磁敏感加权成像及波谱成像在脑星形细胞瘤分级诊断中的价值研究

目的探讨磁敏感加权成像(SWI)及波谱成像(MRS)在脑高、低级别星形细胞瘤鉴别诊断中的价值。资料与方法搜集2009年12月至2011年1月37例经手术病理证实的星形细胞瘤患者的MRI资料,所有患者术前均应用Siemens Verio 3.0 T超导磁共振仪行常规MRI平扫+增强、SWI和2D1H-MRS,并将各自结果同病理结果比较并统计分析,得出敏感度、特异度并同常规MRI比较。结果 (1)SWI序列中显示星形细胞瘤的出血率在高、低级别星形细胞瘤鉴别诊断中无显著性差异(P>0.05),而出血量在高、低级别星形细胞瘤鉴别诊断中有显著性差异(P<0.05)。(2)高、低级别星形细胞瘤瘤体代谢物胆碱(Cho)/N-乙酰天门冬氨酸(NAA)、Cho/肌酸(Cr)、NAA/Cr均有显著性差异(P<0.05)。(3)瘤体出血指数C值和Cho/NAA联合筛检,敏感度100%,特异度83.3%。结论 (1)同常规MRI比较,SWI能提高星形细胞瘤分级诊断的特异度,2D1H-MRS能提高星形细胞瘤分级诊断的准确度。(2)瘤体出血指数C值和Cho/NAA值联合筛检能提高星形细胞瘤分级诊断的敏感度。     

The Value of Susceptibility Weighted Imaging and Magnetic Resonance Spectroscopy in Grading Brain Astrocytoma

目的 探讨磁敏感加权成像(SWI)及波谱成像(MRS)在脑高、低级别星形细胞瘤鉴别诊断中的价值.资料与方法 搜集2009年12月至2011年1月37例经手术病理证实的星形细胞瘤患者的MRI资料,所有患者术前均应用Siemens Verio 3.0 T超导磁共振仪行常规MRI平扫+增强、SWI和2D 1H-MRS,并将各自结果同病理结果比较并统计分析,得出敏感度、特异度并同常规MRI比较.结果 (1)SWI序列中显示星形细胞瘤的出血率在高、低级别星形细胞瘤鉴别诊断中无显著性差异(P＞0.05),而出血量在高、低级别星形细胞瘤鉴别诊断中有显著性差异(P＜0.05).(2)高、低级别星形细胞瘤瘤体代谢物胆碱( Cho)/N-乙酰天门冬氨酸(NAA)、Cho/肌酸(Cr)、NAA/Cr均有显著性差异(P＜0.05).(3)瘤体出血指数C值和Cho/NAA联合筛检,敏感度100％,特异度83.3％.结论 (1)同常规MRI比较,SWI能提高星形细胞瘤分级诊断的特异度,2D 1H-MRS能提高星形细胞瘤分级诊断的准确度.(2)瘤体出血指数C值和Cho/NAA值联合筛检能提高星形细胞瘤分级诊断的敏感度.     

3D多体素1H-MRS对星形细胞瘤分级的诊断价值

目的探讨3D多体素质子波谱成像(1H-MRS)对脑低、高级星形细胞瘤鉴别诊断的价值和限度。资料与方法前瞻分析60例星形细胞瘤患者的传统平扫加增强及3D多体素1H-MRS资料,病理分为高级别组(WHOⅢ、Ⅳ级)和低级别组(WHOⅠ、Ⅱ级)。结果(1)传统MR平扫加增强诊断高级别星形细胞瘤的敏感性为70.5%、特异性为68.8%。(2)瘤体实质区胆碱(Cho)/N-乙酰天门冬氨酸(NAA)的敏感性82.0%,特异性81.0%;瘤周区Cho/NAA的敏感性77.0%,特异性81.0%;瘤体实质区乳酸(Lac)/肌酸(Cr)的敏感性82.0%,特异性88.0%;瘤周区乳酸盐(Lac)/肌酸(Cr)的敏感性91.0%,特异性69.1%。结论同传统MR相比,1H-MRS 3D多体素检查能增加星形细胞瘤分级诊断的敏感性,是传统MR检查的一种重要补充。     

