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Rehman A.A.,Illinois College | Elmore K.B.,Illinois College | Mattei T.A.,INVISION
Neurosurgical Focus | Year: 2015

Glioblastoma is both the most common and most lethal primary CNS malignancy in adults, accounting for 45.6% of all malignant CNS tumors, with a 5-year survival rate of only 5.0%, despite the utilization of multimodal therapy including resection, chemotherapy, and radiation. Currently available treatment options for glioblastoma often remain limited, offering brief periods of improved survival, but with substantial side effects. As such, improvements in current treatment strategies or, more likely, the implementation of novel strategies altogether are warranted. In this topic review, the authors provide a comprehensive review on the potential of alternating electric fields (AEFs) in the treatment of glioblastoma. Alternating electric fields-also known as tumor-treating fields (TTFs)-represent an entirely original therapeutic modality with preliminary studies suggesting comparable, and at times improved, efficacy to standard chemotherapeutic agents in the treatment of recurrent glioblastoma. A recent multicenter, Phase III, randomized clinical trial comparing NovoTTF-100A monotherapy to physician's best choice chemotherapy in patients with recurrent glioblastoma revealed that AEFs have similar efficacy to standard chemotherapeutic agents with a more favorable side-effects profile and improved quality of life. In particular, AEFs were shown to have limited systemic adverse effects, with the most common side effect being contact dermatitis on the scalp at the sites of transducer placement. This study prompted FDA approval of the NovoTTF-100A system in April 2011 as a standalone therapy for treatment of recurrent glioblastoma refractory to surgical and radiation treatment. In addition to discussing the available clinical evidence regarding the utilization of AEFs in glioblastoma, this article provides essential information regarding the supposed therapeutic mechanism as well as modes of potential tumor resistance to such novel therapy, delineating future perspectives regarding basic science research on the issue. © AANS, 2015. Source

Mattei T.A.,INVISION | Rehman A.A.,Illinois College | Issawi A.,University of Illinois at Peoria | Fassett D.R.,University of Illinois at Peoria
European Spine Journal | Year: 2015

Purpose: No standard strategy exists for the management of cervical kyphotic deformity in patients with severe osteoporosis. In fact, in such subpopulation, standard algorithms commonly used in patients with normal bone mineral density may not be applicable. In this Grand Rounds, the authors present a challenging case of a patient with Hajdu–Cheney syndrome, a rare disorder of bone metabolism induced by a Notch-2 mutation, who presented with cervical kyphotic deformity and severe osteoporosis. Methods: A 65-year-old female patient with a previous diagnosis of Hajdu–Cheney syndrome presented with cervical myelopathy and cervical kyphotic deformity. The initial MRi demonstrated multilevel cervical canal stenosis. The CT-scan also revealed marked spondylolisthesis of C6 over C7 as well as numerous laminar and pedicle fractures, resulting in a cervical kyphosis of approximately 50 degrees. Results: The patient was submitted to 360-degree decompression and fusion of the cervical spine consisting of a staged C6 anterior corpectomy and multilevel microdiscectomies with wide opening of the posterior longitudinal ligament in order to provide a satisfactory release of anterior spinal structures, followed by 24 h of cervical halo-traction, a second anterior approach for bone graft implantation in the site of the corpectomy as well as insertion of allografts and completion of the ACDF C2–T1 and plating, and, finally, a posterior C2–T3 pedicle screw instrumentation using intra-operative CT-scan (O-arm) navigation guidance. Conclusions: This case illustrates some intra-operative nuances as well as specific surgical recommendations for cervical deformity surgery in patients with severe osteoporosis, such as avoidance of Caspar pins for interbody distraction, use of intra-operative fluoroscopy for achievement of bicortical purchase of anterior cervical screws and placement of pedicle screws during posterior instrumentation. Moreover, such illustrative case demonstrates that, in the subpopulation of patients with severe osteoporosis, it may be possible to successfully apply cervical distraction after an isolated anterior approach with a satisfactory improvement in the cervical alignment, possibly avoiding more laborious 540-degree approaches such as the previously described back–front–back or front–back–front surgical algorithms. © 2015, Springer-Verlag Berlin Heidelberg. Source

