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.

Cerebral Ultrasound Perfusion Imaging

Cerebral Ultrasound Perfusion Imaging

Ultrasound Perfusion Imaging is feasible to enable detection of cerebral hypoperfusion after aneurysmal subarachnoid hemorrhage, and the left-right difference of time to peak (TTP) values is the most indicative result of this finding 1).

Over the past 20 years, ultrasonic cerebral perfusion imaging (UPI) has been introduced and validated by applying different data acquisition and processing approaches. Clinical data were collected mainly in acute stroke patients. Some efforts were undertaken in order to compare different technical settings and validate results to gold standard perfusion imaging. A review illustrates the evolution of the method, explicating different technical aspects and milestones achieved over time. Up to date, advancements of ultrasound technology, as well as data processing approaches, enable semi-quantitative, gold standard proven identification of critically hypo-perfused tissue in acute stroke patients. The rapid distribution of CT perfusion over the past 10 years has limited the clinical need for UPI. However, the unexcelled advantage of mobile applications raises reasonable expectations for future applications. Since the identification of intracerebral hematoma and large vessel occlusion can also be revealed by ultrasound exams, UPI is a supplementary multi-modal imaging technique with the potential of the pre-hospital application. Some further applications are outlined to highlight the future potential of this underrated bedside method of microcirculatory perfusion assessment 2).

Ultrasound perfusion imaging provides a simple and non-invasive way to detect the VN time window, which increases the feasibility of vascular normalization (VN) in clinical cancer applications 3).

Reitmeir et al. compared contrast-enhanced ultrasound perfusion imaging with magnetic resonance perfusion-weighted imaging or perfusion computed tomography for detecting normo-, hypo-, and nonperfused brain areas in acute middle cerebral artery stroke. We performed high mechanical index contrast-enhanced ultrasound perfusion imaging in 30 patients. The time-to-peak intensity of 10 ischemic regions of interest was compared to four standardized nonischemic regions of interests of the same patient. A time-to-peak >3 s (ultrasound perfusion imaging) or >4 s (perfusion computed tomography and magnetic resonance perfusion) defined hypoperfusion. In 16 patients, 98 of 160 ultrasound perfusion imaging regions of interest of the ischemic hemisphere were classified as normal, and 52 as hypoperfused or nonperfused. Ten regions of interest were excluded due to artifacts. There was a significant correlation between the ultrasound perfusion imaging and magnetic resonance perfusion or perfusion computed tomography (Pearson’s chi-squared test 79.119, p < 0.001) (OR 0.1065, 95% CI 0.06-0.18). No perfusion in ultrasound perfusion imaging (18 regions of interest) correlated highly with diffusion restriction on magnetic resonance imaging (Pearson’s chi-squared test 42.307, p < 0.001). Analysis of receiver operating characteristics proved a high sensitivity of ultrasound perfusion imaging in the diagnosis of the hypoperfused area under the curve, (AUC = 0.917; p < 0.001) and nonperfused (AUC = 0.830; p < 0.001) tissue in comparison with perfusion computed tomography and magnetic resonance perfusion. They presented a proof of concept in determining normo-, hypo-, and nonperfused tissue in acute stroke by advanced contrast-enhanced ultrasound perfusion imaging 4).

A review detail the methodology of ultrasound perfusion imaging, discuss aspects of its safety and present the clinical applications of brain perfusion assessment with ultrasound in acute stroke patients 5).


Fung C, Heiland DH, Reitmeir R, Niesen WD, Raabe A, Eyding J, Schnell O, Rölz R, Z Graggen WJ, Beck J. Ultrasound Perfusion Imaging for the Detection of Cerebral Hypoperfusion After Aneurysmal Subarachnoid Hemorrhage. Neurocrit Care. 2022 Feb 24. doi: 10.1007/s12028-022-01460-z. Epub ahead of print. PMID: 35211837.

