^1H-MRS和DWI在胶质母细胞瘤与单发转移瘤中的鉴别诊断价值

目的评价3T磁共振^1 H-MRS和DWI在胶质母细胞瘤与单发转移瘤中的鉴别诊断价值。方法搜集临床和手术确诊的15例胶质瘤（Ⅳ级）和15例转移瘤,采用西门子公司SKYRA 3.0T超导磁共振行常规MRI、^1 H-MRS、DWI扫描,测定感兴趣区（包括肿瘤实质区、瘤周水肿区、正常对照区）代谢物比值和ADC值。采用两种大小ROI测定ADC值,分析ROI大小对测量肿瘤实质区域ADC值是否存在影响。使用SPSS 13.0进行统计分析,找出两种肿瘤间具有统计学差别的参数。结果两种肿瘤瘤周的NAA/Cr、Cho/Cr、Cho/NAA及ADC值存在显著性差异（P〈0.01）,ADC值在两组肿瘤实质间不存在显著性差异（P〉0.05）。两种大小ROI测得的肿瘤区ADC值之间不存在显著性差异（P〉0.05）。结论肿瘤水肿区^1 H-MRS代谢物比值及ADC值在胶质母细胞瘤与单发转移瘤之间存在显著性差异,有助于两者的鉴别。ROI的大小对肿瘤区域ADC值的测量没有显著影响。     

肺癌脑转移瘤的常规MR、DWI 及MRS诊断价值

目的:总结肺癌脑转移病灶的常规MRI表现,并对其中部分病例行DWI和(或)MRS检查,以提高对肺癌脑转移的认识.材料和方法:回顾性分析经我院检查确诊的肺癌脑转移病例共177例,接受常规MRI序列检查.手术病理或临床病史证实的32例肺癌脑转移瘤病例,临床处理前接受DWI和(或)2D1H-MRS检查.分析其弥散及波谱表现特征,分别测定肿瘤实质、坏死/囊变部分、瘤周水肿部分及正常脑实质ADC值,以及Cho/Cr、NAA/Cr、NAA/Cho等代谢比率.结果:病灶强化方式以环状和结节状为主.环形强化的特征为外壁光滑,内壁毛糙,壁厚薄不均匀,强化不均.肿瘤实质部分ADC值为1.08±0.37×10mm2/s,囊变部分ADC值为2.5±0.36×10mm2/s.与瘤周水肿区及正常脑实质ADC值有显著差异性.肿瘤实质部分Cho峰多降低,CR峰降低,NAA峰多测不到.肿瘤组织与瘤周水肿区及正常脑实质的代谢比率(Cho/Cr)有显著差异性,而瘤周水肿区与正常脑实质的代谢比率无明显差异.结论:肺癌脑转移MRI强化主要表现为环形强化和结节状强化,环形强化有一定的特征表现可与其他病变鉴别.其在弥散及波谱图像上有一定的特点,与常规MRI序列结合可明显提高诊断准确性.     

单发脑转移瘤的MR影像诊断

作者分析了３４例单发脑转移瘤的ＭＲ表现。Ｔ１加权像，肿瘤实体以等信号居多；Ｔ２加权像以等、低信号为主。结节状病灶可见“小结节大水肿”征象。肿瘤中央坏死，液化者，中间呈极高信号，周边绕以等、低信号环。     

MRS联合多b值DWI对高级别胶质瘤与单发脑转移瘤的鉴别诊断价值

【摘要】目的：探讨氢质子磁共振波谱（1H-MRS）联合多b值磁共振扩散加权成像（DWI）的多参数值对术前幕上单发大脑高级别胶质瘤（HGG）与单发脑转移瘤（MET）的鉴别诊断价值。方法：选取术前常规MRI检查考虑为幕上单发的HGG或MET的住院患者,对其进行1H-MRS及多b值DWI成像,利用后处理软件重建波谱图及各b值对应的ADC图,分别于各肿瘤瘤体区、瘤周区及对应正常脑质的合适层面勾画兴趣区（ROI）,分别记录其平均Cho/NAA值、Cho/Cr值、 NAA/Cr值及ADC值,最终满足纳入标准的有49例（经手术病理或临床随访证实HGG 24例,MET 25例）。采用独立样本t检验（正态分布）或Mann-Whitney U检验（非正态分布）比较两组间各参数差异性,绘制受试者操作特征（ROC）曲线分析各参数鉴别HGG与MET的诊断效能。利用二元logistic回归分析得到两种技术联合鉴别HGG与MET的预测概率,然后绘制ROC曲线分析MRS、多b值DWI及两种技术联合三种方法鉴别两种肿瘤的诊断效能。结果：瘤周区平均Cho/Cr值为MRS鉴别两者的最佳参数,其曲线下面积（AUC）为0.936,敏感度为90%,特异度为87%。当b=1000s/mm2时相应的瘤周区ADC值为DWI鉴别两者的最佳参数,其AUC为0.863,敏感度为87%,特异度为78.9%。联合两种技术的最佳鉴别参数,即瘤周区平均Cho/Cr值和b=1000s/mm2时相应的瘤周区ADC值,绘制ROC曲线分析MRS、高b值ADC值及两种技术联合鉴别两者的诊断效能,发现两种技术联合时AUC最大,为0.973,敏感度为86.4%,特异度为100%。结论：1H-MRS联合多b值DWI对两种肿瘤的鉴别诊断效能优于其中任一成像技术的鉴别诊断效能。     

