【作者】 王丽君；

【导师】 徐克；

【作者基本信息】 中国医科大学 ， 影像医学与核医学， 2008， 博士

【摘要】 前言脑胶质瘤是脑内最常见的原发肿瘤,不同级别的胶质瘤的临床病程和治疗手段各异。胶质瘤中星形细胞瘤占大多数,少枝胶质细胞瘤是次之常见的胶质瘤,且与同级别星形细胞瘤相比临床症状轻,生存期长,对放疗或化疗非常敏感。因此术前明确胶质瘤病理级别和组织学类型对患者的治疗和预后判断非常重要。病理组织学细胞形态改变是胶质瘤分级诊断的金标准,可是组织标本需要有创的活检或手术获得,而且采样的误差常不能准确判断肿瘤的恶性度,如何准确判断肿瘤的侵袭能力是临床医生面临的难题。传统MR检查在脑肿瘤的形态显示方面发挥了重要价值,近年来MR功能成像的应用使脑胶质瘤的诊断上升到微观水平,达到形态与生理生化等功能并重,并能在一定程度上进行量化分析,是传统MR检查的必要补充。本研究的创新之处在于从人体脑胶质瘤的代谢改变入手,使用磁共振波谱成像（MRS）中最常用的代谢物比值测量方法应用于星形细胞瘤与含少枝细胞的胶质细胞瘤的鉴别诊断及对胶质瘤的不同强化程度区域进行细化研究;并首次将MRS与肿瘤的发生发展过程中的重要因子PCNA和Survivin进行对照研究,提供MRS判断星形细胞瘤恶性度和侵袭性的理论依据。同时进行弥散张量成像评价胶质瘤的恶性度并与临床表现相结合判断对锥体束的侵袭性,从而实现代谢与组织病理学相联系、形态与功能并重,为临床治疗和预后判断提供重要客观依据。材料与方法研究对象为50例星形细胞瘤（男29例,女21例）,平均年龄45.18岁（11岁～74岁）和10例少枝胶质细胞瘤或少枝星形细胞瘤（男5例,女5例）,平均年龄31.50岁（13岁～47岁）。其中星形细胞瘤组包括星形细胞瘤Ⅱ级（WHO分类标准（2007））10例,Ⅲ级21例,Ⅳ级19例。含少枝细胞的胶质瘤组包括少枝胶质细胞瘤（Ⅱ级）3例、少枝星形细胞瘤（Ⅱ级）1例、间变性少枝胶质细胞瘤和间变性少枝星形细胞瘤（Ⅲ级）各3例。并取20名健康志愿者做对照组。所有检查都在告知被检者检查详情并获同意后进行。进行头部磁共振常规T₁加权成像（T₁WI）、T₂加权成像（T₂WI）、MRS检查及T₁WI增强扫描。磁共振检查采用GE Signa MR/i和Excite HD MR 1.5T超导型磁共振扫描仪。应用Functiontool软件得到波谱图像及代谢物解剖图,对肿瘤实质、瘤周和对照组织测量单个体素的最大Cho/NAA、Cho/Cr和最小NAA/Cr;对强化不均匀的胶质瘤测量肿瘤不同强化程度部分的Cho、NAA、Cr与对照组织的比值（Cho/nCho、NAA/nNAA、Cr/nCr）。对50例星形细胞瘤标本进行PCNA和Survivin免疫组化检查,得到肿瘤PCNA的标记指数（PI）和Survivin的免疫活性指数（IRS）。对星形细胞瘤MRS测值分别进行单因素方差分析,对星形细胞瘤与含有少枝胶质细胞的胶质瘤进行独立样本t检验;对肿瘤实质内显著强化和轻度或无强化部分进行配对t检验。对MRS测得比值与PI和IRS分别进行pearman相关分析。应用SPSS13.0进行统计学分析。P＜0.05为差异有统计学意义。本组另外收集了经手术病理确诊的23例幕上胶质瘤,男12例,女11例,平均年龄45.91岁（22岁～71岁）。其中高级别胶质瘤16例（间变性胶质瘤7例,胶质母细胞瘤9例）,低级别胶质瘤（Ⅱ级）7例。11例术前有肢体感觉和（或）运动异常,包括1例胶质瘤Ⅱ级、3例间变性胶质瘤、7例胶质母细胞瘤;其余12例都没有肢体运动及感觉障碍。术前均行MRI平扫、Gd-DTPA增强扫描及DTI检查。采用1.5T GE Signa Excite HD超导磁共振扫描仪、8通道头颈联合线圈进行检查。DTI采用SE/EPI序列横断位扫描,弥散梯度场取25个不同方向,b值取0和1000s/mm²。统计学检验采用秩和检验及配对t检验。结果一、氢质子磁共振波谱在人脑胶质瘤中应用研究星形细胞瘤Ⅱ级的Cho/Cr和Cho/NAA低于高级别星形细胞瘤（Ⅲ级和Ⅳ级）（P＜0.05）;星形细胞瘤Ⅱ级的NAA/Cr显著高于高级别星形细胞瘤（P＜0.05）。高级别星形细胞瘤（Ⅲ级和Ⅳ级）之间各代谢物比值没有统计学差异（P＞0.05）。星形细胞瘤Ⅱ级瘤周Cho/NAA低于高级别星形细胞瘤瘤周（P＜0.05）,同时星形细胞瘤Ⅲ级瘤周Cho/NAA低于Ⅳ级瘤周（P＜0.05）。星形细胞瘤Ⅱ级瘤周Cho/Cr低于高级别星形细胞瘤瘤周（P＜0.05）,NAA/Cr高于高级别星形细胞瘤（P＜0.05）。高级别星形细胞瘤（Ⅲ级和Ⅳ级）瘤周之间Cho/Cr和NAA/Cr差异都没有统计学意义（P＞0.05）。少枝胶质细胞瘤和少枝星形细胞瘤与级别相同的星形细胞瘤（Ⅱ和Ⅲ级）相比,Cho/Cr和Cho/NAA更高（P＜0.05）,而NAA/Cr没有显著差异（P＞0.05）。对强化不均匀的高级别胶质瘤进行研究显示轻度或无强化的肿瘤实质的Cho/nCho、Cr/nCr和NAA/nNAA都高于显著强化的肿瘤实质（P＜0.05）。二、星形胶质细胞瘤MRS与肿瘤细胞PCNA、Survivin对照研究Survivin的IRS和PCNA的PI随着肿瘤恶性度增加而升高。星形细胞瘤Cho/Cr与IRS显著正相关（r=0.745,P＜0.01）;星形细胞瘤Cho/NAA与IRS显著正相关（r=0.753,P＜0.01）。星形细胞瘤Cho/Cr与PI显著正相关（r=0.818,P＜0.01）;星形细胞瘤Cho/NAA与PI显著正相关（r=0.760,P＜0.01）。星形细胞瘤NAA/Cr与IRS呈负相关（r=-0.374,P＜0.01）,星形细胞瘤NAA/Cr与PI呈负相关（r=-0.436,P＜0.01）。三、DTI在幕上胶质瘤分级及对锥体束侵袭性评价中的应用低级别胶质瘤瘤周MD值高于肿瘤实质组织,而低于瘤内囊变坏死;FA值则高于肿瘤实质和囊变坏死（P＜0.01）;高级别胶质瘤瘤周组织MD值亦高于肿瘤实质（P＜0.01）,FA值则无显著差异（P＞0.05）。高低级别胶质瘤之间肿瘤周边区MD值和FA值比较有显著统计学差异（P＜0.01）,而肿瘤实质和囊变坏死区两组间FA值比较均无统计学差异（P＞0.05）。低级别胶质瘤在锥体束通过的内囊后肢层面、大脑脚层面和脑桥层面的肿瘤侧与对侧MD值和FA值比较差异都没有统计学意义（P＞0.05）。高级别胶质瘤肿瘤侧内囊后肢层面锥体束FA值显著低于对照侧（P＜0.01）,MD值没有差异;大脑脚层面、脑桥层面锥体束FA和MD值与对照侧比较都没有显著差异（P＞0.05）。有肢体感觉和（或）运动异常组肿瘤侧内囊后肢层面锥体束MD值高于对侧;内囊层面和大脑脚层面锥体束FA值低于对侧（P＜0.05）。无肢体感觉和（或）运动障碍组肿瘤侧锥体束通过内囊后肢、大脑脚及脑桥层面MD值和FA值与对侧比较差异都没有统计学意义（P＞0.05）。纤维束示踪成像锥体束与肿瘤关系都得到清晰显示。