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 heterogeneidad del flujo sanguíneo en resonancia magnética, biomarcador para clasificar por grados los astrocitomas cerebrales / The heterogeneity of blood flow on magnetic resonance imaging: a biomarker for grading cerebral astrocytomas

Objetivos: Estudiar si los histogramas de los parámetros cuantitativos de perfusión por RM obtenidos a partir de los volúmenes tumoral y peritumoral permiten clasificar in vivo el grado de los astrocitomas. Material y métodos: Se incluyen 61 pacientes diagnosticados histológicamente de astrocitoma grado II, III o IV, estudiados mediante RM de perfusión T2* con contraste intravenoso, seleccionando manualmente los volúmenes tumoral y peritumoral, cuantificándose vóxel a vóxel diferentes parámetros de perfusión: volumen sanguíneo (VS), flujo sanguíneo (FS), tiempo de tránsito medio (TTM), constante de transferencia (Ktrans), coeficiente de lavado, volumen intersticial y volumen vascular. Para cada volumen se obtuvo el histograma correspondiente con su media, desviación típica y curtosis, estas últimas como medidas de heterogeneidad, comparándose las diferencias por parámetro y grado tumoral. También se calcularon la media y desviación del 10% de los valores máximos. Finalmente se realizó un análisis discriminante multiparamétrico para mejorar la clasificación. Resultados: En el volumen tumoral se obtuvieron diferencias estadísticamente significativas entre los 3 grados tumorales para la media y la desviación de VS, FS y Ktrans, tanto para la distribución completa, como para el 10% máximo. En la región peritumoral no se obtuvieron diferencias significativas para ningún parámetro. El análisis discriminante mejoró ligeramente la clasificación. Conclusiones: La cuantificación de parámetros del volumen total de la región tumoral con VS, FS y Ktrans es útil para establecer el grado de los astrocitomas. La heterogeneidad, representada por la desviación típica del FS, es el parámetro con mayor fiabilidad diagnóstica para separar los tumores de bajo y alto grado (AU)

Objectives: To study whether the histograms of quantitative parameters of perfusion in MRI obtained from tumor volume and peritumor volume make it possible to grade astrocytomas in vivo. Material and methods: We included 61 patients with histological diagnoses of grade II, III, or IV astrocytomas who underwent T2*-weighted perfusion MRI after intravenous contrast agent injection. We manually selected the tumor volume and peritumor volume and quantified the following perfusion parameters on a voxel-by-voxel basis: blood volume (BV), blood flow (BF), mean transit time (TTM), transfer constant (Ktrans), washout coefficient, interstitial volume, and vascular volume. For each volume, we obtained the corresponding histogram with its mean, standard deviation, and kurtosis (using the standard deviation and kurtosis as measures of heterogeneity) and we compared the differences in each parameter between different grades of tumor. We also calculated the mean and standard deviation of the highest 10% of values. Finally, we performed a multiparametric discriminant analysis to improve the classification. Results: For tumor volume, we found statistically significant differences among the three grades of tumor for the means and standard deviations of BV, BF, and Ktrans, both for the entire distribution and for the highest 10% of values. For the peritumor volume, we found no significant differences for any parameters. The discriminant analysis improved the classification slightly. Conclusions: The quantification of the volume parameters of the entire region of the tumor with BV, BF, and Ktrans is useful for grading astrocytomas. The heterogeneity represented by the standard deviation of BF is the most reliable diagnostic parameter for distinguishing between low grade and high grade lesions (AU)

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.

[The heterogeneity of blood flow on magnetic resonance imaging: a biomarker for grading cerebral astrocytomas]. / La heterogeneidad del flujo sanguíneo en resonancia magnética, biomarcador para clasificar por grados los astrocitomas cerebrales.

