3.0T磁共振动态对比增强与弥散加权成像对肌骨肿瘤鉴别诊断的价值

Value of 3T Magnetic Resonance Dynamic Contrast-enhanced and Diffusion-weighted Imaging in Differential Diagnosis of Musculoskeletal Tumors

目的评价磁共振动态对比增强时间-信号强度曲线类型、动态强化参数及弥散加权成像对肌骨肿瘤良恶性鉴别诊断的价值。方法应用GE Signa Excite 3.0 T MR机对63例病理证实肌骨肿瘤同时进行弥散加权成像及动态对比增强。应用单次激发平面回波序列,b值分别为400、600、800和1000 s/mm2,获得平均表观扩散系数值,b=600 s/mm2时在动态对比增强前后,应用相同条件分别进行弥散加权成像。采用三维快速采集多相位增强快速扰相梯度回波序列,对整个肿瘤进行多层面动态增强扫描,得到时间-信号强度曲线(TIC)及强化参数最大上升斜率(MSI)、正性增强积分、信号增强比率及峰值时间(Tpeak)。结果 b值分别为400、600、800和1000 s/mm2时,良恶性肿瘤的平均表观弥散系数值无统计学意义。与正常肌肉比较病灶多呈灯泡样高信号,但良恶性肿瘤之间的弥散加权成像信号比较无统计学意义。b=600 s/mm2时,动态增强前后的表现弥散系数值在良恶性肿瘤间差异无统计学意义。TIC分为4型:Ⅰ型为快升快降型;Ⅱ型快升平坦型;Ⅲ型慢升型;Ⅳ型平坦型。Ⅰ型和Ⅱ型曲线多见于恶性肿瘤(41/47),Ⅲ型和Ⅳ型多见于良性肿瘤(14/38),曲线类型在良恶性肿瘤间差异具有统计学意义(χ2=17.009,P=0.001),以Ⅰ、Ⅱ型为恶性标准,诊断恶性肿瘤的敏感性为87.23%,特异性为50.00%。MSI(F=5.38,P=0.005)及Tpeak(F=6.15,P=0.001)在良恶性肿瘤间差异具有统计学意义,而正性增强积分及信号增强比率差异无统计学意义。以MSI 366.62±174.84为标准,诊断恶性肿瘤的敏感性和特异性分别为86.78%和78.67%;Tpeak≤70s为标准,诊断恶性肿瘤的敏感性和特异性分别为82.89%和85.78%。结论磁共振动态对比增强TIC、MSI、Tpeak均有利于肌骨系统良恶性肿瘤的鉴别诊断,Tpeak诊断恶性肿瘤的特异性最高,TIC的敏感性最高。平均表现弥散系数值不能用于肌骨系统良恶性肿瘤的鉴别诊断。

Objective To evaluate the value of magnetic resonance dynamic contrast-enhanced（MR-DCE） and magnetic resonance diffusion-weighted imaging（MR-DWI） in the differentiation of benign and malignant musculoskeletal tumors.Methods Sixty-three patients with pathologically confirmed musculoskeletal tumors were examined with MR-DCE and MR-DWI.Using single shot spin echo planar imaging sequence and different b values of 400,600,800 and 1000 s/mm2,we obtained the apparent diffusion coefficient（ADC） of the lesions.ADC values were measured before and after MR-DCE,with a b value of 600 s/mm2.The 3D fast acquired multiple phase enhanced fast spoiled gradient recalled echo sequence was obtained for multi-slice of the entire lesion.The time-signal intensity curve（TIC）,dynamic contrast-enhanced parameters,maximum slope of increase（MSI）,positive enhancement integral,signal enhancement ratio,and time to peak（Tpeak） were also recorded.Results ADC showed no significant difference between benign and malignant tumors when the b value was 400,600,800,or 1000 s/mm2,and it was not significantly different between benign and malignant tumors in both pre-MR-DCE and post-MR-DCE with b value of 600 s/mm2.TIC were classified into four types： typeⅠshowed rapid progression and gradual drainage;typeⅡshowed rapid progression but had no or slight progression;type Ⅲshowed gradual progression;and type Ⅳ had no or slight progression.Most lesions of typeⅠor typeⅡ were malignant,whereas most lesions of type Ⅲ or type Ⅳ were benign.When using typeⅠand type Ⅱ as the standards of malignancy,the diagnostic sensitivity and specificity was 87.23% and 50.00%,respectively.The types of TIC showed significant difference between benign and malignant musculoskeletal tumors（χ2=17.009,P=0.001）.When using MSI 366.62±174.84 as the standard of malignancy,the diagnostic sensitivity and specificity was 86.78% and 78.67%,respectively.When using Tpeak≤70s as the standard of malignancy,the diagnostic sensitivity and specificity was 82.89%and 85.78%,respectively.Positive enhancement integral and signal enhancement ratio showed no significant difference between benign and malignant musculoskeletal tumors.Conclusions TIC,MSI and Tpeak of MR-DCE are valuable in differentiating benign from malignant musculoskeletal tumors.Tpeak has the highest diagnostic specificity,and TIC has the highest diagnostic sensitivity.The mean ADC value are no significant difference between benign and malignant tumors.