Radiosurgery Research Articles

Limitations of outcome prediction based on interfractional volume changes of large (≥ 10cm3) brain metastases during fractionated gamma knife radiosurgery.

This study investigated the interfractional volume changes of large (≥ 10 cm3) brain metastases (BMs) during fractionated gamma knife radiosurgery (FGKRS) to assess its predictive value for tumor control outcomes. The patients who underwent FGKRS for large BMs between January 2017 and December 2022 in our center were reviewed. The interfractional volume change was defined as the disparity in tumor volume (TV) measured between the magnetic resonance images acquired on the first treatment day and those obtained after 2 or 3 fractions during the course of FGKRS. A total of 73 lesions in 70 patients with various primary pathologies were included. Over a median follow-up period of 11months (range 1-77), the tumor control rate was 63%. Initial TV (cm3) was associated with progression free survival (PFS) and overall survival (OS) in both univariate and multivariate analyses (p = 0.01). Interfractional TV changes revealed an increase in 13 (17.8%) lesions, no change in 14 (19.2%) lesions, and a decrease in 46 (63.0%) lesions, with a mean volume reduction of 5% ± 0.12. Three cut-offs (5%, 10% and 15% volume decrement) were established and patients were divided into two groups based on each reference point. However, there were no significant differences in PFS and OS between the two groups, irrespective of the chosen cut-off value used. Interfractional volume changes of large BMs were not found to be associated with tumor control outcomes. Neither significant interfractional volume reduction nor significant volume increase necessarily predicts the tumor control, making early close monitoring essential after FGKRS.

Endosaccular Coil Embolization of Ruptured Anterior Inferior Cerebellar Artery Pseudoaneurysm After Gamma Knife Surgery for Vestibular Schwannoma: A Case Report and Literature Review

Background: Ruptured pseudoaneurysm of the distal anterior inferior cerebellar artery (AICA) in patients with a history of gamma knife surgery (GKS) for vestibular schwannoma (VS) is rare. Several previous reports have described treatment strategies for radiation-induced pseudoaneurysm in the AICA: either surgical trapping or endovascular parent artery occlusion of the AICA. Methods: We present the first case of endosaccular coil embolization for a ruptured pseudoaneurysm in a large-diameter AICA after GKS for VS, successfully preserving the parent AICA. Results: Major recanalization of the coiled pseudoaneurysm was observed on follow-up imaging 3 months after the initial endovascular treatment. The patient subsequently underwent additional endosaccular coil embolizations for regrowth of the treated pseudoaneurysm buried in the VS. Two years later, another major recanalization was detected, prompting further retreatment. Subsequently, the patient has remained in a stable condition for 4 years. Conclusions: We suggest that endosaccular coil embolization of the distal AICA aneurysm with parent artery preservation might be a safe and feasible treatment option for radiation-induced saccular pseudoaneurysm arising from a large parent artery. However, close and regular follow-up imaging and preparation for potential retreatment are necessary, as pseudoaneurysms coiled within VSs are prone to recanalization.

Stereotactic radiotherapy for patients with bone metastases: a selected group with low rate of radiation treatment during the last month of life?