3.0T ~1H-MRS在脑内高级别星形细胞瘤及单发转移瘤鉴别诊断中的价值

目的:探讨多体素氢质子磁共振波谱(1 H-MRS)对脑高级别星形细胞瘤、单发脑转移瘤的鉴别诊断价值。方法:收集经手术、活检病理证实的颅脑肿瘤患者37例,其中高级别星形细胞瘤(Ⅲ~Ⅳ级)17例(间变性星形细胞瘤5例,胶质母细胞瘤12例),脑单发转移瘤20例。37例行颅脑常规MRI检查及多体素1 H-MRS分析,分析肿瘤实质强化区、强化边缘区、对侧相应正常区域脑组织的生化代谢物及其比值,并进行对照。结果:1脑高级别星形细胞瘤、脑转移瘤1 H-MRS与对侧相应正常区域对比均表现为Cho峰升高,NAA、Cr峰下降。12例胶质母细胞瘤中,显示Lip峰者11例。20例脑转移瘤中,11例见Lac峰升高,9例Lip峰升高。2高级别星形细胞瘤肿瘤实体区的Cho/NAA明显高于脑转移瘤(P0.05);高级别星形细胞瘤瘤周水肿的Cho/Cr、Cho/NAA明显高于脑转移瘤(P0.05)。结论:3.0T1 H-MRS分析对高级别星形细胞瘤、脑单发转移瘤的诊断和鉴别诊断有重要价值,可作为一种非损伤性的鉴别手段;肿瘤瘤周水肿带的波谱更有利于胶质瘤与转移瘤的鉴别。     

3.0 T磁共振灌注加权成像在脑星形细胞瘤分级诊断中的价值

目的 探讨对比剂首过MR灌注加权成像(perfusion weighted imaging,PWI)在脑高、低级别星形细胞瘤鉴别诊断中的价值.资料与方法 分析40例经手术病理证实的星形细胞瘤患者的MRI资料,所有患者术前均行常规MRI平扫+增强、PWI,其中低级别组(WHOⅠ、Ⅱ级)14例,高级别组(WHO Ⅲ、Ⅳ级)26例.结果 常规MR平扫+增强扫描诊断高级别星形细胞瘤的敏感性为69.2%,特异性为64.3%,阳性预测值为78.3%,阴性预测值为52.9%,准确性为67.5%.高、低级别星形细胞瘤瘤体实质相对脑血容量(rCBV)值和相对脑血流量(rCBF)值差异均有统计学意义(P<0.05),而相对平均通过时间(rMTT)值差异无统计学意义(P>0.05).选择Youden指数最大值作为高、低级别星形细胞瘤最佳诊断临界点时,瘤体实质rCBV值受试者工作特征(ROC)曲线下面积(AUC)为0.961,阈值为2.71,敏感性为85.0%,特异性为100%,阳性预测值为100%,阴性预测值为78.0%;瘤体实质rCBF值ROC曲线的AUC为0.877,阈值为1.45,敏感性为85.0%,特异性为71.0%,阳性预测值为85.0%,阴性预测值为71.0%.结论 与常规MRI比较,对比剂首过PWI能提高术前星形细胞瘤分级诊断的准确性.瘤体实质rCBV值是星形细胞瘤分级诊断的最特异性指标.     

