3D imaging

3D imaging

The word stereoscopy derives from Greek στερεός (stereos), meaning “firm, solid”, and σκοπέω (skopeō), meaning “to look, to see”.

Stereoscopy (also called stereoscopics or 3D imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.

One of the primary restrictions of endoscopic or endoscope assisted surgery is the lack of binocular or stereoscopic vision. Monocular endoscopes and displays create a 2-dimensional (2-D) image that impairs depth perception, hand-eye coordination, and the ability to estimate size 1) 2).

Most stereoscopic methods present two offset images separately to the left and right eye of the viewer. These two-dimensional images are then combined in the brain to give the perception of 3D depth. This technique is distinguished from 3D displays that display an image in three full dimensions, allowing the observer to increase information about the 3-dimensional objects being displayed by head and eye movements.

Operating in a 2D environment requires surgeons to train their hand-eye coordination to respond to visual cues received by the interaction of the operative instruments with the environment to accurately understand the relative depth of structures in the 2-D projection. Surgeons will often move the endoscope in and out or side to side to gain a motion parallax depth cue. This lack of stereoscopic vision has contributed to the steep learning curve in the field of neuroendoscopy. The next obvious step in the evolution of minimal access endoscopic surgery is the development of high-definition stereoendoscopes that produce a 3-dimensional (3-D) image.

Although such stereoendoscopes exist their use in neurosurgery has been limited because of the larger diameter and poor resolution of earlier generations.

It is easy to make errors in estimating the exact size and positioning of neural structures, especially when only using tomographic methods, as a lot of imagination and little precision is required. Wu and Tang found that combining the use of sectional micro-anatomy and micro-stereoscopic anatomy is much more accurate. They believe that his study makes a significant contribution to the literature because they believe that using improved methods to examine the neural structure is vital in future research on the micro-stereoscopic brain anatomy 3)

In neurosurgery stereoscopy has been used very successfully to demonstrate microsurgical anatomy by Albert L. Rhoton and co-workers 4) and Shimizu et al in 2006 5) , explained the importance of 3D neuroanatomical imaging as a teaching tool in neurosurgical training and comprehensively described original techniques for their production.

The use of 3D imaging in neurosurgical training is not as widespread as it could be, partially due to the complexity of some techniques described in the past, the long preparation time in the pre- and post-operative phases and their interference with the operation, making it impractical in busy neurosurgical theatres.

Companies producing microscopes and endoscopes have developed integrated 3D technology making 3D recording and editing less complex, but these are still very expensive.

Abarca et al performed endoscopic dissection in cadaveric specimens fixed with formalin and with the Thiel technique, both prepared using the intravascular injection of colored material. Endonasal approaches were performed with conventional 2D endoscopes. Then they applied the 3D anaglyph technique to illustrate the pictures in 3D.

The most important anatomical structures and landmarks of the sellar region under endonasal endoscopic vision are illustrated in 3D images.

The skull base consists of complex bony and neurovascular structures. Experience with cadaver dissection is essential to understand complex anatomy and develop surgical skills. A 3D view constitutes a useful tool for understanding skull base anatomy 6).

Used effectively, stereoscopic three-dimensional (3D) technologies can engage students with complex disciplinary content as they are presented with informative representations of abstract concepts. In addition, preliminary evidence suggests that stereoscopy may enhance learning and retention in some educational settings. Biological concepts particularly benefit from this type of presentation since complex spatially oriented structures frequently define function within these systems. Viewing biological phenomena in 3D as they are in real life allows the user to relate these spatial relationships and easily grasp concepts making the key connection between structure and function. In addition, viewing these concepts interactively in 3D and in a manner that leads to increased engagement for young prospective scientists can further increase the impact. We conducted two studies evaluating the use of this technology as an instructional tool to teach high school students complex biological concepts. The first study tested the use of stereoscopic materials for teaching brain function and human anatomy to four classes. The second study evaluated stereoscopic images to support the learning of cell structure and DNA in four different high school classes. Most important, students who used stereoscopic 3D had significantly higher test scores than those who did not. In addition, students reported enjoying 3D presentations, and it was among their top choices for learning about these complex concepts. In summary, our evidence adds further support for the benefits of 3D images to students’ learning of science concepts 7).

