient outcomes were determined from chart review. Results: Our cohort had a median number of 13 treated lesions (range 10 to 26 lesions) for a total of 427 treated lesions. The mean dose to the whole brain was determined to be 1.8 ± 0.91 Gy (range 0.70 to 3.8 Gy). Mean dose to the whole brain did not correlate with the number of treated lesions (Pearson r=0.23, p=0.21), but was closely associated with tumor volume (Pearson r=0.95, p<0.0001). There were no significant correlations between overall survival and number of lesions or aggregate tumor volume. Fourteen patients (47%) underwent additional SRS sessions and six patients (20%) underwent WBRT a median of 6.6 months (range 3.0-50 months) after SRS. Two patients (6.6%) developed grade 2 radionecrosis following SRS beyond earlier WBRT.Conclusion: The mean dose to the whole brain in patients treated with GK SRS for 10 or more BM remained low with an acceptable rate of radionecrosis. This strategy allowed the majority of patients to avoid subsequent WBRT.

Segmentation of vestibular schwannoma from MRI - An open annotated dataset and baseline algorithm

Automatic segmentation of vestibular schwannomas (VS) from magnetic resonance imaging (MRI) could significantly improve clinical workflow and assist patient management. We have previously developed a novel artificial intelligence framework based on a 2.5D convolutional neural network achieving excellent results equivalent to those achieved by an independent human annotator. Here, we provide the first publicly-available annotated imaging dataset of VS by releasing the data and annotations used in our prior work. This collection contains a labelled dataset of 484 MR images collected on 242 consecutive patients with a VS undergoing Gamma Knife Stereotactic Radiosurgery at a single institution. Data includes all segmentations and contours used in treatment planning and details of the administered dose. Implementation of our automated segmentation algorithm uses MONAI, a freely-available open-source framework for deep learning in healthcare imaging. These data will facilitate the development and validation of automated segmentation frameworks for VS and may also be used to develop other multi-modal algorithmic models.

Gamma Knife Stereotactic Radiosurgery for Conjunctival Squamous Cell Carcinoma Invading the Anterior Orbit: A Case Series

<b><i>Introduction:</i></b> The aim of the study was to report our experience in the use of Gamma Knife Stereotactic Radiosurgery (GKSTRS) for conjunctival squamous cell carcinoma (SCC) invading the orbit, as an alternative to exenteration surgery. <b><i>Patients and Methods:</i></b> Patients who had GKSTRS for conjunctival SCC invading the orbit but sparing the bone (AJCC eighth ed. T4a) with a minimum of 1-year follow-up were included. Treatment failure was defined as no decrease in tumour size 3 months post-treatment, or further growth during the follow-up period. Patients were followed up 3-monthly for 2 years and 6-monthly afterwards with a minimum of yearly MR Imaging of orbit. <b><i>Results:</i></b> Six patients met the inclusion criteria. MR imaging was used to identify the extent of orbital involvement of SCC. Stereotactic radiosurgery utilizing the Leksell Gamma Knife® Perfexion was delivered in a single session in which patients received 18–20 Gy to the 45–50% isodose. The median follow-up was 29 months. Four patients responded to the treatment and had no evidence of recurrence at their most recent follow-up. The treatment failed in 2 patients, in 1 of whom the tumour was larger and extended deeper into the orbit. The other patient developed a recurrence away from the treated area at 9 months, suggesting a multifocal disease. Both patients had poorly differentiated SCC. <b><i>Conclusion:</i></b> GKSTRS is a potential alternative to orbital exenteration surgery for conjunctival SCC extending into the anterior orbit in a selected group of patients refusing orbital exenteration or has a second blind eye. Nevertheless, the disease is more likely to recur than with exenteration surgery, hence lifelong monitoring and low threshold for surgical intervention or retreatment is prudent.

Gamma Knife stereotactic radiosurgery for intraocular retinoblastoma: a 5-year experience

External beam radiotherapy (EBR) remained for a long time the only method of treatment in children with recurrent and resistant retinoblastoma (RB). This method often leads to serious complications, including the occurrence of secondary malignant tumors. Currently, EBR is used as second-line (salvage) therapy. There is no data in the literature of using Gamma Knife stereotactic radiosurgery (GKRS) in RB treatment. Purpose. To present 5-year experience of using GKRS in patients with RB. Material and methods. 16 children (17 eyes) were treated using GKRS in the period from 2015 to 2019. Mean patient age was 34.7 months (range, 12–114 months). The eyes were classified as group B (n=4), C (n=1), D (n=12). 3 children had the last eye. All patients received systemic and local chemotherapy, all types of local treatment modalities before using GKRS. Recurrent and resistant RB was the indication for GKRS. Marginal 50% mean dose was 22 Gу (range, 20–24 Gу), depending on tumour type and location. Radiation doses were evaluated accounting critical eye structures and the orbit bones. Results. Complete regression was achieved in 11 patients, partial in 2. Four patients underwent enucleation after GKRS. Indications for enucleation were retinoblastoma recurrence (n=2) and vitreous hemorrhage with total retinal detachment (n=2). 13 eyes were salvaged with no signs of keratopathy, uveitis or damage of orbital and surrounding tissues during mean follow-up 30.6 months (range, 7–60 months). Сomplications of different severity occurred in 13 patients, including vitreous hemorrhage in 6 patients, which was successfully treated both conservative (n=3) and using pars plana vitrectomy with simultaneous melphalan irrigation (n=3). Conclusion. The first experience of GKRS as an alternative to enucleation in patients with RB was proved to be reasonable and successful. Key words: retinoblastoma, gamma-knife, stereotactic radiosurgery.

The Effect of Prescription Isodose Variation on Tumor Control and Toxicities in Stereotactic Radiosurgery for Sporadic Vestibular Schwannoma: Propensity Score-Matched Case–Control Study

Objective Vestibular schwannoma (VS) treated with Gamma Knife stereotactic radiosurgery (SRS) was typically performed at 50% isodose line (IDL50); however, the impact of IDL variation on outcomes is poorly understood. This study aimed to compare tumor control (TC) and toxicities between treatment at 40% (IDL40) and 50% (IDL50). Methods and Materials Sporadic/unilateral VS patients treated with SRS dose 12 to 14 Gy and prescription isodose volume ≤10cm3 were included. Propensity score matching was applied to IDL40 cohort to generate an IDL50 companion cohort, adjusting for age and prescription isodose volume. After exclusion of patients with follow-up <24 months, there were 30 and 28 patients in IDL40 and IDL50 cohorts, respectively. Results Median follow-up time was 96 months (24–225 months). Actuarial and radiographic TC rates were 91.8% and clinical TC was 96.2% both at 5 and 10 years. TC was higher in IDL40 cohort but not significant (96.4 vs. 86.7%; p = 0.243). Hearing preservation (HP) rates were 71.9 and 39.2% at 5- and 10-year intervals, with significantly higher rates of HP noted in IDL40 cohort (83.3 vs. 57.1% at 5-year interval; 62.5 vs. 11.4% at 10-year interval; p = 0.017). Permanent facial neuropathy occurred in two patients, both from the IDL50 cohort (3.5%). Rates of post-SRS steroid treatment or shunt placement for hydrocephalus were slightly higher in IDL50 patients (6.9 vs. 17.9%; p = 0.208 and 3.3 vs. 7.1%; p = 0.532). Conclusion For treatment of VS with SRS, dose prescription at IDL40 or IDL50 provides excellent long-term TC and toxicity profiles. IDL40 may be associated with improved long-term HP.