BackgroundComplex high-precision radiotherapy, such as stereotactic body radiotherapy (SBRT), should only be offered to patients with sufficiently long survival. In the context of bone metastases radiotherapy, low rates of treatment close to the end of life, e.g. last 30 days (RT30), may serve as a quality of care indicator. While traditional, pain-relieving short-course regimens have been studied comprehensively, real-world SBRT results are still limited.MethodsRetrospective analysis (2010–2023, n = 1117 episodes) of patients with bone metastases treated with traditional single-fraction (8 Gy × 1) or multi-fraction regimens (often 4 Gy × 5 or 3 Gy × 10) compared to stereotactic single-fraction (12–16 Gy × 1) or multi-fraction regimens.ResultsExcept for gender, almost all baseline variables were uneven distributed. Failure to complete fractionated radiotherapy was uncommon in the stereotactic (4%) and non-stereotactic group (3%), p = 1.0. With regard to RT30, relevant differences emerged (19% for 8-Gy single-fraction versus 0% for stereotactic single-fraction, p = 0.01). The corresponding figures were 11% for multi-fraction non-stereotactic and 2% for multi-fraction stereotactic, p = 0.08. Median overall survival was shortest after 8-Gy single-fraction irradiation (4.2 months) and longest after stereotactic multi-fraction treatment (13.9 months). Neither stereotactic radiotherapy nor multi-fraction treatment improved survival in multivariate Cox regression analysis. Factors significantly associated with longer survival included better performance status, lower LabBM score (5 standard blood test results), stable disease outside of irradiated area(s), metachronous distant metastases, longer time interval from metastatic disease to bone irradiation, and outpatient status.ConclusionThe implementation of SBRT for selected patients has resulted in low rates of non-completion and RT30. Optimal selection criteria remain to be determined, but in current clinical practice we exclude patients with poor performance status, unfavorable blood test results (high LabBM score) and progressive disease sites not amenable to SBRT. Established, guideline-endorsed short-course regimens, especially 8-Gy single-fraction treatment, continue to represent an important palliative approach.

Current Radiotherapy Management of Extensive-Stage Small-Cell Lung Cancer in the Immunotherapy Era: An Italian National Survey on Behalf of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

Background: Extensive-stage small-cell lung cancer (ES-SCLC) treatment has recently been revolutionized by the advent of immune checkpoint inhibitors. This survey was conducted to evaluate the current pattern of care among Italian clinicians, in particular about the integration with radiation therapy (RT). Methods: In June 2023, 225 Italian cancer care professionals were invited to complete a 21-question web-based survey about ES-SCLC management through personal contacts and the Italian Association for Radiotherapy and Clinical Oncology (AIRO) network. Results: We received 90 responses; the majority were radiation oncologists (89%) with more than 10 years of experience (51%). The preferred management of ES-SCLC in patients with a good performance status was concomitant chemo-immunotherapy (84%). Almost all respondents recommended prophylactic cranial irradiation (PCI) (85%), taking into account age and thoracic response; PCI was performed mainly between the end of chemotherapy and before starting immunotherapy (37%), with a three-dimensional conformal technique (46%). Furthermore, 83% of respondents choose to deliver thoracic RT in the case of both an intrathoracic and extrathoracic response, with an RT schedule of 30 Gy/10 fractions. Stereotactic RT is increasingly being used in oligoprogressions. Conclusions: Our analysis showed the variability of real-world management of ES-SCLC. Future clinical trials and developments are needed to improve the multidisciplinary treatment of these patients.

Safety and Feasibility of Interventional Hybrid Fluoroscopy and Nuclear Imaging in the Work-up Procedure of Hepatic Radioembolization.

Purpose To evaluate the safety and feasibility of a novel hybrid nuclear and fluoroscopy C-arm scanner to be used during the work-up procedure of hepatic radioembolization. Materials and Methods In this prospective first-in-human clinical study, 12 participants (median age, 67 years [range: 37-78 years]; nine [75%] male, three [25%] female) with liver tumors undergoing work-up for yttrium 90 radioembolization were included (ClinicalTrials.gov NCT06013774). Work-up angiography and technetium 99m-macroaggregated albumin injection were performed in an angiography suite equipped with a hybrid C-arm that could simultaneously perform fluoroscopy and planar nuclear imaging. Technetium 99m-macroaggregated albumin was injected under real-time hybrid imaging, followed by in-room SPECT imaging. Safety and feasibility were studied by assessing adverse events, technical performance, additional x-ray radiation dose, and questionnaires completed by radiologists and technologists. Results No adverse events were attributed to the hybrid C-arm scanner. The additional x-ray radiation dose was low (median, 19 Gy · cm2; minimum: 12 Gy · cm2; maximum: 21 Gy · cm2 for participants who completed all imaging steps). The interventional personnel considered use of the hybrid C-arm scanner safe and feasible, although the additional time spent in the intervention room was considered long (median, 64 minutes; minimum: 55 minutes; maximum: 77 minutes for participants who completed all imaging steps). Conclusion Use of the hybrid C-arm scanner during the work-up procedure of hepatic radioembolization was found to be safe and feasible in this first-in-human clinical study. Keywords: Angiography, Fluoroscopy, Interventional-Vascular, Radionuclide Studies, Radiosurgery, Gamma Knife, Cyberknife, SPECT, Instrumentation, Physics, Technical Aspects, Technology Assessment Supplemental material is available for this article. Published under a CC BY 4.0 license. Clinical trial registration no. NCT06013774.

