ABSTRACT

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Image denoising problem can be addressed as an inverse problem. One of the most recent approaches to solve an inverse problem is a sparse decomposition over overcomplete dictionaries. In sparse representation, images are represented as a linear combination of dictionary atoms. In this paper, we propose an algorithm for image denoising based on Orthogonal Matching Pursuit (OMP) for determining sparse representation over Gabor Wavelet adaptive dictionary by K-SVD algorithm. The results of this algorithm have more efficiency of image recovery than using DCT dictionary.

ABSTRACT

Introduction Subdural collections, following brain surgeries in pediatrics, are common and unfortunately not always easily treated; especially in huge parenchymal tumors, intraventricular tumors and paraventricular tumors. Different approaches for prevention and treatment of theses subdural collections have been discussed by several studies, but till now no solid consensus has been reached. One of these approaches is to approximate incised cortical edges by suturing the pia, use of fibrin adhesive glue and subsequent Ringer inflation. The aim of our study is to avoid cortical mantle collapse and to prevent the development of progressive pressurizing subdural fluid collections. Patients and methods This study included 12 pediatric cases operated for large sized brain tumors between 2014 and 2019, in the department of Pediatric Neurosurgery at Alexandria University. All cases were operated via transcortical approach. Patients were followed prospectively for postoperative complications including postoperative subdural collections. In all patients, gel foam and fibrin glue on the cortical and ependymal edges, with suture approximation of the cortical edges and subsequent Ringer lactate inflation in the residual cavity were routinely done. Results With the consecutive follow-up images, six cases (50%) showed persistent subdural collection following tumor resection. Three cases had 5–6 mm asymptomatic subdural collection thickness that resolved within 3 to 6 months, and the rest three cases showed more than 7 mm thickness subdural collection. In these 3/12 (25%) cases patients had symptomatic and progressive increase in the subdural fluid collections. A subdural-peritoneal shunt was necessary only for 1 patient (8%). After finishing his adjuvant therapy, it was possible to remove the subdural-peritoneal shunt. While in the other 2 patients, the subdural collection was managed surgically with just a burr hole evacuation. The clinical manifestations resolved postoperatively but complete resolution of these 2 subdural collections occurred within 7 and 9 months. Conclusion The use of sutures and fibrin adhesive to seal surgical defects with inflation of the residual cavity with Ringer lactate solution might decrease the development of subdural fluid collections, through avoiding the cortical mantle collapse.