Deep learning in neuroimaging of epilepsy.

In recent years, artificial intelligence, particularly deep learning (DL), has demonstrated utility in diverse areas of medicine. DL uses neural networks to automatically learn features from the raw data while this is not possible with conventional machine learning. It is helpful for the assessment of patients with epilepsy and whilst most published studies have been aimed at the automatic detection and prediction of seizures from electroencephalographic records, there is a growing number of investigations that use neuroimaging modalities (structural and functional magnetic resonance imaging, diffusion-weighted imaging and positron emission tomography) as input data. We review the application of DL to neuroimaging (sMRI, fMRI, DWI and PET) of focal epilepsy, specifically presurgical evaluation of drug-refractory epilepsy. First, a brief theoretical overview of artificial neural networks and deep learning is presented. Next, we review applications of deep learning to neuroimaging of epilepsy: diagnosis and lateralization, automated detection of lesion, presurgical evaluation and prediction of postsurgical outcome. Finally, the limitations, challenges and possible future directions in the application of these methods in the study of epilepsies are discussed. This approach could become an essential tool in clinical practice, particularly in the evaluation of images considered negative by visual inspection, in individualized treatments, and in the approach to epilepsy as a network disorder. However, greater multicenter collaboration is required to achieve the collection of sufficient data with the required quality together with the open access availability of the developed codes and tools.

Conectividad funcional a partir de la perfusión cerebral en pacientes epilépticos y con enfermedad de Parkinson

Introducción: La epilepsia y la enfermedad de Parkinson han sido descritos como trastornos de redes neurales. El estudio de la conectividad por modalidades moleculares puede ser más relevante fisiológicamente que los basados en señales hemodinámicas. Objetivo: Proponer una metodología para la descripción de patrones de conectividad funcional a partir de la perfusión cerebral por tomografía por emisión de fotón único. Métodos: La metodología incluye cuatro pasos principales: preprocesamiento espacial, corrección del volumen parcial, cálculo del índice de perfusión y obtención de la matriz de conectividad funcional mediante el coeficiente de correlación de Pearson. Se implementó en 25 pacientes con distintos trastornos neurológicos: 15 con epilepsia farmacorresistente y 10 con enfermedad de Parkinson. Resultados: Se encontraron diferencias significativas entre los índice de perfusión de varias regiones de los hemisferios ipsilateral y contralateral tanto en pacientes con epilepsia del lóbulo frontal como en pacientes con epilepsia del lóbulo temporal. Igual resultado se obtuvo en los pacientes con enfermedad de Parkinson con distintos estadios de la enfermedad. Para cada grupo se identificaron patrones de conectividad funcional que involucran a regiones relacionadas con la patología en estudio. Conclusiones: Con el desarrollo de esta metodología se ha demostrado que la tomografía por emisión de fotón único aporta información valiosa para estudiar la organización de las redes funcionales del cerebro. Futuras investigaciones con mayor número de pacientes contribuirían a hacer inferencias sobre los correlatos neurales de los distintos trastornos cerebrales.

Introduction: Epilepsy and Parkinson's disease have been described as disorders of neural networks. The study of connectivity by molecular modalities may be more physiologically relevant than those based on hemodynamic signals. Aim: The aim of the present work is to propose a methodology for the description of functional connectivity patterns from brain perfusion by single photon emission tomography. Methods: The methodology includes four main steps: spatial preprocessing, partial volume correction, calculation of the perfusion index and obtaining the functional connectivity matrix using Pearson's correlation coefficient. It was implemented in 25 patients with different neurological disorders: 15 with drug-resistant epilepsy and 10 suffering Parkinson's disease. Results: Significant differences were found between the perfusion indexes of various regions of the ipsilateral and contralateral hemispheres in both patients with frontal lobe epilepsy and patients with temporal lobe epilepsy. The same result was obtained in Parkinson's disease patients with different stages of the disease. For each group, functional connectivity patterns involving regions related to the pathology under study were identified. Conclusions: With the development of this methodology, it has been demonstrated that single photon emission tomography provides valuable information to study the organization of functional brain networks. Future research with a larger number of patients would contribute to make inferences about the neural correlates of the different brain disorders.

Relation of Brain Perfusion Patterns to Sudden Unexpected Death Risk Stratification: A Study in Drug Resistant Focal Epilepsy.

To explore the role of the interictal and ictal SPECT to identity functional neuroimaging biomarkers for SUDEP risk stratification in patients with drug-resistant focal epilepsy (DRFE). Twenty-nine interictal-ictal Single photon emission computed tomography (SPECT) scans were obtained from nine DRFE patients. A methodology for the relative quantification of cerebral blood flow of 74 cortical and sub-cortical structures was employed. The optimal number of clusters (K) was estimated using a modified v-fold cross-validation for the use of K means algorithm. The two regions of interest (ROIs) that represent the hypoperfused and hyperperfused areas were identified. To select the structures related to the SUDEP-7 inventory score, a data mining method that computes an automatic feature selection was used. During the interictal and ictal state, the hyperperfused ROIs in the largest part of patients were the bilateral rectus gyrus, putamen as well as globus pallidus ipsilateral to the seizure onset zone. The hypoperfused ROIs included the red nucleus, substantia nigra, medulla, and entorhinal area. The findings indicated that the nearly invariability in the perfusion pattern during the interictal to ictal transition observed in the ipsi-lateral putamen F = 12.60, p = 0.03, entorhinal area F = 25.80, p = 0.01, and temporal middle gyrus F = 12.60, p = 0.03 is a potential biomarker of SUDEP risk. The results presented in this paper allowed identifying hypo- and hyperperfused brain regions during the ictal and interictal state potentially related to SUDEP risk stratification.