联合应用MR DCE、DWI与1H-MRS对乳腺肿瘤的诊断价值

目的 探讨MR动态增强扫描(DCE)、DWI、氢质子磁共振波谱(1H-MRS)三者联合检查在乳腺肿瘤的临床应用价值.方法 回顾性分析54例乳腺肿瘤患者(恶性29例,良性25例)的DCE、DWI和1 H-MRS表现,并与手术后病理结果对比,得出以DCE为主,分别联合DWIADC(方法A)、1H-MRS(方法B)及三者结合(方法C)三种方法对乳腺癌诊断的敏感度、特异度、准确率,并分别评价三种方法与病理诊断的一致性.结果 所有患者均得到术后病理证实,方法A诊断乳腺癌的敏感度为84.0％、特异度为72.4％、准确率为77.8％;方法B诊断乳腺癌的敏感度为75.9％、特异度为84.0％、准确率为79.6％;方法C诊断乳腺癌的敏感度为89.6％、特异度为88.0％、准确率为88.9％;方法A、B法、C法与病理诊断的Kappa值分别0.551、0.594、0.777.结论 DCE、DWI和1H-MRS三者联合诊断乳腺癌的敏感度、特异度、准确率均明显高于DCE联合DWI或1H-MRS,且与病理诊断的一致性好.     

MR增强扫描诊断膝关节前交叉韧带部分撕裂

目的:评价MR增强扫描对膝关节前交叉韧带(ACL)部分撕裂的诊断价值。方法:回顾性分析有手术资料的56例患者的膝关节平扫加增强MR扫描图像,分析计算MRI对ACL部分撕裂的诊断价值。结果:MRI平扫诊断ACL 部分撕裂的诊断符合率、特异度、敏感度分别为73．2％、89．2％、82．1％;MRI平扫加增强扫描诊断ACL部分撕裂的诊断符合率、特异度、敏感度分别为91．1％、100％、82．1％。MR平扫加增强对诊断前交叉韧带部分撕裂的诊断符合率明显高于单纯MR平扫,差异有显著性意义(P<0．05);而两者间诊断特异度及敏感度的差异无显著性意义(P>0．05)。结论: 膝关节MR平扫加增强扫描对诊断ACL部分撕裂优于常规MRI扫描。     

IVIM与DSC灌注成像在脑星形细胞瘤分级中的诊断价值

目的：探讨 MR 体素内不相干运动(IVIM)成像与动态磁敏感对比增强(DSC)灌注成像在脑星形细胞瘤分级中的诊断价值。方法对手术病理证实的22例高级别及28例低级别星形细胞瘤患者术前行 MR 常规扫描及 IVIM、DSC 扫描,定量测量2组肿瘤实质区 IVIM 成像参数值,包括标准扩散系数(ADCstandard )、慢扩散系数(D)、快扩散系数(D?)、灌注分数(f)和 DSC 灌注成像参数值,包括相对脑血容量(rCBV)、相对脑血流量(rCBF),采用两独立样本 t 检验分析各参数值在高、低级别脑星形细胞瘤中是否有统计学差异,应用受试者工作特征曲线(ROC)评价单独及联合应用 IVIM 成像和 DSC 灌注成像的诊断效能。结果肿瘤实质区ADCstandard 值、D 值、rCBV 值、rCBF 值在脑星形细胞瘤分级中有明显统计学差异(P <0.01);D?值、f 值在脑星形细胞瘤分级中无统计学差异(P=0.130,P=0.379);各参数值对脑星形细胞瘤分级的 ROC 曲线下面积为：ADCstandard 值0.823,D 值0.854,rCBV 值0.858,rCBF值0.871,D 值与 rCBV 和 rCBF 值联合应用0.952,0.953。结论D 值及 rCBV、rCBF 值可以对脑星形细胞瘤进行分级,联合应用IVIM 成像与 DSC 灌注成像可以提高脑星形细胞瘤分级的准确性。     