OBJECTIVES: To study whether the histograms of quantitative parameters of perfusion in MRI obtained from tumor volume and peritumor volume make it possible to grade astrocytomas in vivo. MATERIAL AND METHODS: We included 61 patients with histological diagnoses of grade II, III, or IV astrocytomas who underwent T2*-weighted perfusion MRI after intravenous contrast agent injection. We manually selected the tumor volume and peritumor volume and quantified the following perfusion parameters on a voxel-by-voxel basis: blood volume (BV), blood flow (BF), mean transit time (TTM), transfer constant (K(trans)), washout coefficient, interstitial volume, and vascular volume. For each volume, we obtained the corresponding histogram with its mean, standard deviation, and kurtosis (using the standard deviation and kurtosis as measures of heterogeneity) and we compared the differences in each parameter between different grades of tumor. We also calculated the mean and standard deviation of the highest 10% of values. Finally, we performed a multiparametric discriminant analysis to improve the classification. RESULTS: For tumor volume, we found statistically significant differences among the three grades of tumor for the means and standard deviations of BV, BF, and K(trans), both for the entire distribution and for the highest 10% of values. For the peritumor volume, we found no significant differences for any parameters. The discriminant analysis improved the classification slightly. CONCLUSIONS: The quantification of the volume parameters of the entire region of the tumor with BV, BF, and K(trans) is useful for grading astrocytomas. The heterogeneity represented by the standard deviation of BF is the most reliable diagnostic parameter for distinguishing between low grade and high grade lesions.

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.

Análisis nosológico con parámetros de perfusión tisular de RM obtenidos mediante los modelos monocompartimental y farmacocinético en los glioblastomas cerebrales / Nosological analysis of MRI tissue perfusion parameters obtained using the unicompartmental and pharmacokinetic models in cerebral glioblastomas

Objetivos. Clasificar las áreas tumorales en pacientes con astrocitoma de grado IV mediante el cálculo y análisis estadístico de parámetros cuantitativos de perfusión por RM. Material y métodos. Se aplicaron 2 modelos de perfusión por RM, monocompartimental y farmacocinético, en 15 pacientes diagnosticados de astrocitoma grado IV. Con el modelo monocompartimental se cuantificó el volumen sanguíneo cerebral (VSC), el tiempo de tránsito medio (TTM) y el flujo sanguíneo cerebral (FSC). Con el farmacocinético se midió la constante de permeabilidad (Ktrans), el coeficiente de extracción (kep), la fracción de volumen del espacio intersticial (ve), la fracción de volumen vascular (vp), la permeabilidad en primer paso (Kfp) y el volumen vascular en primer paso (vpfp). Para cada parámetro se obtuvieron los histogramas del área tumoral total, peritumoral y sana. El análisis estadístico incluyó un análisis de varianza para cada parámetro y un análisis discriminante. Resultados. Las diferencias más significativas entre las regiones se obtuvieron con el VSC, FSC, Ktrans y vpfp, siendo VSC el que mostró mejores resultados. La mejor función clasificatoria mediante análisis discriminante se obtuvo para una combinación de Ktrans y VSC. El análisis de la forma del histograma evidenció diferencias estadísticamente significativas para la curtosis de Ktrans y kep, así como para la asimetría de VSC, FSC, Ktrans y vpfp. Conclusión. El VSC es el parámetro que aisladamente permitió diferenciar mejor entre área tumoral, peritumoral y sana. La función clasificatoria generada a partir de VSC y Ktrans consiguió mejorar estos resultados haciendo más eficaz la clasificación por áreas (AU)

Objectives. To classify the tumor areas in patients with grade IV astrocytoma by calculating and statistically analyzing quantitative MRI perfusion parameters. Material and methods. We applied two models of MRI perfusion, the unicompartmental and the pharmacokinetic models, in 15 patients diagnosed with grade IV astrocytoma. In the unicompartmental model, we quantified cerebral blood volume (CBV), mean transit time (MTT), and cerebral blood flow (CBF). In the pharmacokinetic model, we measured the permeability constant (Ktrans), the extraction coefficient (kep), the fraction of the volume in the interstitial space (ve), the fraction of the volume in the vessels (vp), the permeability in the first pass (Kfp), and the vascular volume in the first pass (vpfp). For each parameter, histograms were obtained for the total tumor area, for the peritumoral area, and for the healthy tissue. The statistical analysis included an analysis of variance for each parameter and a discriminant analysis. Results. The most significant differences between the regions were obtained with CBV, CBF, Ktrans, and vpfp; of these, CBV had the best results. The best classificatory function on the discriminant analysis was the combination of Ktrans and CBV. The analysis of the shape of the histogram showed statistically significant differences for the kurtosis of Ktrans and kep, as well as for the skewness of CBV, CBF, Ktrans, and vpfp. Conclusion. When parameters are considered individually, CBV is the one that best enables differentiation between tumor, peritumoral, and healthy tissue. The classificatory function generated from CBV and Ktrans results in improved classification by areas (AU)