Eyding J, Fung C, Niesen WD, Krogias C. Twenty Years of Cerebral Ultrasound Perfusion Imaging-Is the Best yet to Come? J Clin Med. 2020 Mar 17;9(3):816. doi: 10.3390/jcm9030816. PMID: 32192077; PMCID: PMC7141340.

Ho YJ, Chu SW, Liao EC, Fan CH, Chan HL, Wei KC, Yeh CK. Normalization of Tumor Vasculature by Oxygen Microbubbles with Ultrasound. Theranostics. 2019 Sep 25;9(24):7370-7383. doi: 10.7150/thno.37750. PMID: 31695774; PMCID: PMC6831304.

Reitmeir R, Eyding J, Oertel MF, Wiest R, Gralla J, Fischer U, Giquel PY, Weber S, Raabe A, Mattle HP, Z’Graggen WJ, Beck J. Is ultrasound perfusion imaging capable of detecting mismatch? A proof-of-concept study in acute stroke patients. J Cereb Blood Flow Metab. 2017 Apr;37(4):1517-1526. doi: 10.1177/0271678×16657574. Epub 2016 Jan 1. PMID: 27389180; PMCID: PMC5453469.

Meairs S, Kern R. Intracranial perfusion imaging with ultrasound. Front Neurol Neurosci. 2015;36:57-70. doi: 10.1159/000366237. Epub 2014 Dec 22. PMID: 25531663.

Diffusion tensor imaging for Brainstem cavernous malformation

Diffusion tensor imaging for Brainstem cavernous malformation

A study aimed to systematically review the literature to determine the clinical utility and perspectives of diffusion tensor imaging (DTI) in the management of patients with brainstem cavernous malformations (BSCMs). PubMedEmbase, and Cochrane were searched for English-language articles published until May 10, 2021. Clinical studies and case series describing DTI-based evaluation of patients with BSCMs were included. Fourteen articles were included. Preoperative DTI enabled to adjustment of the surgical approach and choose a brainstem safe entry zone in deep-seated BSCMs. Preoperatively lower fractional anisotropy (FA) of the corticospinal tract (CST) correlated with the severity of CST injury and motor deficits. Postoperatively increased FA and decreased apparent diffusion coefficient (ADC) corresponded with the normalization of the perilesional CST, indicating motor improvement. The positive (PPV) and negative predictive value (NPV) of qualitative DTI ranged from 20 to 75% and from 66.6 to 100%, respectively. The presence of preoperative and postoperative motor deficits was associated with a higher preoperative resting motor threshold (RMT) and lower FA. A higher preoperative corticospinal tract score was indicative of a lower preoperative and follow-up Medical Research Council (MRC) grade. DTI facilitated the determination of a surgical trajectory with minimized risk of WMTs damage. Preoperative FA and RMT might indicate the severity of preoperative and postoperative motor deficits. Preoperative CST score can reliably reflect patients’ preoperative and follow-up motor status. Due to high NPV, normal CST morphology might predict intact neurological outcomes. Contrarily, sparse and relatively low PPV limits the reliable prediction of neurological deficits 1).

In 2016 Januszewski et al. compared with the standard magnetic resonance imaging, DTI provided improved visualization of cavernous malformation involvement in eloquent fiber tracts of the brainstem. This additional information might help in selecting a more appropriate surgical trajectory in selected lesions. Larger patient cohorts are needed to assess the effect of this modality in patients’ outcome 2).

Positive findings on DTT such as fiber tract deviation, deformation, disruption or interruption should be taken cautiously before drawing conclusions of clinically relevant damage of white matter tract3).

Preoperative diffusion tensor imaging may influence the selection of surgical approach or brainstem entry zones, especially in deep-seated lesions without pial or ependymal presentation. DTI/DTT findings may allow for more aggressive management of lesions previously considered surgically inaccessible. Preoperative DTI/DTT changes do not appear to correlate with functional postoperative outcome in long-term follow-up 4)

Intact corticospinal tract (CST) morphology in diffusion tensor imaging DTI predicts a favorable postoperative outcome in patients with BSC. Interrupted CSTs and decreased Fractional anisotropy (FA)-values correlate well within lesion level, nevertheless morphologic characteristics and diffusion parameter changes cannot predict poor prognosis. Caudal and rostral diffusion parameters can provide more information of the integrity of CSTs compared with morphological study alone 5).

