INTRODUCTION: Authors present a 2-dimensional to 3-dimensional (2D-3D) registration algorithm that identifies the position of a C-arm relative to a 3D volume. METHODS: This work utilizes digitally ...reconstructed radiographs (DRR) which are synthetic radiographic images generated by simulating the x-ray projections as they would pass through a CT volume. To evaluate our algorithm, we used cone-beam CT data from 127 patients obtained from a de-identified registry of cervical, thoracic, and lumbar scans. We systematically evaluated and tuned a self-supervised algorithm, quantified the limitations and convergence rate of our model by simulating C-arm registrations with 80 randomly simulated DRRs for each CT volume. The endpoints for this study were the time to convergence, accuracy of convergence for each of the C-arm's degrees of freedom (DoF), and overall registration accuracy based on a voxel-by-voxel measurement. RESULTS: 10,160 unique fluoroscopic images were simulated from 127 CT scans. Our algorithm successfully converged to the correct solution 81% of the time with an average of 1.97 seconds of computation. The fluoroscopic images for which the algorithm converged to the solution achieved 99.9% registration accuracy despite only utilizing single-precision computation for speed. Our algorithm was found to be optimized for convergence when the search space was limited to a ± 45° offset in the RAO/LAO, cranial/caudal and receiver rotation angles with the radiographic isocenter contained within 8000cm3 of the volumetric center of the CT volume. CONCLUSIONS: The machine learning algorithm we present has the potential to aid surgeons with many aspects of spine surgery through an automated 2D-3D registration process. Future work will focus on algorithmic optimizations adn deep-learning to improve the convergence rate and speed profile.
Visual, tactile, and auditory cues are used during surgery to differentiate tissue type. Auditory cues in glioma surgery have not been studied previously. The objectives of this study were 1) to ...evaluate the feasibility of recording sound generated by the suction device during glioma surgery in matched tissue samples, and 2) to characterize the acoustic variation that occurs in different tissue samples.
This was a prospective observational proof-of-concept study. Recordings were attempted in 20 patients in order meet the accrual target of 10 patients with matched sound and tissue data. For each patient, three 30- to 60-second recordings were made at these sites: normal white matter, infiltrative margin, and tumor. Tissue samples at each site were then reviewed by experienced neuropathologists, and agreement with surgical identification was estimated with the kappa statistic. Acoustic parameters were characterized for each sample.
Data from 20 patients were analyzed. Patient-related or technical issues resulted in missing data for 10 patients, but the final 10 patients had both audio and tissue data for analysis. Among all tissue samples, fair agreement was observed between surgeon identification and actual pathology (κ = 0.24, standard error 0.096, p = 0.006). Acoustic data suggested that 1) the acoustic stimulus is broadband, 2) acoustic features are somewhat consistent within cases, 3) high-entropy values indicate irregularity of sound over time, and 4) bimodal pitch distributions could differentially reflect cues of interest.
This study supports the feasibility of collecting intraoperative data on acoustic features during glioma surgery, and it provides an example of how an analysis could be performed to compare different types of tissues.
The goal of this work was to methodically evaluate, optimize, and validate a self-supervised machine learning algorithm capable of real-time automatic registration and fluoroscopic localization of ...the spine using a single radiograph or fluoroscopic frame.
The authors propose a two-dimensional to three-dimensional (2D-3D) registration algorithm that maximizes an image similarity metric between radiographic images to identify the position of a C-arm relative to a 3D volume. This work utilizes digitally reconstructed radiographs (DRRs), which are synthetic radiographic images generated by simulating the x-ray projections as they would pass through a CT volume. To evaluate the algorithm, the authors used cone-beam CT data for 127 patients obtained from an open-source de-identified registry of cervical, thoracic, and lumbar scans. They systematically evaluated and tuned the algorithm, then quantified the convergence rate of the model by simulating C-arm registrations with 80 randomly simulated DRRs for each CT volume. The endpoints of this study were time to convergence, accuracy of convergence for each of the C-arm's degrees of freedom, and overall registration accuracy based on a voxel-by-voxel measurement.
A total of 10,160 unique radiographic images were simulated from 127 CT scans. The algorithm successfully converged to the correct solution 82% of the time with an average of 1.96 seconds of computation. The radiographic images for which the algorithm converged to the solution demonstrated 99.9% registration accuracy despite utilizing only single-precision computation for speed. The algorithm was found to be optimized for convergence when the search space was limited to a ± 45° offset in the right anterior oblique/left anterior oblique, cranial/caudal, and receiver rotation angles with the radiographic isocenter contained within 8000 cm3 of the volumetric center of the CT volume.