The teaching of neuroanatomy in medical education has historically been based on didactic instruction, cadaveric dissections, and intra-operative experience for students. Multiple novel 3-Dimensional (3D) modalities have recently emerged. Among these, stereoscopic anaglyphic video is easily accessible and affordable, however, its effects have not yet formally been investigated.

This study aimed to investigate if 3D stereoscopic anaglyphic video instruction in neuroanatomy could improve learning for content-naive students, as compared to 2D video instruction.

A single-site controlled prospective case control study was conducted at the School of Education. Content knowledge was assessed at baseline, followed by the presentation of an instructional neuroanatomy video. Participants viewed the video in either 2D or 3D format, then completed a written test of skull base neuroanatomy. Pre-test and post-test performances were analyzed with independent t-tests and ANCOVA.

249 subjects completed the study. At baseline, the 2D (n=124, F=97) and 3D groups (n=125, F=96) were similar, although the 3D group was older by 1.7 years (p=.0355) and the curricula of participating classes differed (p<.0001). Average scores for the 3D group were higher for both pretest (2D, M=19.9%, SD=12.5% vs. 3D, M=23.9%, SD=14.9%, p=.0234) and posttest (2D, M=68.5%, SD=18.6% vs. 3D, M=77.3%, SD=18.8%, p=.003), but the magnitude of improvement across groups did not reach statistical significance (2D, M=48.7%, SD=21.3%, vs. 3D, M=53.5%, SD=22.7%, p=.0855).

Incorporation of 3D video instruction into curricula without careful integration is insufficient to promote learning over 2D video 8).

Preoperative 3D imaging provides reliable and detailed information about the intraoperative anatomical relationship between the trigeminal nerve and the SPV. This evaluation is useful for preoperative planning 9).

O arm 3D imaging with stereotactic navigation may be used to localize lesions intraoperatively with real-time dynamic feedback of tumor resection.

Stereotactic guidance may augment resection or biopsy of primary and metastatic spinal tumors. It offers reduced radiation exposure to OR personnel as well as the ability to use minimally invasive approaches that limit tissue injury. Further work may be done to assess the utility of stereotactic image guidance in oncological tumor resection, particularly with respect to outcomes for patients 10).


Badani KK, Bhandari A, Tewari A, Menon M: Comparison of two- dimensional and three-dimensional suturing: Is there a difference in a robotic surgery setting? J Endourol 19:1212–1215, 2005.

Taffinder N, Smith SG, Huber J, Russell RC, Darzi A: The effect of a second- generation 3D endoscope on the laparoscopic precision of novices and expe- rienced surgeons. Surg Endosc 13:1087–1092, 1999.

Wu JZ, Tang CH. Correspondence: A combination of sectional micro-anatomy and micro-stereoscopic anatomy is an improved micro-dissection method. J Anat. 2022 Feb 6. doi: 10.1111/joa.13631. Epub ahead of print. PMID: 35128655.

Ribas GC , Bento RF , Rodrigues AJ . Anaglyphic three-dimensional stereoscopic printing: revival of an old method for anatomical and surgical teaching and reporting . J Neurosurg 2001 ; 95 : 1057 – 66.

Shimizu S , Tanaka R , Rhoton AL , Jr ., e t al . Anatomic dissection and classic three-dimensional documentation: a unit of education for neurosurgical anatomy revisited . Neurosurgery 2006 ; 58 : E1000. discussion E .

Abarca-Olivas J, Monjas-Cánovas I, López-Álvarez B, Lloret-García J, Sanchez-del Campo J, Gras-Albert JR, Moreno-López P. [Three-dimensional endoscopic endonasal study of skull base anatomy]. Neurocirugia (Astur). 2014 Jan-Feb;25(1):1-7. doi: 10.1016/j.neucir.2013.02.009. Epub 2014 Jan 18. Spanish. PubMed PMID: 24447642.

Ferdig R, Blank J, Kratcoski A, Clements R. Using stereoscopy to teach complex biological concepts. Adv Physiol Educ. 2015 Sep;39(3):205-8. doi: 10.1152/advan.00034.2014. PubMed PMID: 26330039.