患侧锥体束显示基本正常或正常者,即1型有12例,包括星形细胞瘤Ⅱ级6例,间变性胶质瘤4例,胶质母细胞瘤2例;锥体束明显移位合并有MD、FA伪彩色异常者,即2型共10例;仅有1例表现为锥体束明显受侵、少部分纤维束中断。所有有肢体感觉运动异常的患者的锥体束改变都为2型和3型。胶质瘤患者肢体感觉和（或）运动障碍在术后都有减轻或消失。结论星形细胞瘤的MRS检测有助于星形细胞瘤级别判定及与同级别少枝胶质细胞瘤的鉴别。强化不均匀的胶质瘤内部代谢物含量不同,轻度强化或无强化的肿瘤部分Cho、Cr、NAA含量高于显著强化区域,有必要对轻度或无强化的肿瘤区域进行活检。MRS基本反映了肿瘤细胞PCNA及Survivin蛋白表达情况,能够无创的在术前预测肿瘤凋亡抑制情况、增殖潜能、侵袭能力和预后,其中Cho/Cr,Cho/NAA较NAA/Cr更有意义。应用DTI对胶质瘤实质和瘤周区MD和FA值的测量有助于高低级别胶质瘤的鉴别。胶质瘤T₂WI可见的瘤周异常信号外可见FA值和MD值的异常改变。对锥体束通过的不同层面FA值和MD值测量有助于揭示常规MR检查不能显示的患者临床肢体感觉障碍和（或）运动异常的病理改变。锥体束的白质纤维束示踪成像可以直观立体显示锥体束与胶质瘤的空间关系,并能通过附加FA和MD值伪彩来显示锥体束的微观改变。DTI联合白质纤维束成像能更有效指导手术治疗和判断预后。更多还原

【Abstract】 PrefaceGlioma is the most common primary brain tumor. The clinical course and treatment method are different according to various grade of the tumor. Astrocytomas account for the majority of gliomas. Oligodendrocytomas and oligoastrocytomas are the second common gliomas. The clinical symptom is less severe and there is longer survival time for oligodendrocytoma and oligoastrocytoma comparing with astrocytoma. They are very allergic to the radiotherapy and chemotherapy. Presurgical determination of malignancy degree and the type of histology of cerebral gliomas plays an important role in clinical work. The morphologic changes of the tumor cells are the golden standard of glioma grading. But the histological specimen can only be obtained by invasive surgery or biopsy. It is difficult to get the accurate malignant degree of the glioma because of inevitable sampling error. How to judge the invasiveness of the tumor accurately is a tough problem for clinical doctors. Routine MR imaging plays a very important role in the morphological diagnosis of gliomas. The application of MR functional techniques makes the diagnosis of glioma to the microscopic scale which provides both morphological changes and biochemical functions. They can also provide the quantitative analysis in some degree and become the necessary complementary methods for routine MR examinations.Our studies begin with the metabolism of gliomas. We use the most commonly used ratios of metabolism that been got from proton MR spectroscopy （¹HMRS） to differentiate astrocytomas and oligodendroglioma or oligodendroastrocytoma. We also use them to investigate various enhanced area of glioma. For the first time, we compared MRS with PCNA （proliferating cell nuclear antigen） and survivin of astrocytomas in order to get the theoretic proof of the ability that MRS can assess the malignancy and invasiveness of gliomas. Meanwhile, DTI was studied in the assessment of malignancy of supra-tentorial gliomas. The correlation between DTI manifestations and clinical manisfestations was performed to evaluate the invasion of gliomas to the pyramidal tracts. We engaged in the study of the metabolism and histopathologic study noninva-sively. The morphologic and functional studis are equally emphasized. It may offer the objective criterion to the therapy and prognosis of gliomas.Materials and MethodsThe study group was composed of two