MR氢质子波谱成像在神经上皮组织肿瘤分级中的应用

目的研究MR氢质子波谱（^1H-MRS）成像在神经上皮组织肿瘤分级中的价值。方法52例颅内神经上皮组织肿瘤患者，低级别29例，高级别23例，均行MRI及^1H-MRS检查。结果52例中，Ⅱ级9例，Ⅲ级11例，Ⅳ级12例，将Ⅱ级列为低级别组，Ⅲ级、Ⅳ级为高级别组，脂质（Lip）[乳酸（Lac）]／肌酸（Cr）、Lip（Lac）／N-乙酰天门冬氨酸（NAA）、Lip（Lac）／胆碱化合物（Cho），Lip（Lac）在组间差异有统计学意义，低级别组各代谢物比值中位数分别为0．14、0．16、0．09、0．32，高级别组各代谢物中位数分别为1．64、1．24、0．87、1．68。Lip（Lac）／Cr≤0．425为低级别肿瘤，Lip（1ac）／Cr＞0．425为高级别肿瘤，诊断敏感度、特异度、阳性予测值、阴性预测值分别为87．0％、96．6％、95.2％、90．3％。常规MR图像诊断肿瘤级别敏感度、特异度、阳性予测值、阴性预测值分别为87．0％、82．8％、80．0％、88．9％。结论^1H-MRS在神经上皮组织肿瘤分级中有一定的价值，常规MR图像结合MRS可明显提高诊断准确率。     

中枢神经系统原发淋巴瘤和高级别星形细胞瘤MR灌注成像的对比研究

目的 探讨MR灌注成像鉴别中枢神经系统原发淋巴瘤(PCNSL)和高级别星形细胞瘤的价值.方法 PCNSL患者12例,高级别星形细胞肿瘤患者23例,手术前行常规MR检查及MR灌注检查,比较其MR灌注伪彩图像和灌注曲线,测量肿瘤实质部分最大相对脑血容量(rCBV),将所测量数值进行t检验.结果 PCNSL实质部分rCBV平均为1.8±0.5;高级别星形细胞瘤实质部分rCBV平均为3.9±0.9,二者之间差异有统计学意义(P<0.05).PCNSL实质区域时间-信号曲线对比剂首过后曲线逐渐接近基线,12例中有7例超过基线水平.高级别星形细胞瘤实质区域时间-信号曲线对比剂首过后曲线逐渐向基线水平靠拢,但均不能完全恢复到基线水平.结论 MR灌注成像有助于鉴别PCNSL和高级别星形细胞瘤.     

Measurements of diagnostic examination performance using quantitative apparent diffusion coefficient and proton MR spectroscopic imaging in the preoperative evaluation of tumor grade in cerebral gliomas

Purpose

Tumor grading is very important both in treatment decision and evaluation of prognosis. While tissue samples are obtained as part of most therapeutic approaches, factors that may result in inaccurate grading due to sampling error (namely, heterogeneity in tissue sampling, as well as tumor-grade heterogeneity within the same tumor specimen), have led to a desire to use imaging better to ascertain tumor grade. The purpose in our study was to evaluate the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), area under the curve (AUC), and accuracy of diffusion-weighted MR imaging (DWI), proton MR spectroscopic imaging (MRSI) or both in grading primary cerebral gliomas.

Materials and methods

We performed conventional MR imaging (MR), DWI, and MRSI in 74 patients with newly diagnosed brain gliomas: 59 patients had histologically verified high-grade gliomas: 37 glioblastomas multiform (GBM) and 22 anaplastic astrocytomas (AA), and 15 patients had low-grade gliomas. Apparent diffusion coefficient (ADC) values of tumor and peritumoral edema, and ADC ratios (ADC in tumor or peritumoral edema to ADC of contralateral white matter, as well as ADC in tumor to ADC in peritumoral edema) were determined from three regions of interest. The average of the mean, maximum, and minimum for ADC variables was calculated for each patient. The metabolite ratios of Cho/Cr and Cho/NAA at intermediate TE were assessed from spectral maps in the solid portion of tumor, peritumoral edema and contralateral normal-appearing white matter. Tumor grade determined with the two methods was then compared with that from histopathologic grading. Logistic regression and receiver operating characteristic (ROC) curve analysis were performed to determine optimum thresholds for tumor grading. Measures of diagnostic examination performance, such as sensitivity, specificity, PPV, NPV, AUC, and accuracy for identifying high-grade gliomas were also calculated.

