Análisis estructural cuantitativo del hueso alveolar trabecular de la mandíbula en tomografía computarizada multidetector: diferencias por tipo y estado dentario / Quantitative structural analysis of trabecular alveolar bone in the mandible by multidetector computed tomography: differences according to tooth presence and type

Antecedentes y objetivo: Existe una carencia de métricas cuantitativas de la calidad del hueso trabecular alveolar, factor determinante en implantología. El objetivo de este estudio es desarrollar una metodología con tomografía computarizada multidetector para objetivar la calidad del hueso trabecular y establecer diferencias entre los distintos tipos y el estado de las piezas dentarias mediante procesado de imágenes y análisis estructural. Materiales y métodos: Se analizan 20 pacientes con exploración de tomografía computarizada multidetector dental para la valoración del hueso mandibular y posiciones dentales. El análisis de las imágenes incluyó la segmentación automática de la mandíbula, obtención de secciones perpendiculares a la arcada dentaria y análisis estructural del hueso trabecular de cada sección. Se obtuvieron la ratio entre volumen de hueso y volumen total de la sección, el grosor, la separación y el número trabecular, y la atenuación promedio en unidades Hounsfield. Se analizaron diferencias entre tipos de diente (incisivos, caninos, premolares y molares) y entre estados de las piezas dentarias (ausente o presente). Resultados: Se obtuvieron diferencias estadísticamente significativas entre los tipos y estados de las piezas. Por tipo, los incisivos mostraron mayor ratio de hueso trabecular, con disminución progresiva para caninos, premolares y molares. Por estado, las secciones pertenecientes a dientes ausentes presentaron mayor ratio de hueso que con el diente presente. Conclusiones: La metodología desarrollada permite cuantificar las propiedades estructurales del hueso alveolar a partir de imágenes de tomografía computarizada multidetector. Los resultados obtenidos objetivan el estado del sustrato óseo de cara a la planificación y seguimiento de la colocación de implantes dentales

Background and objective: There is a lack of quantitative measures of the quality of alveolar trabecular bone, an important factor in implantology. This study aimed to develop a method of objectively assessing the quality of trabecular bone by means of image processing and structural analysis of multidetector computed tomography images and to establish differences between tooth types and tooth presence/absence. Materials and methods: We analyzed 20 patients who underwent multidetector computed tomography to evaluate mandibular bone and tooth positioning. Image analysis included automatic segmentation of the mandible, obtainment of sections perpendicular to the dental arch, and structural analysis of the trabecular bone in each section. We calculated the ratio between the volume of bone and the total volume of the section, the thickness, the trabecular number, and the mean attenuation in Hounsfield units. We analyzed the differences among different tooth types (incisors, canines, premolars, and molars) and between present and absent teeth. Results: We found statistically significant differences between different tooth types and between sections in which teeth were present or absent. Incisors had a greater ratio of trabecular bone; the ratio of trabecular bone progressively decreased from the incisors to the canines, premolars, and molars. The ratio of trabecular bone was greater in sections in which teeth were absent than in those in which teeth were present. Conclusions: The method allows to quantify the structural properties of alveolar bone from multidetector computed tomography images. Our results provide an objective picture of the bone substrate that can be useful for planning and following up dental implant procedures

Quantitative structural analysis of trabecular alveolar bone in the mandible by multidetector computed tomography: differences according to tooth presence and type. / Análisis estructural cuantitativo del hueso alveolar trabecular de la mandíbula en tomografía computarizada multidetector: diferencias por tipo y estado dentario.

BACKGROUND AND OBJECTIVE: There is a lack of quantitative measures of the quality of alveolar trabecular bone, an important factor in implantology. This study aimed to develop a method of objectively assessing the quality of trabecular bone by means of image processing and structural analysis of multidetector computed tomography images and to establish differences between tooth types and tooth presence/absence. MATERIALS AND METHODS: We analyzed 20 patients who underwent multidetector computed tomography to evaluate mandibular bone and tooth positioning. Image analysis included automatic segmentation of the mandible, obtainment of sections perpendicular to the dental arch, and structural analysis of the trabecular bone in each section. We calculated the ratio between the volume of bone and the total volume of the section, the thickness, the trabecular number, and the mean attenuation in Hounsfield units. We analyzed the differences among different tooth types (incisors, canines, premolars, and molars) and between present and absent teeth. RESULTS: We found statistically significant differences between different tooth types and between sections in which teeth were present or absent. Incisors had a greater ratio of trabecular bone; the ratio of trabecular bone progressively decreased from the incisors to the canines, premolars, and molars. The ratio of trabecular bone was greater in sections in which teeth were absent than in those in which teeth were present. CONCLUSIONS: The method allows to quantify the structural properties of alveolar bone from multidetector computed tomography images. Our results provide an objective picture of the bone substrate that can be useful for planning and following up dental implant procedures.

