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Tumors of the Nervous System
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Surgical morbidity of tumor biopsy or resection is largely related to tumor location and skill of the neurosurgeon. In noneloquent brain (nondominant anterior frontal cortex), the risk of neurologic morbidity is usually < 3–5%; in eloquent areas of brain (dominant frontal lobe, thalamus, and brainstem), the risk of neurologic morbidity with resection or biopsy is much higher. However, even in neurologically eloquent areas of the brain, the mortality risk from stereotactic biopsy is usually < 1%. Techniques such as functional MRI and diffusion tractography assist in identification of eloquent areas and can reduce surgical risk. Surgical techniques such as awake craniotomy and intraoperative neurophysiological monitoring with electroencephalography (EEG) or electromyography (EMG) can further mitigate surgical risks.
Anatomical and Biological Imaging of Pediatric Brain Tumor
Published in David A. Walker, Giorgio Perilongo, Roger E. Taylor, Ian F. Pollack, Brain and Spinal Tumors of Childhood, 2020
Rob A. Dineen, Shivaram Avula, Andrew C. Peet, Giovanni Morana, Monika Warmuth-Metz
Although tractography can play an important role in neurosurgical planning, it is prudent to be aware of the variation in construction of the tracts by the different post-processing tools available for clinical use.27,28 The use of DTI in conjunction with functional MRI (fMRI) has been proposed to increase the reliability of DTI in presurgical planning.29 Future directions in the field of tractography include the use of newer advanced diffusion tensor techniques such as high-definition fiber tractography (HDFT) and high angular resolution diffusion imaging (HARDI).30,31
Diffusion Magnetic Resonance Imaging in the Central Nervous System
Published in Shoogo Ueno, Bioimaging, 2020
Kouhei Kamiya, Yuichi Suzuki, Osamu Abe
The unique ability of dMRI tractography to visualize white matter fiber pathways non-invasively made it useful both for clinical medicine and neuroscience research. Despite its limitations (Section 6.5.4), dMRI tractography has at least enabled virtual white matter dissection (Catani & Thiebaut de Schotten, 2008) (Figure 6.12) that roughly matches the results of postmortem studies and has provided good explanations for syndromes caused by disconnection between particular brain regions (Thiebaut de Schotten et al., 2015). Currently, dMRI tractography is an indispensable tool for mapping before neurosurgery (Calabrese, 2016; Voets et al., 2017). The use of higher-order methods has been reported to better predict functional outcomes of surgery for brain tumors by improving the delineation of tracts passing through a peri-tumoral region (Caverzasi et al., 2016).
Intimate partner violence and brain imaging in women: A neuroimaging literature review
Published in Brain Injury, 2023
Jirapat Likitlersuang, David H. Salat, Catherine B. Fortier, Katherine M. Iverson, Kimberly B. Werner, Tara Galovski, Regina E. McGlinchey
Diffusion-weighted imaging is another domain of MRI that can be used to create the contrast image of the diffusion of water molecules within the brain tissue. The diffusion tensor imaging (DTI) is one of the DWI sequences that can evaluate the white matter tractography (3D modeling) of nerve fibers as well as microstructural tissue properties. Specifically, the degree in anisotropy or degree of directionality of water molecules movement within the brain can be extracted. Fractional anisotropy (FA) is a scalar value from 0 to 1 and in diffusion imaging described the fiber density, axonal diameter, and myelination in the brain white matter. A value of one indicates fluid flow in one direction without any restriction (anisotropic), while a value closer to zero indicates leaky axon and unrestricted flow in all directions (isotropic). In other words, the reduced FA value may indicate an alteration of the integrity of the white matter tracts (Figure 2).
Neurosurgical applications of tractography in the UK
Published in British Journal of Neurosurgery, 2021
Sebastian M. Toescu, Patrick W. Hales, Martin M. Tisdall, Kristian Aquilina, Christopher A. Clark
Tractography derived from diffusion MRI is a useful tool in the arsenal of the modern neurosurgeon. In this UK-based survey of practising neurosurgeons, we show that predominantly DTI-based reconstructions are used, that tumour resection remains the most frequent use of the technique, and that large tracts such as the corticospinal tract are most frequently identified. The results point out a number of limitations with the technique, many of which are inherent, such as inaccuracy in representing underlying anatomy, and intra-operative brain shift. The advent of iMRI and rapid-acquisition high angular resolution imaging may mitigate some of the perceived limitations of tractography described in this report. We urge units using tractography to adopt standardised procedures for tract reconstruction, and hope that broader collaboration in the field can lead to the development of ‘best practice’ in this area.
A Cortical Parcellation Based Analysis of Ventral Premotor Area Connectivity
Published in Neurological Research, 2021
John R. Sheets, Robert G. Briggs, Nicholas B. Dadario, Isabella M. Young, Michael Y. Bai, Anujan Poologaindran, Cordell M. Baker, Andrew K. Conner, Michael E. Sughrue
Fiber tractography was done in DSI Studio (http://dsi-studio.labsolver.org) using publicly available imaging data from the Human Connectome Project (HCP) (http://humanconnectome.org, release Q3). Diffusion studies from the HCP utilized a customized Siemens 3T Skyra scanner (Gmax = 100 mT/m) to study 1200 subjects as described previously [20,57]. Tractography in this study was performed individually with 25 randomly chosen adult subjects. A multi-shell diffusion scheme was used, and the b-values were 990, 1985, and 2980 s/mm2. The number of diffusion sampling directions was 90, 90, and 90, respectively. The in-plane resolution was 1.25 mm. The slice thickness was 1.25 mm. The diffusion data were reconstructed using generalized q-sampling imaging with a diffusion sampling length ratio of 1.25 [58].