Results

Statistical analysis demonstrated a threshold minimum ADC tumor value of 1.07 to provide sensitivity, specificity, PPV, and NPV of 79.7%, 60.0%, 88.7%, and 42.9% respectively, in determining high-grade gliomas. Threshold values of 1.35 and 1.78 for peritumoral Cho/Cr and Cho/NAA metabolite ratios resulted in sensitivity, specificity, PPV, and NPV of 83.3%, 85.1%, 41.7%, 97.6%, and 100%, 57.4%, 23.1% and 100% respectively for determining high-grade gliomas. Significant differences were noted in the ADC tumor values and ratios, peritumoral Cho/Cr and Cho/NAA metabolite ratios, and tumoral Cho/NAA ratio between low- and high-grade gliomas. The combination of mean ADC tumor value, maximum ADC tumor ratio, peritumoral Cho/Cr and Cho/NAA metabolite ratios resulted in sensitivity, specificity, PPV, and NPV of 91.5%, 100%, 100% and 60% respectively.

Conclusion

Combining DWI and MRSI increases the accuracy of preoperative imaging in the determination of glioma grade. MRSI had superior diagnostic performance in predicting glioma grade compared with DWI alone. The predictive values are helpful in the clinical decision-making process to evaluate the histologic grade of tumors, and provide a means of guiding treatment.     

Glioma grading: sensitivity, specificity, and predictive values of perfusion MR imaging and proton MR spectroscopic imaging compared with conventional MR imaging

BACKGROUND AND PURPOSE: Sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of conventional MR imaging in predicting glioma grade are not high. Relative cerebral blood volume (rCBV) measurements derived from perfusion MR imaging and metabolite ratios from proton MR spectroscopy are useful in predicting glioma grade. We evaluated the sensitivity, specificity, PPV, and NPV of perfusion MR imaging and MR spectroscopy compared with conventional MR imaging in grading primary gliomas. METHODS: One hundred sixty patients with a primary cerebral glioma underwent conventional MR imaging, dynamic contrast-enhanced T2*-weighted perfusion MR imaging, and proton MR spectroscopy. Gliomas were graded as low or high based on conventional MR imaging findings. The rCBV measurements were obtained from regions of maximum perfusion. Metabolite ratios (choline [Cho]/creatine [Cr], Cho/N-acetylaspartate [NAA], and NAA/Cr) were measured at a TE of 144 ms. Tumor grade determined with the three methods was then compared with that from histopathologic grading. Logistic regression and receiver operating characteristic analyses were performed to determine optimum thresholds for tumor grading. Sensitivity, specificity, PPV, and NPV for identifying high-grade gliomas were also calculated. RESULTS: Sensitivity, specificity, PPV, and NPV for determining a high-grade glioma with conventional MR imaging were 72.5%, 65.0%, 86.1%, and 44.1%, respectively. Statistical analysis demonstrated a threshold value of 1.75 for rCBV to provide sensitivity, specificity, PPV, and NPV of 95.0%, 57.5%, 87.0%, and 79.3%, respectively. Threshold values of 1.08 and 1.56 for Cho/Cr and 0.75 and 1.60 for Cho/NAA provided the minimum C2 and C1 errors, respectively, for determining a high-grade glioma. The combination of rCBV, Cho/Cr, and Cho/NAA resulted in sensitivity, specificity, PPV, and NPV of 93.3%, 60.0%, 87.5%, and 75.0%, respectively. Significant differences were noted in the rCBV and Cho/Cr, Cho/NAA, and NAA/Cr ratios between low- and high-grade gliomas (P <.0001,.0121,.001, and.0038, respectively). CONCLUSION: The rCBV measurements and metabolite ratios both individually and in combination can increase the sensitivity and PPV when compared with conventional MR imaging alone in determining glioma grade. The rCBV measurements had the most superior diagnostic performance (either with or without metabolite ratios) in predicting glioma grade. Threshold values can be used in a clinical setting to evaluate tumors preoperatively for histologic grade and provide a means for guiding treatment and predicting postoperative patient outcome.     