La elastografía mediante técnica Acoustic radiation force impulse es eficaz en la detección de fibrosis hepática en el niño / Acoustic radiation force impulse imaging elastography is efficacious in detecting hepatic fibrosis in children

Objetivo. Evaluar el rendimiento diagnóstico de ARFI para detectar fibrosis hepática significativa en la edad pediátrica. Material y métodos. El estudio fue aprobado por el comité de ética hospitalario, con el consentimiento informado de los pacientes o sus representantes. Estudiamos 96 niños (50 varones, 46 hembras; edad media 8 años); 16 voluntarios sin enfermedad hepática conocida y 80 con patologías que pueden evolucionar a fibrosis y cirrosis hepática. La muestra final incluyó 31 pacientes con biopsia y 16 controles sanos. En todos los casos se realizó ecografía abdominal incluyendo Doppler y elastografía con ARFI. El valor ARFI expresado como velocidad (m/s) de propagación de las ondas transversales a través del tejido se calculó promediando 16 medidas en ambos lóbulos hepáticos. Comparamos las medias con el test de ANOVA de un factor. Los tests t de Student y chi cuadrado se usaron para datos categóricos. La significación estadística se estableció para una p < 0,05. Resultados. La velocidad en niños con fibrosis ≥ F2 fue significativamente más alta (1,80 ± 0,45 m/s) que en controles y pacientes con F0-F1 (1,38 ± 0,22 m/s) (p < 0,001). La esteatosis no se relacionó con la velocidad. La actividad necroinflamatoria se relacionó muy significativamente con la velocidad (p < 0,01). Fibrosis y actividad necroinflamatoria se relacionaron muy significativamente (p < 0,0001). Conclusión. La velocidad de propagación de las ondas ARFI se relacionó significativamente en los niños con el grado de fibrosis hepática (AU)

Objective. To evaluate the diagnostic performance of acoustic radiation force impulse imaging (ARFI) in detecting significant hepatic fibrosis in children. Material and methods. Our hospital's ethics committee approved the study and all patients or their representatives provided informed written consent. We included 96 children (50 boys, 46 girls; mean age, 8 y). We also studied 16 volunteers without liver disease as controls and 80 patients with diseases that can lead to fibrosis and cirrhosis of the liver. The final sample included 31 patients with biopsies and the 16 controls. All patients underwent abdominal ultrasonography including Doppler imaging and elastography with ARFI. The ARFI value, expressed as velocity (m/s) of shear wave propagation through the tissue, was calculated by averaging 16 measurements in both liver lobes. We used one-way analysis of variance to compare means between groups; we set statistical significance at P<.05. We used Student's t-tests and chi-square tests for categorical data. Results. The ARFI value in children with fibrosis ≥ F2 was higher (1.80 ± 0.45 m/s) than in controls and higher than in patients with F0-F1 (1.38 ± 0.22 m/s). The difference was significant (P<.001) for detecting F ≥ 2. Steatosis was not related with the ARFI value (Student's t-test, P>.84). Necroinflammatory activity was strongly associated with the ARFI value (Student's t-test, P<.01). Fibrosis and necroinflammatory activity were strongly associated with each other (chi-square test, P<.0001). Conclusion. The speed of shear wave propagation is significantly associated with the degree of hepatic fibrosis in children (AU)

[Acoustic radiation force impulse imaging elastography is efficacious in detecting hepatic fibrosis in children]. / La elastografía mediante técnica Acoustic radiation force impulse es eficaz en la detección de fibrosis hepática en el niño.

OBJECTIVE: To evaluate the diagnostic performance of acoustic radiation force impulse imaging (ARFI) in detecting significant hepatic fibrosis in children. MATERIAL AND METHODS: Our hospital's ethics committee approved the study and all patients or their representatives provided informed written consent. We included 96 children (50 boys, 46 girls; mean age, 8 y). We also studied 16 volunteers without liver disease as controls and 80 patients with diseases that can lead to fibrosis and cirrhosis of the liver. The final sample included 31 patients with biopsies and the 16 controls. All patients underwent abdominal ultrasonography including Doppler imaging and elastography with ARFI. The ARFI value, expressed as velocity (m/s) of shear wave propagation through the tissue, was calculated by averaging 16 measurements in both liver lobes. We used one-way analysis of variance to compare means between groups; we set statistical significance at P<.05. We used Student's t-tests and chi-square tests for categorical data. RESULTS: The ARFI value in children with fibrosis ≥ F2 was higher (1.80±0.45m/s) than in controls and higher than in patients with F0-F1 (1.38±0.22m/s). The difference was significant (P<.001) for detecting F ≥ 2. Steatosis was not related with the ARFI value (Student's t-test, P>.84). Necroinflammatory activity was strongly associated with the ARFI value (Student's t-test, P<.01). Fibrosis and necroinflammatory activity were strongly associated with each other (chi-square test, P<.0001). CONCLUSION: The speed of shear wave propagation is significantly associated with the degree of hepatic fibrosis in children.