Goodarzi A, EdM SM, Lee D, Girgis F. The effect of stereoscopic anaglyphic 3-dimensional video didactics on learning neuroanatomy. World Neurosurg. 2017 Jul 29. pii: S1878-8750(17)31219-6. doi: 10.1016/j.wneu.2017.07.119. [Epub ahead of print] PubMed PMID: 28765017.

Xiong NX, Zhou X, Yang B, Wang L, Fu P, Yu H, Wang Q, Abdelmaksoud A, Yuan Y, Liu W, Huang Y, Budrytė K, Huang T, Zheng X. Preoperative MRI Evaluation of Relationship between Trigeminal Nerve and Superior Petrosal Vein: Its Role in Treating Trigeminal Neuralgia. J Neurol Surg A Cent Eur Neurosurg. 2019 Mar 26. doi: 10.1055/s-0038-1669399. [Epub ahead of print] PubMed PMID: 30913572.

Rubber hand illusion

Rubber hand illusion

The rubber hand illusion (RHI) is a perceptual experience that often occurs when an administered tactile stimulation of a person’s real hand hidden from view, occurs synchronously with a corresponding visual stimulation of an observed rubber hand placed in full vision of the person in a position corresponding to where their real hand might normally be. The perceptual illusion is that the person feels a sense of “ownership” of the rubber hand which they are looking at. Most studies have focused on the underlying neural properties of the illusion and the experimental manipulations that lead to it. The illusion could also be used for exploring the sense of limb and prosthetic ownership for people after amputation. Cortical electrodes such as those used in sensorimotor stimulation surgery for pain may provide an opportunity to further understand the cortical representation of the illusion and possibly provide an opportunity to modulate the individual’s sense of body ownership. Thus, the RHI might also be a critical tool for the development of neurorehabilitative interventions that will be of great interest to the neurosurgical and rehabilitation communities 1).

The widely used rubber hand illusion (RHI) paradigm provides insight into how the brain manages conflicting multisensory integration regarding bodily self-consciousness. Previous functional neuroimaging studies have revealed that the feeling of body ownership is linked to activity in the premotor cortex, the intraparietal areas, the occipitotemporal cortex, and the insula. Matuz-Budai et al. from Pécs, investigated whether the individual differences in the sensation of body ownership over a rubber hand, as measured by the subjective report and the proprioceptive drift, are associated with structural brain differences in terms of cortical thickness in 67 healthy young adults. Matuz-Budai et al. found that individual differences measured by the subjective report of body ownership are associated with the cortical thickness in the somatosensory regions, the temporoparietal junction, the intraparietal areas, and the occipitotemporal cortex, while the proprioceptive drift is linked to the premotor cortex and the anterior cingulate cortex. These results are in line with functional neuroimaging studies indicating that these areas are indeed involved in processes such as cognitive-affective perspective-taking, visual processing of the body, and the experience of body ownership and bodily awareness. Consequently, these individual differences in the sensation of body ownership are pronounced in both functional and structural differences 2)


Ramakonar H, Franz EA, Lind CR. The rubber hand illusion and its application to clinical neuroscience. J Clin Neurosci. 2011 Dec;18(12):1596-601. doi: 10.1016/j.jocn.2011.05.008. Epub 2011 Oct 13. PMID: 22000838.

Matuz-Budai T, Lábadi B, Kohn E, Matuz A, Zsidó AN, Inhóf O, Kállai J, Szolcsányi T, Perlaki G, Orsi G, Nagy SA, Janszky J, Darnai G. Individual differences in the experience of body ownership are related to cortical thickness. Sci Rep. 2022 Jan 17;12(1):808. doi: 10.1038/s41598-021-04720-8. PMID: 35039541.

Superior frontal gyrus

Superior frontal gyrus

The superior frontal gyrus (SFG) makes up about one-third of the frontal lobe of the human brain. It is bounded laterally by the superior frontal sulcus.

The superior frontal gyrus, like the inferior frontal gyrus and the middle frontal gyrus, is more of a region than a true gyrus.

Lateral penetration of the Superior frontal gyrus (SFG) in the left hemisphere is associated with worsening phonemic verbal fluency and has greater explanatory power than active contact location. This may be explained by lesioning of the lateral SFG-Broca area pathway, which is implicated in language function 1).

