A novel stereotactic frame for real PET-guided biopsies: A preclinical proof-of-concept.

PURPOSE: To design, build and test a stereotactic device that allows PET image-guided biopsies to be performed. METHODS: An initial prototype consisting of four main pieces, one of which contains radioactive markers to make it visible in the PET images, was built using a 3D printer. Once the device is mounted, a spherical coordinate system is built with the entrance needle point in the skin as the origin of coordinates. Two in-house software programs, namely getCoord.ijm, which obtains the spherical coordinates of the tumour tissue to be biopsied, and getNeedle.ijm, which virtualizes the inner needle tip once the puncture has taken place, were written. This prototype was tested on an FDG-doped phantom to characterize both the accuracy of the system and the procedure time. RESULTS: Up to 11 complete biopsy procedures were conducted. The mean total procedure time was less than 20min, which is less than the procedure time of conventional standard CT-guided biopsies. The overall accuracy of the system was found to be 5.0±1.3mm, which outperforms the criterion used in routine clinical practice when targeting tumours with a diameter of 10mm. CONCLUSIONS: A stereotactic frame to conduct real PET image-guided biopsies has been designed and built. A proof-of-concept was performed to characterize the system. The procedure time and accuracy of the system were found to meet the current needs of physicians performing biopsies.

Identification of low variability textural features for heterogeneity quantification of 18F-FDG PET/CT imaging / Identificación de texturas de baja variabilidad para la cuantificación de la heterogeneidad en imagen 18F-FDG PET/TC

Objective. To identify those textural features that are insensitive to both technical and biological factors in order to standardise heterogeneity studies on 18F-FDG PET imaging. Materials and methods. Two different studies were performed. First, nineteen series from a cylindrical phantom filled with different 18F-FDG activity concentration were acquired and reconstructed using three different protocols. Seventy-two texture features were calculated inside a circular region of interest. The variability of each feature was obtained. Second, the data for 15 patients showing non-pathological liver were acquired. Anatomical and physiological features such as patient's weight, height, body mass index, metabolic active volume, blood glucose level, SUV and SUV standard deviation were also recorded. A liver covering region of interest was delineated and low variability textural features calculated in each patient. Finally, a multivariate Spearman's correlation analysis between biological factors and texture features was performed. Results. Only eight texture features analysed show small variability (<5%) with activity concentration and reconstruction protocol making them suitable for heterogeneity quantification. On the other hand, there is a high statistically significant correlation between MAV and entropy (P<0.05). Entropy feature is, indeed, correlated (P<0.05) with all patient parameters, except body mass index. Conclusions. The textural features that are correlated with neither technical nor biological factors are run percentage, short-zone emphasis and intensity, making them suitable for quantifying functional changes or classifying patients. Other textural features are correlated with technical and biological factors and are, therefore, a source of errors if used for this purpose (AU)

Objetivo. Identificar las texturas que son independientes de los factores técnicos y biológicos en imagen PET con 18F-FDG con el fin de estandarizar la heterogeneidad en imagen PET. Material y métodos. Se realizaron 2 estudios. En primer lugar, se estudió la variabilidad de 72 parámetros texturales en una región de interés circular en el interior de un maniquí cilíndrico, con 19 concentraciones de actividad y 3 protocolos de reconstrucción diferentes. A continuación, se estudió una población de 15 pacientes sin captaciones hepáticas. De cada paciente se registraron el peso, altura, índice de masa corporal, volumen metabólico activo, niveles de glucosa en sangre, SUV y desviación estándar de SUV. Se obtuvieron las texturas de baja variabilidad de una región de interés centrada en hígado. Finalmente, se realizó un análisis de correlación multivariado de Spearman entre los factores biológicos y los parámetros texturales. Resultados. Solo 8 parámetros texturales muestran baja variabilidad (<5%) con la concentración de actividad y el protocolo de reconstrucción, haciéndolos adecuados para cuantificar la heterogeneidad de la región captante. Por otro lado, existe una correlación estadísticamente significativa entre el volumen metabólico activo y la entropía (p<0,05). La entropía está, además, correlacionada con los demás parámetros, excepto el índice de masa corporal. Conclusiones. Las únicas texturas que no están correlacionadas con ninguno de los parámetros anatómicos o fisiológicos son run percentage, short-zone emphasis e intensidad, siendo estas las más adecuadas para realizar análisis cuantitativos de heterogeneidades mediante parámetros de textura. Otras texturas están relacionadas con factores técnicos y biológicos y, por tanto, constituyen una fuente de errores cuando se utilizan para este fin (AU)