P188 Stereotactic MRI-guided adaptive radiotherapy for renal tumors in a solitary kidney

P188 Stereotactic MRI-guided adaptive radiotherapy for renal tumors in a solitary kidney

A Comparison of Stereotactic Radiation Therapy in Elderly Patients with Central or Peripheral Stage I-II (T1-3 N0 M0) Non-Small Cell Lung Cancer

A Comparison of Stereotactic Radiation Therapy in Elderly Patients with Central or Peripheral Stage I-II (T1-3 N0 M0) Non-Small Cell Lung Cancer

PSOR07 Presentation Time: 12:00 PM: Salvage Tumor-Targeted HDR Brachytherapy Boost to Stereotactic Radiotherapy: Early Experience

PSOR07 Presentation Time: 12:00 PM: Salvage Tumor-Targeted HDR Brachytherapy Boost to Stereotactic Radiotherapy: Early Experience

Investigation of intrafractional spinal cord and spinal canal movement during stereotactic MR-guided online adaptive radiotherapy for kidney cancer.

This study aimed to investigate the intrafractional movement of the spinal cord and spinal canal during MR-guided online adaptive radiotherapy (MRgART) for kidney cancer. All patients who received stereotactic MRgART for kidney cancer between February 2022 and February 2024 were included in this study. Patients received 30-42 Gy in 3-fraction MRgART for kidney cancer using the Elekta Unity, which is equipped with a linear accelerator and a 1.5 Tesla MRI. MRI scans were performed at three points during each fraction: for online planning, position verification, and posttreatment assessment. The spinal cord was contoured from the upper edge of Th12 to the medullary cone, and the spinal canal was contoured from Th12 to L3, using the first MRI. These contours were adjusted to the second and third MR images via deformable image registration, and movements were measured. Margins were determined via the formula "1.3×Σ+0.5×σ" and 95% prediction intervals. A total of 22 patients (66 fractions) were analyzed. The median interval between the first and third MRI scans were 38 minutes. The mean ± standard deviation of the spinal cord movements after this interval were -0.01 ± 0.06 for the x-axis (right-left), 0.01 ± 0.14 for the y-axis (caudal-cranial), 0.07 ± 0.05 for the z-axis (posterior-anterior), and 0.15 ± 0.08 for the 3D distance, respectively. The correlation coefficients of the 3D distance between the spinal cord and the spinal canal was high (0.92). The calculated planning organ at risk volume margin for all directions was 0.11 cm for spinal cord. The 95% prediction intervals for the x-axis, y-axis, and z-axis were -0.11-0.09 cm, -0.23-0.25 cm and -0.14-0.03 cm, respectively. Margins are necessary in MRgART to compensate for intrafractional movement and ensure safe treatment delivery.

