Tomografía computarizada para el diagnóstico de la apendicitis aguda en adultos / Computed tomography for diagnosis of acute appendicitis in adults

¿Por qué es importante mejorar el diagnóstico de la apendicitis? El propósito de utilizar la tomografía computarizada (TC) en personas con sospecha de apendicitis es ayudar al médico a diferenciar entre los pacientes que necesitan una cirugía con resección del apéndice (apendicectomía) y los que no necesitan este procedimiento. ¿Cuál es el objetivo de esta revisión? El objetivo de esta revisión Cochrane fue averiguar cómo de precisa es la TC de abdomen y pelvis para el diagnóstico de apendicitis en adultos. Los investigadores de Cochrane incluyeron 64 estudios en la revisión para responder a esta pregunta. ¿Qué se estudió en la revisión? Una TC puede realizarse de varias maneras. La calidad de la imagen puede mejorarse mediante el uso de material de contraste intravenoso, y la visualización del apéndice puede ser mejor cuando se utiliza contraste oral o rectal. La TC también puede realizarse con una dosis baja de radiación. La exposición a la radiación relacionada con la TC puede aumentar el riesgo de cáncer de por vida. Esta revisión estudió la precisión de los siguientes tipos de TC: cualquier tipo de TC, TC según el tipo de contraste, y TC de baja dosis. ¿Cuáles son los principales resultados? Esta revisión incluyó 64 estudios relevantes que informaron de los resultados de 71 poblaciones de estudio diferentes con un total de 10.280 participantes. Los resultados generales indican que, en teoría, si se utilizara una TC de cualquier tipo urgencias en un grupo de 1.000 personas, de las cuales el 43% tuviese apendicitis, entonces se estima que: a) 443 personas tendrían una TC que indicaría apendicitis y, de estas, el 8% no tendría apendicitis aguda; y b) 557 personas tendrían una TC que indicaría que no hay apendicitis, y el 4% tendría en realidad apendicitis aguda. La TC de baja dosis sería tan precisa como la TC de dosis estándar para diagnosticar la apendicitis. La TC con material de contraste intravenoso, rectal u oral e intravenoso sería igual de precisa, y más precisa que la TC sin contraste. ¿Cómo de fiables son los resultados de los estudios en esta revisión? Entre los estudios incluidos, el diagnóstico final de apendicitis se basó en los hallazgos quirúrgicos o en el examen microscópico del apéndice resecado. Entre los participantes sin cirugía, la apendicitis se descartó mediante un seguimiento para ver si sus síntomas se resolvían sin apendicectomía. Es probable que este haya sido un método fiable para decidir si los pacientes realmente tenían apendicitis si el seguimiento fue cuidadoso y completo. Lamentablemente, no fue así en una proporción sustancial de los estudios incluidos. En general, se observaron algunos problemas en la forma de realizar los estudios. Esto puede haber dado lugar a que la TC parezca más precisa de lo que realmente es, aumentando así el número de resultados correctos de la TC. ¿A quién son aplicables los resultados? Los estudios incluidos en la revisión se realizaron principalmente en los servicios de urgencias. Se sospechó que todos los participantes tenían apendicitis después del examen clínico y los análisis de sangre. Los estudios incluidos evaluaron una amplia gama de tipos de TC. La edad promedio de los participantes varió entre 25 y 46años, porcentaje de mujeres varió entre el 26% y el 100%, y el porcentaje de participantes con un diagnóstico final de apendicitis varió entre el 13% y el 92% (promedio: 43%). ¿Cuáles son las implicaciones? La TC es una prueba precisa que probablemente ayude a los médicos a tratar a las personas con posible apendicitis. Los resultados de esta revisión indican que la probabilidad de que un clínico diagnostique erróneamente una apendicitis aguda parece ser baja (8% cuando la TC sugiere que tienen apendicitis). La probabilidad de no obtener un diagnóstico de apendicitis también es baja (4% cuando la TC sugiere que no tienen apendicitis). ¿Cómo de actualizada es esta revisión? Se incluyeron estudios publicados hasta el 16 de junio de 2017

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Computed tomography for diagnosis of acute appendicitis in adults.