Proton magnetic resonance spectroscopy of brain tumors correlated with pathology

RATIONALE AND OBJECTIVES: Evaluate proton magnetic resonance spectroscopy ((1)H-MRS) for assessing and grading brain tumors. MATERIALS AND METHODS: The research was done at Detroit Medical Center in a 1.5-T Siemens MR magnet using single-voxel or multivoxel MRS. This study consisted of 27 patients: 10 females and 17 males ages 22-83 years (average age 43.8). The data were recorded for three peaks-N-acetyl aspartate (NAA), choline (Cho), creatine (Cr)-which were used to calculate the ratios Cho/NAA and Cho/Cr. RESULTS: Abnormal spectra were seen in 25 patients and normal spectra in 2. In 16 patients with brain astrocytoma of various grades, the pathology grading was correlated with Cho/NAA and Cho/Cr. These values were 6.53 and 3.35 for nine patients with Grade 4 astrocytoma; 1.85 and 1.62 for three patients with Grade 3 astrocytoma; 2.21 and 1.50 for three patients with Grade 2 astrocytoma; and 1.45 and 1.49 for one patient with Grade 1 astrocytoma. The remaining nine patients with abnormal spectra were also correlated with pathology. CONCLUSION: MRS ratios can be used to differentiate malignant and nonmalignant lesions from normal brain tissue. In general, high-grade astrocytoma have higher Cho/NAA and Cho/Cr ratios compared with low-grade astrocytoma.     

磁共振波谱在星形细胞肿瘤术前分级中的价值

目的 研究磁共振波谱(MRS)在星形细胞肿瘤术前分级中的价值. 方法 52例患者均经病理证实,其中弥漫性星形细胞瘤(WHO 2级)20例,间变性星形细胞瘤(WHO 3级)14例,胶质母细胞瘤(WHO 4级)18例.MRS采用多体素PRESS序列.结果 ①星形细胞肿瘤在MRS上常表现为Cho升高、NAA降低,级别越高变化越明显.在高度恶性星形细胞肿瘤中还可出现Lip峰.②对病例组中32例高度恶性星形细胞肿瘤采用Pearson相关回归分析法显示,肿瘤实质区的Cho/Cr(r＝0.656,P=0.000)、Lip1.3/Cr(r＝0.559,P=0.001)及Glx/Cr(r＝0.482,P=0.005)均与肿瘤的病理分级呈显著正相关;Cho/NAA(r＝0.395,P=0.025)、Lip0.9/Cr(r＝0.386,P=0.029)与病理分级呈正相关.③当Cho/Cr＝2时,诊断WHO 4级星形细胞肿瘤的敏感性为94.4%,特异性为64.3%,阳性预测值为77.3%,阴性预测值为90%.④当Lip1.3/Cr＝0.526时,诊断为WHO 4级星形细胞肿瘤的敏感性为88.9%,特异性为92.9%,阳性预测值为94.1%,阴性预测值为86.7%. 结论 MRS是一种有潜力的方法,有助于对肿瘤术前进行分级.     

脑星形细胞肿瘤多体素1H-MRS代谢物含量变化及其与Ki-67的相关性

目的:探讨脑星形细胞肿瘤中多体素1H-MRS代谢物含量的变化及其与Ki-67间的相关性。方法:应用SiemensSonata 1.5T超导型MR成像系统对41例脑星形细胞肿瘤患者进行常规MR扫描及MRS检查,其中28例进行了Ki-67抗原指标的免疫组化染色。磁共振波谱分析采用四通道正交头部专用线圈3D-CSI序列扫描,比较分析不同级别星形细胞肿瘤间代谢物情况。用兔抗人Ki-67单克隆抗体测定肿瘤标本的Ki-67抗原标记指数。应用SPSS统计软件进行统计学相关性分析。结果:低级别组脑星形细胞肿瘤多体素?1H-MRS均表现为Cho峰不同程度增高和NAA峰不同程度的降低,5例出现Lac峰,无出现Lip峰。高级别组脑星形细胞肿瘤均表现为Cho峰明显增高,NAA不同程度的明显降低,21例出现Lac峰,11例出现Lip峰。高低级别肿瘤间Cho/Cr,Cho/NAA和Lac/Cr比值有统计学意义的差别。Cho/Cr、Cho/NAA比值与Ki-67指数间均存在明显的相关关系(其相关系数分别为0.640、0.694)。结论:多体素1H-MRS代谢物含量与Ki-67间有良好的相关性,磁共振波谱分析能够为星形细胞肿瘤治疗方案的制定提供更多信息。     