sub-groups. The first sub-group included 50 patients of astrocytoma （29 men and 21 women, age range 11-74 years, with a median age of 45.18 years）: Low-grade astrocytoma （WHO gradeⅡ） in 10 patients, anaplastic astrocytoma （WHO gradeⅢ） in 21 patents and glioma multiform （WHO gradeⅣ） in 19 patients. The second sub-group included 10 patients （5 men and 5 women; age range from 13 to 47 years, with a median age of 31.50 years）: oligoden-droglioma （WHO gradeⅡ） in 3 patients, oligodendroastrocytoma （WHO gradeⅡ） in 1 patient, anaplastic oligodendroglioma （WHO gradeⅢ） in 3 patients, anaplastic oligodendroastrocytoma （WHO gradeⅢ） in 3 patients. The control group included 20 healthy volunteers. All the studies were informed to all the subjects and acceptances were obtained from all of them. The examinations included routine precontrast T₁ weighted spin-echo imaging （T₁WI）, T₂ weighted spin-echo imaging （T2WI）, ¹HMRS examination and postcontrast T₁WI. They were performed with GE Signa MR/ior Excite HD 1.5 T superconductive MR system. The raw data was imported to GE workstation. MRS images and met-anatomic images were obtained with Functiontool software. The maximal values of Cho/NAA and Cho/Cr and the minimal value of NAA/Cr in the tumor parenchyma, peri-tumorous region and contralateral brain were recorded. The ratios of tumour Cho、NAA、Cr to the contralateral side（Cho/nCho、NAA/nNAA、Cr/nCr） were also recorded. The immunohistochemical stainings of PCNA and survivin were performed for all the astrocytomas. The proliferative index（PI） of PCNA and im-munoreactive score（IRS） of survivin were obtained. The metabolism ratios of astrocytomas were compared by one way ANOVA. Independent- samples t test was used for the comparison between astrocytomas and gliomas with oligodendrocyte. Pared-samples t test was used for analysis between the strongest enhanced regions and the less enhanced or non-enhanced regions of the high grade gliomas. Separate statistical comparisons of the three MRS parameters （met-ratios of Cho/NAA、Cho/Cr and NAA/Cr） with PI values of tumors, the met-ratios with IRS values were made using Pearson correlation analysis. Statistical software （SPSS 13.0） was used for analysis and P values of less than 0.05 were considered to indicate a statistically significant difference.Twenty-three patients with supra-tentorial gliomas confirmed by surgery were also included in this study （12 men and 11 women; age range from 22 to 71 years, with a median age of 45.91 years）. This group included low-grade glioma （WHO gradeⅡ） in 7 patients and high-grade glioma in 16 patients （WHO gradeⅢin seven patients and WHO grade IV in nine patients）. Eleven patients experienced preoperative sensorimo-tor deficits （low-grade glioma in 1 patient, anaplastic glioma in 3 patients, glioblastoma in 7 patients）. The rest 12 cases didn’t suffer from sensorimotor deficits. Conventional gadolinium-DTPA enhanced T₁WI, and diffusion-tensor imaging （DTI） were performed