Simulation of surgery for supratentorial gliomas in virtual reality using a 3D volume rendering technique: a poor man's neuronavigation

OBJECTIVE Different techniques of performing image-guided neurosurgery exist, namely, neuronavigation systems, intraoperative ultrasound, and intraoperative MRI, each with its limitations. Except for ultrasound, other methods are expensive. Three-dimensional virtual reconstruction and surgical simulation using 3D volume rendering (VR) is an economical and excellent technique for preoperative surgical planning and image-guided neurosurgery. In this article, the authors discuss several nuances of the 3D VR technique that have not yet been described. METHODS The authors included 6 patients with supratentorial gliomas who underwent surgery between January 2019 and March 2021. Preoperative clinical data, including patient demographics, preoperative planning details (done using the VR technique), and intraoperative details, including relevant photos and videos, were collected. RadiAnt software was used for generating virtual 3D images using the VR technique on a computer running Microsoft Windows. RESULTS The 3D VR technique assists in glioma surgery with a preoperative simulation of the skin incision and craniotomy, virtual cortical surface marking and navigation for deep-seated gliomas, preoperative visualization of morbid cortical surface and venous anatomy in surfacing gliomas, identifying the intervenous surgical corridor in both surfacing and deep-seated gliomas, and pre- and postoperative virtual 3D images highlighting the exact spatial geometric residual tumor location and extent of resection for low-grade gliomas (LGGs). CONCLUSIONS Image-guided neurosurgery with the 3D VR technique using RadiAnt software is an economical, easy-to-learn, and user-friendly method of simulating glioma surgery, especially in resource-constrained countries where expensive neuronavigation systems are not readily available. Apart from cortical sulci/gyri anatomy, FLAIR sequences are ideal for the 3D visualization of nonenhancing diffuse LGGs using the VR technique. In addition to cortical vessels (especially veins), contrast MRI sequences are perfect for the 3D visualization of contrast-enhancing high-grade gliomas.

Clinical importance and configuration of collateral vessel systems in patients with Takayasu arteritis or with thymoma visualized by three-dimensional volume rendering computed tomographic angiography

Background Collateral vessels form after gradual blood vessel occlusion. We speculate that in Takayasu arteritis (TA) and thymoma patients, before planning surgical procedures, a complex artery/venous system should be examined using three dimensional (3D) volume rendering computed tomographic (CT) angiography. Purpose To seek the clinical importance and actual complex configuration of collateral vessel systems in patients with TA or with thymoma using 3D volume rendering CT angiography with special acquisition method. Methods We performed 3D CT angiography in patients with Takayasu arteritis (TA) with occluded arteries (N=6) or thymoma (N=2) with occluded superior-vena-cava (SVC), respectively. For CT angiography in thymoma patients, diluted (1/4) iodinated-contrast was injected in right and left medial cubital-veins simultaneously, and images acquired 10 seconds after contrast-injection. Results Occluded and collateral-arteries (TA group) and occluded SVC and collateral-veins (thymoma group) were successfully visualized (Figures a-h). Collateral-arteries form from the inferior mesenteric artery (Figure a) or de novo arteries from the abdominal aorta (Figure b) after superior mesenteric artery occlusion (Figure c, d). In patients with thymoma, an SVC thymoma disrupts venous return in the neck and upper extremities; a complex venous system forms on the abdominal surface (Figure e-h). Conclusion In TA and thymoma patients, before planning surgical procedures, a complex artery/venous system should be examined using 3D volume rendering CT angiography. For CT in thymoma, diluted (1/4) iodinated contrast should be injected in both medial cubital veins, and images should be acquired 10 seconds after contrast-injection. 3D volume rendering CT angiography Funding Acknowledgement Type of funding source: None

Optimization of Breast Tomosynthesis Visualization through 3D Volume Rendering

3D volume rendering may represent a complementary option in the visualization of Digital Breast Tomosynthesis (DBT) examinations by providing an understanding of the underlying data at once. Rendering parameters directly influence the quality of rendered images. The purpose of this work is to study the influence of two of these parameters (voxel dimension in z direction and sampling distance) on DBT rendered data. Both parameters were studied with a real phantom and one clinical DBT data set. The voxel size was changed from 0.085 × 0.085 × 1.0 mm3 to 0.085 × 0.085 × 0.085 mm3 using ten interpolation functions available in the Visualization Toolkit library (VTK) and several sampling distance values were evaluated. The results were investigated at 90º using volume rendering visualization with composite technique. For phantom quantitative analysis, degree of smoothness, contrast-to-noise ratio, and full width at half maximum of a Gaussian curve fitted to the profile of one disk were used. Additionally, the time required for each visualization was also recorded. Hamming interpolation function presented the best compromise in image quality. The sampling distance values that showed a better balance between time and image quality were 0.025 mm and 0.05 mm. With the appropriate rendering parameters, a significant improvement in rendered images was achieved.

In Vivo Computed Tomography Direct Volume Rendering of the Anterior Ethmoidal Artery: A Descriptive Anatomical Study

Introduction The clinical relevance of the anatomy and variations of the anterior ethmoidal artery (AEA) is outstanding, considering its role as a landmark in endoscopic surgery, its importance in the therapy of epistaxis, and the high risks related to iatrogenic injuries. Objective To provide an anatomical description of the course and relationships of the AEA, based on direct computed-tomography (CT)-based 3D volume rendering. Methods Direct volume rendering was performed on 18 subjects who underwent (CT) with contrast medium for suspected cerebral aneurism. Results The topographical location of 36 AEAs was assessed as shown: 10 dehiscent (27.8%), 20 intracanal (55.5%), 6 incomplete canals (16.7%). Distances from important topographic landmarks are reported. Conclusion This work demonstrates that direct 3D volume rendering is a valid imaging technique for a detailed description of the anterior ethmoidal artery thus representing a useful tool for head pre-operatory assessments.