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目的研究氢质子磁共振波谱(protonmagnetic resonance spectroscopy,lH-MRS)和弥散张量成像(diffusion tensor imaging,DTI)对颅内良、恶性肿瘤鉴别诊断的价值。方法经病理证实的颅内肿瘤33例,其中包括脑膜瘤10例,听神经瘤4例,血管母细胞瘤1例,混合性胶质神经元肿瘤1例,胶质瘤11例,转移瘤5例,原始神经外胚层肿瘤1例。根据病理结果,将颅内肿瘤分为良性组(19例)和恶性组(14例)进行观察分析。所有患者均进行常规MRI和DTI扫描,22例行lH-MRS分析。lH-MRS感兴趣区包括肿瘤组织和瘤周组织,分别观察各个区域的胆碱(choline,Cho)、N-乙酰天冬氨酸(N-acetyla spartate,NAA)、肌酸(creatine,Cr)、脂质(lipid,Lip)和乳酸(lactate,Lac)峰,并比较Cho/NAA、Cho/Cr、NAA/Cr值和Lip、Lac峰值。测量肿瘤实质区、坏死囊变区、周边水肿区、水肿周边正常白质区和对侧白质区感兴趣区的平均弥散系数(meandiffusivity,MD)、各向异性(fractionalanisotropy,FA)值。结果良、恶性肿瘤在1H-MRS代谢图上都表现为Cho峰升高、NAA峰降低,良性肿瘤实质区Cho/NAA和Cho/Cr值均显著低于恶性肿瘤,差异具有统计学意义(P<0.01)。虽然良性肿瘤NAA/Cr值高于恶性肿瘤组,但差异无统计学意义(P>0.05)。13例良性肿瘤中8例检测到Lac峰,2例检测到低Lip峰。9例恶性肿瘤中7例检测到Lac峰,5例检测到Lip峰;良性肿瘤实质部分和瘤周正常白质区FA值明显高于恶性肿瘤,且差异具有统计学意义(P<0.05),而2组肿瘤间坏死囊变部分和瘤周水肿区FA值比较无显著差异(P>0.05)。良性肿瘤水肿周边正常白质区FA值明显高于对侧相应部位脑白质,且有统计学差异(P<0.05);恶性肿瘤水肿周边白质FA值虽低于对侧脑白质,但差异不显著(P>0.05);MD值在良性肿瘤实质部分显著高于恶性肿瘤(P<0.05),但在坏死囊变区、水肿区和周边正常白质区差异均无统计学意义(P>0.05);肿瘤实质部分MD值和FA值均与Cho/Cr呈线性负相关。结论1H-MRS能无创地分析颅内肿瘤代谢信息,Cho/NAA和Cho/Cr有助于肿瘤良、恶性的鉴别;Cho/Cr与MD、FA值呈负性相关,Cho/NAA与Cho/Cr值和FA、MD值可以有效的鉴别颅内良、恶性肿瘤。
Objective To study the value of proton magnetic resonance spectroscopy (1H-MRS) and diffusion tensor imaging (DTI) in differential diagnosis of intracranial benign and malignant tumors. Methods Totally 33 intracranial tumors were confirmed by pathology. Among them, 10 were meningioma, 4 acoustic neuroma, 1 hemangioblastoma, 1 mixed glial neuron tumor, 11 glioma and 5 metastatic tumor , 1 case of primitive neuroectodermal tumor. According to the pathological results, the intracranial tumors were divided into benign group (19 cases) and malignant group (14 cases). All patients underwent routine MRI and DTI scan, 22 cases of lH-MRS analysis. The region of interest of the H-MRS included tumor tissues and peritumoral tissues. Choline (Cho), N-acetyla spartate (NAA), creatine (Cr) Lipid and Lac, and Cho / NAA, Cho / Cr, NAA / Cr and Lip, Lac were compared. The mean diffusion coefficient (meandiffusivity, MD) and fractionalanisotropy (FA) of tumor area, necrotic area, peripheral edema area, edematous normal white matter area and contralateral white matter area of interest were measured. Results Both the Cho peak and the NAA peak of the benign and malignant tumors were significantly lower than that of the malignant tumors in 1H-MRS metabolites (P <0.05). The difference was statistically significant (P <0.01). Although the NAA / Cr value of benign tumor was higher than that of malignant tumor group, the difference was not statistically significant (P> 0.05). Of the 13 benign tumors, Lac peak was detected in 8 cases and low Lip peak was detected in 2 cases. Among 9 malignant tumors, Lac peak was detected in 7 cases and Lip peak was detected in 5 cases. The FA value in the parenchyma and peritumoral normal white matter of benign tumor was significantly higher than that of malignant tumor (P <0.05), while the difference was statistically significant There was no significant difference in FA between the cystic necrosis of 2 groups and the peritumoral edema (P> 0.05). The FA value of normal white matter around benign tumor edema was significantly higher than that of the corresponding contralateral white matter (P <0.05), while the FA values of white matter surrounding malignant tumor edema were lower than contralateral white matter, but the difference was not significant (P> 0.05). The MD value in the parenchyma of benign tumor was significantly higher than that in malignant tumor (P <0.05), but there was no significant difference in necrotic area, edema area and surrounding normal white matter area (P> 0.05) The substantial part of MD and FA values were negatively correlated with Cho / Cr. Conclusions 1H-MRS can non-invasively analyze intracranial tumor metabolic information. Cho / NAA and Cho / Cr can be helpful in differentiating benign and malignant tumors. Cho / Cr has negative correlation with MD and FA, Cr value and FA, MD value can effectively identify intracranial benign and malignant tumors.