Multimodal MRI in the characterization of glial neoplasms: the combined role of single-voxel MR spectroscopy,diffusion imaging and echo-planar perfusion imaging

INTRODUCTION: Diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and MR spectroscopy (MRS) provide useful data for tumor evaluation. To assess the contribution of these multimodal techniques in grading glial neoplasms, we compared the value of DWI, PWI and MRS in the evaluation of histologically proven high- and low-grade gliomas in a population of 105 patients. METHODS: Independently for each modality, the following variables were used to compare the tumors: minimum apparent diffusion coefficient (ADC) and maximum relative cerebral blood volume (rCBV) normalized values between tumor and healthy tissue, maximum Cho/Cr ratio and minimum NAA/Cr ratio in tumor, and scored lactate and lipid values in tumor. The Mann-Whitney and Wilcoxon tests were employed to compare DWI, PWI and MRS between tumor types. Logistic regression analysis was used to determine which parameters best increased the diagnostic accuracy in terms of sensitivity, specificity, and positive and negative predictive values. ROC curves were determined for parameters with high sensitivity and specificity to identify threshold values to separate high- from low-grade lesions. RESULTS: Statistically significant differences were found for rCBV tumor/normal tissue ratio, and NAA/Cr ratio in tumor and Cho/Cr ratio in tumor between low- and high-grade tumors. The best performing single parameter for group classification was the normalized rCBV value; including all parameters, statistical significance was reached by rCBV tumor/normal tissue ratio, NAA/Cr tumor ratio and lactate. From the ROC curves, a high probability for a neoplasm to be a high-grade lesion was associated with a rCBV tumor/normal tissue ratio of >1.16 and NAA/Cr tumor ratio of <0.44. CONCLUSION: Combining PWI and MRS with conventional MR imaging increases the accuracy of the attribution of malignancy to glial neoplasms. The best performing parameter was found to be the perfusion level.     

Multiparametric 3T MR approach to the assessment of cerebral gliomas: tumor extent and malignancy

Introduction Contrast-enhanced MR imaging is the method of choice for routine assessment of brain tumors, but it has limited sensitivity and specificity. We verified if the addition of metabolic, diffusion and hemodynamic information improved the definition of glioma extent and grade.Methods Thirty-one patients with cerebral gliomas (21 high- and 10 low-grade) underwent conventional MR imaging, proton MR spectroscopic imaging (¹H-MRSI), diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI) at 3 Tesla, before undergoing surgery and histological confirmation. Normalized metabolite signals, including choline (Cho), N-acetylaspartate (NAA), creatine and lactate/lipids, were obtained by ¹H-MRSI; apparent diffusion coefficient (ADC) by DWI; and relative cerebral blood volume (rCBV) by PWI.Results Perienhancing areas with abnormal MR signal showed 3 multiparametric patterns: “tumor”, with abnormal Cho/NAA ratio, lower ADC and higher rCBV; “edema”, with normal Cho/NAA ratio, higher ADC and lower rCBV; and “tumor/edema”, with abnormal Cho/NAA ratio and intermediate ADC and rCBV. Perienhancing areas with normal MR signal showed 2 multiparametric patterns: “infiltrated”, with high Cho and/or abnormal Cho/NAA ratio; and “normal”, with normal spectra. Stepwise discriminant analysis showed that the better classification accuracy of perienhancing areas was achieved when regarding all MR variables, while ¹H-MRSI variables and rCBV better differentiated high- from low-grade gliomas.Conclusion Multiparametric MR assessment of gliomas, based on ¹H-MRSI, PWI and DWI, discriminates infiltrating tumor from surrounding vasogenic edema or normal tissues, and high- from low-grade gliomas. This approach may provide useful information for guiding stereotactic biopsies, surgical resection and radiation treatment.