[Nosological analysis of MRI tissue perfusion parameters obtained using the unicompartmental and pharmacokinetic models in cerebral glioblastomas]. / Análisis nosológico con parámetros de perfusión tisular de RM obtenidos mediante los modelos monocompartimental y farmacocinético en los glioblastomas cerebrales.

OBJECTIVES: To classify the tumor areas in patients with grade IV astrocytoma by calculating and statistically analyzing quantitative MRI perfusion parameters. MATERIAL AND METHODS: We applied two models of MRI perfusion, the unicompartmental and the pharmacokinetic models, in 15 patients diagnosed with grade IV astrocytoma. In the unicompartmental model, we quantified cerebral blood volume (CBV), mean transit time (MTT), and cerebral blood flow (CBF). In the pharmacokinetic model, we measured the permeability constant (K(trans)), the extraction coefficient (k(ep)), the fraction of the volume in the interstitial space (v(e)), the fraction of the volume in the vessels (v(p)), the permeability in the first pass (K(fp)), and the vascular volume in the first pass (v(pfp)). For each parameter, histograms were obtained for the total tumor area, for the peritumoral area, and for the healthy tissue. The statistical analysis included an analysis of variance for each parameter and a discriminant analysis. RESULTS: The most significant differences between the regions were obtained with CBV, CBF, K(trans), and v(pfp); of these, CBV had the best results. The best classificatory function on the discriminant analysis was the combination of K(trans) and CBV. The analysis of the shape of the histogram showed statistically significant differences for the kurtosis of K(trans) and k(ep), as well as for the skewness of CBV, CBF, K(trans), and v(pfp). CONCLUSION: When parameters are considered individually, CBV is the one that best enables differentiation between tumor, peritumoral, and healthy tissue. The classificatory function generated from CBV and K(trans) results in improved classification by areas.

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)

[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.

Resonancia magnética del ventrículo izquierdo en sujetos sanos: valores normales de morfología, función, perfusión y viabilidad / Magnetic resonance Imaging of the left ventricle in healthy subjects: normal values for morphology, function, perfusion, and viability

Objetivos: Definir unos patrones de normalidad en la cuantificación de la función, la perfusión y la viabilidad cardíaca del ventrículo izquierdo (VI) mediante resonancia magnética (RM), analizando las diferencias relevantes por edad y sexo. Material y métodos: Se analizaron 18 sujetos sanos con edad comprendida entre los 15 y los 77 años. Las adquisiciones se realizaron utilizando 2 equipos de RM de 1,5 y 3 teslas. Mediante una herramienta informática para el procesado de las imágenes (Cardio-RM, View Forum, Philips Sistemas Médicos) se evaluaron parámetros morfofuncionales (volumen telediastólico y telesistólico, volumen latido, fracción de eyección, gasto cardíaco, masa miocárdica, espesor miocárdico, engrosamiento y movimiento miocárdico), de perfusión (pendiente ascendente máxima relativa, realce máximo relativo) y de realce tardío (porcentaje de hiperrealce tardío). Para el análisis estadístico se utilizó la prueba de la t de Student. Resultados: Se observaron diferencias entre sexos, con un aumento estadísticamente significativo de los volúmenes telediastólico y telesistólico, del volumen latido y de la masa miocárdica en los varones. Las mujeres presentaron un aumento estadísticamente significativo de la fracción de eyección. Los sujetos sanos mayores de 45 años presentan diferencias estadísticamente significativas en el espesor del miocardio. Conclusión: Se describen los valores de referencia de los parámetros morfofuncionales, de perfusión y de realce tardío para los estudio de RM del corazón. El sexo y la edad tienen que tenerse en cuenta como covariables relacionadas con algunos de estos parámetros (AU)

