| Background and purpose:In recent years, the incidence of bone tumors and tumor-like lesions present an upward trend, seriously affecting the patient's quality of life and threatening the lives of patients. Hence, in order to prolong life and the treatment of cancer disease, early detection, early diagnosis and early treatment of are considered to be very important. As the bone tumor and tumor-like lesions of different materials in, take different tumor location, pathology results obtained may be different. Therefore, there is no doubt-that imaging examination of bone tumors and tumor-like lesions in the diagnosis and evaluation of its partial phases, observing tumor radiotherapy chemotherapy and postoperative areas were followed up with more superiority. With the further development of clinical studies, the new MRI imaging technology and MRI molecular imaging are continuously introduced to musculoskeletal system disease research. As studies of bone tumors on the high field magnetic resonance in the country is less purpose of, this study is to analyze bone tumors and tumor-like lesions in plain MRI, dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)and diffusion weighted imaging(DWI) to explore the clinical diagnosis and differential diagnosis of them. Materials and methods:61 cases were selected from December 2008 to January 2010 in the First Affiliated Hospital of Zhengzhou University, which had integrated clinical data of the treatment of bone tumors and tumor-like lesions, in addition to a few bone metastases check before the primary lesions conformed by pathology (primary tumor confirmed by surgical pathology or puncture cytology) of 7 patients of bone metastases, all cases were not carried out MR biopsy, radiation therapy, interventional therapy and systemic chemotherapy drugs and other intervention measures before the examination, and after the MRI examination do surgical resection or biopsy pathology in one week.37 males and 24 females, with the mean age was 37.69±2.6 years (range 9 to 78 years). Initial symptoms are mainly local pain, a total number of 61 cases include 23 cases of benign tumors and tumor-like lesions and 38 cases of malignant bone tumors.With using Siemens Magnetom Trio Tim 3.0T MRI, the first step was MRI plain scan, and then turned to DWI scan and DCE-MRI by successively setting many different b values, and finally conventional contrast-enhanced MRI scan should be done after the dynamic contrast-enhanced MRI scan. Contrast agent Magnevist (Gd-DTPA), dose O.lmmol/kg, injection speed of 3.0ml/s; collected one phase image as the original chips before injection, then began to start injection while scanning and collecting images of 18 phases in all. Choosing 5 different sensitivity of the diffusion coefficient (b value) of DWI, respectively 0s/mm2,400s/mm2,800s/mm2, 1000s/mm2, 1500s/mm2, and the corresponding apparent diffusion coefficient (ADC) map was received, at the same time select interesting regions to calculate the ADC values(10-3 mm2/s)which the adjacent normal muscle, bone marrow of the ADC value can be as a reference. The use of Mean Curve analysis software which is equipped with dynamic contrast-enhanced workstation can directly receive the Time-signal intensity curve (TIC) of the lesion parenchyma, adjacent muscles and the same level of arteries, measurement of indicators such as TIC type, Slope and Rrim-center. Statistical analysis was analyzed by SPSS 13.0 version for windows statistical analysis software, all the statistical results was presented as mean values plus or minus standard deviation (x±sd). Statistical results of each group with P<0.05 indicated that the difference was statistically significant.Results:(1)Compared with 61 morphological benign and malignant bone tumors as follows, among 23 cases of benign lesions and 38 cases of malignant bone tumors, the shape of the edge and boundary definition between benign and malignant lesions were both of statistically significance, the signal uniformity within lesions and the availability of bone marrow edema around lesions was not statistically significant. (2) In the matter of strengthening extent, malignant bone tumors are different degree of strengthening, while 3 cases of benign bone tumors and tumor-like lesions are no enhancement, so benign and malignant lesions with regard to the degree of enhancement were different. (3) When it come to TIC type, among 23 benign bone tumors and tumor-like lesions,0 cases of TIC is type I,7 cases is typeⅡ, accounting for 30.4%,13 cases is typeⅢ, accounting for 56.5%,3 cases were typeⅣ, accounting for 13.0%; among 38 cases of malignant bone tumors,11 cases of TIC were type I, accounting for 28.9%,17 cases of TIC were typeⅡ, accounting for 44.7%,10 cases were of typeⅢ, accounting for 26.4%,0 cases were typeⅣ; TIC types of distribution of benign and malignant bone tumors is significantly different; I,Ⅱ-type curve of time-signal intensity curve were defined as malignant diagnostic criteria, and the sensitivity of diagnosis of malignant tumors reached 73.68%, specificity of 69.57%, accuracy of 72.13%, positive predicted value of 80%, negative predicted value of 61.54%. (4)With regard to comparison of dynamic enhancement parameters, Slope of benign bone tumor is 4.67±2.36%/s and Rrim-center is 0.39±0.22, while Slope of malignant bone tumor is 10.72±9.57%/s, and Rrim-center is 0.63±0.27, so dynamic contrast-enhanced parameters of the bone tumors and tumor-like lesions between benign and malignant were of significant statistical differences. (5)None of lesions in this group showed low signal of DWI, on the contrary manifested high signal, thus difference of the DWI signal between benign and malignant bone tumor was not significant. (6)When taking b values were 400,800,1000 and 1500s/mm2 respectively, the ADC values of parenchyma lesion of benign bone tumors and tumor-like lesions were higher than those of malignant bone tumor, while the malignant bone tumor are much larger than the those of normal bone marrow; moreover the ADC value and b value is a negative correlation,which is between parenchyma of the benign and malignant bone tumors and tumor-like lesions and adjacent normal the bone marrow, that is, as the b value increased, ADC value decreased. Benign and malignant bone tumors and tumor-like lesions and normal parenchyma adjacent to the bone marrow of the ADC value and b value is a negative correlation, that is, as the b value increased, ADC values decrease; when b= 400,800,1000s/mm2, the ADC values between benign and malignant bone tumors were of significant differences; when b=1500s/mm2, the ADC values between benign and malignant bone tumors showed no significant differences; when b =800s/mm2, in addition to the ADC values between the two groups of lesions showed statistically significant, ADC images were clearer and the measured ADC values were steady. According to the axes point of ROC curve we can see when different b values under the C values were 1.124×10-3mm2/s (b= 400s/mm2),1.000×10-3mm2/s (b= 800s/mm2),0.907×10-3mm2/s (b= 1000 s/mm2), and 0.690×10-3mm2/s (b= 1500 s/mm2), the sensitivity and specificity of diagnosis respectively was 60.9% and 60.5%; 69.6% and 65.8%; 69.6% and 60.5%; 60.9% and 57.9%.Conclusions:(1)There were differences between malignant and benign bone tumors as well as tumor-like lesions, acorroding to their ill or well defined margins and characteristic boundaries on precontrast MRI study. However, homogeneous or heterogeneous signal intensities within the lesion as well as peritumoral bone marrow edema showed no differential value between those lesions. (2)Bone malignities usually showed prominent enhancement, while there were only mild enhancement for benign bone lesions. On postcontast MRI study. A malignant bone tumor could be excluded if there was no enhancement at all. (3)The distribution of the type of TIC between the malignant and benign lesions was of signifcantly different. (4)The dynamic contrast-enhanced parameters between malignant and benign bone lesions were of significant different statistically. Thus it might be helpful for the differentiation between these lesions. (5)DWI had proved to be a sensitive method to show lesions of malignant and benign bone tumor, but was lacked in specificity. (6)ADC value was useful for distinguish malignant and benign tumors, So it was recommend that b =800s/mm2 to be the proper b value for the differential diagnosis of bone tumors.
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