Hemorrhagic brainstem CMs can disrupt and displace perilesional white matter tracts with the latter occurring in unpredictable directions. This requires the use of tractography to accurately define their orientation to optimize surgical entry point, minimize morbidity, and enhance neurological outcomes. Observed anisotropy decreases in the perilesional segments are consistent with neural injury following hemorrhagic insults. A model using these values in different CST segments can be used to longitudinally monitor its craniocaudal integrity. Diffusion connectometry is a complementary approach providing longitudinal information on the rostrocaudal involvement of the CST 6).

In 2007 compared with the information provided by conventional MR imaging, DTI and WMT provided superior quantification and visualization of lesion involvement in eloquent fiber tracts of the brainstem. Moreover, DTI and WMT were found to be beneficial for white matter recognition in the neurosurgical planning and postoperative assessment of brainstem lesions 7).


Rogalska M, Antkowiak L, Mandera M. Clinical application of diffusion tensor imaging and fiber tractography in the management of brainstem cavernous malformations: a systematic review. Neurosurg Rev. 2022 Feb 25. doi: 10.1007/s10143-022-01759-7. Epub ahead of print. PMID: 35211879.

Januszewski J, Albert L, Black K, Dehdashti AR. The Usefulness of Diffusion Tensor Imaging and Tractography in Surgery of Brainstem Cavernous Malformations. World Neurosurg. 2016 Sep;93:377-88. doi: 10.1016/j.wneu.2016.06.019. Epub 2016 Jun 14. PMID: 27312394.

Topcuoglu OM, Yaltirik K, Firat Z, Sarsilmaz A, Harput V, Sarikaya B, Ture U. Limited Positive Predictive Value of Diffusion Tensor Tractography in Determining Clinically Relevant White Matter Damage in Brainstem Cavernous Malformations: A Retrospective Study in a Single Center Surgical Cohort. J Neuroradiol. 2019 Sep 17. pii: S0150-9861(19)30438-9. doi: 10.1016/j.neurad.2019.07.005. [Epub ahead of print] PubMed PMID: 31539583.

Flores BC, Whittemore AR, Samson DS, Barnett SL. The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations. J Neurosurg. 2015 Mar;122(3):653-62. doi: 10.3171/2014.11.JNS13680. Epub 2015 Jan 9. PubMed PMID: 25574568.

Yao Y, Ulrich NH, Guggenberger R, Alzarhani YA, Bertalanffy H, Kollias SS. Quantification of corticospinal tracts with diffusion tensor imaging in brainstem surgery: Prognostic value in 14 consecutive cases at 3T-MRI. World Neurosurg. 2015 Mar 5. pii: S1878-8750(15)00067-4. doi: 10.1016/j.wneu.2015.01.045. [Epub ahead of print] Review. PubMed PMID: 25749578.

Faraji AH, Abhinav K, Jarbo K, Yeh FC, Shin SS, Pathak S, Hirsch BE, Schneider W, Fernandez-Miranda JC, Friedlander RM. Longitudinal evaluation of corticospinal tract in patients with resected brainstem cavernous malformations using high-definition fiber tractography and diffusion connectometry analysis: preliminary experience. J Neurosurg. 2015 Jun 5:1-12. [Epub ahead of print] PubMed PMID: 26047420.

Chen X, Weigel D, Ganslandt O, Buchfelder M, Nimsky C. Diffusion tensor imaging and white matter tractography in patients with brainstem lesions. Acta Neurochir (Wien). 2007 Nov;149(11):1117-31; discussion 1131. doi: 10.1007/s00701-007-1282-2. Epub 2007 Aug 23. PMID: 17712509.
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