【作者】 赵修义；

【导师】 张雪林；

【作者基本信息】 中国人民解放军第一军医大学 ， 影像诊断学， 2003， 博士

【摘要】 【目的】 1．定量地分析不同年龄段正常脑白质磁共振扩散加权成像ADC值，建立正常脑白质及灰质ADC值标准，为评价放射性脑损伤提供参考值。 2．探讨MR DWI在放射性脑损伤诊断中的表现及意义，进一步评价MR DWI定量分析脑微观病理改变的价值。 【材料与方法】 1．年龄因素所致ADC值变化的相关研究：选取50例具有正常MRI表现的患者作为研究对象，按其年龄段分为四组：第一组(16～30岁，n=13)，第二组(31～45岁，n=12)，第三组(46～60，n=14)及第四组(＞60岁，n=11)；定量测量白质区及丘脑ADCav值，比较分析不同年龄段ADCav值特性。 2．颞叶正常参考值的研究：选取30例年龄结构与放疗后正常表现组相匹配具有正常MRI表现的患者作为正常对照组，定量地测量颞叶正常脑组织ADC值及CV值，为放射治疗后扩散成像研究提供正常的对比参考指标。 3．鼻咽癌放射治疗后正常表现脑灰质及脑白质的定量研究：选取30例放疗后具有正常MRI表现的患者作为放疗后正常表现组，定量地计算颞叶正常脑组织ADC值及CV值。 4．放射性脑损伤DWI临床应用研究：对51例鼻咽癌放射治疗后颞叶放射性脑损伤患者的临床表现及MRI资料进行回顾性分析，按照分型和分期标准分为灰质型和白质型，其中白质型分为白质型Ⅰ期、白质型Ⅱ期。定量分析比较病变区和对照区ADC值及CV值。 5．上述资料采用单因素方差分析、t检验、最小显著性方法及相关回归分析进行统计学检验。 【结果】 1．年龄因素所致ADC值变化的相关研究：脑白质ADCav值为(0.71±0.08)x10一3rnmZzs:不同年龄段四组ADcav值分别为:(0 .69士o.06)x10-3tlun勺s，(0.71士0.的)x一0-3训rnZzs，(0.71士0.09)x 10-3tnmZzs，(0.73士o.10)xlo-3rnmZzs;第一组ADc值与第四组ADc值间存在显著性差异(尸二0.014);年龄大于60岁与年龄小于或等于60岁两组ADCav值分别为(0.73士0.10)x 10一3nunZ/s、(0.70士0.价)x 10一3tnmZzs，两组比较存在显著性差异(尸=0.026)。丘脑ADcav值为(0 .83士0.07)x 10-3nnnZzs，与白质ADCav值比较，两组间存在显著性差异伊<0.001)。各年龄段ADCav值间没有显著性差异;年龄大于60岁与年龄小于或等于60岁两组ADCav值分别为(0.54士0.06)x 10一3 nunZzs、(0.53士0.05)x 10-3mrnZzs，两组比较没有显著性差异(尸二0.376)o2.颗叶正常参考值的研究:颗叶白质的ADCav=(o .82士O.OS)X10-3mm勺s，ADeT=(0.52士0.10)x一0-3nunZzs，两者比较无显著性差异(t=一0.34，尸二。.734);颖叶灰质的ADeH=(0.9一士0.22)x 10一3mmZ/s，与颖叶白质ADcT=(0.82士0.10) x10一3rnmZzs比较有显著性差异(t= 4.32，p二0.000);颖叶白质存在扩散的各向异性，各向异性变异系数CV为(17.68士6 .69)%。3.鼻咽癌放射治疗后正常表现脑灰质及脑白质的定量研究:颖叶白质的^n eav=(0 .76士。一2)xl汀3rnmZzs，ADeT=(0 .76士0.1一)x 10-3mmZls，两者比较无显著性差异(t= 0.21，尸二0.984);颖叶灰质的ADCH=(0 .89士0.09)x一。一3rnmZzs，与颖叶白质ADeT==(0 .76士0.11)x 10-3nnnZzs比较有显著性差异(t=一5.46，尸二0.000);颖叶白质在某些方向间存在扩散的各向异性，各向异性变异系数CV为(13.601士5.62)%。放疗后颖叶白质ADC及CV值均较对照组降低，表现为受限性扩散，采用t检验进行统计分析，两组间存在显著性差异，尸值均小于0.05;放疗后颖叶灰质ADC值与对照组比较，其大小也呈下降趋势，但统计学分析结果显示两组间没有显著性差异。4.放射性脑损伤DV八I陆床应用研究:51例放射性脑损伤按照分型及分期标准，包括4O例白质型及n例灰质型，其中40例白质型包括白质型 I期24例、白质型H期16例。增强扫描具有一定的特征性，早期改变表现为灰质内的局灶性强化灶;白质内早期的水肿在FLA[R序列上表现为局灶性边界清晰的高信号。白质型及灰质型放射性脑损伤病灶的ADC值较对照区ADC值均升高，采用t检验进行统计分析，P值均小于或等于0.01，说明在扩散加权成像上，放射性脑损伤病灶的ADC值与对照区ADC值间在统计学上有显著性差异，以白质型ADC值升高更为明显。白质型放射性脑损伤病灶的CV值较对照区CV值均降低，采用t检验进行统计分析，尸值均小于0.05，说明白质型放射性脑损伤病灶的CV值与对照区CV值间在统计学上有显著性差异，以白质型n期降低更为明显，反映出CV值的变化与其病理改变的一致性。【结论】1.D丫Vl所提供的组织图像对比不同于Tl丫Vl、TZ节/I，其成像的基础是水分子随机扩散运动，ADC值主要反映组织水分子随机扩散能力的大小，而CV值反映出组织水分子扩散各向异性的程度。2.D丫Vl需要快速扫描序列，最常用的是SE EPI。本研究采用DWI图像和ADc图两种观察方法。采用2个b值(o、10oomrnZzs)进行ADc值的计算。序列1既能提供三向各向异性图像，又能提供扩散追踪成像(tr aceimaging)，后者ADC值的计算相对简单方便，并消除了各向异性的影响，且成像质量相对稳定;序列2较低b值成像及ADC图在本研究定量计算价值不?更多还原