DWI在脑转移瘤诊断中的临床应用

磁共振扩散成像（DWI）是目前在活体上进行水分子扩散测量与成像的唯一方法。水分子扩散运动速率与状态反映的是微米数量级的运动变化,与人体组织中细胞的大小处于同一数量级。因此,与以往的T1WI,T2WI不同,水分子扩散成像使磁共振成像对人体的研究深入到了更微观的水平,反映着人体组织的微观几何结构,以及细胞内外水分子的转移与跨膜运动、温度等变化。本文将DWI在脑转移瘤诊断中的临床应用及进展作一综述。     

单发脑实质内转移瘤的MRI诊断

目的:分析单发脑实质内转移瘤的MRI表现,并探讨其与脑内其它病变的鉴别要点。材料和方法:选择经临床和手术病理证实的20例单发脑转移瘤,其中11例有原发恶性肿瘤史,9例先有脑部转移灶后发现原发灶。结果:典型单发脑转移瘤呈长T_1长T_2信号,瘤体小而周围水肿面积较大,占位效应显著。增强扫描呈不规则环状、结节状强化,且有原发恶性肿瘤史。结论:单发脑转移瘤一般均有较典型表现,注意密切结合病史及临床表现,实验室检查有助于诊断和鉴别诊断。     

DWI在恶性胶质瘤和单发脑转移瘤鉴别中的应用研究

恶性胶质瘤和单发脑转移瘤有着相似的临床及常规影像学表现,是临床诊断及鉴别诊断一难点。由于两者治疗方法不同,准确的诊断及鉴别诊断对治疗方法的选择和病人的预后有重要作用。DWI能够反映活体组织水分子的扩散信息,能定量分析组织的微观结构和功能改变,在一定程度上可反映肿瘤的细胞密度、核浆比及瘤周浸润情况,在脑肿瘤诊断上已经获得越来越多的认可。就扩散加权成像在恶性胶质瘤和单发脑转移瘤鉴别中的应用予以综述。     

颞叶癫痫~1H-MRS和DWI的变化及其相关性研究

目的 探讨~1H-MRS和DWI在反映海马硬化病理结构改变中的价值.方法 采用3.0T磁共振扫描仪对12例伴有单侧海马硬化的发作间期颞叶癫痫(TLE)患者及12例正常对照者行单体素~1H-MRS及DWI检查.比较海马N-乙酰天门冬氨酸/肌酸+胆碱[NAA/(Cr+Cho)]值,表观弥散系数(ADC)值在患侧、对侧和对照组之间的差异,分析NAA/(Cr+Cho)和ADC值之间的相关性.结果 TLE患者患侧海马NAA/(Cr+Cho)值低于对侧海马及对照组;发作间期海马ADC值高于对侧海马及对照组;患侧海马NAA/(Cr+Cho)和ADC值之间存在相关性(r=-0.79,P=0.002).结论 TLE患者患侧发作间期海马NAA/(Cr+Cho)值降低,ADC值升高,两者之间呈显著的负相关;~1H-MRS联合DWI可在活体无创反映海马硬化的病理结构改变.     