before surgical resection using GE Signa Exicite HD 1.5 T superconductive MR machine with a 8-channel phased-array head and neck coil. A single-shot spin-echo echo-planar sequence with axial-plane was applied for DTI. Diffusion gradients encoding in 25 directions with b=1000s/mm² and 0 s/mm² were performed. Statistic analysis was made by using Mann-Whitney U test and 2-sided pared t test.Results1. Application of ¹HMRS in the human brain gliomasThe met ratios of Cho/Cr and Cho/NAA in the low-grade astrocytomas were lower than high-grade astrocytomas （WHO gradeⅢand gradeⅣ） （P<0.05） and the met ratio of NAA/Cr was higher than high-grade astrocytomas （P<0.05）, but there were no significant deviations of the met ratios within high-grade astrocytomas （P>0.05）. The ratios of Cho/NAA and Cho/Cr in the peri-tumorous region in low grade astroctyomas were lower than that in high grade astrocytomas （P<0.05） and NAA/Cr was higher than that of high grade astrocytoma （P<0.05）. The ratio of Cho/NAA in astrocytomas gradeⅢin the peri-tumorous region was lower than that of gradeⅣ（P<0.05）, but there was no significant deviation of Cho/Cr and NAA/Cr between gradeⅢand gradeⅣastro- cytomas （P>0.05）.The met ratios of Cho/Cr and Cho/NAA were higher in oligodendrogliomas and oligodendroastrocytomas than astrocytomas of the same grade （P<0.05）, but there was no significant difference of NAA/Cr between them （P>0.05）. The ratios of Cho/nCho、Cr/nCr and NAA/nNAA were higher in the less or non-enchanced region than the most significant enhanced region（P<0.05）.2.¹HMRS manifestation of astrocytomas in patients and the compare study with the PCNA and survivin of the post-surgery specimenThe IRS of survivin and PI of PCNA were higher accompanying the higher grade of gliomas. There was a strongly positive correlation between the ratio of Cho/Cr and IRS （r=0.745, P<0.01）, and also between the ratio of Cho/NAA and IRS （r=0.753, P<0.01）. We found strongly positive correlation between the ratio of Cho/Cr and PI （r=0.818, P<0.01）, and between the ratio of Cho/NAA and PI （r=0.760, P<0.01）. There was a weak negative correlation of NAA/Cr with IRS （r=-0.374, P<0.01） and PI（r=-0.436, P<0.01）.3. Application of DTI in the grading and evaluation of invasiveness of supra-tentorial gliomasThe MD value in the peritumoural region of low grade glioma was higher than the solid part of the glioma and lower than the necrotic and cystic region, but the FA value was higher than those region （P<0.01）. The MD value in the peri-tumoural region of high grade glioma was higher than the tumour parenchyma （P<0.01）, but there was no significant difference of FA values between them （P>0.05）. There were significant differences in MD and FA values of the peri-tumoural regions within the high grade gliomas （P<0.01）, but there were no differences in the FA values of parenchyma and cystic region between them （P>0.05）.There were no significant deviations for the MD and FA values of pyramidal