磁共振扩散加权成像和磁共振波谱在卵巢肿瘤中的应用

磁共振扩散加权成像(DWI)和磁共振波谱(MRS)均属于无创性MRI功能成像技术,分别通过分析组织扩散系数的差异和对组织代谢物的定量分析来描述病变的特征,实现了影像检查技术从形态学到功能学的转变,对卵巢肿瘤的鉴别诊断有重要意义,本文就其原理及其在卵巢肿瘤的临床应用价值做一综述。     

磁共振扩散张量成像在阿尔茨海默病中的应用

阿尔茨海默病是导致痴呆的主要发病因素。对于阿尔茨海默病的早期诊断和监控，MRI检查是有效的。扩散张量成像较常规MRI对显示阿尔茨海默病早期纤维束的受损情况更敏感，不仅可在一定程度上反映该病的病理变化，而且可反映其微观结构的变化，有助于在脑皮质发生明显萎缩之前对阿尔茨海默病进行早期诊断。     

磁共振扩散加权成像在前列腺疾病中的应用

目的 探讨磁共振扩散加权成像在前列腺疾病中的应用价值.方法 对29例前列腺疾病患者(前列腺增生22例,前列腺癌7例)进行扩散加权成像,并测量表观扩散系数值(ADC值).结果 前列腺增生的中央叶及外围叶的ADC值分别为(1.95±0.09)×10-3mm2/s和(2.69 ±0.12)×10-3mm2/s,而前列腺癌灶与邻近未被癌组织侵及的中央叶及外围叶的ADC值分别为(1.26±0.08)×10-3mm2/s,(1.93±0.07)×10-3mm2/s和(2.61 ±0.07)×10-3mm2/s.前列腺增生病变中中央叶及外围叶的ADC值之间有统计学差异(t=23.09,P＜0.05);前列腺癌灶的ADC值分别与邻近未被癌组织侵及的中央叶及外围叶的ADC值之间存在统计学差异(t=15.50,P＜0.05;t=30.56,P＜0.05),同时前列腺癌灶与前列腺增生病变组中的中央叶及外围叶的ADC值之间亦分别存在着统计学差异(t=17.63,P＜0.05;t=27.09,P＜0.05).结论 磁共振扩散加权成像对前列腺疾病的诊断及鉴别诊断有一定的价值.     

磁共振扩散张量成像在前列腺疾病诊断中的应用

目的 探讨磁共振扩散张量成像(DTI)在诊断良性前列腺增生(benign prostate hyperplasia,BPH)和前列腺癌(PCa)中的价值.资料与方法 研究对象为经病理证实的20例PCa和25例BPH患者,DTI都采用Siemens Sonata 1.5 T超导成像仪和腹部相控阵线圈,应用Siemens Leonardo工作站相应的软件进行数据处理.DTI记录感兴趣区各向异性(FA)值和平均表观扩散系数(ADC)值并绘制相应参数图和纤维示踪图像.对比不同感兴趣区的相应成像指标的差异.结果 正常外周带、BPH和PCa的FA值分别为0.16±0.03、0.23±0.04和0.46±0.02(P＜0.05).正常外周带、BPH和PCa的平均ADC值分别为(1.85±0.34)×10-3 mm2/s、(1.37±0.27)×10-3mm2/s和(0.61±0.09)×10-3 mm2/s,三者差异具有统计学意义(P＜0.05).结论 正常前列腺组织、BPH和PCa组织DTI指标存在差异,结合常规MRI检查有助于PCa的鉴别诊断.     

卵巢肿瘤磁共振扩散加权成像初步研究

目的探讨磁共振扩散加权成像(DWI)对卵巢肿瘤的鉴别诊断价值。资料与方法回顾分析经病理证实的15例卵巢良性肿瘤和20例卵巢恶性肿瘤患者的影像资料,分别比较良恶性肿瘤的实性部分及囊性部分的表观扩散系数(ADC)值并进行统计学分析。结果卵巢良性肿瘤囊性部分ADC值(2.40±0.99)×10-3mm2/s与恶性肿瘤的囊性部分ADC值(2.46±0.87)×10-3mm2/s差异无统计学意义(P=0.922>0.05)。而卵巢良性肿瘤实性部分ADC值(1.48±0.54)×10-3mm2/s与恶性肿瘤的实性部分ADC值(0.99±0.28)×10-3mm2/s差异具有统计学意义(P=0.013<0.05)。结论卵巢肿瘤实性部分DWI的定量分析有助于卵巢肿瘤的鉴别诊断。     