The investigated machine learning algorithm has the potential to aid surgeons in level localization, surgical planning, and intraoperative navigation through a completely automated 2D-3D registration process. Future work will focus on algorithmic optimizations to improve the convergence rate and speed profile.
Emerging data suggest immune checkpoint inhibitors (ICI) and stereotactic radiosurgery (SRS) or radiotherapy (SRT) may work synergistically, potentially increasing both efficacy and toxicity. This ...manuscript characterizes factors associated with intracranial control and radiation necrosis in this group.
All patients had non-small cell lung cancer, renal cell carcinoma, or melanoma and were treated from 2013 to 2021 at two institutions with ICI and SRS/SRT. Univariate and multivariate analysis were used to analyze factors associated with local failure (LF) and grade 2+ (G2 + ) radiation necrosis.
There were 179 patients with 549 metastases. The median follow up from SRS/SRT was 14.7 months and the median tumor size was 7 mm (46 tumors ≥ 20 mm). Rates of LF and G2 + radiation necrosis per metastasis were 5.8% (32/549) and 6.9% (38/549), respectively. LF rates for ICI +/- 1 month from time of radiation versus not were 3% (8/264) and 8% (24/285) (p = 0.01), respectively. G2 + radiation necrosis rates for PD-L1 ≥ 50% versus < 50% were 17% (11/65) and 3% (5/203) (p=<0.001), respectively. PD-L1 ≥ 50% remained significantly associated with G2 + radiation necrosis on multivariate analysis (p = 0.03). Rates of intracranial failure were 54% (80/147) and 17% (4/23) (p = 0.001) for those without and with G2 + radiation necrosis, respectively.
PD-L1 expression (≥50%) may be associated with higher rates of G2 + radiation necrosis, and there may be improved intracranial control following the development of radiation necrosis. Administration of ICIs with SRS/SRT is overall safe, and there may be some local control benefit to delivering these concurrently.
Abstract
PURPOSE/OBJECTIVE(S)
Stereotactic radiosurgery (SRS), compared to whole brain radiotherapy is limited in its ability to prevent development of brain metastases in untreated areas. The ...purpose of this study is to assess whether low-dose volumes delivered to uninvolved regions of the brain during SRS can reduce the risk of developing brain metastases in those regions.
MATERIALS AND METHODS
Data were collected for 69 patients with brain metastases who were treated with SRS at least two occasions. The regions of uninvolved brain receiving a high, intermediate, and low dose of incidental radiotherapy were defined as the volume receiving at least 10, 5, and 2.5 Gy if the prescribed dose was < 25 Gy (1-3 fraction plans) or the volume receiving at least 15, 7.5, and 5 Gy if the prescribed dose was ≥ 25 Gy (5 fraction plans). A second round metastasis was considered to occur within a given dose level if 20% or more of the tumor was found within that dose level. Probabilities were calculated based on the volume of each dose level as a percentage of total brain volume and were used to estimate the expected number of cases with at least one metastasis occurring in each dose level.
RESULTS
The average number of metastases treated in both rounds of SRS was two. The expected and observed number of cases with at least one second round metastasis were 0 and 2 for the high dose level (p=0.151), 7 and 3 for the intermediate dose level (p=0.018), and 17 and 11 for the low dose level (p=0.094).
CONCLUSION
We observed fewer than expected new metastases within prior SRS low dose levels based on volumetric probabilities, though this difference was only significant for the intermediate dose level. This suggests that low dose volumes from SRS may provide benefit in preventing future regional metastases.
Abstract
BACKGROUND
For patients with operable intracranial neoplasms, there are opportunities to augment local control beyond traditional methods, such as external beam radiation therapy. ...Brachytherapy, the implantation of radioactive sources into the resection cavity, can be useful in this setting by providing immediate initiation of radiation and limiting the exposure of surrounding normal tissue to radiation. Traditional intracranial brachytherapy has been limited by uneven dose distributions, complicated workflows, extended procedural times, cost of dedicated equipment, and frequent adverse events. To address these issues, a permanently implanted device with Cs-131 radiation seeds embedded in a bioresorbable collagen carrier tile (GammaTile, GT Medical Technologies, Tempe, AZ USA) was developed. Described as surgically targeted radiation therapy (STaRT), it is FDA-cleared for use in newly-diagnosed malignant intracranial neoplasms and recurrent intracranial tumors, and has demonstrated excellent safety and efficacy in early commercial use. The primary objectives of this multicenter, prospective, observational (phase IV) registry study are to evaluate “real-world” clinical outcomes and patient-reported outcomes that measure the safety and efficacy of STaRT using the GammaTile.