Identification of low variability textural features for heterogeneity quantification of 18F-FDG PET/CT imaging.

OBJECTIVE: To identify those textural features that are insensitive to both technical and biological factors in order to standardise heterogeneity studies on 18F-FDG PET imaging. MATERIALS AND METHODS: Two different studies were performed. First, nineteen series from a cylindrical phantom filled with different 18F-FDG activity concentration were acquired and reconstructed using three different protocols. Seventy-two texture features were calculated inside a circular region of interest. The variability of each feature was obtained. Second, the data for 15 patients showing non-pathological liver were acquired. Anatomical and physiological features such as patient's weight, height, body mass index, metabolic active volume, blood glucose level, SUV and SUV standard deviation were also recorded. A liver covering region of interest was delineated and low variability textural features calculated in each patient. Finally, a multivariate Spearman's correlation analysis between biological factors and texture features was performed. RESULTS: Only eight texture features analysed show small variability (<5%) with activity concentration and reconstruction protocol making them suitable for heterogeneity quantification. On the other hand, there is a high statistically significant correlation between MAV and entropy (P<0.05). Entropy feature is, indeed, correlated (P<0.05) with all patient parameters, except body mass index. CONCLUSIONS: The textural features that are correlated with neither technical nor biological factors are run percentage, short-zone emphasis and intensity, making them suitable for quantifying functional changes or classifying patients. Other textural features are correlated with technical and biological factors and are, therefore, a source of errors if used for this purpose.

Localización atípica de metástasis de carcinoma de ovario detectada con 18F-FDG PET/TC / Atypical location of metastatic ovarian carcinoma detected by 18F-FDG PET/CT

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Eosinofilia y diarrea secundarias a enalapril: a propósito de un caso / No disponible

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Hiperplasia gingival secundaria a amlodipino: a propósito de un caso / Gingival hyperplasia secondary to amlodipine: a case report

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[Pleural effusion due to Listeria monocytogenes. A case report and review of the literature]. / Derrame pleural por Listeria monocytogenes. Presentación de un caso y revisión de la literatura.

The infection caused by Listeria monocytogenes is a relatively common condition in immunosuppressed patients. The most frequent presentation in adults are sepsis and meningitis. Pleural fluid infection due to this pathogen is a rare finding in the literature. Most cases are found in immunosuppressed patients, particularly in those with haematologic malignancies. We report one case of pleural fluid infection due to Listeria monocytogenes in a patient with hepatic cirrhosis (the third case in the literature). We also review the seventeen cases previously reported and describe the clinical manifestations, its immunosuppression states relationship, the treatment of choice and the mortality.

Derrame pleural por Listeria monocytogenes. Presentación de un caso y revisión de la literatura / Pleural fluid infection caused by listeria monocytogenes: case report and literature review

La infección por Listeria monocytogenes es relativamente frecuente en pacientes inmunodeprimidos, la sepsis y la afectación neuromeníngea son las formas de presentación más habituales. La infección de la cavidad pleural por este germen es una entidad escasamente descrita en la literatura, en la mayoría de los casos se presenta en pacientes inmunodeprimidos, sobre todo con enfermedades hematológicas malignas. Presentamos un caso de infección pleural por Listeria monocytogenes en un paciente con cirrosis hepática (tercer caso descrito) y revisamos diecisiete casos previos analizando las formas de presentación, su relación con estados de inmunodepresión, tratamiento de elección y mortalidad (AU)