Magnetic Resonance Imaging Evaluation of Possible Neonatal Sinovenous Thrombosis
Harvard University, Cambridge, Massachusetts, United StatesPediatric Neurology (Impact Factor: 1.7). 12/2007; 37(5):317-23. DOI: 10.1016/j.pediatrneurol.2007.06.018
There are few data on magnetic resonance imaging findings in newborns for whom there is a concern for cerebral sinovenous thrombosis. The study objective was to document findings on magnetic resonance imaging or magnetic resonance venography in cases of suspected neonatal sinovenous thrombosis. A retrospective search of the institutional database was performed to find neonates whose cranial computed tomography raised the suspicion for thrombus. Documented abnormalities were detected on magnetic resonance venography, diffusion-weighted imaging, and T(2)-weighted imaging. Of 15 neonates with suspicious computed tomography studies, 2 had a definite intraluminal clot in the deep venous system; the remainder showed decreased flow-related enhancement within the dural venous sinuses. In all these cases, the sinus was compressed by adjacent subdural hematoma or sutural diastasis. Of the 15 patients, 5 had parenchymal abnormalities (2 of these had definite intraluminal clot). Parenchymal abnormalities were classified as hemorrhage (3/5), cytotoxic edema (3/5), or vasogenic edema (1/5). Intraluminal clot in the newborn is more often identified in the deep than in the superficial venous system. With evidence of venous injury in the absence of identified thrombus, it is possible that either clots dissolve quickly, escaping detection, or that the superficial venous system is vulnerable to mechanical forces during delivery.
Conference Paper: Novel electronic hardware for pulse-mode neural circuits[Show abstract] [Hide abstract]
ABSTRACT: A new approach to the electronic hardware implementation of pulse-mode neural circuits is described that is not based on the use of conventional transistors, but on a novel semiconductor device called a Multi-Quantum Well Injection Mode Diode (MQW-IMD). Described is the physics of the device's operation and the device's use in simple circuits which exhibit neural-like characteristics, i.e. pulse generation, a sigmoidal frequency-bias characteristic, and input signal integration and summation over multiple inputs with synaptic weighting including both excitatory and inhibitory capabilities. Preliminary experimental and simulation results are describedCircuits and Systems, 1996., IEEE 39th Midwest symposium on; 09/1996
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ABSTRACT: To separate and recover multiple signals in data communications, antenna arrays and acoustic sensor arrays, the impulse responses of multiple-input/multiple-output (MIMO) channels have to be identified explicitly or implicitly. This paper deals with the blind identification of MIMO FIR channels based on second-order statistics of the channel outputs and its application in blind channel equalization and signal-separation. We first investigate the identifiability of MIMO FIR channels, and obtain a necessary and sufficient condition for MIMO FIR channels to be identifiable up to a unitary ambiguity matrix using second-order statistics. Next, we extend the identification algorithms for single-input/multiple-output (SIMO) FIR channels, such as the algebraic algorithm and the subspace algorithm to the identification of MIMO FIR channels. Since the ambiguity matrix cannot be estimated using second-order statistics, we then present a fourth-order cumulant based ambiguity matrix estimation algorithm. Finally, we demonstrate effectiveness of the algorithms in this paper by computer simulationsGlobal Telecommunications Conference, 1996. GLOBECOM '96. 'Communications: The Key to Global Prosperity; 12/1996
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ABSTRACT: Background: Cerebral venous thrombosis is a rare disease in children, but it is considered an important cause of infarction due to its potential morbidity. Since magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) are widely used, the reports with confirmed diagnosis are increased. Objectives: To identify the common clinical presentations and radiological findings of cerebral venous sinus thrombosis (CVST) in pediatric age group, and to investigate thoroughly the underlying predisposing conditions. Methodology: This study included 13 children with CVST confirmed by MRI and MRV. Patients were submitted to complete general and neurological examination, Electroencephalography (EEG), and routine laboratory tests in addition to complete coagulation profiles including protein C, protein S, and Anti thrombin III, hemoglobin electrophoresis, Anticardiolipin autoantibodies, and antinuclear antibodies. Screening tests for homocystein, lactate, pyruvate and ammonia serum levels were done and Factor V Leiden was done for 5 cases only. Results: Headache was the main presenting clinical picture of cases, followed by nausea, vomiting, seizures and papilledema. MRI brain was done prior to MRV and most patients 12/13 (92.3%) showed loss of normal signal void pattern of involved sinuses. Ten patients (76.9%) showed cerebral parechymal changes, and MRV showed that superior sagittal sinus (SSS) was the most common vessel to be involved (84.4%) either alone or in combination with other dural sinuses, followed by transverse and sigmoid sinuses either alone or in combination with SSS (53.8%). Ten cases (76.9%) had detectable identifiable factors which included dehydration, prothrombotic disorders either hereditary or acquired disorders, and we had one patient with recurrent CVST and Moya-Moya disease. Conclusion: MRI in conjunction with MRV are both sensitive and specific enough to provide the best non-invasive method of diagnosing CVST in pediatric patients, in whom hereditary or acquired prothrombotic risk factors should be tested carefully.Egyptian Journal of Neurology, Psychiatry and Neurosurgery 07/2008; 45(2):361 - 374.
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