BACKGROUND: Diagnosing acute appendicitis (appendicitis) based on clinical evaluation, blood testing, and urinalysis can be difficult. Therefore, in persons with suspected appendicitis, abdominopelvic computed tomography (CT) is often used as an add-on test following the initial evaluation to reduce remaining diagnostic uncertainty. The aim of using CT is to assist the clinician in discriminating between persons who need surgery with appendicectomy and persons who do not. OBJECTIVES: Primary objective Our primary objective was to evaluate the accuracy of CT for diagnosing appendicitis in adults with suspected appendicitis. Secondary objectives Our secondary objectives were to compare the accuracy of contrast-enhanced versus non-contrast-enhanced CT, to compare the accuracy of low-dose versus standard-dose CT, and to explore the influence of CT-scanner generation, radiologist experience, degree of clinical suspicion of appendicitis, and aspects of methodological quality on diagnostic accuracy. SEARCH METHODS: We searched MEDLINE, Embase, and Science Citation Index until 16 June 2017. We also searched references lists. We did not exclude studies on the basis of language or publication status. SELECTION CRITERIA: We included prospective studies that compared results of CT versus outcomes of a reference standard in adults (> 14 years of age) with suspected appendicitis. We excluded studies recruiting only pregnant women; studies in persons with abdominal pain at any location and with no particular suspicion of appendicitis; studies in which all participants had undergone ultrasonography (US) before CT and the decision to perform CT depended on the US outcome; studies using a case-control design; studies with fewer than 10 participants; and studies that did not report the numbers of true-positives, false-positives, false-negatives, and true-negatives. Two review authors independently screened and selected studies for inclusion. DATA COLLECTION AND ANALYSIS: Two review authors independently collected the data from each study and evaluated methodological quality according to the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2) tool. We used the bivariate random-effects model to obtain summary estimates of sensitivity and specificity. MAIN RESULTS: We identified 64 studies including 71 separate study populations with a total of 10,280 participants (4583 with and 5697 without acute appendicitis). Estimates of sensitivity ranged from 0.72 to 1.0 and estimates of specificity ranged from 0.5 to 1.0 across the 71 study populations. Summary sensitivity was 0.95 (95% confidence interval (CI) 0.93 to 0.96), and summary specificity was 0.94 (95% CI 0.92 to 0.95). At the median prevalence of appendicitis (0.43), the probability of having appendicitis following a positive CT result was 0.92 (95% CI 0.90 to 0.94), and the probability of having appendicitis following a negative CT result was 0.04 (95% CI 0.03 to 0.05). In subgroup analyses according to contrast enhancement, summary sensitivity was higher for CT with intravenous contrast (0.96, 95% CI 0.92 to 0.98), CT with rectal contrast (0.97, 95% CI 0.93 to 0.99), and CT with intravenous and oral contrast enhancement (0.96, 95% CI 0.93 to 0.98) than for unenhanced CT (0.91, 95% CI 0.87 to 0.93). Summary sensitivity of CT with oral contrast enhancement (0.89, 95% CI 0.81 to 0.94) and unenhanced CT was similar. Results show practically no differences in summary specificity, which varied from 0.93 (95% CI 0.90 to 0.95) to 0.95 (95% CI 0.90 to 0.98) between subgroups. Summary sensitivity for low-dose CT (0.94, 95% 0.90 to 0.97) was similar to summary sensitivity for standard-dose or unspecified-dose CT (0.95, 95% 0.93 to 0.96); summary specificity did not differ between low-dose and standard-dose or unspecified-dose CT. No studies had high methodological quality as evaluated by the QUADAS-2 tool. Major methodological problems were poor reference standards and partial verification primarily due to inadequate and incomplete follow-up in persons who did not have surgery. AUTHORS' CONCLUSIONS: The sensitivity and specificity of CT for diagnosing appendicitis in adults are high. Unenhanced standard-dose CT appears to have lower sensitivity than standard-dose CT with intravenous, rectal, or oral and intravenous contrast enhancement. Use of different types of contrast enhancement or no enhancement does not appear to affect specificity. Differences in sensitivity and specificity between low-dose and standard-dose CT appear to be negligible. The results of this review should be interpreted with caution for two reasons. First, these results are based on studies of low methodological quality. Second, the comparisons between types of contrast enhancement and radiation dose may be unreliable because they are based on indirect comparisons that may be confounded by other factors.

Liver metastases from colorectal cancer: imaging with superparamagnetic iron oxide (SPIO)-enhanced MR imaging, computed tomography and positron emission tomography.

The literature about superparamagnetic iron oxide-enhanced MR imaging, computed tomography (CT) and PET (positron emission tomography using fluorine-18 labelled fluoro-deoxy-glucose) in detection of liver metastases (LM) from colorectal cancer is reviewed in this update. Special emphasis is given to studies with surgical standard of reference allowing for the lesion-by-lesion sensitivity to be determined. Based on the review, it is concluded that state-of-the-art anatomical imaging, e.g., SPIO-enhanced MR imaging and multidetector CT (MDCT), must be considered more sensitive than PET in detection of individual LM, due to technical developments in MR imaging, such as liver specific contrast agents, modern sequences and high performance gradients, and in modern MDCT have increased the performance of these modalities. MR imaging with a liver specific contrast agent is recommended for the preoperative evaluation before liver surgery for LM because of high sensitivity and better discrimination between small LM and cysts compared to MDCT. PET or PET/CT can be used for detection of extra-hepatic tumor before liver surgery.

[Mirizzi's syndrome--diagnosed preoperatively by MR scanning]. / Mirizzis syndrom--diagnosticeret praeoperativt med MR-scanning.

A case of Mirizzi's syndrome in a 30-year-old woman diagnosed preoperatively by MR-scanning is presented. The MR-scanning showed an impacted stone in the gallbladder neck and surrounding soft-tissue mass compressing the hepatic duct causing a narrow stricture of the duct. There were moderate dilatation of the intrahepatic bile ducts as well as gallbladder stones but the common duct was normal. The findings were consistent with Mirizzi's syndrome, which was confirmed by surgery. Awareness of Mirizzi's syndrome because of its potential complications and MR-scanning as a potential diagnostic tool is advocated.