Stereotactic radiosurgery (SRS) for patients with brainstem cerebral cavernous malformations (CCMs): an international, multicentric study

Brainstem cerebral cavernous malformations (CCM) are clinically more aggressive compared to superficial CCMs. Due to their location, resection can be challenging, making stereotactic radiosurgery (SRS) an attractive alternative for symptomatic patient. Brainstem CCM patients (n = 170) were treated with Gamma Knife SRS at 11 radiosurgical centers. Hemorrhagic risk reduction, risk factors of post-SRS hemorrhage, and clinical outcomes were retrospectively analyzed. Most patients had a single (165/170 patients) brainstem CCMs treated; the majority of CCMs (165/181) presented with bleeding. Single-session SRS decreased the risk of repeat hemorrhage in patients with hemorrhagic brainstem CCM (HR: 0.17, p < 0.001) using recurrent multivariate analysis. The annual hemorrhage rate decreased from 14.8 per 100 CCM-years before SRS to 2.3 after treatment. Using univariate Cox-analysis, the probability of a new hemorrhages after SRS was reduced for patient older than 35 years (HR = 0.21, p = 0.002) and increased with a margin dose > 13 Gy (HR = 2.57, p = 0.044). Adverse radiation effect (ARE) occurred in 9 patients (5.3%) and was symptomatic in four (2.4%). At a median follow-up of 3.4 years (Inter-quartile range: 5.4), 13 patients (8.0%) had a worsened clinical status, with the treated CCM being the cause in 5.6% (10) of the patients. Single-session SRS decreased the risk of repeat hemorrhage in patients with hemorrhagic brainstem CCM and conveyed this benefit with a low risk of advrse radiation effects (ARE) and worsening clinical status.

3D target definition and initial results from the electroanatomic substrate-guided stereotactic ablative radiotherapy for refractory ventricular tachycardia (ELSTAR-VT)

Abstract Background/introduction Noninvasive stereotactic radiotherapy (STAR) is an emerging transmural ablative therapy for refractory ventricular tachycardia (VT). Delineation of the arrhythmogenic gross target volume (GTV) relies on electrical (exit and isthmus) VT characteristics and anatomical scar detailing. 17-AHA segmental approaches or eyeballing techniques are adopted to transfer the GTV to the treatment planning CT. An individualized 3D GTV delineated with ADAS3D based on the areas of interest of each modality could lead to a smaller GTV compared to 17-AHA segmental approaches. Purpose We investigated whether our workflow using ADAS3D for the delineating of the GTV renders smaller GTV compared to 17-AHA segmental approaches whilst remaining effective for VT treatment during follow-up. Methods We targeted 3D-personalized GTV with STAR in patients with refractory VT in structural heart disease. Electroanatomical detailing was achieved by combining high-resolution invasive and noninvasive (ECG imaging during noninvasive programmed stimulation) mapping, combined with wall thickness analyses by cardiac CT. After coregistration in ADAS3D, a 3D DICOM-radiation therapy file including the delineated target volume was generated and transferred into the free-breathing and respiration-corrected 4D CT scan. Standard STAR using a single-fraction of 20-25 Gy was applied. We compared conventional (17-AHA segmental approaches) versus 3D-based GTV demarcation, and assessed VT burden and procedural safety. Results From January 2023 to February 2024 STAR was successfully performed in three patients (all male, mean age 73±1 years, two ischemic cardiomyopathy, one laminopathy) with persistent VT despite ≥2 catheter-based (endocardial/epicardial) ablation procedures. The 3D-derived GTVs showed a statistical trend towards smaller volumes compared to conventional segmental delineation (11±4 versus 21±3 cm3, p=0.07). VT burden and ICD therapy was reduced by 100% over 9 patients-months (8-week blanking period). No acute or subacute adverse events occurred. One patient died of progressive heart failure. Conclusion 3D-individualized target volume annotation may hold promise for effective and safe STAR employment.ELSTAR workflow

Twelve-year experience of pineal region meningiomas: long-term outcomes of maximal safe resection.