Estudio cuantitativo del flujo de líquido cefalorraquídeo mediante resonancia magnética en contraste de fase: método para identificar a los pacientes con hidrocefalia a presión normal / Quantitative phase-contrast MRI study of cerebrospinal fluid flow: A method for identifying patients with normal-pressure hydrocephalus

Objetivos: El objetivo de este estudio es valorar si la RM en contraste de fase es una herramienta útil en el diagnóstico de la hidrocefalia a presión normal (HPN), así como su diferenciación con otras afecciones neurológicas muy similares clínicamente. Métodos: Se incluyó a un total de 108 sujetos, de los cuales 61 eran sujetos sanos control, y 47 pacientes; 19 de ellos fueron clasificados en el grupo de pacientes con enfermedad cerebrovascular isquémica (ECI) y 28 pacientes dentro del grupo de HPN. A todos los pacientes se les realizó una RM en contraste de fase con cuantificación de parámetros de flujo y velocidad de LCR en el acueducto de Silvio. Se evaluó la capacidad de clasificación de los parámetros individualmente y combinándolos mediante análisis discriminantes. Resultados: Los parámetros de velocidad máxima diastólica, flujo promedio y volumen por ciclo mostraron diferencias estadísticamente significativas para separar a los pacientes con HPN y con ECI (p < 0,001). El volumen por ciclo y el flujo promedio no presentaron falsos positivos, con tasas de acierto del 86% y 79%, respectivamente. El resto de parámetros y la combinación de todos ellos no mejoraron los resultados. Conclusiones: La RM en contraste de fase es una herramienta muy útil para el diagnóstico precoz de los pacientes con HPN. La cuantificación de parámetros de flujo de LCR junto con la valoración del estudio morfológico de la RM convencional permite diferenciar a los pacientes con HPN de los pacientes con ECI

Objectives: The aim of this study is to evaluate the use of phase-contrast MR imaging to diagnose normal pressure hydrocephalus (NPH) and differentiate it from other neurological disorders with similar clinical symptoms. Methods: The study included 108 subjects, of whom 61 were healthy controls and 47, patients; in the patient group, 19 had cerebrovascular disease (CVD) and 28 had NPH. All patients underwent a phase-contrast MRI study and several CSF flow and velocity parameters were measured at the aqueduct of Sylvius. Discriminant analyses were performed to evaluate the classification capacity of both individual parameters and the combination of different parameters. Results: Maximum diastolic velocity, mean flow, and stroke volume showed statistically significant differences that could be used to distinguish between NPH and CVD patients (P<.001). Stroke volume and mean flow showed no false positive results and successful classification rates of 86% and 79%, respectively. No other parameters or combination produced better results. Conclusions: Phase-contrast MR imaging is a useful tool for the early diagnosis of patients with NPH. CSF flow quantitative parameters, along with morphological features in a conventional MR study, enable us to differentiate between NPH and CVD patients

Reproducibilidad y exactitud en la cuantificación morfométrica y mecánica del hueso trabecular a partir de imágenes de resonancia magnética de Tesla / Reproducibility and accuracy in the morphometric and mechanical quantification of trabecular bone from 3 Tesla magnetic resonance images

Objetivo. En este trabajo se analizan en un modelo animal la reproducibilidad y la exactitud de ciertos biomarcadores de imagen de calidad ósea utilizando como patrón de referencia la microtomografía computarizada (mTC). Material y métodos. Se estudiaron con RM y mTC 5 metáfisis tibiales de oveja. Las imágenes de RM (3 Tesla) se adquirieron con una secuencia eco de gradiente potenciada en T1 y una resolución espacial isotrópica de 180 mm. Las imágenes de mTC se adquirieron en un escáner con una resolución espacial de 7,5 mm en vóxeles isotrópicos. En la preparación de las imágenes se aplicaron algoritmos de ecualización, interpolación y umbralización. En el análisis cuantitativo se calculó el porcentaje de volumen de hueso (BV/TV), el grosor trabecular (Tb.Th), la separación trabecular (Tb.Sp), el índice trabecular (Tb.N), la dimensión fractal en 2 D (D2D) y 3 D (D3D) y el módulo elástico en las 3 direcciones del espacio (Ex, Ey y Ez). Resultados. La cuantificación morfométrica y mecánica del hueso esponjoso con la RM fue muy reproducible, con porcentajes de variación por debajo del 9% para todos los parámetros. Su exactitud con respecto a la mTC fue alta, con errores inferiores al 15% para BV/TV, D2D, D3D y Eappx, Eappy y Eappz. Conclusiones. Los resultados experimentales en animales confirman que los parámetros de BV/TV, D2D, D3D y Eappx, Eappy y Eappz obtenidos a partir de RM tienen una excelente reproducibilidad y precisión, y pueden emplearse como biomarcadores de imagen de la calidad del hueso trabecular (AU)

