Incidental enchondromas at knee magnetic resonance imaging: intraobserver and interobserver agreement and prevalence of imaging findings

Abstract

Objective: To evaluate intra-and interobserver agreement in the identification of incidental enchondromas at knee magnetic resonance imaging, and to assess the prevalence of imaging findings. Materials and Methods: Retrospective study reviewing 326 knee magnetic resonance images acquired in the period between November 2009 and September 2010. The images were independently and blindly analyzed by two specialists in musculoskeletal radiology, with the objective of identifying incidental enchondromas, presence of foci with signal similar to bone marrow and foci of signal absence suggestive of calcifications within the enchondromas. Inter-and intraobserver agreements were analyzed. Results: Eleven lesions compatible with enchondromas (3.3%) were identified. The interobserver agreement for the presence of enchondroma was high. Prevalence of foci of bone marrow signal inside the enchondromas was of 54.55%, and foci suggestive of calcification corresponded to 36.36%. The intraobserver agreement for foci of bone marrow signal in enchondromas was perfect, and interobserver agreement was high. Conclusion: The prevalence of incidental enchondromas in the current study was compatible with data in the literature. Excellent agreement was observed in the identification of enchondromas and in the assessment of imaging findings. A higher prevalence of fat signal foci was observed as compared with signal absence suggestive of calcifications. Keywords: Enchondromas; Magnetic resonance imaging; Knee; Bone marrow.Objetivo: Avaliar a confiabilidade intra e interobservador na identificação de encondromas incidentais na ressonância magnética de joelho e estudar a prevalência das características de imagens destas lesões. Materiais e Métodos: Estudo retrospectivo, com revisão de 326 ressonâncias magnéticas do joelho realizadas entre novembro de 2009 e setembro de 2010. As imagens foram analisadas por dois médicos especialistas em radiologia musculoesquelética, de forma independente e às cegas, visando a identificar encondromas incidentais, presença de focos com sinal semelhante à medula óssea e focos de ausência de sinal sugestivos de calcificações no interior dos encondromas. Foram realizadas análises das concordâncias inter e intraobservador. Resultados: Foram identificadas 11 lesões compatíveis com encondromas (3,3%). A concordância interobservador para presença de encondroma foi alta. A prevalência de focos de sinal de medula óssea no interior dos encondromas foi 54,55% e de focos sugestivos de calcificação foi 36,36%. A concordância intraobservador para focos de sinal de medula óssea nos encondromas foi perfeita, e a concordância interobservador foi alta. Conclusão: A prevalência de encondromas incidentais no trabalho atual foi consistente com a literatura. Foi observada excelente concordância no estudo de confiabilidade da identificação de encondromas e de suas características, notando-se maior prevalência de focos com sinal de gordura do que de calcificações. Unitermos: Encondromas; Ressonância magnética; Joelho; Medula óssea. Ab...

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