磁共振扩散张量成像在阿尔茨海默病中的应用

阿尔茨海默病是导致痴呆的主要发病因素.对于阿尔茨海默病的早期诊断和监控,MRI检查是有效的.扩散张量成像较常规MRI对显示阿尔茨海默病早期纤维束的受损情况更敏感,不仅可在一定程度上反映该病的病理变化,而且可反映其微观结构的变化,有助于在脑皮质发生明显萎缩之前对阿尔茨海默病进行早期诊断.     

正常前列腺的磁共振扩散张量成像研究

目的探讨前列腺磁共振扩散张量成像(DTI)的可行性及正常外周带和中央腺区DTI特征。方法研究对象为20例健康男性志愿者,DTI都采用Siemens Sonata1.5T超导成像仪和腹部相控阵线圈,应用西门子Leonardo工作站相应的软件进行数据处理。DTI记录感兴趣区各向异性(FA)比值和平均ADC值,并绘制相应参数图和纤维示踪影像。对比不同感兴趣区的相应成像指标的差异。结果正常外周带(PZ)和中央区(CZ)的FA值分别为0.16±0.03和0.23±0.04,两者差异具有统计学意义(P0.05)。PZ和CZ的平均ADC值分别为(1.85±0.34)×10-3mm2/s和(1.37±0.27)×10-3mm2/s,两者差异具有统计学意义(P0.05)。结论正常前列腺DTI具有可行性,中央腺区与外周带DTI指标存在明显差异。     

磁共振扩散成像及磁敏感加权成像在脊髓损伤中的应用

目前,脊髓MR成像常规检查是诊断脊髓损伤的最佳手段,能清楚地显示受损伤脊髓形态及信号改变,以此明确疾病,但是当MRI常规检查出现信号改变时往往提示脊髓损伤严重,并非病变的早期,使得病人错过最佳治疗时期。而MR扩散加权成像(DWI)和磁敏感加权成像(SWI)对脊髓损伤的早期诊断、治疗和预后均具有重要价值。对DWI及SWI在急慢性脊髓损伤中的应用情况及研究进展进行综述。     

MR扩散成像在癫痫研究中的应用

MR扩散加权成像和扩散张量成像能够发现癫痫发作期脑内部分区域的ADC值短暂下降，可提供新近癫痫活动的定位信息。发作间期ADC值的升高和FA值的下降反映了慢性癫痫病灶特征性的病理改变。综述MR扩散成像对癫痫病人的功能应用研究。     

磁共振扩散张量成像在脑梗死中的初步应用

目的:采用MR扩散张量成像(DTI)对不同时期的脑梗死灶进行观察,探讨皮质脊髓束的受累情况与患者运动功能损害的相互关系,评价DTI对判断脑梗死的治疗效果及预后评估的价值。方法:对25例超急性或急性期脑梗死患者行DTI检查,对所得的原始数据利用纤维束后处理软件行三维皮质脊髓束图像重组,观察脑梗死灶与皮质脊髓束的关系;并对每例患者进行2次临床神经功能症状评分,作为临床评价标准。结果:25例中DTI显示8例者皮质脊髓束从梗死灶边缘通过,表现为无受压、移位、中断等,临床上患者的运动功能表现为无或轻微损害;10例显示皮质脊髓束部分从梗死灶中通过,表现为部分受压、中断,临床上患者运动功能出现受损的症状,治疗后症状部分恢复;7例皮质脊髓束全部从梗死灶中通过,表现为大部分中断、破坏,临床上患者表现为即使进行治疗,大多数运动功能无恢复或仅轻微改善。结论:通过DTI可对脑梗死治疗效果及预后评估提供重要的功能解剖学依据。     