Objective: We used an animal model to analyze the reproducibility and accuracy of certain biomarkers of bone image quality in comparison to a gold standard of computed microtomography (mCT). Material and methods: We used magnetic resonance (MR) imaging and mCT to study the metaphyses of 5 sheep tibiae. The MR images (3 Teslas) were acquired with a T1-weighted gradient echo sequence and an isotropic spatial resolution of 180 mm. The mCT images were acquired using a scanner with a spatial resolution of 7.5 mm isotropic voxels. In the preparation of the images, we applied equalization, interpolation, and thresholding algorithms. In the quantitative analysis, we calculated the percentage of bone volume (BV/TV), the trabecular thickness (Tb.Th), the trabecular separation (Tb.Sp), the trabecular index (Tb.N), the 2 D fractal dimension (D2D), the 3 D fractal dimension (D3D), and the elastic module in the three spatial directions (Ex, Ey and Ez). Results: The morphometric and mechanical quantification of trabecular bone by MR was very reproducible, with percentages of variation below 9% for all the parameters. Its accuracy compared to the gold standard (mCT) was high, with errors less than 15% for BV/TV, D2D, D3D, and Eappx, Eappy and Eappz. Conclusions: Our experimental results in animals confirm that the parameters of BV/TV, D2D, D3D, and Eappx, Eappy and Eappz obtained by MR have excellent reproducibility and accuracy and can be used as imaging biomarkers for the quality of trabecular bone (AU)

Quantitative phase-contrast MRI study of cerebrospinal fluid flow: a method for identifying patients with normal-pressure hydrocephalus.

OBJECTIVES: The aim of this study is to evaluate the use of phase-contrast MR imaging to diagnose normal pressure hydrocephalus (NPH) and differentiate it from other neurological disorders with similar clinical symptoms. METHODS: The study included 108 subjects, of whom 61 were healthy controls and 47, patients; in the patient group, 19 had cerebrovascular disease (CVD) and 28 had NPH. All patients underwent a phase-contrast MRI study and several CSF flow and velocity parameters were measured at the aqueduct of Sylvius. Discriminant analyses were performed to evaluate the classification capacity of both individual parameters and the combination of different parameters. RESULTS: Maximum diastolic velocity, mean flow, and stroke volume showed statistically significant differences that could be used to distinguish between NPH and CVD patients (P<.001). Stroke volume and mean flow showed no false positive results and successful classification rates of 86% and 79%, respectively. No other parameters or combination produced better results. CONCLUSIONS: Phase-contrast MR imaging is a useful tool for the early diagnosis of patients with NPH. CSF flow quantitative parameters, along with morphological features in a conventional MR study, enable us to differentiate between NPH and CVD patients.

[Reproducibility and accuracy in the morphometric and mechanical quantification of trabecular bone from 3 Tesla magnetic resonance images]. / Reproducibilidad y exactitud en la cuantificación morfométrica y mecánica del hueso trabecular a partir de imágenes de resonancia magnética de Tesla.

OBJECTIVE: We used an animal model to analyze the reproducibility and accuracy of certain biomarkers of bone image quality in comparison to a gold standard of computed microtomography (µCT). MATERIAL AND METHODS: We used magnetic resonance (MR) imaging and µCT to study the metaphyses of 5 sheep tibiae. The MR images (3 Teslas) were acquired with a T1-weighted gradient echo sequence and an isotropic spatial resolution of 180µm. The µCT images were acquired using a scanner with a spatial resolution of 7.5µm isotropic voxels. In the preparation of the images, we applied equalization, interpolation, and thresholding algorithms. In the quantitative analysis, we calculated the percentage of bone volume (BV/TV), the trabecular thickness (Tb.Th), the trabecular separation (Tb.Sp), the trabecular index (Tb.N), the 2D fractal dimension (D(2D)), the 3D fractal dimension (D(3D)), and the elastic module in the three spatial directions (Ex, Ey and Ez). RESULTS: The morphometric and mechanical quantification of trabecular bone by MR was very reproducible, with percentages of variation below 9% for all the parameters. Its accuracy compared to the gold standard (µCT) was high, with errors less than 15% for BV/TV, D(2D), D(3D), and E(app)x, E(app)y and E(app)z. CONCLUSIONS: Our experimental results in animals confirm that the parameters of BV/TV, D(2D), D(3D), and E(app)x, E(app)y and E(app)z obtained by MR have excellent reproducibility and accuracy and can be used as imaging biomarkers for the quality of trabecular bone.

