The Value Of MRI Intravoxel Incoherent Motion Imaging(IVIM) And Diffusion Kurtosis Imaging(DKI) In The Differential Diagnosis Of Benign And Malignant Bone And Soft Tissue Tumors Of Lower Extremity

Objective: To evaluate the value of magnetic resonance intravoxel incoherent motion(IVIM)and diffusion kurtosis imaging in the differential diagnosis of benign and malignant bone and soft tissue tumors of lower extremity.Methods: We collected 54 patients who did lower extremity MRI examination found bone or soft tissue masses in the radiology department of our hospital in November 2016 to October 017.All patients underwent IVIM scan with 14 b values(0、10、20、30、40、50、75、100、150、200、400、800、1000、1500s/mm2)and DKI scan with 5 b values(0、100、700、1400、2100 s/mm2)and routine MRI examination with a 3T MR scanner.IVIM and DKI parameters including ADC,D,D*,f,MK,MD values were measured at a workstation.Patients were divided into benign and malignant bone and soft tissue tumors according to pathological results.Independent two-samples t test was used to evaluate those parameters in differentiating benign and malignant bone and soft tissue tumors.ROC curves were used to evaluate the diagnostic performance of these parameters.Logistic analysis was used to evaluate the diagnostic performance when combinating the parameters of IVIM and DKI.Results: The ADC(1.23±0.27×10-3 mm2/s)、D(1.12±0.22×10-3 mm2/s)、MD(1.26±0.46×10-3 mm2/s)values of malignant bone tumors were statistically lower than that of benign bone tumors(1.95±0.39×10-3 mm2/s)、(1.78±0.42×10-3 mm2/s)、(1.91±0.53×10-3 mm2/s)(P﹤0.05).The f value of malignant tumors(10.0%±3.98%)was statistically higher than that of benign tumors(3.43%±2.99%)(P﹤0.05).The MK value(0.76±0.45×10-3 mm2/s)was statistically higher than that of benign tumors(0.36±0.22×10-3 mm2/s),(P﹤0.05).There were no significant difference between D* value of benign and malignant tumors(P>0.05).The area under the ROC curves of ADC、D、f、D*、MK、MD were 0.935、0.939、0.891、0.701、0.840、0.844.When the optimal threshold of ADC,D,MK and MD was 1.64×10-3 mm2/s、1.45×10-3 mm2/s、0.56×10-3 mm2/s、1.86×10-3 mm2/s,the corresponding diagnostic sensitivity and specificity were 85.7%,95.2%;85.7%,95.2%;71.4%,100%;71.4%,95.2%.Similiarly,The ADC(1.27±0.38×10-3 mm2/s)、D(1.04±0.35×10-3 mm2/s)、MD(1.53±0.55×10-3 mm2/s)values of malignant soft tissue tumors were statistically lower han that of benign soft tissue tumors(1.90±0.43×10-3 mm2/s)、(1.71±0.45×10-3 mm2/s)、(2.24±0.60×10-3 mm2/s)(P﹤0.05).The f value of malignant tumors(8.20%±3.84%)was lower than that of benign tumors(9.62%±4.47%)(P>0.05).The MK value(0.82±0.56×10-3 mm2/s)was statistically higher than that of benign tumors(0.45±0.97×10-3 mm2/s)(P<0.05).There were no significant difference between D* value of benign and malignant tumors(P>0.05).The area under the ROC curves of ADC、D、f、D*、MK、MD were 0.876、0.885、0.633、0.552、0.894、0.812.When the optimal threshold of ADC,D,MK and MD was 1.33×10-3 mm2/s、1.42×10-3 mm2/s、0.60×10-3 mm2/s、1.71×10-3 mm2/s,the corresponding diagnostic sensitivity and specificity were 100%,60%;72.7%,93.3%;60.0%,100%;90.9%,66.7%.Conclusion: IVIM parameters ADC,D and DKI parameters MK,MD can help to distinguish benign and malignant bone and soft tissue tumors of lower extremity.The combination of parameters of IVIM and DKI can improve the accuracy of the diagnosis of lower extremity tumors.