Artificial-intelligence-driven measurements of brain metastases' response to SRS compare favorably with current manual standards of assessment.

Background: Evaluation of treatment response for brain metastases (BMs) following stereotactic radiosurgery (SRS) becomes complex as the number of treated BMs increases. This study uses artificial intelligence (AI) to track BMs after SRS and validates its output compared with manual measurements. Methods: Patients with BMs who received at least one course of SRS and followed up with MRI scans were retrospectively identified. A tool for automated detection, segmentation, and tracking of intracranial metastases on longitudinal imaging, MEtastasis Tracking with Repeated Observations (METRO), was applied to the dataset. The longest three-dimensional (3D) diameter identified with METRO was compared with manual measurements of maximum axial BM diameter, and their correlation was analyzed. Change in size of the measured BM identified with METRO after SRS treatment was used to classify BMs as responding, or not responding, to treatment, and its accuracy was determined relative to manual measurements. Results: From 71 patients, 176 BMs were identified and measured with METRO and manual methods. Based on a one-to-one correlation analysis, the correlation coefficient was R2 = 0.76 (P = .0001). Using modified BM response classifications of BM change in size, the longest 3D diameter data identified with METRO had a sensitivity of 0.72 and a specificity of 0.95 in identifying lesions that responded to SRS, when using manual axial diameter measurements as the ground truth. Conclusions: Using AI to automatically measure and track BM volumes following SRS treatment, this study showed a strong correlation between AI-driven measurements and the current clinically used method: manual axial diameter measurements.

Preoperative Velopharyngeal Closure Predicts Hypernasality Outcomes of Secondary Furlow Double-Opposing Z-Plasty.

OBJECTIVE: To determine if preoperative velopharyngeal closure percentage (VCP) is predictive of successful Furlow double opposing Z-plasty (DOZP) and subsequently determine the optimal velopharyngeal closure cutoff for successful DOZP. DESIGN: Retrospective study. SETTING: Tertiary academic center. PATIENTS: 110 patients with repaired cleft lip and palate having hypernasality treated with DOZP. INTERVENTIONS: Speech videofluoroscopy images were used to obtain the preoperative VCP and other measurements. MAIN OUTCOME MEASURES: Changes in hypernasality scores using the Cleft Audit Protocol for Speech-Augmented-Americleft Modification (CAPS-A-AM) rating system were used as the primary outcome measure. A successful DOZP was defined as a postoperative hypernasality score of ≤ 1 or an improvement of 2 or more scores from baseline. A receiver operating characteristic (ROC) curve was calculated to determine preoperative VCP cutoff. RESULTS: There were 110 patients who underwent DOZP for treatment of velopharyngeal insufficiency. Of these patients, 94 (85%) had successful surgery as determined by their postoperative CAPS-A-AM hypernasality score. Preoperative VCP was a statistically significant predictor of successful DOZP (P < .0001). The ROC curve with Youden index (J) determined a cutoff (c*) of 55% preoperative VCP or greater to optimize surgical success rate. Grouping by preoperative VCP showed that surgical success increases directly with preoperative VCP, and patients with low VCP had above a 50% success rate in reducing hypernasality scores. CONCLUSIONS: Preoperative VCP was significantly associated with improved hypernasality ratings postoperatively. A preoperative VCP of ≥55% may be used to help predict success of Furlow palatoplasty treatment. Patients with lower VCP can still benefit from secondary DOZP.

Assessing Treatment of Floating Lateral Mass (FLM) Fractures of the Subaxial Cervical Spine.

STUDY DESIGN: Retrospective cohort. OBJECTIVE: The purpose of the study was to evaluate differences across surgical approaches (anterior, posterior, or combined anterior-posterior) in terms of outcomes following treatment for floating lateral mass (FLM) fractures. Furthermore, we sought to determine whether operative approach to FLM fracture treatment remains superior to nonoperative treatment in terms of clinical outcomes. BACKGROUND DATA: FLM fractures of the subaxial cervical spine involves separation of the lateral mass from the vertebrae via a disruption of both the lamina and pedicle, resulting in a disconnection of the superior and inferior articular processes. This subset of cervical spine fractures is highly unstable, making proper treatment selection of great importance. METHODS: In this single-center, retrospective study, we identified patients meeting the definition of an FLM fracture. Radiological imaging from the date of injury was reviewed to ensure presence this injury pattern. Treatment course was assessed to determine nonoperative versus operative treatment. Operative treatment was divided into patients who underwent anterior, posterior, or combined anterior-posterior spinal fusion. We then reviewed postoperative complications among each of the subgroups. RESULTS: Forty-five patients were determined to have a FLM fracture over a 10-year span. The nonoperative group had n=25, and evidently, there were no patients that crossed over to surgery due to subluxation of the cervical spine after nonoperative treatment. The operative treatment group had n=20, and consisted of 6 anterior, 12 posterior, and 2 combined approaches. Complications appeared in posterior and combined groups. Two hardware failures were noted in the posterior group, along with two postoperative respiratory complications in the combined group. No complications were observed for the anterior group. CONCLUSIONS: None of the nonoperative patients in this study required further operation or management of their injury, indicating nonoperative treatment as a potentially satisfactory management for appropriately selected FLM fractures.