Integrando el informe de biomarcadores de imagen en el informe radiológico estructurado / Integrating information about imaging biomarkers into structured radiology reports

Los biomarcadores de imagen describen características objetivas que están relacionadas con procesos biológicos normales, enfermedades, o la respuesta al tratamiento. Permiten a los radiólogos incorporar datos de estructura, función y componentes tisulares a sus informes. Con el fin de aprovechar al máximo las ventajas de la cuantificación de imagen médica se plantea un procedimiento para integrar los biomarcadores de imagen, acercando el nuevo paradigma de medicina personalizada al flujo de trabajo radiológico. Así, los resultados de cuantificación pueden complementar el diagnóstico radiológico tradicional, mejorando su precisión y la evaluación de la eficacia de los tratamientos. Un informe radiológico más personalizado, estandarizado y estructurado debe implementar los análisis cuantitativos como una buena alternativa complementaria al informe radiológico cualitativo convencional en casos previamente seleccionados (AU)

Imaging biomarkers describe objective characteristics that are related to normal biological processes, diseases, or the response to treatment. They enable radiologists to incorporate into their reports data about structure, function, and tissue components. With the aim of taking maximum advantage of the quantification of medical images, we present a procedure to integrate imaging biomarkers into radiological reports, bringing the new paradigm of personal medicine closer to radiological workflow. In this manner, the results of quantification can complement traditional radiological diagnosis, improving accuracy and the evaluation of the efficacy of treatments. A more personalized, standardized, structured radiological report should include quantitative analyses to complement conventional qualitative reporting in selected cases (AU)

[Integrating information about imaging biomarkers into structured radiology reports]. / Integrando el informe de biomarcadores de imagen en el informe radiológico estructurado.

Imaging biomarkers describe objective characteristics that are related to normal biological processes, diseases, or the response to treatment. They enable radiologists to incorporate into their reports data about structure, function, and tissue components. With the aim of taking maximum advantage of the quantification of medical images, we present a procedure to integrate imaging biomarkers into radiological reports, bringing the new paradigm of personal medicine closer to radiological workflow. In this manner, the results of quantification can complement traditional radiological diagnosis, improving accuracy and the evaluation of the efficacy of treatments. A more personalized, standardized, structured radiological report should include quantitative analyses to complement conventional qualitative reporting in selected cases.

Biomarcadores de imagen, imagen cuantitativa y bioingeniería / Imaging biomarkers, quantitative imaging, and bioengineering

Los biomarcadores de imagen definen características objetivas extraídas de las imágenes médicas, relacionadas con procesos biológicos normales, enfermedades o respuestas terapéuticas. Para desarrollar un biomarcador de imagen es necesario realizar una serie de pasos destinados a validar su relación con la realidad estudiada y controlar su validez, tanto clínica como técnica. Este proceso incluye la definición de pruebas de concepto y de mecanismo; la adquisición estandarizada y optimizada de imágenes anatómicas, funcionales y moleculares; el análisis de los datos mediante modelos computacionales; la visualización adecuada de los resultados; la obtención de medidas estadísticas apropiadas; y la realización de pruebas de principio, eficacia y efectividad. Nuestro objetivo en este trabajo es mostrar los pasos que deben establecerse para aplicar adecuadamente los biomarcadores de imagen, desde su concepción teórica hasta su implantación asistencial, en un entorno hospitalario. Para ello se planteará como ejemplo la valoración de la angiogénesis del cartílago articular (AU)

Imaging biomarkers define objective characteristics extracted from medical images that are related to normal biological processes, diseases, or the response to treatment. To develop an imaging biomarker, it is necessary to carry out a series of steps to validate its relation with the reality studied and to check its clinical and technical validity. This process includes defining tests for the concepts and mechanisms; obtaining standardized and optimized anatomic, functional, and molecular images; analyzing the data with computer models; displaying data appropriately; obtaining the appropriate statistic measures; and conducting tests on the principle, efficacy, and effectiveness. In this article, we aim to explain the steps that must be established to enable biomarkers to be correctly applied, from their theoretical conception to their clinical implementation. To this end, we use the evaluation of angiogenesis in articular cartilage as an example (AU)

[Imaging biomarkers, quantitative imaging, and bioengineering]. / Biomarcadores de imagen, imagen cuantitativa y bioingeniería.