Alagapan et al. combined electrocorticography and direct cortical stimulation in three patients implanted with subdural electrodes to assess if superior frontal gyrus is indeed involved in working memory. They found left SFG exhibited task-related modulation of oscillations in the theta and alpha frequency bands specifically during the encoding epoch. Stimulation at the frequency matched to the endogenous oscillations resulted in reduced reaction times in all three participants. The results provide evidence for SFG playing a functional role in working memory and suggest that SFG may coordinate working memory through low-frequency oscillations thus bolstering the feasibility of using intracranial electric stimulation for restoring cognitive function 2).

The supplementary motor area syndrome is a characteristic neurosurgical syndrome that can occur after surgery in the superior frontal gyrus.

The superior frontal gyrus (SFG) is thought to contribute to higher cognitive functions and particularly to working memory (WM), although the nature of its involvement remains a matter of debate. To resolve this issue, methodological tools such as lesion studies are needed to complement the functional imaging approach.

du Boisgueheneuc et al have conducted the first lesion study to investigate the role of the SFG in WM and address the following questions: do lesions of the SFG impair WM and, if so, what is the nature of the WM impairment? To answer these questions, they compared the performance of eight patients with a left prefrontal lesion restricted to the SFG with that of a group of 11 healthy control subjects and two groups of patients with focal brain lesions prefrontal lesions sparing the SFG (n = 5) and right parietal lesions (n = 4)] in a series of WM tasks. The WM tasks (derived from the classical n-back paradigm) allowed us to study the impact of the SFG lesions on domain (verbal, spatial, face) and complexity (1-, 2- and 3-back) processing within WM. As expected, patients with a left SFG lesion exhibited a WM deficit when compared with all control groups, and the impairment increased with the complexity of the tasks. This complexity effect was significantly more marked for the spatial domain. Voxel-to-voxel mapping of each subject’s performance showed that the lateral and posterior portion of the SFG (mostly Brodmann area 8, rostral to the frontal eye field) was the subregion that contributed the most to the WM impairment. These data led us to conclude that (i) the lateral and posterior portion of the left SFG is a key component of the neural network of WM; (ii) the participation of this region in WM is triggered by the highest level of executive processing; (iii) the left SFG is also involved in spatially oriented processing.

The findings support a hybrid model of the anatomical and functional organization of the lateral SFG for WM, according to which this region is involved in higher levels of WM processing (monitoring and manipulation) but remains oriented towards spatial cognition, although the domain specificity is not exclusive and is overridden by an increase in executive demand, regardless of the domain being processed. From a clinical perspective, this study provides new information on the impact of left SFG lesions on cognition that will be of use to neurologists and neurosurgeons 3).

Superior frontal gyrus tumor.

The superior frontal gyrus (SFG) makes up about two thirds of the frontal lobe of the human brain


The role of the superior frontal gyrus (SFG) is not yet clear


The superior frontal gyrus (SFG) plays a functional role in working memory



Askari A, Greif TR, Lam J, Maher AC, Persad CC, Patil PG. Decline of verbal fluency with lateral superior frontal gyrus penetration in subthalamic nucleus deep brain stimulation for Parkinson disease. J Neurosurg. 2022 Jan 28:1-6. doi: 10.3171/2021.11.JNS211528. Epub ahead of print. PMID: 35090137.

Alagapan S, Lustenberger C, Hadar E, Shin HW, Frӧhlich F. Low-frequency direct cortical stimulation of left superior frontal gyrus enhances working memory performance. Neuroimage. 2019 Jan 1;184:697-706. doi: 10.1016/j.neuroimage.2018.09.064. Epub 2018 Sep 27. PubMed PMID: 30268847; PubMed Central PMCID: PMC6240347.

du Boisgueheneuc F, Levy R, Volle E, Seassau M, Duffau H, Kinkingnehun S, Samson Y, Zhang S, Dubois B. Functions of the left superior frontal gyrus in humans: a lesion study. Brain. 2006 Dec;129(Pt 12):3315-28. Epub 2006 Sep 19. PubMed PMID: 16984899.
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