Neurologic emergencies in HIV-negative immunosuppressed patients. / Urgencias neurológicas en el paciente inmunosuprimido no VIH.

HIV-negative immunosuppressed patients comprise a heterogeneous group including transplant patients, patients undergoing treatment with immunosuppressors, uremic patients, alcoholics, undernourished patients, diabetics, patients on dialysis, elderly patients, and those diagnosed with severe or neoplastic processes. Epileptic seizures, focal neurologic signs, and meningoencephalitis are neurologic syndromes that require urgent action. In most of these situations, neuroimaging tests are necessary, but the findings can be different from those observed in immunocompetent patients in function of the inflammatory response. Infectious disease is the first diagnostic suspicion, and the identification of an opportunistic pathogen should be oriented in function of the type and degree of immunosuppression. Other neurologic emergencies include ischemic stroke, cerebral hemorrhage, neoplastic processes, and pharmacological neurotoxicity. This article reviews the role of neuroimaging in HIV-negative immunodepressed patients with a neurologic complication that requires urgent management.

Development and validation of an open source quantification tool for DSC-MRI studies.

MOTIVATION: This work presents the development of an open source tool for the quantification of dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion studies. The development of this tool is motivated by the lack of open source tools implemented on open platforms to allow external developers to implement their own quantification methods easily and without the need of paying for a development license. MATERIALS AND METHODS: This quantification tool was developed as a plugin for the ImageJ image analysis platform using the Java programming language. A modular approach was used in the implementation of the components, in such a way that the addition of new methods can be done without breaking any of the existing functionalities. For the validation process, images from seven patients with brain tumors were acquired and quantified with the presented tool and with a widely used clinical software package. The resulting perfusion parameters were then compared. RESULTS: Perfusion parameters and the corresponding parametric images were obtained. When no gamma-fitting is used, an excellent agreement with the tool used as a gold-standard was obtained (R(2)>0.8 and values are within 95% CI limits in Bland-Altman plots). CONCLUSION: An open source tool that performs quantification of perfusion studies using magnetic resonance imaging has been developed and validated using a clinical software package. It works as an ImageJ plugin and the source code has been published with an open source license.

Estudio de la perfusión cerebral mediante técnicas de susceptibilidad magnética: técnica y aplicaciones / Studying cerebral perfusion using magnetic susceptibility techniques: technique and applications

Las técnicas de perfusión por resonancia magnética (PRM) permiten la valoración de la microvasculatura cerebral mediante los cambios de señal debidos al paso intravascular de un trazador. La técnica más empleada se basa en la susceptibilidad magnética del gadolinio en secuencias T2* y los parámetros más comúnmente valorados son: el volumen sanguíneo cerebral, el flujo sanguíneo cerebral y el tiempo de tránsito medio. En los estudios de PRM deben considerarse diversos aspectos técnicos como la secuencia empleada, la dosis o la velocidad de inyección del contraste. También debe valorarse la existencia de fuentes de error como las debidas a la fuga de contraste por alteración en la permeabilidad de la barrera hematoencefálica. Las aplicaciones clínicas más extendidas de la PRM incluyen la determinación del grado de agresividad de gliomas, la diferenciación de algunos tipos histológicos tumorales o de lesiones pseudotumorales y la valoración del área de penumbra en la isquemia aguda (AU)

Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in signal due to a tracer passing through blood vessels. The most commonly used technique is based on the magnetic susceptibility of gadolinium in T2*-weighted sequences, and the most commonly evaluated parameters are cerebral blood volume, cerebral blood flow, and mean transit time. Diverse technical aspects, like the sequence used, and the dose and speed of contrast material injection, must be taken into account in perfusion MRI studies. It is also essential to consider possible sources of error like contrast material leaks due to changes in the permeability of the blood-brain barrier. The most widely used clinical applications of perfusion MRI include the determination of the degree of aggressiveness of gliomas, the differentiation of some histological types of tumors or pseudotumors, and the evaluation of the penumbral area in acute ischemia (AU)

[Studying cerebral perfusion using magnetic susceptibility techniques: technique and applications]. / Estudio de la perfusión cerebral mediante técnicas de susceptibilidad magnética: técnica y aplicaciones.

Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in signal due to a tracer passing through blood vessels. The most commonly used technique is based on the magnetic susceptibility of gadolinium in T2*-weighted sequences, and the most commonly evaluated parameters are cerebral blood volume, cerebral blood flow, and mean transit time. Diverse technical aspects, like the sequence used, and the dose and speed of contrast material injection, must be taken into account in perfusion MRI studies. It is also essential to consider possible sources of error like contrast material leaks due to changes in the permeability of the blood-brain barrier. The most widely used clinical applications of perfusion MRI include the determination of the degree of aggressiveness of gliomas, the differentiation of some histological types of tumors or pseudotumors, and the evaluation of the penumbral area in acute ischemia.

Neuralgia intercostal en hiperostosis esquelética idiopática difusa (HEID) / Intercostal neuralgia in diffuse idiopathic skeletal hyperostosis (DISH)

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