Segmentación del hígado en imágenes de tomografía computarizada

RESUMEN Fundamento: la segmentación del hígado utilizando datos de tomografía computarizada es el primer paso para el diagnóstico de enfermedades hepáticas. Actualmente la segmentación de estructuras y órganos, basado en imágenes, que se realiza en los hospitales del país, dista de tener los niveles de precisión que se obtienen de los modernos sistemas 3D, por lo que se requiere buscar alternativas viables utilizando el PDI sobre ordenador. Objetivo: determinar una variante eficaz y eficiente desde el punto de vista computacional en condiciones de rutina hospitalaria, para la segmentación de imágenes hepáticas con fines clínicos. Métodos: se compararon dos métodos modernos de segmentación (Graph Cut y EM/MPM) aplicándolos sobre imágenes de tomografía de hígado. Se realizó un análisis evaluativo y estadístico de los resultados obtenidos en la segmentación de las imágenes a partir de los coeficientes de Dice, Vinet y Jaccard. Resultados: con el método Graph Cut, en todos los casos, se segmentó la región deseada, incluso cuando la calidad de las imágenes era baja, se observó gran similitud entre la imagen segmentada y la máscara de referencia. El nivel de detalles visuales es bueno y la reproducción de bordes permanece fiel a la máscara de referencia. La segmentación de las imágenes por el método de EM/MPM, no siempre fue satisfactoria. Conclusiones: el método de segmentación Graph Cut obtuvo mayor precisión para segmentar imágenes de hígado.

ABSTRACT Background: liver segmentation using computed tomography data is the first step for the diagnosis of liver diseases. Currently, the segmentation of structures and organs, based on images, which is carried out in the country's hospitals, is far from having the levels of precision obtained from modern 3D systems, it is necessary to search for viable alternatives using the PDI on a computer. Objective: to determine an effective and efficient variant from the computational point of view in routine hospital conditions, for the segmentation of liver images for clinical purposes. Methods: Two modern segmentation methods (Graph Cut and EM/MPM) were compared by applying them to liver tomography images. An evaluative and statistical analysis of the results obtained in the segmentation of the images from the Dice, Vinet and Jaccard coefficients was carried out. Results: with the Graph Cut method, in all cases, the desired region was segmented, even when the quality of the images was low, great similarity was observed between the segmented image and the reference mask. The level of visual detail is good, and edge reproduction remains true to the reference skin. Image segmentation by the EM/MPM method was not always satisfactory. Conclusions: the Graph Cut segmentation method obtained greater precision to segment liver images.

Pancreatic Cystic Neoplasm: Radiologic Evaluation and Differential Diagnosis / 대한췌담도학회지

Pancreatic cystic neoplasm is a clinically challenging entity. Its incidence estimated up to 45% of the general population. The biological behavior ranges from benign to malignant disease. The strategy for pancreatic cystic neoplasm could be to prevent progression to pancreatic cancer while minimizing the costs. The first step for the correct management is correct diagnosis. In this paper, the radiological differential diagnosis of them will be described.

Implicancia pronóstica de los estudios gated-SPECT normales en pacientes mayores de 70 años / Pronostic implication of normal gated SPECT studies in patients over 70 years old

Introducción: un resultado normal en la centellografía de perfusión miocárdica gatillada (gated-SPECT) tiene un alto valor predictivo negativo para enfermedad coronaria grave; existe un período de tiempo variable en que los pacientes permanecen con una tasa de eventos baja (menor a 1%). Sin embargo, algunas evidencias sugieren que este período de garantía (PG) no es el mismo en todos los grupos etarios. Objetivo: establecer el período de tiempo en el cual los pacientes ancianos (mayores de 70 años) mantienen una tasa de eventos cardíacos por debajo de 1%. Material y método: se estudiaron 554 pacientes mediante gated-SPECT, divididos en dos grupos: Grupo 1: (n=354) con gated-SPECT normal, y Grupo 2: (n=200) con gated-SPECT anormal. Definimos un gated-SPECT normal como aquel con score de suma en estrés (SSS) < 4 y parámetros funcionales normales. El seguimiento medio fue de 30,6 meses (rango: 12-62 meses) para la pesquisa de los eventos cardiovasculares (EC): muerte cardíaca (MC) e infarto agudo de miocardio no fatal (IAMNF), y eventos combinados (ECB): EC+ angioplastia coronaria, cirugía de revascularización miocárdica e implante de cardiodesfibrilador. Se utilizó prueba no paramétrica de Pearson y se calculó el estadístico x2, con un valor de p ?0,05 para el rechazo de la hipótesis nula (IC: 95%). Resultados: la comparación entre ambos grupos muestra diferencias en los tres primeros años para la aparición de EC (p <0,0001), MC (p <0,0001) y ECB (p <0,0001). La tasa de EC en el Grupo 1 para cada año fue de 0,56%, 0,59% y 0,50%, respectivamente, con una tasa acumulada a tres años de 1,65%. La tasa en el Grupo 2 fue de 2,50%, 1,58% y 3,84%, respectivamente (tasa acumulada: 7,92%). El período de tiempo en el cual los pacientes del Grupo 1 mantuvieron un riesgo de EC por debajo de 1% fue de 18 meses. Conclusión: el pronóstico de los pacientes ancianos que presentan un resultado normal en el gated-SPECT es muy bueno, con una tasa de EC menor a 1% por un lapso de 18 meses.