Objective: To define normal values of MRI parameters related to cardiac morphology, function, perfusion, and delayed enhancement of the left ventricle and to analyze differences based on age and sex. Material and methods: We used 1.5T and 3T MRI scanners to analyze 18 healthy subjects ranging in age from 15 to 77 years old. Dedicated image processing software (Cardio-MR, View Forum, Philips Medical Systems) was used to evaluate morphological and functional parameters (end-diastolic and end-systolic volume, stroke volume, ejection fraction, cardiac output, wall mass, wall thickness, wall thickening, wall motion), perfusion parameters (relative maximum upslope, relative maximum enhancement), and delayed enhancement (percentage of late hyperenhancement). Student's t-test was used for statistical analyses. Results: Sex differences were observed: end-diastolic and end-systolic volumes, stroke volume, and wall mass were significantly higher in men and the ejection fraction was significantly larger in women. Healthy subjects over 45 years of age had significantly greater wall thickness. Conclusion: We report cardiac MRI reference values for morphological, functional, perfusion, and delayed enhancement parameters. Sex and age should be taken into account as important variables related to some of these parameters (AU)

Resonancia magnética en la respuesta al tratamiento del síndrome de hiperestimulación ovárica: comparación de modelos farmacocinéticos / Magnetic resonance for evaluating the response to treatment for ovarian hyperstimulation syndrome: comparison of pharmokinetic models

Objetivo Valorar el efecto del tratamiento con cabergolina en el síndrome de hiperestimulación ovárica (SHO) mediante la aplicación de modelos mono y bicompartimentales en resonancia magnética (RM). Material y métodosSe estudiaron 20 mujeres donantes de óvulos con riesgo de desarrollar SHO, divididas en 2 grupos (placebo y tratamiento). Se realizaron 2 estudios de RM de perfusión, antes y tras el inicio del tratamiento. Se comparó el modelo monocompartimental, con parámetros de permeabilidad vascular (Ktrans), ratio de extracción (kep) y fracción de espacio extravascular extracelular (ve), y el bicompartimental, que añade la fracción de espacio intravascular (vp). El análisis de las diferencias entre grupos (placebo frente a tratamiento) para los 2 estudios de RM y para cada modelo farmacocinético se realizó con una prueba t para muestras independientes. El coeficiente de correlación intraclase (CCI) analizó la variabilidad de las medidas. ResultadosEn el grupo placebo se observó un incremento significativo de Ktrans para ambos modelos (p=0,021 para un compartimiento, y p<0,001 para 2 compartimientos). En las pacientes tratadas no hubo diferencias en ningún parámetro para ninguno de los modelos. Por diferencias entre grupos, para 2 compartimentos Ktrans aumentó un 168,6±151,9% para placebo y un 43,3±54,5% para tratamiento (p=0,04). Para un único compartimiento no hubo diferencias significativas. En el análisis de variabilidad se obtuvo un CCI >0,95 para todos los parámetros, excepto vp (CCI=0,89). ConclusionesLa permeabilidad capilar calculada empleando modelos farmacocinéticos bicompartimentales tras la administración de un contraste en RM es un biomarcador del efecto del tratamiento en pacientes con SHO (AU)