【Abstract】 [Objective ]1. To quantitatively study the ADC values of normal white matter with advancing age on diffusion and establish reference values of ADC for further studies of radiation-induced injury.2. To elucidate the manifestations and significance on MR DWI in diagnosis of radiation-induced injury and further evaluate the clinical value of quantitative measurement of mild structure changes on MR DWI.[Materials and Methods]1. The correlative study of ADC changes with advancing age: The study included 50 patients with normal appearing white matter. The subjects were divided into four group by age; age groups were first group(16~30years, n=13), second group(31~45years, n=12), third group(46~60years, n=14), fourth group(>60years, n=11). The ADCav of white matter and thalamus were measured and compared in various age groups.2. The study of normal reference values of temporal lobe: The study included 30 age-matched control subjects compared with normal appearing group following radiotheraphy, defined as control group with normal white matter. ADC and CV values were calculated to provide normal reference values for comparison analysis between control group and normal appearing group following radiotheraphy.3. The quantitative study of normal appearing group following radiotherapy for nasopharyngeal carcinoma on diffusion weighted-imaging: The study included 30 patients with normal appearing MRI following radiotherapy, defined as normal appearing group following radiotherapy. ADC and CV values were measured and compared with the control group.4. The study of clinical application on DWI for radiation-induced temporal lobe injury: 51 patients with ratiation-induced injury in nasopharyngeal carcinoma (NPC) were review. All patients were diagnosed by clinical manifestations and MR imaging. The disease was divided into white matter type and gray matter type by described criterion, and the white matter type included white matter type I phase and white matter type II phase. The ADC and CV values were analyzed and compared between lesion and control region.5. All these data were analyzed with statistical methods of one-way ANOVA, t-test, least-significant difference, correlative ang regression analysis.[Results]1. The correlative study of ADC changes with advancing age: In white matter, the ADCav among all patients was (0.71± 0.08)×10-3mm2/s; the ADCav of white matter in the first to fourth group were (0.69±0.06)× 10-3mm2/s, (0.71±0.07) ×10-3mm2/s, (0.71±0.09)× 10’3mm2/s, (0.73 ± 0.10)×10-3mm2/s. ADCav in the first group was significantly different from ADCav for patients in the fourth( P=0.014); patients older than 60 years had an ADCav for white matter of (0.73 ± 0.10) × 10-3mm2/s , which is significantly higher than the ADCav among all patients 60 years or younger(0.70±0.07)× 10-3mm2/s ( P=0.026) .For the thalamus, the ADCav among the entire study population was (0.83±0.07)× 10-3mm2/s, which was significantly different from the ADCav in white matter(P<0.001). The thalamic ADCav was not significantly different each other in various age groups. Comparison of the thalamic ADCav in patients older than 60 years[(0.84±0.06) × 10-3 mm2/s] with those 60 years or younger[(0.83 ± 0.08) × 10-3mm2/s] also showed not significantly different( P=0.376).2. The study of normal reference values of temporal lobe: In white matter, the ADCav among all patients was (0.71± 0.08)× 10"3mm2/s; ADCT was (0.82±0.10) × 10-3mm2/s; ADCav and ADCT was not significantly different each other (t= -0.34, P=0.734) . In gray matter, the ADCH among the entire study population was (0.91±0.12) × 10-3mm2/s, which was significantlydifferent from the ADCT in white matter(P<0.001) (t= 4.32, P=0.000) . In the white matter of temporal lobe , diffusion was anisotropic, and the coefficient of variation in anisotropic diffusion was (17.68 ± 6.69)%.3. The quantitative study of normal appearing group following radiotherapy for nasopharyngeal carcinoma on diffusion weighted-im更多还原