Comparison of wavelet transformations to enhance convolutional neural network performance in brain tumor segmentation.

INTRODUCTION AND GOAL TO BACKGROUND: Due to the importance of segmentation of MRI images in identifying brain tumors, various methods including deep learning have been introduced for automatic brain tumor segmentation. On the other hand, using a combination of methods can improve their performance. Among them is the use of wavelet transform as an auxiliary element in deep networks. The analysis of the requirements of such combinations has been addressed in this study. METHOD: In this developmental study, different wavelet functions were used to compress brain MRI images and finally as an auxiliary element in improving the performance of the convolutional neural network in brain tumor segmentation. RESULTS: Based on the results of the tests performed, the Daubechies1 function was most effective in enhancing network performance in segmenting MRI images and was able to balance the performance and computational overload. CONCLUSION: Choosing the wavelet function to optimize the performance of a convolutional neural network should be based on the requirements of the problem, also taking into account some considerations such as computational load, processing time, and performance of the wavelet function in optimizing CNN output in the intended task.

Combined endonasal and sublabial endoscopic transmaxillary approach to the pterygopalatine fossa and orbital apex.

BACKGROUND: The pterygopalatine fossa (PPF) and inferomedial orbital apex are difficult regions for open neurosurgical access. The traditional extensive anterior approach (transfacial or transmandibular) and lateral/posterolateral (transcranial) approach were used to access the PPF. The combined endonasal and sublabial transmaxillary approach is a less invasive access route for these lesions. In this study, we present the technical and clinical details of our experience with the combined endoscopic endonasal and transmaxillary approach. METHODS: A retrospective analysis of our patients operated on using a combined endoscopic endonasal and transmaxillary approach was done. The preoperative, intraoperative and postoperative images and all the clinical data were evaluated. The accessibility to the area and extent of surgical resection were reviewed. The surgery-related complications and postoperative morbidities were analyzed. The main items of interest were the exposure of the target area and possibility for safe removal. RESULTS: Five patients with pathologies located in the area of the PPF and orbital apex were operated on using the combined endoscopic sublabial and endonasal transmaxillary approach. The technique provided sufficient exposure of the area and allowed for safe removal of the preoperatively determined target in all of the patients. One patient developed dry eye and a neurotrophic corneal ulcer, and another patient developed temporary postoperative facial numbness. In the follow-up, only one patient with skull base chordoma had an asymptomatic tumor regrowth. The other patients had no recurrence or regrowth. CONCLUSIONS: The combined endoscopic sublabial and endonasal transmaxillary approach is a safe and effective method for resection of lesions in the PPF and inferomedial orbital apex.

Remarkable improvement of neurological deficits after surgery in patients with Idiopathic spinal cord herniations. The impact of peroperative neuromonitoring. Case reports.

Introduction: Chronic Idiopathic Spinal Cord Herniation (ISCH) is a very rare spinal cord deformation occurring predominantly in thoracic levels. ISCH lead to progressive myelopathy, spastic paraparesis and Brown Séquard syndrome. Research question: We want to hypothesize that a) the herniated segment can regain its function after untethering despite long-term and complete neurologic dysfunction. b) Intraoperative Electrophysiologic Monitoring (IOEPM) may identify intraoperative changes by monitoring specific neural pathways confirming the efficacy of the intervention in the forthcoming cases. Material & method: It is a retrospective review of data of two cases prospectively collected showing improvement of neurological deficit in cases of ISCH in thoracic levels. We describe two patients with progressive neurological deficits due to ISCH who underwent surgery using electrophysiologic monitoring and have been followed to reach remarkable clinical improvement. Results: The spastic paraparesis of the first case improved remarkably after surgery. Complete foot drop of the other case, persistent for 7 months before intervention, improved after the release of the herniated segment of the cord. Peroperative electrophysiological monitoring did not show changes during surgery. Conclusion: We want to hypothesize that the herniated segment can regain its function after untethering despite long-term and complete neurologic dysfunction. Intraoperative Electrophysiologic Monitoring (IOEPM) may confirm the efficacy of the intervention in the forthcoming cases.

Recovery of diabetes insipidus after Chiari malformation decompression: A rare manifestation of Chiari malformation.

This paper aims to introduce a patient with Chiari type 1 malformation presented with upper extremity pain and diabetes insipidus. After laboratory examinations, we confirmed our case's central diabetes insipidus diagnosis. The patient has undergone posterior fossa decompression, tonsilopexy, and duraplasty. After 6 months of follow-up, pain and diabetes insipidus were improved. We introduced a rare presentation of Chiari malformation in this article.

Mixed malignant glioblastoma and schwannoma in spinal cord with metachronous ependymoma: A case report.