The purpose of this research was to summarize the clinical and prognostic features of pineal region meningiomas, evaluate treatment strategies and long-term prognoses, and improve the management of pineal region meningiomas. We retrospectively studied the data of 37 patients who received surgical resection for pineal region meningiomas at West China Hospital of Sichuan University from 2009 to 2021. Adjuvant gamma knife radiosurgery (GKRS) was conducted according to the extent of resection (EOR). Progression-free survival (PFS), Karnofsky performance status (KPS) scores and recovery of neurological function were adopted to assess a comprehensive management strategy for pineal region meningiomas. The most common symptom was headache associated with intracranial hypertension (75.7%). The occipital transtentorial approach (40.5%) and supracerebellar infratentorial approach (29.7%) were performed in most cases. Gross total resection (GTR) was achieved in 27 patients (73.0%) and the remaining patients were treated with subtotal resection (STR) combined with postoperative GKRS. With a mean follow-up period of 87.0 months, the progression rate was 10.0%, the 5-year PFS rate was 92.9%, and the ΔKPS was 16.3. Multivariate analysis revealed that the STR + GKRS and supracerebellar infratentorial approach were beneficial to the recovery of quality of life of patients. Pineal region meningiomas are sporadic but challenging. It is necessary to select the most appropriate surgical approach, EOR, and hydrocephalus treatment strategy for patients with pineal region meningiomas. Maximal safe resection to protect neurovascular function combined with postoperative GKRS can significantly improve the quality of life of patients.

MSOR6 Presentation Time: 5:25 PM: Intraoperative or Postoperative Stereotactic Radiotherapy for Brain Metastases: Time to Systemic Treatment Onset and Other Patient-Relevant Outcomes

MSOR6 Presentation Time: 5:25 PM: Intraoperative or Postoperative Stereotactic Radiotherapy for Brain Metastases: Time to Systemic Treatment Onset and Other Patient-Relevant Outcomes

Gold-siRNA supraclusters enhance the anti-tumor immune response of stereotactic ablative radiotherapy at primary and metastatic tumors.

Strategies to enhance the anti-tumor immune response of stereotactic ablative radiotherapy (SABR) at primary tumors and abscopal sites are under intensive investigation. Here we report a metabolizable binary supracluster (BSCgal) that combines gold nanoclusters as radiosensitizing adjuvants with small interfering RNA (siRNA) targeting the immunosuppressive mediator galectin-1 (Gal-1). BSCgal comprises reversibly crosslinked cationic gold nanoclusters and siRNA complexes in a polymer matrix that biodegrades over weeks, facilitating clearance (90.3% in vivo clearance at 4 weeks) to reduce toxicity. The particle size well above the renal filtration threshold facilitates passive delivery to tumors. Using mouse models of head and neck cancer, we show that BSCgal augments the radiodynamic and immunotherapeutic effects of SABR at the primary and metastatic tumors by promoting tumor-inhibitory leukocytes, upregulating cytotoxic granzyme B and reducing immunosuppressive cell populations. It outperforms SABR plus Gal-1 antagonists, chemoradiation drug cisplatin or PD-1 inhibitor. This work presents a translatable strategy to converge focal radiosensitization with targeted immune checkpoint silencing for personalized radioimmunotherapy.

Radiosurgical biologically effective dose on trigeminal root division and section for outcomes of idiopathic trigeminal neuralgia type 1: a multicentre retrospective cohort study

The wide variability in the efficacy of Gamma Knife surgery (GKS) treating trigeminal neuralgia type 1 (TN1) has not been completely elucidated. We aimed to investigate the association between outcomes of TN1 and the radiosurgical biologically effective dose (BED) on the specific part of the trigeminal root. We performed a multicentre retrospective cohort study for 548 patients with refractory TN1 treated by GKS. BED-volume histogram was formed for the trigeminal root, responsible division within the trigeminal root affected by TN1 (RD), trigeminal root section adjacent to the root entry zone (S1) and brainstem to generate the maximum BED (DMaxBED), and the volume percentage enclosed by iso-BED 1000 Gy2.47 (V%BED1000) as plan quality metrics. The outcomes included pain relief, recurrence, and complications. Logistic regression and Cox proportional hazards models were used to analyse BED parameters. There were 344 (62.77%), 144 (26.28%), and 54 (9.85%) patients with Barrow Neurological Institute (BNI) pain relief class III within 1 month, recurrence, and facial hypoesthesia. Patient-level analysis screened V%BED1000 of the trigeminal root associated with BNI class III within 1 month and recurrence. DMaxBED of the brainstem + V%BED1000 of the S1 significantly predicted facial hypoesthesia. Division-level analysis showed that DMaxBED + V%BED1000 of the RD significantly predicted BNI class III within 1 month and recurrence. The efficacy and safety of GKS treating TN1 may depend on the sufficient coverage of high BED on the division affected by pain and tolerated BED on the root entry zone.