tracts in the plane of posterior limb of internal capsule、cerebral peduncle and pons of low grade glioma between the two sides（P>0.05）. The FA value in the ipsilateral side was lower than contralateral location in the section of posterior limb of internal capsule （P<0.01）. There was no significant difference in the other two planes. The MD values in all the planes were similar between the two sides （P>0.05）. In patients suffering sensorimotor deficits, we found significantly decreased FA and increased MD for the ipsilateral pyramidal tracts in the plane of internal capsule, but for the patients without deficits, there were no differences in the MD and FA values on all the planes between two sides （P>0.05）.All the pyramidal tracts were clearly showed by the diffusion tensor tractography. There were 12 patients （WHO gradeⅡin six patients, gradeⅢin four patients and gradeⅣin two patients） had normal or approximately normal fiber tracts （type one）. There were shifts of the pyramidal tracts with abnormal pseudo-color of MD and FA （type two） in the 10 cases. There was obvious invasion and interruption of some fibers in the rest one case. We didn’t find completely interruption of the fibers in all the group of patients. All of the patients suffering sensorimotor deficients had the pyramidal tract changes of type two and three and the symptoms relieved or disappeared postsurgery.ConclusionMRS examination is very helpful for astrocytomas in grading and discrimination with oligodendroglioms and ologodendroastrocytomas. The contents of metabolisms are different in the nonhomogeneous enhanced gliomas. The biopsy of the weak enhanced or non-enhanced region is suggested respecting there is more Cho、Cr and NAA in that region.MRS has strongly correlation with the protein manifestation of PCNA and sur-vivin of astrocytomas. MRS provides a helpful and noninvasive method in the preop-erative assessment of apoptosis、reproductive activity、invasive activity and predicting the prognosis of astrocytomas. The ratios of Cho/Cr and Cho/NAA are more useful than NAA/Cr.Measurements of MD and FA values from DTI in the tumor parenchyma and peri-tumoural region are assisted in differentiation between high-grade and low-grade gliomas. We have found changes of FA and MD values outside the tumor abnormal-appearing region on T2WI. The measurements of FA and MD values of pyramidal tracts on different sections are very helpful in revealling the pathologic changes of the deficient patients which are not detectable on conventional MR imaging. The reconstruction of pyramidal tracts shows us the three-dimensional relationship of the fiber bundles and gliomas. In addition, it can show us the micro changes of the pyramidal tracts by adding the pseudo-colour of MD and FA values. DTI in combination with fiber tracking can provide more important imformations which are very helpful in making the plan of surgery and prognostic assessment of the patient with glioma.更多还原