Imaging biomarkers define objective characteristics extracted from medical images that are related to normal biological processes, diseases, or the response to treatment. To develop an imaging biomarker, it is necessary to carry out a series of steps to validate its relation with the reality studied and to check its clinical and technical validity. This process includes defining tests for the concepts and mechanisms; obtaining standardized and optimized anatomic, functional, and molecular images; analyzing the data with computer models; displaying data appropriately; obtaining the appropriate statistic measures; and conducting tests on the principle, efficacy, and effectiveness. In this article, we aim to explain the steps that must be established to enable biomarkers to be correctly applied, from their theoretical conception to their clinical implementation. To this end, we use the evaluation of angiogenesis in articular cartilage as an example.

Abnormal activation of the motor cortical network in idiopathic scoliosis demonstrated by functional MRI.

The aetiology of idiopathic scoliosis (IS) remains unknown, but there is growing support for the possibility of an underlying neurological disorder. Functional magnetic resonance imaging (fMRI) can characterize the abnormal activation of the sensorimotor brain network in movement disorders and could provide further insights into the neuropathogenesis of IS. Twenty subjects were included in the study; 10 adolescents with IS (mean age of 15.2, 8 girls and 2 boys) and 10 age-matched healthy controls. The average Cobb angle of the primary curve in the IS patients was 35° (range 27°-55°). All participants underwent a block-design fMRI experiment in a 1.5-Tesla MRI scanner to explore cortical activation following a simple motor task. Rest periods alternated with activation periods during which participants were required to open and close their hand at an internally paced rate of approximately 1 Hz. Data were analyzed with Statistical Parametric Mapping (SPM5) including age, sex and laterality as nuisance variables to minimise the presence of bias in the results. Compared to controls, IS patients showed significant increases in blood oxygenation level dependent (BOLD) activity in contralateral supplementary motor area when performing the motor task with either hand. No significant differences were observed when testing between groups in the functional activation in the primary motor cortex, premotor cortex and somatosensory cortex. Additionally, the IS group showed a greater interhemispheric asymmetry index than the control group (0.30 vs. 0.13, p < 0.001). This study demonstrates an abnormal pattern of brain activation in secondary motor areas during movement execution in patients with IS. These findings support the hypothesis that a sensorimotor integration disorder underlies the pathogenesis of IS.

Modificación del tiempo de relajación longitudinal (T1) como biomarcador de la degeneración del cartílago patelar / Modification of longitudinal relaxation time (T1) as a biomarker of patellar cartilage degeneration

Objetivos. Estudiar la viabilidad del tiempo de relajación longitudinal (T1) en RM del cartílago patelar como biomarcador del grado de degeneración. Material y métodos. Se incluyeron 15 sujetos clasificados mediante criterios clínicos (dolor, limitación funcional y duración de la sintomatología) y de imagen como normales (3 hombres, 2 mujeres, 30±14 años), con degeneración inicial del cartílago patelar (3 hombres, 2 mujeres, 30±6 años) y con degeneración avanzada (3 hombres, 2 mujeres, 57±10 años). A todos se les realizó un estudio de RM con secuencias especiales eco de gradiente para segmentar el cartílago y calcular los mapas de T1. Se seleccionó el cartílago completo y las regiones de interés clasificadas en base a criterios clínico-radiológicos como normalidad, degeneración inicial y degeneración avanzada. Los valores de T1 del cartílago se obtuvieron píxel a píxel y se calcularon como la media para todo el cartílago o por subregiones (normal, inicial, avanzada). Las diferencias entre grupos para el cartílago completo y las regiones se analizaron mediante ANOVA Student-Newman-Keuls. La reproducibilidad se estudió mediante el coeficiente de varianza. Resultados. El análisis global del cartílago no presentó diferencias estadísticamente significativas entre los 3 grupos (normal: 1.003±172ms; inicial: 1.064±124ms; avanzada: 1.041±308ms, p=0,665). En cambio, en el análisis por regiones se obtuvieron diferencias significativas (normal: 908±53ms; degeneración inicial: 1.057±157 ms; degeneración avanzada: 1.133±116 ms; p=0,029). El estudio de reproducibilidad ofreció variaciones del 1,3% para el cálculo global, del 3,7% para el regional, y del 8,2% para la adquisición. Conclusión. En este estudio preliminar, el cálculo del T1 del cartílago permite diferenciar regiones con diferente grado de degeneración (AU)