Stereotactic Radiotherapy Plus Nivolumab in Patients with Locally Advanced Pancreatic Cancer: Results from Phase 1/2 Clinical CA209-9KH Trial.

The dismal prognosis of pancreatic ductal adenocarcinoma (PDAC) highlights the urgent need for novel therapeutic strategies. Immune checkpoint inhibitors (ICIs) seem to be ineffective in most PDAC studies. Therefore, we conducted an open-label, multicenter phase 1/2 study (CA209-9KH) to evaluate the safety of stereotactic radiotherapy (SRT) and sequential ICI therapy in PDAC, as well as to validate the efficacy of this regimen as a potential activator of antitumor immunity. Patients aged ≥ 18years with unresectable non-metastatic PDAC following four FOLFIRINOX induction cycles were included. Treatment comprised SRT (4 × 8Gy) and sequential nivolumab administration until disease progression or unacceptable toxicity. The primary endpoints were safety and toxicity assessment. Secondary endpoints included progression-free survival (PFS), overall survival (OS), biomarker evaluation, and quality of life (QoL) analysis. Twenty-two patients were screened, with 15 enrolled. Eleven (median) nivolumab cycles were administered. SRT demonstrated low and clinically nonsignificant toxicity, whereas nivolumab toxicity aligned with prior safety profiles, without grade 4-5 events observed. Three patients discontinued therapy owing to toxicity. Median PFS and OS were 8.1 and 13.0months, respectively, with 12-month PFS and OS rates of 0% and 66.7%, respectively, and a 24-month OS rate of 8.9%. Biomarker levels correlated with clinical or radiological disease control. Patient-reported QoL remained acceptable, deteriorating with disease progression. SRT and nivolumab therapy exhibited manageable toxicity profiles consistent with previous findings; however, long-term treatment responses were not achieved with this regimen in locally advanced PDAC. Another strategy to trigger antitumor immunity in PDAC needs to be sought. EudraCT: 2017-003404-52; ClinicalTrials.gov: NCT04098432.

Six-degrees-of-freedom pelvic bone monitoring on 2D kV intrafraction images to enable multi-target tracking for locally advanced prostate cancer.

Patients with locally advanced prostate cancer require the prostate and pelvic lymph nodes to be irradiated simultaneously during radiation therapy treatment. However, relative motion between treatment targets decreases dosimetric conformity. Current treatment methods mitigate this error by having large treatment margins and often prioritize the prostate at patient setup at the cost of lymph node coverage. Treatment accuracy can be improved through real-time multi-target adaptation which requires simultaneous motion monitoring of both the prostate and lymph node targets. This study developed and evaluated an intrafraction pelvic bone motion monitoring method as a surrogate for pelvic lymph node displacement to be combined with prostate motion monitoring to enable multi-target six-degrees-of-freedom (6DoF) tracking using 2D kV projections acquired during treatment. A method to monitor pelvic bone translation and rotation was developed and retrospectively applied to images from 20 patients treated in the TROG 15.01 Stereotactic Prostate Ablative Radiotherapy with Kilovoltage Intrafraction Monitoring (KIM) trial. The pelvic motion monitoring method performed template matching to calculate the 6DoF position of the pelvis from 2D kV images. The method first generated a library of digitally reconstructed radiographs (DRRs) for a range of imaging angles and pelvic rotations. The normalized 2D cross-correlations were then calculated for each incoming kV image and a subset of DRRs and the DRR with the maximum correlation coefficient was used to estimate the pelvis translation and rotation. Translation of the pelvis in the unresolved direction was calculated using a 3D Gaussian probability estimation method. Prostate motion was measured using the KIM marker tracking method. The pelvic motion monitoring method was compared to the ground truth obtained from a 6DoF rigid registration of the CBCT and CT. The geometric errors of the pelvic motion monitoring method demonstrated sub-mm and sub-degree accuracy and precision in the translational directions ( , , ) and rotational directions ( , , ). The 3D relative displacement between the prostate and pelvic bones exceeded 2, 3, 5, and 7mm for approximately 66%, 44%, 12%, and 7% of the images. Accurate intrafraction pelvic bone motion monitoring in 6DoF was demonstrated on 2D kV images, providing a necessary tool for real-time multi-target motion-adapted treatment.