MR扩散张量成像在前列腺癌诊断中的价值

目的 探讨MR DTI在前列腺癌诊断中的价值.方法 回顾性分析2009年10月至2010年12月期间,临床怀疑为前列腺癌且行MR常规检查及DTI扫描的44例患者的资料.病理证实为前列腺癌16例、良性前列腺增生28例.采用t检验比较前列腺癌、良性前列腺增生患者间各向异性分数(FA)值及ADC值的差异,采用ROC曲线分析FA值及ADC值对前列腺癌诊断效能,并初步确定前列腺癌FA值及ADC值诊断阈值.结果 前列腺癌区和良性前列腺增生的FA值分别为0.308±0.084和0.203±0.029,ADC值分别为(0.883±0.192)×10-3和( 1.408±0.130)×10-3mm2/s,差异均有统计学意义(￡值分别为4.833和10.779,P值均＜0.01).ROC曲线上,ADC曲线下面积为0.996(95％可信区间为0.984～1.007),FA值曲线下面积为0.904(95％可信区间为0.812～0.996),FA值联合ADC值的曲线下面积为0.996(95％可信区间为0.984～1.007).ADC值阈值为0.725×10-3mm2/s,敏感度为100.0％,特异度为96.0％;FA值阈值为0.311,敏感度为100.0％,特异度为68.7％.结论 DTI成像能为前列腺癌诊断及鉴别诊断提供有价值的信息,有助于提高对前列腺癌的诊断能力.     

Diffusion tensor MR imaging in pediatric head trauma

PURPOSE: We propose to investigate the fractional anisotropy (FA) values in pediatric patients with closed head trauma and correlate them with the initial Glasgow Coma Scale (GCS). MATERIALS AND METHODS: A retrospective evaluation of 24 pediatric patients (15 men, 9 women; mean age, 13 years; range, 2-18 years) who underwent both unenhanced head computed tomography and cerebral magnetic resonance imaging (MRI), including the tensor diffusion sequence, within 30 days of the incident. Twenty-two atraumatic control patients (9 men, 13 women; mean age, 9 years; range, 4-17 years) were randomly selected from the records of the radiology department within the same period. Fractional anisotropy measurements were taken from each of 6 major white matter volumes. Data extracted from the record of each subject included GCS, initial head computed tomographic results, and length of hospital stay. Kruskal-Wallis and t tests were used for statistical evaluation. RESULTS: The mean acute score on the GCS was 9.7 +/- 5. Mean duration of hospitalization days was 8.7 +/- 10. Statistically significant differences in mean FA values between trauma and control subjects were noted in corpus callosum. Trauma patients with positive findings on MRI and with GCS less than 10 also had lower FA values than patients with GCS greater than 10 and patients who had normal MRI findings. There was a negative correlation between time to discharge and FA values. CONCLUSIONS: In pediatric head trauma, MRI diffusion FA measurements can show abnormalities despite normal-appearing brain MRI findings. Larger investigations are required to verify the stability of correlations.     

Diffusion tensor MR imaging in diffuse axonal injury

BACKGROUND AND PURPOSE: Disruption of the cytoskeletal network and axonal membranes characterizes diffuse axonal injury (DAI) in the first few hours after traumatic brain injury. Histologic abnormalities seen in DAI hypothetically decrease the diffusion along axons and increase the diffusion in directions perpendicular to them. DAI therefore is hypothetically associated in the short term with decreased diffusion anisotropy. We tested this hypothesis by measuring the diffusion characteristics of traumatized brain tissue with use of diffusion tensor MR imaging. METHODS: Five patients with mild traumatic brain injuries and 10 control subjects were studied with CT, conventional MR imaging, and diffusion tensor imaging. All patients were examined within 24 hours of injury. In each participant, diffusion tensor indices from homologous normal-appearing white matter regions of both hemispheres were compared. These indices were also compared between homologous regions of each patient and the control group. In two patients, diffusion tensor images from the immediate post-trauma period were compared with those at 1 month follow-up. RESULTS: Patients displayed significant reduction of diffusion anisotropy in several regions compared with the homologous ones in the contralateral hemisphere. Such differences were not observed in the control subjects. Significant reduction of diffusion anisotropy was also detected when diffusion tensor results from the patients were compared with those of the controls. This reduction was often less evident 1 month after injury. CONCLUSION: White matter regions with reduced anisotropy are detected in the first 24 hours after traumatic brain injury. Therefore, diffusion tensor imaging may be a powerful technique for in vivo detection of DAI.     

