Comparative Study In Soft Tissues Changes Of Osteomyelitis And Malignant Bone Tumor

Objective To evaluate the diagnostic value of soft tissues changes in differentiation between osteomyelitis and malignant bone tumor. Methods The CT and (or) MRI findings of soft tissues changes in 57 cases of osteomyelitis and 70 cases of malignant bone tumor were observed. Criteria for diagnosis: (1) soft-tissue swelling: intermuscular space swelling demonstrate ill-defined intermuscular planes on CT, and string-like intermediate signal intensity on MR T1-weighted images and high signal intensity on MR T2-weighted images. Subcutaneous soft tissues swelling demonstrate reticulated soft-tissue density in thickened subcutaneous fat on CT, intermediate signal intensity on MR Tl-weighted images and high signal intensity on T2-weighted images; muscles swelling demonstrate low density or high-signal-intensity patchy area in muscles, or a piece of muscle enlarged with density decreased on CT and signal intensity increased on T2-weighted images . According to the statistical results, we divided soft swelling into four degrees. We defined a piece of muscle, a single intermuscular space, a piece of bone or subcutaneous tissues as a tissue unit. And draw a line from the most distant Soft-tissue swelling to the center of the bone, and according to the number of tissue units between two points, we defined: no swelling in soft tissue is 0 degree; swelling located in tissue units proximated bone lesions belongs to I degree; swelling located in 2 pieces of proximated units is II degree; and swelling distant to 2 pieces of proximated units belongs to III degree.(2) soft-tissue abscesses: demonstrate a well-demarcated low-attenuation fluid collection surrounded by a contrast material-enhancing rim on CT examination; for MR imaging were focal, well-defined fluid collections within soft tissue with high signal intensity similar to that of water on Tl and T2-weithted images.(3)gas in soft tissues: round-like or ellipse-like lowdensity on CT and low signal intensity on every MR sequence.(4)fat-fluid level: fat-liked density and signal intensity above the level, and water or soft tissue-liked density and signal intensity below the level.(5)sinus tract: string or canal-like soft tissue density from cortical bone to skin surface on CT. (6) soft-tissue masses: abut against bone leision, homogeneous or unhomogeneous density and signal intensity, well-demarcated boundary on T2-weighted images.(7)bone shell or shell-liked calcification in the rim of soft-tissue masses: arc-liked high density lied in the rim of soft-tissue masses , concave surface face to the bone leisions. (8)neoplastic bone or neoplastic calcified cartilage: the former demonstrate ill-defined patched, radial or conglomeratic high density area in CT; the latter demonstrate spotty or circled high density in CT. (9) unidentified calcification or ossification in soft tissues: spotty, irregular block high density in extraskeletal soft tissue, soft-tissue masses center or rim on CT images. Results Soft-tissue swelling degree, soft-tissue abscesses, fat-fluid level, soft-tissue masses, bone shell or shell-liked calcification in the rim of soft tissue masses, and neoplastic bone or neoplastic calcified cartilage were significantly different(p<0.05) between osteomyelitis group and malignant bone tumor group on CT examination. Soft-tissue abscesses, fat-fluid level and soft tissue masses were significantly different (p<0.05) between osteomyelitis group and malignant bone tumor group on MR examination. Conclusion Our research indicated that presence of different swelling degree in soft tissues, soft-tissue abscesses, fat-fluid level, soft-tissue masses, bone shell or shell-liked calcification in the rim of soft tissue masses, neoplastic bone or neoplastic and calcified cartilage were important characteristics for differentiating osteomyelitis and malignant bone tumor.