Objectives. To study the viability of longitudinal relaxation time (T1) of patellar cartilage as a biomarker of the degree of degeneration. Material and methods. We included 15 subjects classified into three groups according to clinical criteria (pain, functional limitation, and duration of symptoms) and imaging criteria as follows: (a) normal (3 men, 2 women; age 30±14 years), (b) with initial degeneration of the patellar cartilage (3 men, 2 women; age 30±6 years), or (c) with advanced degeneration (3 men, 2 women; age 57±10 years). All underwent MRI examination using special echo-gradient sequences to segment the cartilage and calculate the T1 maps. We selected the entire cartilage and the regions of interest classified according to clinical and imaging criteria as normal, initial degeneration, and advanced degeneration. The T1 values of the cartilage were obtained pixel by pixel and were calculated as the mean for the entire cartilage or by subregions (normal, initial, advanced). Differences between groups for the entire cartilage and the regions were analyzed using Student-Newman-Keuls post-hoc ANOVA. Reproducibility was evaluated using the coefficient of variance. Results. No significant differences in the overall analysis of the entire cartilage were found between the three groups (normal: 1003±172ms, initial: 1064±124ms, advanced: 1041±308ms, p=0.665). However, the analysis by regions revealed significant differences (normal: 908±53ms, initial degeneration: 1057±157ms, advanced degeneration: 1133±116ms, p=0.029). The reproducibility analysis found variations of 1.3% for the overall calculation, 3.7% for the regional calculation, and 8.2% for the acquisition. Conclusion. In this preliminary study, calculating the T1 of the cartilage enabled regions with different degrees of degeneration to be differentiated (AU)

[Thalamic metabolism and neurological outcome after traumatic brain injury. A voxel-based morphometric FDG-PET study]. / Metabolismo talámico y situación neurológica tras un traumatismo craneoencefálico. Estudio mediante PET-FDG y morfometría basada en vóxel.

OBJECTIVE: to study the relationship between thalamic metabolism and neurological outcome in patients who had sustained a traumatic brain injury (TBI). METHODS: nineteen patients who had sustained a severe TBI and ten control subjects were included in this study. Six of the 19 patients had a low level of consciousness (vegetative state or minimally conscious state), while thirteen showed normal consciousness. All patients underwent a PET with 18F-FDG, 459.4 +/- 470.9 days after the TBI. The FDG-PET images were normalized in intensity, with a metabolic template being created from data derived from all subjects. The thalamic trace was generated automatically with a mask of the region of interest in order to evaluate its metabolism. A comparison between the two groups was carried out by a two sample voxel-based T-test, under the General Linear Model (GLM) framework. RESULTS: patients with low consciousness had lower thalamic metabolism (MNI-Talairach coordinates: 12, -24, 18; T = 4.1) than patients with adequate awareness (14, -28, 6; T = 5.5). Control subjects showed the greatest thalamic metabolism compared to both patients groups. These differences in metabolism were more pronounced in the internal regions of the thalamus. CONCLUSIONS: the applied method may be a useful ancillary tool to assess neurological outcomes after a TBI, since it permits an objective quantitative assessment of metabolic function for groups of subjects. Our results confirm the vulnerability of the thalamus to suffering the effects of the acceleration-deceleration forces generated during a TBI. It is hypothesized that patients with low thalamic metabolism represent a subset of subjects highly vulnerable to neurological and functional disability after TBI.

[Modification of longitudinal relaxation time (T1) as a biomarker of patellar cartilage degeneration]. / Modificación del tiempo de relajación longitudinal (T1) como biomarcador de la degeneración del cartílago patelar.

OBJECTIVES: To study the viability of longitudinal relaxation time (T1) of patellar cartilage as a biomarker of the degree of degeneration. MATERIAL AND METHODS: We included 15 subjects classified into three groups according to clinical criteria (pain, functional limitation, and duration of symptoms) and imaging criteria as follows: (a) normal (3 men, 2 women; age 30+/-14 years), (b) with initial degeneration of the patellar cartilage (3 men, 2 women; age 30+/-6 years), or (c) with advanced degeneration (3 men, 2 women; age 57+/-10 years). All underwent MRI examination using special echo-gradient sequences to segment the cartilage and calculate the T1 maps. We selected the entire cartilage and the regions of interest classified according to clinical and imaging criteria as normal, initial degeneration, and advanced degeneration. The T1 values of the cartilage were obtained pixel by pixel and were calculated as the mean for the entire cartilage or by subregions (normal, initial, advanced). Differences between groups for the entire cartilage and the regions were analyzed using Student-Newman-Keuls post-hoc ANOVA. Reproducibility was evaluated using the coefficient of variance. RESULTS: No significant differences in the overall analysis of the entire cartilage were found between the three groups (normal: 1003+/-172 ms, initial: 1064+/-124 ms, advanced: 1041+/-308 ms, p=0.665). However, the analysis by regions revealed significant differences (normal: 908+/-53 ms, initial degeneration: 1057+/-157 ms, advanced degeneration: 1133+/-116 ms, p=0.029). The reproducibility analysis found variations of 1.3% for the overall calculation, 3.7% for the regional calculation, and 8.2% for the acquisition. CONCLUSION: In this preliminary study, calculating the T1 of the cartilage enabled regions with different degrees of degeneration to be differentiated.