Introduction: a normal result in myocardial perfusion scintigraphy (gated-SPECT) has a high negative predictive value for severe coronary artery disease; there is a period of time in which patients remain with a low event rate (less than 1%). However, some evidence suggests that this guarantee period (PG) is not the same in all age groups. Objectives: to establish the period of time in which elderly patients (older than 70 years) maintain a rate of cardiac events below 1%. Material and methods: 554 patients were studied through gated-SPECT, divided into two groups: Group 1: (n = 354) with normal gated-SPECT, and Group 2: (n = 200) with abnormal gated-SPECT. We define a normal gated-SPECT as that with a stress sum score (SSS) <4 and normal functional parameters. The mean follow-up was 30.6 months (range: 12-62 months), for the investigation of cardiovascular events (CE): cardiac death (CD) and nonfatal infarction (NFAMI), and combined events (CBE): CE + coronary angioplasty, myocardial revascularization surgery and implanted cardiodefibrillator (ICD). Pearson's nonparametric test was used and the Χ2 statistic was calculated, with a value of p <0.05 for the rejection of the null hypothesis (CI: 95%). Results: the comparison between both groups shows differences for the appearance of CE: (p <0.0001), CD: (p <0.0001) and CBE: (p <0.0001). The CE rate in Group 1 for each year was 0.56, 0.59 and 0.50%, respectively, with a cumulative 3-year rate of 1.65%. The rate in Group 2 was 2.5, 1.58 and 3.84%, respectively (cumulative rate: 7.92%). The period in which Group 1 patients maintained a risk of CD below 1% was 18 months. Conclusion: the prognosis of elderly patients presenting a normal gated-SPECT result is very good, with a cardiac event rate of less than 1% for a period of 18 months.

Comparison of rectal cancer tumor volume parameters measured by MRI sequences and CT with those by pathological specimen / 中国肿瘤临床

Objective:This study aimed to compare rectal cancer tumor volume parameters measured by MRI sequences (T1WI, T2WI, and DWI) and/or CT with those by pathological specimen. Methods:Twenty-two patients with rectal cancer were prospectively enrolled. MRI sequences including T1WI, T2WI, and DWI, and/or CT of the pelvis were performed before operation. Volume parameters, such as tumor length along the rectal axis, maximum tumor width perpendicular to rectal axis, and tumor actual area in that perpendicular plane, were measured on T1WI, T2WI, DWI, and CT, respectively, for each patient. The respective pathological parameters were further measured in surgical specimen after total mesorectal excision. The two kinds of parameter values measured in imaging and pathology were statistically compared and accuracy appraisal was performed. Results:The mean Lpath-L was 4.06±1.14 cm. The mean LT1-L, LT2-L, LDWI-L, and LCT-L were 3.91± 1.51, 4.62±1.41, 3.39±1.05, and 3.94±1.23 cm, respectively. Correlation coefficients were 0.688, 0.635, 0.688, and 0.720 (P<0.05). An average 6 mm overestimation was found in T2WI, and 1 to 6 mm underestimation in T1WI, DWI, and CT in length values compared with those measured in surgical specimen. The mean Lpath-W was 2.56 ±0.94 cm. The mean LT1-W, LT2-W, LDWI-W, and LCT-W were 3.62±0.99, 3.66±0.76, 3.23±0.58, and 3.64±1.04 cm, respectively. The magnitude of mean overestimation ranged from 5.1 to 11.1 mm. The Apath was 4.30 ±2.83 cm2. AT1, AT2, ADWI, and ACT were 8.98±3.90, 8.99±3.43, 8.41±3.09, and 9.63±4.40 cm2, respectively, which double overestimated the tumor area in the perpendicular rectal plane. Conclusion:The difference in longitudinal length between MRI sequences/CT and pathological specimen was in the range of?6 mm to 6 mm. The mean maximum tumor width and areas in the maximum tumor perpendicular plane were overestimated. This study indicated that gross tumor volume delineation based on CT or MRI for rectal cancer irradiation should be conservative in the axial images of rectum, and meticulous consideration is required along the rectum.

