Preservation of the optic radiations based on comparative analysis of diffusion tensor imaging tractography and anatomical dissection

Abstract

Background: Visualization of the precise course of the visual pathways is relevant to prevent damage that may inflict visual field deficits during neurosurgical resections. In particular the optic radiations (OR) are susceptible to such damage during neurosurgery. Cortical pathways can be mapped in vivo, by using Diffusion Tensor Imaging (DTI). Visualization of these pathways would be potentially helpful to prevent neurosurgical visual morbidity. In this study an anatomical dissection of the visual pathways was compared to DTI fiber tractography (DTI-FT) data of four human brains. The feasibility of a definition of a Safety Zone is investigated.Methods: Four adult brains were dissected using Klingler's fiber dissection method, which allowed preparation of the OR. Measurements before and after dissection were used to establish distances from the cortex to the OR. DTI-scans were also obtained from these brains to determine the same distances.Results: Measurements from specific landmark points on the cortex to the lateral border of the OR were performed in four brains. Analysis through DTI tractography corresponded with the dissection results. Based on the combined results of both dissection and DTI-FT, we defined a quantitative surgical Safety Zone with respect to various anatomical landmarks (in particular the ventricle system).Conclusion: We conclude that there is a good correlation between the visualizations of the optic pathways based on dissection and DTI. Furthermore, we conclude that defining a neurosurgical Safety Zone which could preserve the integrity of the OR during surgery, based on the combination of DTI-FT images and dissection is feasible.

Microstructural Investigations of the Visual Pathways in Pediatric Epilepsy Neurosurgery: Insights From Multi-Shell Diffusion Magnetic Resonance Imaging

“…The timeframe of these changes is not clear, but if this is the case, it is possible that brain shift has contributed to an underestimation of the segmented resection area. In the absence of proper a validation technique other than post-mortem dissections, the comparison between pre-and intra-operative tractography reconstructions as well as the combination with other MRI modalities and electrophysiological recordings should also provide further assurance regarding the use of tractography for neurosurgical purposes (Schmitt et al, 2014;Alvarez et al, 2015;Nooij et al, 2015;Nimsky et al, 2016). A further limitation is the absence of a complete set of ophthalmology data in all the patients studied, although in the data available a clear correspondence between optic radiation involvement and visual field defect was demonstrated.…”

Klingler’s method of brain dissection: review of the technique including its usefulness in practical neuroanatomy teaching, neurosurgery and neuroimaging

“…Those authors also drew attention to the preservation of inferior occipitofrontal fasciculus, which allows the preservation of the eloquent functions it subserves [45]. Nooij et al [37] also stated that precise visualisation of the course of the visual pathways is relevant to prevent visual field deficits after neurosurgical resections.…”

Defining the relationship of the optic radiation to the roof and floor of the ventricular atrium: a focused microanatomical study

“…However, even with this recent advent, the accurate topographic anatomy of the optic radiation has yet to be clarified. 2,8,11,24,26,35,48 It should be noted that these elegant radiological methods, when applied to narrow and anatomically complex parenchymal areas, have the tendency to generate multiple artifacts as a result of the effect of "crossing," "kissing," and "bending" white matter fibers. 6,7,14,25,47 In particular, and with regard to the optic radiations, which have a complex inherent trajectory and morphology, even the most advanced neuroimaging techniques are prone to anatomical inaccuracies, distortions, and errors and are not superior to the classical dissection methods.…”

“…6,7,14,25,47 In particular, and with regard to the optic radiations, which have a complex inherent trajectory and morphology, even the most advanced neuroimaging techniques are prone to anatomical inaccuracies, distortions, and errors and are not superior to the classical dissection methods. 2,11,24,26,35,48 The fiber microdissection technique is still the gold standard for exploring intricate white matter pathways, which is why we chose it to be our basic method of investigation. 11,19,22,24,26,30,35,48 Through these focused white matter dissections, we consistently observed the roof of the atrium to be covered by claustrocortical fibers, parietopontine fibers, and fibers of the parietal thalamic radiation and tapetum and found no evidence of optic radiation fibers arching over this segment of the ventricular trigone.…”

“…2,11,24,26,35,48 The fiber microdissection technique is still the gold standard for exploring intricate white matter pathways, which is why we chose it to be our basic method of investigation. 11,19,22,24,26,30,35,48 Through these focused white matter dissections, we consistently observed the roof of the atrium to be covered by claustrocortical fibers, parietopontine fibers, and fibers of the parietal thalamic radiation and tapetum and found no evidence of optic radiation fibers arching over this segment of the ventricular trigone. Accordingly, neurosurgical approaches that aim to access the atrium through its roof do not potentially place the visual pathway at risk of injury and therefore do not increase surgery-related morbidity.…”