Mattei T.A.,INVISION | Rodriguez A.H.,University of Illinois at Peoria | Sambhara D.,University of Illinois at Peoria | Mendel E.,Ohio State University
Neurosurgical Review | Year: 2014

Neurosurgery is one of the most demanding surgical specialties in terms of precision requirements and surgical field limitations. Recent advancements in robotic technology have generated the possibility of incorporating advanced technological tools to the neurosurgical operating room. Although previous studies have addressed the specific details of new robotic systems, there is very little literature on the strengths and drawbacks of past attempts, currently available platforms and prototypes in development. In this review, the authors present a critical historical analysis of the development of robotic technology in neurosurgery as well as a comprehensive summary of the currently available systems that can be expected to be incorporated to the neurosurgical armamentarium in the near future. Finally, the authors present a critical analysis of the main technical challenges in robotic technology development at the present time (such as the design of improved systems for haptic feedback and the necessity of incorporating intraoperative imaging data) as well as the benefits which robotic technology is expected to bring to specific neurosurgical subspecialties in the near future. © 2014 Springer-Verlag. Source

Braga I.L.S.,INVISION | Moraes F.S.,State University of Norte Fluminense
Geophysics | Year: 2013

We have developed and applied an inverse Q filter formulation using the continuous wavelet transform (CWT), which provides a natural domain for time-variant operations, such as compensation for propagation in attenuating and dispersive media. The well-known linear attenuation model, given as a function of time and frequency, was applied very efficiently over wavelet coefficients in the time-frequency domain to correct for amplitude and phase distortions, as necessary. The inverse CWT yields the recovered trace with a broader bandwidth. The process works on a trace-by-trace basis, making no distinction if the data is pre-or poststack. Our motivation was to develop gather conditioning tools to enhance prestack interpretation techniques such as amplitude variation with offset (AVO) analysis and inversion -a technique that is often compromised by tuning and other propagation related issues that degrade seismic resolution. Thus, we investigated the AVO fidelity of our filter and the sensitivity of the results to incorrect values of Q, using real and synthetic data. Our synthetic data experiments clearly showed that AVO anomalies are recovered and preserved in a stable manner, even with values of Q off by 50% of its correct value. The application in time-migrated gathers shows a very natural increase in the vertical definition of the events, especially due to the partial elimination of the tuning effect. The benefits for imaging are also evidenced by comparing stacked sections before and after inverse Q filtering. The higher resolution of seismic sections leads to a better definition of smaller scale stratigraphic and structural features. © 2013 Society of Exploration Geophysicists. Source

Oliveira S.A.M.,North Fluminense State University | Oliveira S.A.M.,INVISION | Lupinacci W.M.,North Fluminense State University
Geophysical Prospecting | Year: 2013

In order to perform a good pulse compression, the conventional spike deconvolution method requires that the wavelet is stationary. However, this requirement is never reached since the seismic wave always suffers high-frequency attenuation and dispersion as it propagates in real materials. Due to this issue, the data need to pass through some kind of inverse-Q filter. Most methods attempt to correct the attenuation effect by applying greater gains for high-frequency components of the signal. The problem with this procedure is that it generally boosts high-frequency noise. In order to deal with this problem, we present a new inversion method designed to estimate the reflectivity function in attenuating media. The key feature of the proposed method is the use of the least absolute error (L1 norm) to define both the data and model error in the objective functional. The L1 norm is more immune to noise when compared to the usual L2 one, especially when the data are contaminated by discrepant sample values. It also favours sparse reflectivity when used to define the model error in regularization of the inverse problem and also increases the resolution, since an efficient pulse compression is attained. Tests on synthetic and real data demonstrate the efficacy of the method in raising the resolution of the seismic signal without boosting its noise component. © 2013 European Association of Geoscientists & Engineers. Source

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