Metabolismo talámico y situación neurológica tras un traumatismo craneoencefálico. Estudio mediante PET-FDG y morfometría basada en vóxel / Thalamic metabolism and neurological outcome after traumatic brain injury. A voxel-based morphometric FDG-PET study

Objetivos: Estudiar la relación entre el metabolismo talámico y la situación neurológica en pacientes que han sufrido un traumatismo craneoencefálico (TCE). Material y métodos: Se incluyó a 19 pacientes que habían sufrido un TCE grave y 10 sujetos control. De los 19 pacientes, 6 presentaban un grado de alerta bajo (estado vegetativo o estado de mínima conciencia), mientras que 13 mostraban un grado de alerta normal. A todos los pacientes se les realizó una tomografía con emisión de positrones (PET) con 18-fluorodesoxiglucosa (18F-FDG) 459,4 ± 470,9 días después del TCE. Las imágenes de PET-FDG se normalizaron en intensidad, creándose posteriormente una plantilla metabólica del grupo entre todos los sujetos. El trazado talámico se generó automáticamente con una máscara de la región de interés. Se comparó el metabolismo talámico de los dos grupos de pacientes respecto al grupo control, para ello se utilizó un método de análisis basado en vóxel, con significación estadística, p < 0,05 corregido para múltiples comparaciones. Resultados: Los pacientes con grado de alerta bajo mostraron menor metabolismo talámico (coordenadas MNI-Talairach, 12, -24, 18; T = 4,1), con respecto a los sujetos control, que los pacientes con grado de alerta adecuado (14, -28, 6; T = 5,5). Estas diferencias en el metabolismo fueron más acentuadas en las regiones internas del tálamo. Conclusiones: La PET-FDG puede ser una herramienta útil para valorar la situación neurológica después de un TCE. El método utilizado permite una evaluación objetiva y cuantitativa de imágenes de PET-FDG para grupos de sujetos. Nuestros resultados confirman la vulnerabilidad del tálamo a sufrir los efectos de las fuerzas de aceleración-desaceleración generadas durante un TCE (AU)

Objective: To study the relationship between thalamic metabolism and neurological outcome in patients who had sustained a traumatic brain injury (TBI). Methods: Nineteen patients who had sustained a severe TBI and ten control subjects were included in this study. Six of the 19 patients had a low level of consciousness (vegetative state or minimally conscious state), while thirteen showed normal consciousness. All patients underwent a PET with 18F-FDG, 459.4 ± 470.9 days after the TBI. The FDG-PET images were normalized in intensity, with a metabolic template being created from data derived from all subjects. The thalamic trace was generated automatically with a mask of the region of interest in order to evaluate its metabolism. A comparison between the two groups was carried out by a two sample voxel-based T-test, under the General Linear Model (GLM) framework. Results: Patients with low consciousness had lower thalamic metabolism (MNI-Talairach coordinates: 12, -24, 18; T = 4.1) than patients with adequate awareness (14, -28, 6; T = 5.5). Control subjects showed the greatest thalamic metabolism compared to both patients groups. These differences in metabolism were more pronounced in the internal regions of the thalamus. Conclusions: The applied method may be a useful ancillary tool to assess neurological outcomes after a TBI, since it permits an objective quantitative assessment of metabolic function for groups of subjects. Our results confirm the vulnerability of the thalamus to suffering the effects of the acceleration-deceleration forces generated during a TBI. It is hypothesized that patients with low thalamic metabolism represent a subset of subjects highly vulnerable to neurological and functional disability after TBI (AU)

Left orbitofrontal and superior temporal gyrus structural changes associated to suicidal behavior in patients with schizophrenia.

Suicidal attempts are relatively frequent and clinically relevant in patients with schizophrenia. Recent studies have found gray matter differences in suicidal and non-suicidal depressive patients. However, no previous neuroimaging study has investigated possible structural abnormalities associated to suicidal behaviors in patients with schizophrenia. A whole-brain magnetic resonance voxel-based morphometric examination was performed on 37 male patients meeting the DSM-IV criteria for schizophrenia. Thirteen (35.14%) patients had attempted suicide. A non-parametric permutation test was computed to perform the comparability between groups. An analysis of covariance (AnCova) model was constructed with a statistical threshold of p<0.05 corrected for multiple comparisons. After controlling for age and severity of illness, results showed significant gray matter density reduction in left superior temporal lobe (p=0.03) and left orbitofrontal cortex (p=0.04) in patients who had attempted suicide when comparing with non-suicidal patients. Although sample size limitations and potential clinical heterogeneity preclude definitive conclusions, these data point to structural differences in key cerebral areas. Neuroimaging studies are necessary to expand our knowledge of biological mechanisms underlying suicide in schizophrenia.