Here, we report a very rare case of mixed spinal tumor comprising of malignant glioblastoma and schwannoma, who was initially treated with tumor resection and adjuvant chemoradiation, but relapsed three years later with grade 3 ependymoma.

Wavelet-enhanced convolutional neural network: a new idea in a deep learning paradigm.

PURPOSE: Manual brain tumor segmentation is a challenging task that requires the use of machine learning techniques. One of the machine learning techniques that has been given much attention is the convolutional neural network (CNN). The performance of the CNN can be enhanced by combining other data analysis tools such as wavelet transform. MATERIALS AND METHODS: In this study, one of the famous implementations of CNN, a fully convolutional network (FCN), was used in brain tumor segmentation and its architecture was enhanced by wavelet transform. In this combination, a wavelet transform was used as a complementary and enhancing tool for CNN in brain tumor segmentation. RESULTS: Comparing the performance of basic FCN architecture against the wavelet-enhanced form revealed a remarkable superiority of enhanced architecture in brain tumor segmentation tasks. CONCLUSION: Using mathematical functions and enhancing tools such as wavelet transform and other mathematical functions can improve the performance of CNN in any image processing task such as segmentation and classification.

A preliminary study of the clinical application of optic pathway diffusion tensor tractography in suprasellar tumor surgery: preoperative, intraoperative, and postoperative assessment.

OBJECT Visual impairments are the most common objective manifestations of suprasellar lesions. Diffusion tensor imaging (DTI) is a noninvasive MRI modality that depicts the subcortical white matter tracts in vivo. In this study the authors tested the value of visual pathway tractography in comparison with visual field and visual acuity analyses. METHODS This prospective study consisted of 25 patients with progressive visual impairment due to suprasellar mass lesions and 6 control patients with normal vision without such lesions. Visual acuity, visual field, and the optic fundus were examined preoperatively and repeated 1 week and 3 months after surgery. Visual pathway DTI tractography was performed preoperatively, intraoperatively immediately after tumor resection, and 1 week and 3 months after surgery. RESULTS In the control group, pre- and postoperative visual status were normal and visual pathway tractography revealed fibers crossing the optic chiasm without any alteration. In patients with suprasellar lesions, vision improved in 24 of 25. The mean distance between optic tracts in tractography decreased after tumor resection and detectable fibers crossing the optic chiasm increased from 12% preoperatively to 72% postoperatively 3 months after tumor resection, and undetectable fibers crossing the optic chiasm decreased from 88% preoperatively to 27% postoperatively 3 months after tumor resection. Visual improvement after tumor removal 1 week and 3 months after surgery was significantly correlated with the distance between optic tracts in intraoperative tractography (p < 0.01). CONCLUSIONS Visual pathway DTI tractography appears to be a promising adjunct to the standard clinical and paraclinical visual examinations in patients with suprasellar mass lesions. The intraoperative findings, in particular the distance between optic tract fibers, can predict visual outcome after tumor resection. Furthermore, postoperative application of this technique may be useful in following anterior optic pathway recovery.

Decision Making for Patients With Concomitant Pituitary Macroadenoma and Ophthalmologic Comorbidity: A Clinical Controversy.

BACKGROUND: Coexisting complex visual field defects and serious ophthalmologic comorbidities make the management of the pituitary macroadenomas more challenging. Diffusion tensor imaging (DTI) magnetic resonance imaging that tracks neural fibers in the white matter has been used recently to visualize the impact of different pathologies on cranial nerves. This study explains application of anterior optic pathway tractography for patients with ophthalmologic comorbidities and pituitary adenoma. METHODS: Two patients with atypical visual field defects caused by nonfunctional pituitary macroadenoma and simultaneous ophthalmologic morbidities (one glaucoma and the other giant cell arteritis) were selected for surgical decompression of the anterior optic apparatus. Standard perimetry and optic pathway DTI were done preoperatively, intraoperatively, and 3 months after surgery. RESULTS: The nontypical pattern of visual field defect could not differentiate between the ophthalmologic disease and the chiasmatic compression attributable to pituitary macroadenoma as the main cause. Preoperative visual pathway DTI tractography showed lack of decussating chiasmatic fibers in both of the patients. DTI tractography revealed the reappearance of these fibers intraoperatively in one and postoperatively in the other one. Three months after surgery, the visual field and acuity improved and DTI tractography confirmed presence of crossing chiasmatic fibers. CONCLUSION: Visual pathway DTI tractography is a promising adjunct to the standard perimetry in preoperative assessment of pituitary macroadenoma with serious ophthalmologic comorbidities. It also may be useful in the intraoperative determination of the optic pathway decompression and for following the visual outcome of these patients after surgery.