增强MR及DWI在脑转移瘤诊断应用

目的：探讨增强MR及DWI在脑转移瘤诊断应用价值。方法：回顾分析70例明确诊断为脑转移瘤病例,全部病例均进行MRI增强检查,其中44例同时行DWI检查,分别测定肿瘤实质、坏死囊变区、瘤周水肿及正常脑实质ADC值。结果：增强MRI共发现病灶525个,强化类型为结节状强化（289）、环状强化（198）、片状强化（13）和环斑片状强化（25）。转移瘤病灶部位ADC值：实质区（1．136±0．320）X10一、囊变坏死区（2．166±0．492）×10^-3、周围水肿区（1．587±0．228）×10^-3和正常脑实质区（0．802±0．148）×10^-3,这四者间ADC值差异显著性。结论：增强MRI检查能够准确反应脑转移瘤分布、大小、形态及周围组织受累情况,并能检出更多MRI平扫所不能显示微小病灶,DWI检查及ADC值能反应脑转移瘤组织微观结构变化,对于脑转移瘤诊断起到一定辅助诊断作用。     

Role of diffusion weighted imaging and proton magnetic resonance spectroscopy in ring enhancing brain lesions

Aim of the work

To assess and compare the usefulness and efficacy of both diffusion weighted imaging (DWI) and proton magnetic resonance spectroscopy (¹HMRS) in brain lesions with ring enhancement in post contrast T1WI and to determine which method is more effective.

Subjects and methods

Thirty patients with ring-enhanced brain lesions were classified into 2 groups, abscess group (11 patients) and tumor group (19 patients), were examined using diffusion-weighted imaging (DWI) and H-proton magnetic resonance spectroscopy (¹HMRS).

Results

Restricted diffusion and low ADC value were seen in 9 (81%) patients of brain abscesses, however, free diffusion and high ADC value were found in 18 (94%) patients with necrotic brain tumor. The abscess group showed aminoacids, acetate and lactate in 9 patients and extra peak of succinate was found in 1 patient; however in the tumor group lactate alone was found in 12 patients, lactate and choline were seen in 5 patients, none of the patients showed amino acids, succinate or acetate.

Conclusion

Both DWI and ¹HMRS are useful and efficient imaging techniques in ring enhancing brain lesions and differentiate between pyogenic brain abscesses and necrotic tumors, but DWI is accurate, has less imaging time than ¹HMRS, also is available in many imaging centers.     

Phenylketonuria: diffusion magnetic resonance imaging and proton magnetic resonance spectroscopy

Two patients with phenylketonuria are reported with white matter lesions. Diffusion magnetic resonance (MR) imaging revealed restricted diffusion patterns (high signal) on b = 1000 s/mm2 images associated with low apparent diffusion coefficient values ranging between 0.44 x 10-3 mm2/s and 0.56 x 10-3 mm2/s. On proton MR spectroscopy obtained in 1 of the patients, a prominent peak resonating at approximately 3.80 ppm was consistently present attributable to the peak rising from the alpha-proton of the phenylalanine molecule.     

Diagnostic yield of combined magnetic resonance spectroscopy and diffusion weighted imaging in intracranial neoplasms

Purpose

Our intention was to evaluate the role of combined diffusion magnetic resonance imaging and spectroscopy in diagnosis and grading of brain tumors.

Materials and methods

Ninety-three included cases underwent magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of the brain lesion, stereotactic or open biopsies and histopathological examination. MRI protocol included DWI and calculated ADC values. Multivoxel MRS spectroscopic technique (MVS) was used and all MRS metabolic parameters were obtained.

Results

High grade tumors had significantly lower ADC values than low grade tumors (P < 0.001). ADC values were the lowest in lymphoma (0.54 × 10⁻³ mm²/s) and the highest in craniopharyngioma (1.9 × 10⁻³ mm²/s). MRS revealed a statistically significant difference in CHO/NAA and CHO/Cr ratios between low and high grade tumors with P < 0.01 and P < 0.001, respectively. The mI/Cr ratio and presence of lactate, lipid and taurine also aided in differentiation and grading of brain tumors. The overall MRI/MRS sensitivity and specificity were 91%, 90.5%, respectively.

Conclusion

MRS has a robust diagnostic accuracy in cases of well defined high or low grade brain neoplasms. ADC value had the ability to confirm and differentiate low from high grade tumors in many situations where there were diagnostic confusions with MRS due to borderline values.     

Sturge-Weber syndrome: diffusion magnetic resonance imaging and proton magnetic resonance spectroscopy findings

We report on the diffusion magnetic resonance imaging (MRI) and proton MR spectroscopy findings of a 26-year-old female patient with Sturge-Weber syndrome. Echo-planar trace diffusion MRI revealed mildly high signal intensity changes at parieto-occipital lobes on b = 1000 s/mm² images, suggesting restricted diffusion. On corresponding apparent diffusion coefficient maps, those areas had moderately high signal intensity and high apparent diffusion coefficient values (around 0.9×10(-3) mm²/s) compared with the contralateral symmetrical normal side of the brain (0.776×10(-3) mm²/s). This finding was consistent with increased motion of water molecules (disintegration of the neural tissue) in these regions. Proton MR spectroscopy revealed decreased N-acetyl aspartate and increased choline peaks, indicating disintegration of neural tissue associated with neuronal loss as well.     

