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)

[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.

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.

[Association of cavernous and venous angiomas]. / Asociación de angiomas cavernosos con venosos.

INTRODUCTION: Isolated cavernous and venous angiomas are common vascular cerebral malformations. The routine use of magnetic resonance imaging (MRI) in cerebral studies has shown their frequent association. OBJECTIVE: An analysis of the association characteristics of both lesions (cavernous and venous angiomas), and the relationships with localization, size, patient sex and the use of intravenous contrast material in the diagnosis with MR. METHODS: A retrospective analysis of the cerebral MRI studies of 37 patients with cavernous angiomas. Statistical relations were established with contingency tables and statistical methods of Pearson c2 and t of Student for independent samples. Results. 52 cavernous angiomas were identified in the 37 patients. No significant statistical differences were found that related the cavernous angioma size, localization or patient sex with the existence of an associated venous angioma. Only the administration of contrast material has shown a statistical significance for the diagnosis. CONCLUSIONS: The association of cavernous and venous angioma is frequent (30%). This association has prognostic implications, due to bleeding risk, and surgical as it is not recommended the resection of the venous anomaly due to the possible venous infarction. To detect venous angiomas is necessary the administration of contrast material.

[Update on lung cancer staging]. / Actualización en la estadificación del cáncer de pulmón.

Clinical staging is fundamental in lung cancer, as this descriptive system facilitates the transmission of the extension of the disease, provides prognostic information, helps in choosing the most appropriate treatment program, and provides a standardized system that enables the treatment outcomes of different series of patients to be compared. The most important technique for defining local, regional, and remote extension of the disease continues to be chest and abdominal CT. Functional imaging techniques play a complementary role that is becoming increasingly important in the noninvasive characterization of mediastinal lymph-node involvement.

Actualización en la estadificación del cáncer de pulmón / Update on lung cancer staging

La estadificación clínica del cáncer de pulmón es fundamental, ya que se trata de un sistema descriptivo que facilita la transmisión de la extensión de la enfermedad, aporta información pronóstica, ayuda a elegir el programa terapéutico más apropiado y proporciona un sistema estandarizado que permite la comparación de resultados terapéuticos entre series de pacientes. La técnica más importante para definir la extensión loco-regional y a distancia de la enfermedad, continúa siendo la tomografía computarizada torácica y abdominal. Las técnicas de imagen funcional tienen un carácter complementario que va ganando progresivamente protagonismo, principalmente en la caracterización no invasora de la afectación ganglionar mediastínica

Clinical staging is fundamental in lung cancer, as this descriptive system facilitates the transmission of the extension of the disease, provides prognostic information, helps in choosing the most appropriate treatment program, and provides a standardized system that enables the treatment outcomes of different series of patients to be compared. The most important technique for defining local, regional, and remote extension of the disease continues to be chest and abdominal CT. Functional imaging techniques play a complementary role that is becoming increasingly important in the noninvasive characterization of mediastinal lymph-node involvement

[The contribution of magnetic resonance spectroscopy to the classification of high grade gliomas. The predictive value of macromolecules]. / Contribución de la espectroscopía de Resonancia Magnética a la clasificación del glioma de alto grado. Valor predictivo de las macromoléculas.

INTRODUCTION: 1H MRS allows the study of metabolite concentration changes in intracranial tumours, relating them, more or less successfully, to the histological type and grade of the tumour. OBJECTIVE: To analyse the patterns which are useful for classifying the grades of cerebral gliomas by means of various ratios obtained using 1H MRS with two echo times (ET), with and without water suppression, paying special attention to the macromolecules. PATIENTS AND METHODS: We studied 8 gliomas (1 grade II, 2 grade III and 5 grade IV) with single volume 1H MRS at ET 31 ms (8/8) and 136 ms (7/8). The intensities of the metabolites, including macromolecules (MMA, 0.9 ppm; MMB, 1.3 ppm), were normalised to water signal intensity for ET 31, to Cr at ET 31 and 136 ms and NAA/Cho for both ET and the ratio MMA/MMB at ET 31. RESULTS: There were significant differences between the three grades on the ratios MMA/MMB (p= 0.000) with descent of the MMA/MMB coefficient as the grade increases, and NNA/Cho at ET 136 (p= 0.018). We found an inverse relationship between the quantity in mI and the increase in grade. No macromolecules were found at ET 136 in any of the tumours of grade II or III. CONCLUSIONS: The spectra of gliomas with ET 31 showed macromolecules around 0.9 and 1.3 ppm with different relative ratios for each tumour grade. The ET 136 spectra informs about the content of NNA and Cho. Apart from the increase in MMB (0.9 ppm), with short ET the higher grades showed lower content of mI. The study of gliomas using 1H MRS with ET 31 and 136 ms contributes to the diagnosis of the grade of tumour.

Contribución de la espectroscopía de resonancia magnética a la clasificación del glioma de alto grado.Valor predictivo de las macromoléculas / The contribution of magnetic resonance spectroscopy to the classification of high grade gliomas. The predictive value of macromolecules

Introducción. La 1H ERM permite estudiar los cambios en las concentraciones de metabolitos en los tumores intracraneales, relacionándolos con éxito variable con el tipo histológico y el grado tumoral. Objetivo. Analizar los patrones útiles en la gradación de gliomas cerebrales mediante diversos cocientes obtenidos con 1H ERM a dos tiempos de eco (TE), con y sin supresión del agua, con especial interés en la aportación de las macromoléculas. Pacientes y métodos. Se estudiaron ocho gliomas (1grado II, 2 grado III y 5 grado IV) con 1H ERM de volumen único a TE 31 ms (8/8) y 136 ms (7/8). Las intensidades de diversos metabolitos, incluyendo macromoléculas (MMA, 0,9 ppm; MMB, 1,3 ppm), se normalizaron al H2O para TE 31, a Cr para TE 31 y 136 ms y NAA/Co para ambos TE y la relación MMA/MMB para TE 31. Resultados. Existen diferencias significativas para los tres grados en los cocientes MMA/MMB (p=0,000), con un descenso del cociente MMA/MMB al aumentar el grado, y NAA/Co a TE 136 (p=0,018). Se observó una relación inversa entre la cantidad de mio-inositol (mI) y el aumento de grado, pero no se detectaron macromoléculas a TE 136 en ninguno de los tumores de grado II o III. Conclusiones. En los espectros de gliomas a TE 31 aparecen macromoléculas a 0,9 y 1,3 ppm con proporción relativa distinta para cada uno de los grados. Los espectros a TE medio informan del contenido de NAA y Co. Además del aumento de MMB (0,9 ppm), a TE corto, los grados más altos presentan una disminución del contenido de mI. El estudio de gliomas mediante 1H ERM con TE corto y medio contribuye al diagnóstico del grado tumoral (AU)