Diffusion tensor MR imaging of high-grade cerebral gliomas

BACKGROUND AND PURPOSE: Optimizing high-grade glioma treatment requires the delineation of edematous and normal brain from tumor, perhaps by using potential differences in the absolute diffusion parameters of water. Our purpose was to determine whether mean diffusivity and diffusion anisotropic MR imaging data help in this differentiation. METHODS: Nine patients with high-grade cerebral glioblastoma underwent contrast-enhanced structural and diffusion tensor MR imaging before therapy. Tumor, edematous brain, and apparently normal white matter regions were determined on T2-weighted and contrast-enhanced T1-weighted structural images. Fractional anisotropy (FA) and were measured in each tissue type. Differences in these values among the tissue types were assessed with a standard analysis of variance. RESULTS: was highest in the necrotic tumor core (1825.38 +/-404.06) x 10(-6) mm(2)/s, followed by edematous brain (1411.23 +/- 322.31) x 10(-6) mm(2)/s, enhancing tumor core (1308.67 +/- 292.50) x 10(-6) mm(2)/s, enhancing tumor margin (1229.80 +/- 206.80) x 10(-6) mm(2)/s, and normal brain (731.53 +/- 35.21) x 10(-6) mm(2)/s. FA was highest in normal brain (0.47 +/- 0.08) and lowest in the necrotic core (0.09 +/- 0.03). was significantly different in enhancing tumor margins and edematous brain in all patients; FA was significantly different in only seven. These values were significantly different from those of normal brain in all cases in which they were measurable. CONCLUSION: values can be used to differentiate normal white matter, edematous brain, and enhancing tumor margins. Diffusion anisotropic data added no benefit to tissue differentiation. Further studies are required to determine if a value that corresponds to the limit of tumor invasion can be identified.     

Diffusion tensor magnetic resonance imaging of prostate cancer

PURPOSE: To explore the feasibility of 3T magnetic resonance (MR) diffusion tensor imaging (DTI) and fiber tracking (FT) in patients with prostate cancer. MATERIALS AND METHODS: Thirty consecutive patients (mean age, 62.5 years) with biopsy proven prostate cancer underwent 3T-MR imaging (MRI) and DTI using a 6-channel external phased-array coil before radical prostatectomy. Regions of interest of 14 pixels were defined in tumors and nonaffected areas in the peripheral zone (PZ) and central gland (CG), according to histopatology after radical prostatectomy. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were determined. Differences in mean ADC and FA values among prostate cancer, normal PZ and CG were compared by 2-sided Student t test. The predominant diffusion direction of the prostate anisotropy was color coded on a directionally encoded color (DEC) map. A 3D reconstruction of fiber tract orientations of the whole prostate was determined using the continuous tracking method. The overall image quality for tumor localization and local staging was assessed in retrospective matching with whole-mount section histopathology images. Nodules detected at MRI were classified as matched lesions if tumor presence and extension were evidenced at histopathology. RESULTS: For all the patients, the DTI sequence images were suitable for the evaluation of the zonal anatomy of the prostate gland and the tumor localization. Quantitative evaluation of the regions of interest (ROIs) showed a mean ADC value significantly lower in the peripheral neoplastic area (1.06 +/- 0.37 x 10(-3) mm2/s) than in the normal peripheral portion (1.95 +/- 0.38 x 10(-3) mm2/s) (P < 0.05). The mean FA values calculated in the normal peripheral (0.47 +/- 0.04) and central area (0.41 +/- 0.08) were very similar (P > 0.05). The mean FA values in the neoplastic lesion (0.27 +/- 0.05) were significantly lower (P < 0.05) than in the normal peripheral area and in the normal central and adenomyomatous area. DEC map showed a top-bottom type preferential direction in the peripheral but not in the central area, with the tumor lesions reducing the diffusion coding direction represented as color zones tending toward gray. Tractographic analysis permitted good delineation of the prostate anatomy (capsule outline, peripheral and central area borders) and neoplastic lesion extension and capsule infiltration compared with histopathology. CONCLUSIONS: Three Tesla DTI of the prostate gland is feasible and has the potential for providing improved diagnostic information.     

Diffusion tensor imaging in normal aging and neuropsychiatric disorders

The application of diffusion imaging to the quantitative study of the effects of normal aging and neuropsychiatric diseases on brain tissue microstructure has witnessed its greatest development just over the last few years. Measures derived from diffusion imaging have already been shown to have great utility in identifying age- and disease-related degradation of regional microstructure, particularly of white matter. Investigations comparing diagnoses hold promise for contribution to differential diagnosis. Correlations with cognitive and motor performance provide evidence for functional ramifications of these diffusion measures.