Automatically tracking brain metastases after stereotactic radiosurgery.

Background and purpose: Patients with brain metastases (BMs) are surviving longer and returning for multiple courses of stereotactic radiosurgery. BMs are monitored after radiation with follow-up magnetic resonance (MR) imaging every 2-3 months. This study investigated whether it is possible to automatically track BMs on longitudinal imaging and quantify the tumor response after radiotherapy. Methods: The METRO process (MEtastasis Tracking with Repeated Observations was developed to automatically process patient data and track BMs. A longitudinal intrapatient registration method for T1 MR post-Gd was conceived and validated on 20 patients. Detections and volumetric measurements of BMs were obtained from a deep learning model. BM tracking was validated on 32 separate patients by comparing results with manual measurements of BM response and radiologists' assessments of new BMs. Linear regression and residual analysis were used to assess accuracy in determining tumor response and size change. Results: A total of 123 irradiated BMs and 38 new BMs were successfully tracked. 66 irradiated BMs were visible on follow-up imaging 3-9 months after radiotherapy. Comparing their longest diameter changes measured manually vs. METRO, the Pearson correlation coefficient was 0.88 (p < 0.001); the mean residual error was -8 ± 17%. The mean registration error was 1.5 ± 0.2 mm. Conclusions: Automatic, longitudinal tracking of BMs using deep learning methods is feasible. In particular, the software system METRO fulfills a need to automatically track and quantify volumetric changes of BMs prior to, and in response to, radiation therapy.

Design and Validation of a Multi-Point Injection Technology for MR-Guided Convection Enhanced Delivery in the Brain.

Convection enhanced delivery (CED) allows direct intracranial administration of neuro-therapeutics. Success of CED relies on specific targeting and broad volume distributions (VD). However, to prevent off-target delivery and tissue damage, CED is typically conducted with small cannulas and at low flow rates, which critically limit the maximum achievable VD. Furthermore, in applications such as gene therapy requiring injections of large fluid volumes into broad subcortical regions, low flow rates translate into long infusion times and multiple surgical trajectories. The cannula design is a major limiting factor in achieving broad VD, while minimizing infusion time and backflow. Here we present and validate a novel multi-point cannula specifically designed to optimize distribution and delivery time in MR-guided intracranial CED of gene-based therapeutics. First, we evaluated the compatibility of our cannula with MRI and common viral vectors for gene therapy. Then, we conducted CED tests in agarose brain phantoms and benchmarked the results against single-needle delivery. 3T MRI in brain phantoms revealed minimal susceptibility-induced artifacts, comparable to the device dimensions. Benchtop CED of adeno-associated virus demonstrated no viral loss or inactivation. CED in agarose brain phantoms at 3, 6, and 9 µL/min showed >3x increase in volume distribution and 60% time reduction compared to single-needle delivery. This study confirms the validity of a multi-point delivery approach for improving infusate distribution at clinically-compatible timescales and supports the feasibility of our novel cannula design for advancing safety and efficacy of MR-guided CED to the central nervous system.

Gels, jets, mosquitoes, and magnets: a review of implantation strategies for soft neural probes.

Implantable neuroelectronic interfaces have enabled breakthrough advances in the clinical diagnosis and treatment of neurological disorders, as well as in fundamental studies of brain function, behavior, and disease. Intracranial electroencephalography (EEG) mapping with stereo-EEG (sEEG) depth electrodes is routinely adopted for precise epilepsy diagnostics and surgical treatment, while deep brain stimulation has become the standard of care for managing movement disorders. Intracortical microelectrode arrays for high-fidelity recordings of neural spiking activity have led to impressive demonstrations of the power of brain-machine interfaces for motor and sensory functional recovery. Yet, despite the rapid pace of technology development, the issue of establishing a safe, long-term, stable, and functional interface between neuroelectronic devices and the host brain tissue still remains largely unresolved. A body of work spanning at least the last 15 years suggests that safe, chronic integration between invasive electrodes and the brain requires a close match between the mechanical properties of man-made components and the neural tissue. In other words, the next generation of invasive electrodes should be soft and compliant, without sacrificing biological and chemical stability. Soft neuroelectronic interfaces, however, pose a new and significant surgical challenge: bending and buckling during implantation that can preclude accurate and safe device placement. In this topical review, we describe the next generation of soft electrodes and the surgical implantation methods for safe and precise insertion into brain structures. We provide an overview of the most recent innovations in the field of insertion strategies for flexible neural electrodes such as dissolvable or biodegradable carriers, microactuators, biologically-inspired support structures, and electromagnetic drives. In our analysis, we also highlight approaches developed in different fields, such as robotic surgery, which could be potentially adapted and translated to the insertion of flexible neural probes.