高场多b值DWI在骨肿瘤定性诊断中的价值

Value of high-field MRI intravoxel incoherent motion technique in differential diagnosis of bone neoplasms

目的探讨高磁场强度下多b值扩散加权成像结合双指数模型在骨肿瘤定性诊断中的价值。方法对北京大学首钢医院骨肿瘤科的76例患者行常规MRI及多b值(0、50、100、150、200、400、600、800、1 000、1 500、2 000 s/mm2)扩散加权成像检查。利用基于体素内不相干运动(intravoxel incoherent motion,IVIM)理论的双指数模型计算快速表观弥散系数(fast ADC,ADCfast)、慢速表观弥散系数(slow ADC,ADCslow)和灌注相关体积分数(perfusion fraction,f),利用单指数模型计算标准表观弥散系数(Standard ADC,ADCtot)。根据病理结果,将病变分为良性(17例)、中间型(25例)及恶性(34例),以患者自身正常骨髓作为对照,并对3组肿瘤之间以及肿瘤与对照组之间ADCtot、ADCfast、ADCslow及f值的差异进行统计学分析。结果良性骨肿瘤的b值-信号强度曲线斜率高于恶性骨肿瘤。4组ADCslow值组间比较差异均有统计学意义(P<0.05),恶性组ADCslow值明显低于良性组和中间型组,对照组ADCslow值最小,明显低于其余3组(P<0.05);各组ADCfast值均大于ADCslow值,且各组ADCfast组间比较,仅恶性组与对照组差异有统计学意义,即前者明显大于后者(P<0.05);良性组f值明显小于恶性组和对照组(P<0.05);4组ADCtot值均大于相应各组ADCslow值,各组间比较差异均无统计学意义(P>0.05),但恶性组排除脊索瘤患者后,良性组ADCtot值明显高于恶性组(P<0.05)。结论 Mb-DWI可作为MRI检查的有益补充对骨肿瘤不同性质病变进行定性诊断,ADCslow有助于区分良性、中间性和恶性肿瘤,提高骨肿瘤的诊断准确性。

Objective To investigate the differential diagnosis of benign and malignant bone neoplasms using multiple b-values and biexponential attenuation model diffusion-weighted imaging(DWI)in high-f ield MRI.Methods Seventy-six patients with pathology-proven pr imary bone neoplasms underwent multiple b-values and biexponential at tenuation model diffusion-weighted imaging(b values of 0, 50, 100, 150, 200, 400, 600, 800, 1 000, 1 500, 2 000 s/mm2),including 17 benign lesions, 25 junction lesions and 34 malignant lesions.The parameters of the double exponential model included ADCfast, ADCslow, f and ADCtot. With the patients’ own normal bone marrow as the control, the ADCfast, ADCslow, f and ADCtot were compared between the three groups of lesions and between the lesion group and control group before they were analyzed statistically. Single factor analysis of variance was used for statistical analysis. Results The b value-signal intensity curve slope of benign lesions was higher than that of malignant ones. There were significant differences in ADCslow values between the four groups(P<0.05).The ADCslow of malignant lesions was significantly lower than those of benign lesions, junction lesions and the control group(P<0.05).The ADCfast of the four groups was all larger than the ADCslow. The ADCfast of m alignant lesions was significantly higher than that of the control group(P<0.05). The f of benign lesions was significantly lower than that of malignant ones and the control group(P<0.05). The ADCtot of the four groups was all larger than the ADCslow, but there was no statistically signif icant difference between the four groups(P>0.05). However, after chordoma patients were excluded from the malignant lesion group, the ADCtot of benign lesions was signif icantly higher than that of malignant lesions(P<0.05). Conclusion The parameters of IVIM can help differentiate benign tumors from borderline ones or malignant ones in the musculoskeletal system,which can improve the accuracy of diagnosis of bone neoplasms.