Diagnostic performance of magnetic resonance imaging in the assessment of periosteal reactions in bone sarcomas using conventional radiography as the reference

Sa Neto JL, Simao MN, Crema MD, Engel EE, Nogueira-Barbosa MH. Diagnostic performance of magnetic resonance imaging in the assessment ofperiosteal reactions in bone sarcomas using conventional radiography as the reference. Radiol Bras. 2017 Mai/Jun;50(3):176–181.AbstractResumoObjective: To evaluate the performance of magnetic resonance imaging (MRI) in detecting periosteal reactions and to compare MRI andconventional radiography (CR) in terms of the classification of periosteal reactions.Materials and Methods: Retrospective study of 42 consecutive patients (mean age, 22 years; 20 men) with a confirmed diagnosis ofosteosarcoma or Ewing’s sarcoma, MRI and CR images having been acquired pretreatment. Three blinded radiologists detected peri-osteal reactions and evaluated each periosteal reaction subtype in CR and MRI images: Codman’s triangle; laminated; and spicula ted.The CR was used as a benchmark to calculate the diagnostic performance. We used the kappa coefficient to assess interobserverreproducibility. A two-tailed Fisher’s exact test was used in order to assess contingency between CR and MRI classifications.Results: In the detection of periosteal reactions, MRI showed high specificity, a high negative predictive value, and low-to-moderatesensitivity. For CR and for MRI, the interobserver agreement for periosteal reaction was almost perfect, whereas, for the class ification ofdifferent subtypes of periosteal reaction, it was higher for the Codman’s triangle subtype and lower for the spiculated subtype . There wasno significant difference between MRI and CR in terms of the classifications ( p < 0.05).Conclusion: We found no difference between MRI and CR in terms of their ability to classify periosteal reactions. MRI showed highspecificity and almost perfect interobserver agreement for the detection of periosteal reactions. The interobserver agreement w as variablefor the different subtypes of periosteal reaction.Keywords: Periosteum; Osteosarcoma; Sarcoma, Ewing; Magnetic resonance imaging; Radiography; Reproducibility of results.Objetivo: Avaliar o desempenho da ressonância magnetica (RM) na deteccao de reacao periosteal e comparar a classificacao depresenca ou ausencia de reacoes periosteais entre a RM e a radiografia convencional (RC).Materiais e Metodos: Estudo retrospectivo incluindo 42 pacientes consecutivos (idade media, 22 anos; 20 homens) com diagnosticoconfirmado de osteossarcoma ou sarcoma de Ewing, tendo exames de RM e RC adquiridos pre-tratamento. Tres radiologistas avaliara mas cegas a presenca ou ausencia de reacao periosteal e de cada subtipo de reacao periosteal nas imagens de RC e RM: triângulo d eCodman, multilamelada e espiculada. A RC foi usada como padrao de referencia para calculo do desempenho diagnostico. Foi utiliz adoo coeficiente kappa para reprodutibilidade interobservador. Adicionalmente, foi realizado teste exato de Fisher bicaudal para a valiar sehouve diferenca significativa entre as leituras da RC e RM.Resultados: A RM mostrou alta especificidade, alto valor preditivo negativo e baixa sensibilidade na deteccao de reacao periosteal. Aconcordância interobservador para a reacao periosteal foi quase perfeita para a RC e RM. A concordância interobservador para a clas-sificacao dos diferentes subtipos de reacao periosteal foi maior para o subtipo triângulo de Codman e menor para o subtipo espi culada.Nao houve diferenca na deteccao por RM e RC ( p < 0,05).Conclusao: Nao houve diferenca significativa entre as classificacoes da presenca ou ausencia de reacoes periosteais entre os metodosRC e RM. A RM apresentou alta especificidade e concordância interobservador quase perfeita para a deteccao de reacao periosteal . Aconcordância interobservador para os diferentes subtipos de reacao periosteal foi variavel.Unitermos: Periosteo; Osteossarcoma; Sarcoma de Ewing; Ressonância magnetica; Radiografia convencional; Reprodutibilidade.