Trace apparent diffusion coefficients of metabolites in human brain using diffusion weighted magnetic resonance spectroscopy.

The rotationally invariant trace/3 apparent diffusion coefficients (ADC) of N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), and choline (Cho) were determined using a diffusion-weighted stimulated echo acquisition mode sequence at 3 T in three separate human brain regions, namely the subcortical white matter, occipital gray matter, and frontal gray matter. The measurement of the mean diffusivity eliminates the dependence of the measured ADC on the direction of the diffusion gradient relative to the tissue microstructure (i.e., anisotropy). Macroscopic brain motions induce phase errors that were compensated for by phasing (zero and first order) on the single average spectrum (zero order on the NAA peak) prior to summing the individual spectra. This method yielded reproducible trace/3 ADC values in the expected range without the use of cardiac gating. The mean diffusivity of NAA (0.14 +/- 0.03 x 10(-3) mm(2)/s) appears to be less than that of tCr (0.17 +/- 0.04 x 10(-3) mm(2)/s) and Cho (0.18 +/- 0.05 x 10(-3) mm(2)/s) in human brain.     

Solitary thyroid nodule: Diagnostic yield of combined diffusion weighted imaging and magnetic resonance spectroscopy

Aim

The scope of this study is to evaluate the combined application of MR-DWI and MRS in differentiating between benign and malignant thyroid nodules.

Tyrosinemia: computed tomography, magnetic resonance imaging, diffusion magnetic resonance imaging, and proton spectroscopy findings in the brain

In a 5-month-old boy with tyrosinemia, computed tomography revealed diffuse hypodensity in the centrum semiovale. Magnetic resonance (MR) imaging revealed partial signal differences in the white matter and perirolandic regions, and the posterior limbs of the internal capsules revealed higher signal compared with the remainder of the white matter. There were high-signal changes (restricted water diffusion) in the corresponding regions on images of diffusion-weighted MR imaging (b = 1000 s/mm). This likely represented the presence of intramyelinic edema attributable to status spongiosus. Proton MR spectroscopy (repetition time = 1500 milliseconds, echo time = 40 milliseconds) from the lesion sites revealed 2 separate prominent peaks spread between 3.4 and 3.9 ppm. These peaks could represent the CH and CH2 aliphatic protons of the tyrosine molecule.     

L-2 hydroxyglutaric aciduria: proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging findings

A 10-month-old boy was reported with the diagnosis of L-2 hydroxyglutaric aciduria. Amino acid chromatographic analysis revealed an 80-fold increase of hydroxyglutaric acid in the urine. Proton magnetic resonance (MR) spectroscopy of the brain obtained with the hybrid chemical shift imaging sequence (repetition time = 1,500 milliseconds, echo time = 40 milliseconds) revealed prominent peaks resonating at 2.50 ppm, which were attributable to L-2 hydroxyglutaric acid. Diffusion MR imaging was obtained using the echo-planar trace sequence (repetition time = 5,700 milliseconds, echo time = 139 milliseconds). Two different diffusion patterns were evident: a restricted diffusion pattern in the globi pallidi and an increased diffusion pattern in the white matter.     

Diagnostic interplay of proton magnetic resonance spectroscopy and diffusion weighted images with apparent diffusion coefficient values in suspicious breast lesions

Aim of the work

To study the diagnostic performance of combined single voxel 1H-MRS and DW-MRI with ADC values as a non-contrast diagnostic tool, compared to the DCE-MRI, in suspicious breast lesions.

磁共振全身弥散成像的临床应用价值

从20世纪90年代以来,随着磁共振成像(MRI)技术的飞速进展,弥散加权成像(diffusion-weighted imaging,DWI)技术已广泛应用于扫描腹部、盆腔等颅外部位[1].高梯度场的应用、多通道线圈、平板回波成像(echo planar imaging,EPI)、并行采集(ASSET)等技术[2-3]拓展了DWI的应用范围,特别是并行采集技术缩短了TE时间、回波链长度及K-空间填充时间,从而使运动伪影大大减少,提高了弥散图像质量.