Search Results (5)

During magnetic-resonance-guided focused ultrasound ablation of the ventral intermediate thalamic nucleus (VIM) for essential tremor (ET) and Parkinson’s disease (PD), targeting is generally performed using a standard atlas-based stereotactic approach. The purpose of our work is to evaluate the anatomic variations in the venous vasculature of the thalamus in patients treated with MRgFUS, as a possible landmark for targeting. We retrospectively evaluated the relationship between the obtained thalamotomy lesion and the ipsilateral superior thalamic vein (STV). A total of 36 patients (25 ET and 11 PD) who underwent MRgFUS treatment were evaluated, and the STV was studied with susceptibility weighted imaging (SWI) sequences. Based on the axial SWI images, the distance between the STV and the center of the lesion at the presumed site of the VIM was measured in follow-up MRI images one month after treatment. Statistical analysis shows that there is a correlation between the STV and the presumed site of the VIM. The STV visible in SWI could be used as an additional, real-time, and patient-specific anatomical landmark for VIM identification during MR examination and just before and during FUS treatment. Full article

Background and Objectives: Brain metastases (BMs) pose significant clinical challenges in systemic cancer patients. They often cause symptoms related to brain compression and are typically managed with multimodal therapies, such as surgery, chemotherapy, whole brain radiotherapy (WBRT), and stereotactic radiosurgery (SRS). With modern oncology treatments prolonging survival, concerns about the neurocognitive side effects of BM treatments are growing. WBRT, though widely used for multiple BMs, has recognized neurocognitive toxicity. SRS, particularly Gamma Knife (GK) therapy, offers a minimally invasive alternative with fewer side effects, suitable for patients with a quantifiable number of metastases and better prognoses. Materials and Methods: A retrospective analysis was conducted on 94 patients with multiple BMs treated exclusively with GK at an academic medical center. Patients with prior WBRT were excluded. This study focused on the mean radiation dose received by the hippocampal area, estimated according to the ‘Hippocampal Contouring: A Contouring Atlas for RTOG 0933’ guidelines. Results: The precision of GK equipment results in mean doses of radiation that are lower than those suggested by RTOG 0933 and observed in other studies. This precision may help mitigate cognitive dysfunction and other side effects of hippocampal irradiation. Conclusions: GK therapy facilitates the administration of smaller, safer radiation doses to the hippocampi, which is advantageous even for lesions in the temporal lobe. It is feasible to treat multiple metastases, including cases with more than 10, but it is typically reserved for patients with fewer metastases, with an average of 3 in this study. This underlines GK’s potential for reducing adverse effects while managing BMs effectively. Full article

Following the recent acquisition of unprecedented anatomical details through state-of-the-art neuroimaging, stereotactic procedures such as microelectrode recording (MER) or deep brain stimulation (DBS) can now rely on direct and accurately individualized topographic targeting. Nevertheless, both modern brain atlases derived from appropriate histological techniques involving post-mortem studies of human brain tissue and the methods based on neuroimaging and functional information represent a valuable tool to avoid targeting errors due to imaging artifacts or insufficient anatomical details. Hence, they have thus far been considered a reference guide for functional neurosurgical procedures by neuroscientists and neurosurgeons. In fact, brain atlases, ranging from the ones based on histology and histochemistry to the probabilistic ones grounded on data derived from large clinical databases, are the result of a long and inspiring journey made possible thanks to genial intuitions of great minds in the field of neurosurgery and to the technical advancement of neuroimaging and computational science. The aim of this text is to review the principal characteristics highlighting the milestones of their evolution. Full article

The consequence of cardiac substructure irradiation in patients receiving stereotactic body radiation therapy (SBRT) is not well characterized. We reviewed the charts of patients with central lung tumors managed by definitive SBRT from June 2010–April 2019. All patients were treated with five fractions, typically either 5000 cGy (44.6%) or 5500 cGy (42.2%). Via a multi-patient atlas, fourteen cardiac substructures were autosegmented, manually reviewed and analyzed using dosimetric parameters. A total of 83 patients were included with a median follow up of 33.4 months. Univariate Cox regression analysis identified a D45% dose to the right atria and ventricle for further study. Sequential log-rank testing evaluating an association between non-cancer associated survival and D45% dose to the right atria or ventricle and association was employed, identifying candidate cutoff values of 890.3 cGy and 564.4 cGy, respectively. Kaplan–Meier analysis using the reported cutoff values found the D45% right atria constraint to be significantly associated with non-cancer associated (p ≤ 0.001) and overall survival (p ≤ 0.001) but not the right ventricle constraint. Within a multivariate model, the proposed right atria D45% cutoff remained significantly correlated with non-cancer associated survival (Hazard’s Ratio (HR) ≤ 8.5, 95% confidence interval (CI) 1.1–64.5, p ≤ 0.04) and OS (HR ≤ 6.1, 95% CI 1.0–36.8, p ≤ 0.04). In conclusion, a dose to D45% of the right atria significantly correlated with outcome and the candidate constraint of 890 cGy stratified non-cancer associated and OS. The inclusion of these findings with previously characterized relationships between proximal airway constraints and survival enhances our understanding of why centrally located tumors are high risk and potentially identifies key constraints in organ at risk prioritization. Full article

Objective: To answer the question of whether the anatomical center of the subthalamic nucleus (STN), as calculated indirectly from stereotactic atlases or by direct visualization on magnetic resonance imaging (MRI), corresponds to the best functional target. Since the neighboring red nucleus (RN) is well visualized on MRI, we studied the relationships of the final target to its different borders. Methods: We analyzed the data of 23 PD patients (46 targets) who underwent bilateral frame-based STN deep brain stimulation (DBS) procedure with microelectrode recording guidance. We calculated coordinates of the active contact on DBS electrode on postoperative MRI, which we referred to as the final “functional/optimal” target. The coordinates calculated by the atlas-based “indirect” and “direct” methods, as well as the coordinates of the different RN borders were compared to these final coordinates. Results: The mean ± SD of the final target coordinates was 11.7 ± 1.5 mm lateral (X), 2.4 ± 1.5 mm posterior (Y), and 6.1 ± 1.7 mm inferior to the mid-commissural point (Z). No significant differences were found between the “indirect” X, Z coordinates and those of the final targets. The “indirect” Y coordinate was significantly posterior to Y of the final target, with mean difference of 0.6 mm (p = 0.014). No significant differences were found between the “direct” X, Y, and Z coordinates and those of the final targets. Conclusions: The functional STN target is located in direct proximity to its anatomical center. During preoperative targeting, we recommend using the “direct” method, and taking into consideration the relationships of the final target to the mid-commissural point (MCP) and the different RN borders. Full article