METHODS
Patients undergoing resection (R) of brain tumors with intra-operative GammaTile placement are eligible for enrollment. Planned sample size is 600 at up to 50 enrolling sites. First subject was enrolled 10/14/2020. Tumor pathology, overall survival, radiation- and surgery-related adverse events, patient- and provider-reported quality of life, serial MRIs, and timing of surgical bed and/or distant recurrence are collected. Powered primary endpoints for recurrent brain metastases, recurrent glioblastoma, and recurrent meningioma (surgical bed-progression free survival (PFS), overall survival, and PFS, respectively), compare STaRT to standard-of-care benchmarks. Results will be used to improve awareness and access to this treatment, benchmark clinical outcomes in the real-world setting, allow for comparisons to existing treatments, facilitate the design of future clinical trials, and contribute to the optimal sequencing of treatments for intracranial neoplasms.
Abstract
OBJECTIVE
The toxicities associated with stereotactic radiosurgery (SRS) are important factors when considering treatment options and supportive management for patients with brain ...metastases. We assessed the association between brain metastasis location and rates of toxicity after SRS.
METHODS
We conducted a retrospective single-institution review of 170 patients treated with SRS for brain metastases from 2008–2016 with median follow-up of 8.6 months. Typical SRS doses were 18-20Gy in 1 fraction (lesions <2cm), 18-21Gy in 3 fractions (lesions 2-3cm), and 25-30Gy in 5 fractions (lesions > 3cm). Toxicity measures evaluated included radiation necrosis, seizure, and dexamethasone requirement.
RESULTS
A total of 221 lesions were treated among frontal (29%), cerebellar (23%), parietal (16%), temporal (15%), occipital (14%), and other (brainstem, thalamus, basal ganglia) (4%) regions. The rate of SRS-related radionecrosis was 4% for all patients and significantly correlated with metastasis volume (increasing from 1% to 7% for lesions ≤1cm3 to > 3cm3) and prior whole brain radiotherapy (WBRT) but not with metastasis location or prior resection on multi-variable analysis (P<0.05). Post-SRS seizure occurred in 9% of all patients but was significantly higher after SRS to primary motor cortex and sensory cortex lesions, associated with 50% and 33% seizure rates, respectively (P<0.05). Of patients who initially presented with seizure and were on anti-epileptic medication during SRS, 62% had no further seizures, while 38% did have post-SRS seizures, nearly all with motor cortex lesions. Only 5% of patients had new-onset seizure after SRS, related to lesion hemorrhage or motor cortex location. Dexamethasone use > 3 months post-SRS was higher for motor strip lesions.
CONCLUSION
Brain metastasis location in the primary motor cortex was associated with higher rates of post-SRS seizure, including new-onset seizures and breakthrough seizures on anti-epileptic medication during SRS. Rates of radionecrosis were associated with lesion volume and prior WBRT but not with metastasis location.
Animal models of human diseases are widely used to address questions of tumor development. Selection of a particular animal model depends upon a variety of factors, among them: animal cost, species ...lifespan, and hardiness; availability of biomolecular and genetic tools for that species; and evolutionary distance from humans. In spite of the growth in genomic data in the past several years, many animal models cannot yet be studied extensively due to gaps in genetic mapping, sequencing and functional analyses. Thus, alternative molecular genetic approaches are needed. We have designed an interspecies comparative genomic hybridization approach to analyze genetic changes in radiation-induced brain tumors in the non-human primate, Macaca mulatta. Using homologies between the primate and human genomes, we adapted widely-available CGH techniques to generate cytogenetic profiles of malignant gliomas in 4 monkey tumors. Losses and gains were projected onto the corresponding homologous chromosomal regions in the human genome, thus directly translating the status of the monkey gliomas into human gene content. This represents a novel method of comparative interspecies cytogenetic mapping that permits simultaneous analysis of genomic imbalance of unknown sequences in disparate species and correlation with potential or known human disease-related genes.
Abstract We report the neuroimaging and histopathologic findings of a 12-year-old female patient with a disseminated oligodendroglial-like leptomeningeal tumor with anaplastic progression and ...presumed extraneural metastatic disease. These tumors may represent distinct pathology primarily seen in pediatric patients. Neuroimaging demonstrates diffuse, progressive enhancement of the leptomeninges often with interval development of intraparenchymal lesions on follow-up. Disease is typically confined to the central nervous system, though diffuse peritoneal disease was seen in our case, possibly through metastatic seeding of the abdomen via ventriculoperitoneal shunt.
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