ObjectiveTo evaluate the response to treatment with cabergoline for ovarian hyperstimulation syndrome (OHS) using mono- and bi-compartmental MRI models. Material and methodsWe studied 20 ovum donors with a high risk of developing OHS, divided in two groups (placebo vs. treatment). MRI perfusion studies were performed before and after the beginning of treatment. We compared the monocompartmental model, with the parameters vascular permeability (Ktrans), extraction ratio (kep), and extravascular extracellular space fraction (ve), against the bicompartmental model, with the same parameters as in the monocompartmental model and the additional parameter vascular space fraction (vp). The differences between groups (placebo vs. treatment) on the two MRI studies and for each pharmacokinetic model were analyzed using t-tests for independent samples. The intraclass correlation coefficient (ICC) was used to assess the variability of the measurements. ResultsIn the placebo group, a significant increase in Ktrans was observed with both models (p=0.021 for one compartment; and p<0.001 for two compartments). In the treatment group, no statistically significant differences were found for any parameter in either model. Regarding differences between groups, in the bicompartmental model Ktrans increased 168.6%±151.9% in the placebo group versus 43.3%±54.5% in the treatment group, p=0.04). In the monocompartmental model, no differences were found between groups. In the variability analysis, the ICC was higher than 0.95 for all parameters except vp (ICC=0.89). ConclusionsCapillary permeability calculated with bicompartmental pharmacokinetic models after MRI contrast administration is a biomarker of the treatment effect in OHS patients (AU)

[Magnetic resonance imaging of the left ventricle in healthy subjects: normal values for morphology, function, perfusion, and viability]. / Resonancia magnética del ventrículo izquierdo en sujetos sanos: valores normales de morfología, función, perfusión y viabilidad.

OBJECTIVE: To define normal values of MRI parameters related to cardiac morphology, function, perfusion, and delayed enhancement of the left ventricle and to analyze differences based on age and sex. MATERIAL AND METHODS: We used 1.5T and 3T MRI scanners to analyze 18 healthy subjects ranging in age from 15 to 77 years old. Dedicated image processing software (Cardio-MR, View Forum, Philips Medical Systems) was used to evaluate morphological and functional parameters (end-diastolic and end-systolic volume, stroke volume, ejection fraction, cardiac output, wall mass, wall thickness, wall thickening, wall motion), perfusion parameters (relative maximum upslope, relative maximum enhancement), and delayed enhancement (percentage of late hyperenhancement). Student's t-test was used for statistical analyses. RESULTS: Sex differences were observed: end-diastolic and end-systolic volumes, stroke volume, and wall mass were significantly higher in men and the ejection fraction was significantly larger in women. Healthy subjects over 45 years of age had significantly greater wall thickness. CONCLUSION: We report cardiac MRI reference values for morphological, functional, perfusion, and delayed enhancement parameters. Sex and age should be taken into account as important variables related to some of these parameters.

[Magnetic resonance for evaluating the response to treatment for ovarian hyperstimulation syndrome: comparison of pharmokinetic models.]. / Resonancia magnética en la respuesta al tratamiento del síndrome de hiperestimulación ovárica: comparación de modelos farmacocinéticos.

OBJECTIVE: To evaluate the response to treatment with cabergoline for ovarian hyperstimulation syndrome (OHS) using mono- and bi-compartmental MRI models. MATERIAL AND METHODS: We studied 20 ovum donors with a high risk of developing OHS, divided in two groups (placebo vs. treatment). MRI perfusion studies were performed before and after the beginning of treatment. We compared the monocompartmental model, with the parameters vascular permeability (K(trans)), extraction ratio (k(ep)), and extravascular extracellular space fraction (v(e)), against the bicompartmental model, with the same parameters as in the monocompartmental model and the additional parameter vascular space fraction (v(p)). The differences between groups (placebo vs. treatment) on the two MRI studies and for each pharmacokinetic model were analyzed using t-tests for independent samples. The intraclass correlation coefficient (ICC) was used to assess the variability of the measurements. RESULTS: In the placebo group, a significant increase in K(trans) was observed with both models (p=0.021 for one compartment; and p<0.001 for two compartments). In the treatment group, no statistically significant differences were found for any parameter in either model. Regarding differences between groups, in the bicompartmental model K(trans) increased 168.6%+/-151.9% in the placebo group versus 43.3%+/-54.5% in the treatment group, p=0.04). In the monocompartmental model, no differences were found between groups. In the variability analysis, the ICC was higher than 0.95 for all parameters except v(p) (ICC=0.89). CONCLUSIONS: Capillary permeability calculated with bicompartmental pharmacokinetic models after MRI contrast administration is a biomarker of the treatment effect in OHS patients.