Metodología de la gammagrafía con leucocitos marcados en el diagnóstico de infección osteoarticular protésica/no protésica: ¿análisis visual o semicuantitativo? ¿Protocolo de uno o 2 días? / Diagnostic methodology in labelled leukocyte scan for prosthetic / non-prosthetic osteoarticular infection: Visual or semi-quantitative analysis? One- or two-day protocol?

Objetivo: Como hay poca literatura sobre el tema, nos propusimos comparar la utilidad diagnóstica del análisis semicuantitativo versus el análisis visual en la escintigrafía de glóbulos blancos etiquetados (WBCS) para la infección osteoarticular. Se evaluaron protocolos de uno y dos días, en particular en los dispositivos ortopédicos.Material y métodos: Estudio prospectivo de 79 pacientes consecutivos con sospecha de infección osteoarticular. En todos los pacientes, la SCBM se realizó a los 30 min, 4 h, 8 h y 24 h. Las imágenes se analizaron agrupándolas en dos protocolos: protocolo de un día (los expertos evaluaron imágenes planas de 30 min, 4 h y 8 h) y protocolo de dos días (los expertos evaluaron imágenes planas de 30 min, 4 h y 24 h). Las imágenes planas se interpretaron cualitativa y semicuantitativamente y también se compararon agrupando a los pacientes con y sin dispositivos ortopédicos. Para determinar qué valor de corte de la variación porcentual podía predecir la infección osteoarticular, se calcularon múltiples valores de corte en ambos protocolos a partir del índice de Youden. Tres lectores ciegos analizaron las imágenes.Resultados: Comparando el diagnóstico final, el análisis visual del protocolo de un día proporcionó mejores resultados con una sensibilidad del 95,5%, una especificidad del 93% y una precisión diagnóstica del 93,7% (p < 0,01) que el protocolo de dos días con valores del 86,4%, 94,7% y 92,4%, respectivamente (p < 0,01). Para el análisis semicuantitativo, el protocolo de un día también obtuvo mejores resultados con una sensibilidad del 72,7%, una especificidad del 78,9% y una precisión del 77,2% (p < 0,01) que el protocolo de dos días (sin resultados significativos; p = 0,14), especialmente en el grupo de pacientes con aparatos ortopédicos (sensibilidad del 100%, especificidad del 79,5% y precisión del 82,7%; p < 0,01)

Objective: As scarce literature on the topic is available, we aimed to compare diagnostic utility of semi-quantitative versus visual analysis in labelled white blood cell scintigraphy (WBCS) for osteoarticular infection. One-day and two-day protocols were assessed, particularly in orthopaedic devices.Material and methods: Prospective study of 79 consecutive patients with suspected osteoarticular infection. In all patients, WBCS were performed at 30min, 4h, 8h and 24h. Images were analysed by grouping in two protocols: one-day-protocol (experts evaluated 30min, 4h and 8h planar images) and two-day-protocol (experts evaluated 30min, 4h and 24h planar images). Planar images were interpreted qualitative and semiquantitatively and also were compared grouping patients with and without orthopaedic devices. To find which cut-off value of the percentage variation could predict of osteoarticular infection, multiple cut-off values were calculated in both protocols from the Youden index. Three blinded readers analysed the images.Results: Comparing final diagnosis visual analysis of the one-day-protocol provided better results with sensitivity of 95.5%, specificity of 93% and diagnostic accuracy of 93.7% (P<.01) than the two-day-protocol with values of 86.4%, 94.7% and 92.4%, respectively (P<.01). For semi-quantitative analysis, the one-day-protocol also obtained better results with sensitivity of 72.7%, specificity of 78.9% and accuracy of 77.2% (P<.01) than two-day-protocol (no significant results; P=.14), especially in the group of patients with orthopaedic devices (sensitivity of 100%, specificity of 79.5% and accuracy of 82.7%; P<.01).Conclusions: Most accurate approach in the diagnosis of osteoarticular infection corresponded to visual analysis in one-day-protocol that showed greater sensitivity and specificity than semi-quantitative analysis. Semi-quantitative analysis only could be useful when visual analysis is doubtful

Diagnostic methodology in labelled leukocyte scan for prosthetic / non-prosthetic osteoarticular infection: Visual or semi-quantitative analysis? One- or two-day protocol? / Metodología de la gammagrafía con leucocitos marcados en el diagnóstico de infección osteoarticular protésica/no protésica: ¿análisis visual o semicuantitativo? ¿Protocolo de uno o 2 días?

OBJECTIVE: As scarce literature on the topic is available, we aimed to compare diagnostic utility of semi-quantitative versus visual analysis in labelled white blood cell scintigraphy (WBCS) for osteoarticular infection. One-day and two-day protocols were assessed, particularly in orthopaedic devices. MATERIAL AND METHODS: Prospective study of 79 consecutive patients with suspected osteoarticular infection. In all patients, WBCS were performed at 30min, 4h, 8h and 24h. Images were analysed by grouping in two protocols: one-day-protocol (experts evaluated 30min, 4h and 8h planar images) and two-day-protocol (experts evaluated 30min, 4h and 24h planar images). Planar images were interpreted qualitative and semiquantitatively and also were compared grouping patients with and without orthopaedic devices. To find which cut-off value of the percentage variation could predict of osteoarticular infection, multiple cut-off values were calculated in both protocols from the Youden index. Three blinded readers analysed the images. RESULTS: Comparing final diagnosis visual analysis of the one-day-protocol provided better results with sensitivity of 95.5%, specificity of 93% and diagnostic accuracy of 93.7% (P<.01) than the two-day-protocol with values of 86.4%, 94.7% and 92.4%, respectively (P<.01). For semi-quantitative analysis, the one-day-protocol also obtained better results with sensitivity of 72.7%, specificity of 78.9% and accuracy of 77.2% (P<.01) than two-day-protocol (no significant results; P=.14), especially in the group of patients with orthopaedic devices (sensitivity of 100%, specificity of 79.5% and accuracy of 82.7%; P<.01). CONCLUSIONS: Most accurate approach in the diagnosis of osteoarticular infection corresponded to visual analysis in one-day-protocol that showed greater sensitivity and specificity than semi-quantitative analysis. Semi-quantitative analysis only could be useful when visual analysis is doubtful. In patients with joint prostheses, an increase in percentage variation above 9% obtained maximum sensitivity and negative predictive value.