Prognostic Value of Infarct size Measured by Gated sPECT scintigraphy / Valor pronóstico del tamaño del infarto de miocardio cuantificado mediante SPECT gatillada

Background: Despite the improved sensitivity and specificity of SPECT myocardial perfusion imagingto detect myocardial involve-ment after acute myocardial infarction (AMI), there is little information about the usefulness of early infarct size (IS) measurement by this method for risk stratification and prognosis. Objectives: The goal of this study was to evaluate the usefulness of quantifying IS by gated SPECT scintigraphy to predict cardio­vascular events in patients with a first AMI. Methods: Patients with a first ST-segment elevation AMI were included from 2009 to 2014. Infarct size was estimated using the Cedars QPS software. The incidence of events (heart failure, ventricular arrhythmias, mortality and a composite of the three events) was evaluated at one year. Results: One-hundred and forty nine patients were included in the study; mean age was 59±11 years and 81.9% were men. Diabetes was present in 16.1% of cases, 9.4% had a history of myocardial revascularization, 84.6% were admitted in Killip and Kimball class A, 43% of AMIs were located in the anterior wall and 69.8% of the patients underwent reperfusion. Left ventricular ejection fraction estimated by gated SPECT scintigraphy was 51%±14%. Follow-up was completed in 95.9% of cases. An IS cutoff point of 22% (ROC curve) was established to predict the composite endpoint at follow-up (sensitivity 92%, specificity 81%, AUC: 0.94%), dividing the sample into two groups: Group I (IS <22%) and Group II (IS ≥22%). The prevalence of the composite endpoint was greater in Group II (2.1% Group I vs. 50% Group II; p<0.001). Infarct size ≥ 22% was the only variable identified as predictor of events during follow-up (OR 1.978; 95% CI 1.887-1.996; p<0.001). Conclusion: Early quantification of IS by gated SPECT scintigraphy is an independent risk predictor at one year that allows risk stratification in patients with a first AMI.

Introducción: Si bien la SPECT de perfusión miocárdica ha mejorado la sensibilidad y la especificidad en la detección del compromiso miocárdico luego de un infarto agudo de miocardio (IAM), aún es escasa la información sobre la determinación precoz del tamaño del infarto (TI) con este método para la estratificación del riesgo y su valor pronóstico. Objetivos: Evaluar la utilidad de la cuantificación del TI estimado por SPECT gatillada en la predicción de complicaciones cardio­vasculares en pacientes con un primer IAM. Material y métodos: Se analizaron los pacientes con IAM con elevación del ST desde 2009 a 2014, excluyéndose aquellos con IAM previo. El cálculo del TI se realizó con el softwareCedars QPS. Se evaluaron eventos al año: insuficiencia cardíaca, arritmias ventri-culares, muerte y la combinación de los tres eventos. Resultados: Se incluyeron 149 pacientes, con edad media de 59±11 años,el 81,9% de sexo masculino. El 16,1% eran diabéticos y el 9,4% presentaban revascularización previa. El 84,6% ingresaron en Killip y Kimball A, el 43% de los IAM fueron de territorio anterior y el 69,8% de los pacientes fueron reperfundidos. La fracción de eyección del ventrículo izquierdo por SPECT gatillada fue del 51% ±14%. Se realizó seguimiento clínico en el 95,9% de los casos. El punto de corte del TI (curva ROC) para predecir eventos combinados al seguimiento se estableció en 22% (sensibilidad: 92%, especificidad: 81%, ABC: 0,94),con el cual la muestra se dividió en dos grupos: Grupo I (TI<22%) y Grupo II (TI≥22%). La prevalencia de eventos combinados fue mayor en el Grupo II (2,1% Grupo Ivs. 50% Grupo II; p<0,001). El TI ≥22% se identificó como la única variable predictora de eventos al seguimiento (OR 1,978; IC 95% 1,887-1,996; p<0,001). Conclusión: La cuantificación precoz del TI mediante SPECT es un predictor independiente de riesgo al año que permite establecer una estratificación del riesgo en pacientes con un primer IAM.

CT Appearances of Mesenteric Tumors and the Differential Diagnosis / 中国普外基础与临床杂志

Objective To review the CT appearances and important differential diagnoses of various primary and secondary mesenteric neoplasms.Methods By describing the mesenteric anatiomy and major routes for the dissemination of metastatic mesenteric tumors, the article presents both the common and rare types of various primary and secondary mesenteric neoplasms, and addresses the characteristic CT appearances and important aspects of the differential diagnosis.Results CT study, especially the multi-slice spiral CT (MSCT), along with the clinical history and other related information, can nicely depict various mesenteric tumors and well differentiate them from infectious, inflammatory or vascular processes affecting the mesentery.Conclusion CT is the imaging method of choice for the evaluation of tumors of small bowel mesentery.