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Applications of Nanoparticles in the Treatment of Gliomas
Published in Hala Gali-Muhtasib, Racha Chouaib, Nanoparticle Drug Delivery Systems for Cancer Treatment, 2020
Gerardo Caruso, Elena Fazzari, Salvator M. Cardali, Maria Caffo
The treatment of gliomas is characterized by a high rate of failure due to their infiltrative and aggressive nature, the presence of the BBB, which restricts entry of therapeutic entities to the tumor area, the recurrent nature of the tumor, the paucity of antigen presenting cells, and the immune suppressive nature of the tumor microenvironment. The use of new, multiple, preoperative, and intraoperative techniques such as intra-operative MRI, electrophysiologic monitoring, navigated transcranial magnetic stimulation, neuronavigation, and the use of 5-aminolevulinic acid (5-ALA), has allowed an improvement of the rates of successful complete tumor resection to 96.2% [14]. Molecular biology studies are certainly more interesting, and allow the identification of many molecular biomarkers that, if affected, could cause a slowing of the tumor progression. However, classical molecular therapy has various limitations. Gliomas show a complex heterogeneity at the genomic and molecular levels. Moreover, the use of EGFR inhibitors, MET and/or PDGFR inhibitors would maintain activation of downstream pathways, which is a theoretical mechanism of therapy resistance [83]. Several studies evaluated the presence of crosstalks between PI3K-MAPK-p53-RB pathways, which can balance any single pathway alteration [84]. Recent research showed the presence of EGFR-VEGF(R) cross-talk in both tumor and tumor-associated endothelial cells which is involved in tumor survival and angiogenesis [85]. Gliomas are also characterized by genomic instability, which favors gene mutations and chromosomal alterations, such that the use of cytotoxic agents and radiotherapy would accelerate the mutagenesis. Another serious obstacle is represented by the fact that the chosen target can be activated by multiple pathways, in different phases, during tumor progression, thus rendering the treatment ineffective. Radio- and chemotherapy treatments have limited action and are burdened by severe side effects.
Audiovisual augmentation for coil positioning in transcranial magnetic stimulation
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Laura Schütz, Emmanuelle Weber, Wally Niu, Bruce Daniel, Jennifer McNab, Nassir Navab, Christoph Leuze
The present study will investigate audiovisual augmentation for the task of coil positioning in transcranial magnetic stimulation (TMS). One important application of TMS therapy is depression treatment. During treatment an electromagnetic coil is close to the patient’s head to stimulate brain regions that regulate mood and behaviour. Repeated sessions of repetitive TMS have been shown to improve depression symptoms (Loo and Mitchell 2005). Accurate coil placement using neuronavigation (Denslow et al. 2005) has been shown to improve treatment efficacy (Fitzgerald et al. 2009). However, current neuronavigation solutions are costly. Complex user interfaces require training and lengthy setup increases treatment time. This has hindered the widespread use of neuronavigation in clinical settings. As an alternative to neuronavigation some studies propose robot-guided TMS systems for precise localisation and treatment (Richter et al. 2011; Xiao et al. 2018). Although the use of robotic systems has great potential to increase targeting accuracy, they too suffer from high costs and complex setups. Therefore, most TMS procedures are still executed without navigation or guidance systems using a measuring tape and standard scalp measurements for targeting. While this is faster and easier to use, such a targeting approach does not account well for individual differences in head shape and brain anatomy leading to decreased targeting accuracy for some patients (Herwig et al. 2001).
Computer-assisted surgery in medical and dental applications
Published in Expert Review of Medical Devices, 2021
Yen-Wei Chen, Brian W. Hanak, Tzu-Chian Yang, Taylor A. Wilson, Jenovie M. Hsia, Hollie E. Walsh, Huai-Che Shih, Kanako J. Nagatomo
Various types of imaging studies and even imaging modalities are often merged preoperatively using neuronavigation software to render a complete three-dimensional and functional image of a patient’s unique neuroanatomy. Combining brain mapping techniques with more conventional anatomic imaging studies frequently helps to better define surgical targets and resection margins as well as the surrounding ‘no-fly zones’ (critical brain structures that need to be preserved during an operation to avoid morbidity/mortality). For example, when planning a brain tumor resection, merging diffusion tensor imaging tractography (a technique that creates a rendering of the connectivity of subcortical white matter tracts that relay information from one region of the brain to another) with MRI sequences that demonstrate the tumor well (frequently T1+ or T2) is useful to visualize the displacement of normal white matter tracts by the tumor so that an operative approach for tumor resection can be designed to minimize injury to important white matter tracts [14,15]. Similarly, functional MRI (a technique that highlights which portions of a patient’s neocortex are responsible for carrying out various neurologic functions) can also be merged with anatomic MRI sequences so that eloquent neocortex critical for functions such as speaking, reading, and motor movements can be defined and avoided in the operative plan [14]. A good example of using merge techniques to define the surgical target comes from epilepsy surgery. When performing a resection of a seizure focus (or brain region giving rise to seizures), anatomic MRI sequences may be merged with ictal SPECT (single photon emission CT; a technique that can detect the increase in regional blood flow to the seizure foci in patients with localization-related epilepsy) to enhance visualization and three-dimensional topographic understanding of an otherwise grossly invisible seizure focus.