Herramienta basada en código abierto para el cálculo de blindaje en las instalaciones de Medicina Nuclear / Open Source Based Tool for Shielding Calculation in Nuclear Medicine Installations

Uno de los requerimientos indispensables en el diseño de las instalaciones donde se trabaja con radiación ionizante es la determinación del espesor adecuado de las paredes, pisos, techo y puertas de los locales, que garanticen dosis por debajo de las restricciones establecidas por la autoridad regulatoria. El objetivo del presente trabajo es desarrollar una herramienta interactiva, libre y de código abierto para calcular los blindajes requeridos en una instalación de Medicina Nuclear. En el código, desarrollado en Phyton utilizando el entorno interactivo Jupiter Notebook, se incluyó el análisis tanto para Tomografía por Emisión de Fotón Único como para Tomografía por Emisión de Positrones. La herramienta fue implementada para el cálculo de los blindajes de un departamento de Medicina Nuclear del Centro Internacional de Restauración Neurológica (CIREN). Esta herramienta libre y de código abierto facilita los cálculos de blindaje aumentando la velocidad, lo que contribuye a lograr una optimización de la protección radiológica, pero también puede usarse como herramienta pedagógica(AU)

One of the indispensable requirements in the design of the facilities where ionizing radiation is used is the determination of the adequate thickness of the walls, floors, ceiling and doors of the premises, which guarantee doses below the restrictions established by the regulatory authority. The goal of this work is to develop an interactive, free and open source tool to calculate the shields required in a Nuclear Medicine installation. Analysis for both Single Photon Emission Tomography and Positron Emission Tomography was included in the code, developed in Phyton using the interactive Jupiter Notebook environment. The tool was implemented to calculate the shields of a Nuclear Medicine department of the International Center for Neurological Restoration (CIREN). This free and open source tool facilitates shielding calculations by increasing speed, which contributes to the optimization of radiation protection, but can also be used as a pedagogical tool(AU)

Cirugía de zona epileptogénica localizada en un área elocuente dellóbulo frontal en un adolescente con epilepsia / Epileptogenic zone surgery located in an eloquent area of the frontal lobe in an adolescent with epilepsy

Objetivo: Describir los resultados de la evaluación prequirúrgica, transquirúrgica y postquirúrgica, en un adolescente con epilepsia farmacorresistente con zona epileptogénica estimada en un área elocuente del lóbulo frontal izquierdo.Caso clínico: Paciente masculino, de 18 años, con epilepsia frontal izquierdafarmacorresistente desde los tres años, con una frecuencia de crisis de desconexión, atónicas y, en ocasiones, tónico clónico bilateral entre 30 y 40 diarias, previo a la cirugía. Laevaluación prequirúrgica identificó la zona de inicio ictal frontal izquierda, no lesional por imagen de resonancia magnética de 3 tesla. Se indicó tomografía computarizada por emisiónde fotón único interictal / ictal corregistrada con resonancia magnética, donde se identificó hiperperfusión frontal izquierda. Se realizó la cirugía con el uso de potenciales evocadossomatosensoriales para identificar el surco central, la estimulación cortical directa para mapear el área motora primaria, y la electrocorticografía transoperatoria para delimitar la zona de resección. Se empleó la técnica combinada desconectiva (callosotomía anterior) y resectiva del giro frontal superior y medio izquierdos, con modificación del patrón eléctrico en la electrocorticografía posterior a la cirugía. El resultado anatomopatológico fue displasia cortical focal tipo IA. En el seguimiento postquirúrgico, el paciente presenta solo entre 2-3 crisis semanales.Conclusiones: La cirugía de epilepsia extratemporal no lesional y con zona epileptogénica que incluye áreas elocuentes del lóbulo frontal es factible de realizar en nuestro país con mínima invasividad y buenos resultados(AU)

Objective: To describe the results of pre-surgical, trans-surgical and post-surgical assessment of an adolescent with drug-resistant epilepsy and an estimated epileptogenic zone in an eloquent area of the left frontal lobe.Clinical case: Male patient, 18 years old, who had drug-resistant left frontal epilepsy since the age of three. Before surgery, the patient suffered 30 and 40 daily disconnection episodes, atonic and, occasionally, daily bilateral clonic tonic. The pre-surgical evaluation identifiedthe left frontal, non-lesional ictal onset zone using 3-tesla magnetic resonance imaging. An interictal / ictal single photon emission computed tomography corrected with magnetic resonance imaging was indicated, which identified left frontal hyperperfusion. Surgery wasperformed using somatosensory-evoked potentials to identify the central sulcus, direct cortical stimulation to map the primary motor area, and intraoperative electrocorticography to delimit the resection area. Combined disconnective technique (anterior callosotomy) andresective technique of the left superior and middle left gyrus was used, modifying the electrical pattern in the electrocorticography after surgery. The pathological result was type IA focal cortical dysplasia. In the post-surgical follow-up, the patient only has 2-3 weekly crises.Conclusions: Surgery is feasible in a non-lesional extra-temporal epilepsy with an epileptogenic zone that includes eloquent frontal lobe areas in our country with minimal invasiveness and good results(AU)