软组织肿瘤的MR灌注成像与MR波谱成像的比较研究

目的 通过分析软组织肿瘤同一病例相同感兴趣区的MR灌注加权成像(MR-PWI)及MR氢质子波谱(1H-MRS)的功能影像信息,比较两者用于软组织肿瘤的定性诊断价值.方法 研究同时行MR-PWI、1H-MRS的全身各部位软组织肿瘤共40例.比较MR-PWI及1H-MRS各参数在良、恶性肿瘤中的差异,进而对2种诊断方法进行评价.所获数据采用t检验或配对四格表确切概率法分析.结果 MR-PWI良、恶性软组织肿瘤的血流量(BF)值差异有统计学意义(t=2.531,P<0.05),血容量(BV)及平均通过时间(MTT)值差异均无统计学意义(t值分别为1.587和1.732,P值均>0.05);以BF值=4.35 ml·100 mg-1·min-1为阈值,MR-PWI诊断恶性肿瘤的敏感度为81.8%(18/22),特异度为72.2%(13/18).良、恶性软组织肿瘤的时间信号曲线(TIC)类型比较:Ⅰ a型在良性肿瘤中占3/18,在恶性肿瘤中占17/22;Ⅰ b型在良性肿瘤中占12/18,在恶性肿瘤中占3/22;Ⅰ c型在恶性肿瘤中占2/22.Ⅱ型在良性肿瘤中占3/18.良、恶性软组织肿瘤的胆碱(Cho)、肌酸复合物(Cr)、脂质(Lip)值差异均无统计学意义(t值分别为1.332、1.637、1.986,P值均>0.05),而Cho/Cr比值的差异有统计学意义(t=2.927,P<0.05);以Cho/Cr比值=3.22为阈值,1H-MRS诊断恶性肿瘤的敏感度为86.4%(19/22),特异度为88.9%(16/18).1H-MRS谱线比较:18例良性及17例恶性软组织肿瘤在2.0～2.1ppm(×10-6)处均未出现异常峰,而2例恶性神经鞘瘤和3例恶性纤维组织细胞瘤均在2.0～2.1ppm处出现异常峰.MR-DWI与1H-MRS用于恶性肿瘤诊断准确度的差异无统计学意义(X2=0.125,P>0.05).结论 软组织肿瘤的MR-PWI的BF值、1H-MRS的Cho/Cr比值有利于软组织肿瘤良、恶性的鉴别;软组织肿瘤的TIC形态有助于肿瘤良、恶性的鉴别.MR-PWI和1H-MRS两者用于诊断恶性软组织肿瘤的准确度无明显差异,1H-MRS诊断恶性软组织肿瘤的敏感度和特异度较高.

The comparative study of MR perfusion-weighted imaging and 1 H-MR spectroscopy in diagnosing soft tissue tumors

Objective To evaluate multiple magnetic resonance (MR) imaging techniques in the differentiation of benign and malignant soft tissue tumors by comparing different information from MR perfusion-weighted Imaging (MR-PWI) and 1 HMR spectroscopy (1 H-MRS).Methods Forty patients with soft tissue tumors underwent conventional MR imaging,dynamic contrast-enhanced T2*-weighted MR-PWI and 1 H proton MR spectroscopy.The differences of perfusion and 1 H-MRS parameters of benign and malignant tumors were analyzed with t test.Results There was significant difference between benign and malignant tumoral tissues of BF value and Cho/Cr ratio(t=2.531,2.927,P < 0.05),while BV,MTT,Cho,Cr or Lip peak value were not.TIC was different between benign group (Ib) and malignant group (Ia).When the threshold value of BF was 4.35 ml ·100 mg-1·min-1,sensitivity and specificity for determining malignant tumors were 81.8%(18/22),72.2%(13/18),respectively.When the threshold value of Cho/Cr ratio was 3.22,Sensitivity and specificity for determining malignant tumors were 86.4% (19/22),88.9% (16/18),respectively.The abnormal wave crest is detected at 2.0-2.1ppm in 5 malignant tumors (2 malignant schwannoma and 3 malignant fibrous histiocytoma),while the other 35 cases were not.Conclusion The BF value and Cho/Cr ratio were both valuable diagnostic parameters in differentiating benign and malignant soft tissue tumors.TIC was helpful to distinguish malignant tumors from benign tumors,while the sensitivity and specificity of 1 H-MRS in diagnosing malignant soft tissue tumors were both higher.