Non-Invasive Treatment of Pterygopalatine Fossa Schwannoma with Gamma Knife Radiosurgery.

Non-Invasive Treatment of Pterygopalatine Fossa Schwannoma with Gamma Knife Radiosurgery.

Can Patient Characteristics and Pre-Treatment MRI Features Predict Survival After Stereotactic Ablative Radiotherapy (SABR) Treatment in Hepatocellular Carcinoma (HCC): Preliminary Assessment.

The study purpose was to develop a machine learning (ML)-based predictive model for event-free survival (EFS) in patients with hepatocellular carcinoma (HCC) undergoing stereotactic ablative radiotherapy (SABR). Patients receiving SABR for HCC at a single institution, between 2017 and 2020, were included in the study. They were split into training and test (85%:15%) cohorts. Events of interest were HCC recurrence or death. Three ML models were trained, the features were selected, and the hyperparameters were tuned. The performance was measured using Harrell's C index with the best-performing model being tested on the unseen cohort. Overall, 41 patients were included (training = 34, test = 7) and 64 lesions were analysed (training = 50, test = 14), resulting in 30 events (60% rate) in the training set (death = 6, recurrence = 24) and 8 events (57% rate) in the test set (death = 5, recurrence = 3). A Cox regression model, using age at treatment, albumin, and intra-lesional fat identified through MRI as variables, had the best performance with a mean training score of 0.78 (standard deviation (SD) 0.02), a mean validation of 0.78 (SD 0.18), and a test score of 0.94. Predicting the outcomes in patients with HCC, following SABR, using a novel model is feasible and warrants further evaluation.

Early experience with an artificial intelligence-based module for brain metastasis detection and segmentation.

- Accurate detection, segmentation, and volumetric analysis of brain lesions are essential in neuro-oncology. Artificial intelligence (AI)-based models have improved the efficiency of these processes. This study evaluated an AI-based module for detecting and segmenting brain metastases, comparing it with manual detection and segmentation. - MRIs from 51 patients treated with Gamma Knife radiosurgery for brain metastases were analyzed. Manual lesion identification and contouring on Leksell Gamma Plan at the time of treatment served as the gold standard. The same MRIs were processed through an AI-based module (Brainlab Smart Brush), and lesion detection and volumes were compared. Discrepancies were analyzed to identify possible sources of error. - Among 51 patients, 359 brain metastases were identified. The AI module achieved a sensitivity of 79.2% and a positive predictive value of 95.6%, compared to a 93.3% sensitivity for manual detection. However, for lesions > 0.1cc, the AI's sensitivity rose to 97.5%, surpassing manual detection at 93%. Volumetric agreement between AI and manual segmentations was high (Spearman's ρ = 0.997, p < 0.001). Most lesions missed by the AI (53.8%) were near anatomical structures that complicated detection. - The AI module demonstrated higher sensitivity than manual detection for metastases larger than 0.1cc, with robust volumetric accuracy. However, human expertise remains critical for detecting smaller lesions, especially near complex anatomical areas. AI offers significant potential to enhance neuro-oncology practice by improving the efficiency and accuracy of lesion management.