Three-Dimensional Imaging as a Teaching Method in Anterior Circulation Aneurysm Surgery

Stereoscopy in Surgical Neuroanatomy: Past, Present, and Future

Since the dawn of antiquity, scientists, philosophers, and artists have pondered the nature of optical stereopsis-the perception of depth that arises from binocular vision. The early 19th century saw the advent of stereoscopes, devices that could replicate stereopsis by producing a 3D illusion from the super-imposition of 2D photographs. This phenomenon opened up a plethora of possibilities through its usefulness as an educational tool-particularly in medicine. Before long, photographers, anatomists, and physicians were collaborating to create some of the first stereoscopic atlases available for the teaching of medical students and residents. In fields like neurosurgery-where a comprehensive visuospatial understanding of neuro-anatomical correlates is crucial-research into stereoscopic modalities are of fundamental importance. Already, medical institutions all over the world are capitalizing on new and immersive technologies-such as 3D intraoperative recording, and 3D endoscopes-to refine their pedagogical efforts as well as improve their clinical capacities. The present paper surveys the history of stereoscopy from antiquity to the modern era-with a focus on its role in neurosurgery and medical education. Through the tracking of this evolution, we can discuss potential benefits, future directions, and highlight areas in which further research is needed. By anticipating these factors, we may strive to take full advantage of an emergent field of technology, for our ultimate goal of improving patient care.

Stereoscopic Images from Computed Tomography Angiograms

OBJECTIVE

To present an adaptation of the anaglyph photography technique to be used with radiological images from computed tomography angiograms, enabling stereoscopic visualization of a patient's individual abnormal vascular anatomy for teaching, case discussion, or surgical planning purposes.

METHODS

Traditional anaglyph procedures with actual objects yield 2 independent photographs, simulating the image perceived by each eye. Production of anaglyphs from angiograms involve 3 basic procedures: volume rendering, image capture, and image fusion. Volume renderings were reconstructed using a free, open-source DICOM (Digital Imaging and Communications in Medicine) reader. Subsequently, the virtual object was positioned to mimic the operator's angle of view, and different perspectives of the reconstructed volume could be obtained through exclusively horizontal rotation. The 2 images were then fused after their color composition was modified so that each eye would perceive only 1 image when using anaglyph glasses.

RESULTS

Forty-three angiograms were reviewed for the purpose of this study and a total of 6 examinations were selected for illustration of the technique. Stereoscopic display was possible for all of them and in the 3 types of support tested: computer monitor, tablet, and smartphone screens.

CONCLUSIONS

Anaglyph display of computed tomography angiograms is an effective and low-cost alternative for the stereoscopic visualization of a patient's individual intracranial vascular anatomy.

Three-Dimensional Printed Modeling of Diffuse Low-Grade Gliomas and Associated White Matter Tract Anatomy

BACKGROUND

Diffuse low-grade gliomas (DLGGs) represent several pathological entities that infiltrate and invade cortical and subcortical structures in the brain.

OBJECTIVE

To describe methods for rapid prototyping of DLGGs and surgically relevant anatomy.

METHODS

Using high-definition imaging data and rapid prototyping technologies, we were able to generate 3 patient DLGGs to scale and represent the associated white matter tracts in 3 dimensions using advanced diffusion tensor imaging techniques.

RESULTS

This report represents a novel application of 3-dimensional (3-D) printing in neurosurgery and a means to model individualized tumors in 3-D space with respect to subcortical white matter tract anatomy. Faculty and resident evaluations of this technology were favorable at our institution.

CONCLUSION

Developing an understanding of the anatomic relationships existing within individuals is fundamental to successful neurosurgical therapy. Imaging-based rapid prototyping may improve on our ability to plan for and treat complex neuro-oncologic pathology.

The learning rate in three dimensional high definition video assisted microvascular anastomosis in a rat model

Three-dimensional (3D) high definition (HD) video systems are changing microsurgical practice by providing stereoscopic imaging not only for the surgeon and first assistant using the binocular microscope, but also for others involved in the surgery. The purpose of this study was to evaluate the potential to replace the binocular microscope for microarterial anastomoses and assess the rate of learning based on surgeons' experience. Two experienced and two novice microsurgeons performed a total of 88 rat femoral arterial anastomoses: 44 using a 3D HD video device ('Trenion', Carl Zeiss Meditech) and 44, a binocular microscope. We evaluated anastomosis time and modified OSATS scores as well as the subjects' preference for comfort, image adequacy and technical ease. Experienced microsurgeons showed a steep learning curve for anastomosis times with equivalent OSATS scores for both systems. However, prolonged anastomosis times were required when using the novel 3D-HD system rather than direct binocular vision. Comparable learning rates for anastomosis time were demonstrated for novice microsurgeons and modified OSATS scores did not differ between the different viewing technologies. All microsurgeons reported improved comfort for the 3D HD video system but found the image quality of the conventional microscope superior, facilitating technical ease. The present study demonstrates the potential of 3D HD video systems to replace current binocular microscopes, offering qualitatively-equivalent microvascular anastomosis with improved comfort for experienced microsurgeons. However, image quality was rated inferior with the 3D HD system resulting in prolonged anastomosis times. Microsurgical skill acquisition in novice microsurgeons was not influenced by the viewing system used.

Three-Dimensional Imaging in Neurosurgical Research and Education

OBJECTIVE

We describe the setup and use of different 3-dimensional (3-D) recording modalities (macroscopic, endoscopic, and microsurgical) in our laboratory and operating room and discuss their implications in neurosurgical research and didactics. We also highlight the utility of 3-D images in providing depth perception and discernment of structures compared with 2-dimensional (2-D) images.

METHODS

The technical details for equipment and laboratory setup for obtaining 3-D images were described. The stereoscopic pair of images was obtained using a modified "shoot-shift-shoot" method and later converged to a 3-D image. For microsurgical procedures, 3-D images were obtained using an integrated 3-D video camera coupled to the surgical microscope in both the laboratory and the operating room. Illustrative cases were used to compare 2-D and 3-D images.

RESULTS

Side-by-side comparisons of 2-D and 3-D images obtained using all modalities revealed that 3-D imaging was superior to 2-D imaging in providing depth perception and structure identification.

CONCLUSIONS

This is the first report in the literature of the methodology for obtaining 3-D endoscopic endonasal images using the 2-D endoscope. The use of 3-D imaging is invaluable in neurosurgical research and education, as it provides immediate depth perception (third dimension), allowing efficient understanding of key spatial relationships. Integration of 3-D imaging in neurosurgical residency programs may increase learning efficiency and shorten learning curves. However, use of 3-D imaging should not replace direct hands-on practice.