【作者】 伍建林； 张竟文；

【机构】 大连医科大学附属一院放射科；

【摘要】 目的通过对73例脑肿瘤以及5例炎性病变瘤(灶)周水肿区行磁共振弥散加权成像(diffusion-weightedimaging,DWI)和氢质子磁共振波谱(proton magnetic resonance spectroscopy,1H-MRS)检查,探讨瘤(灶)周水肿的DWI和1H-MRS表现在脑肿瘤诊断及界限界定方面的临床应用价值。方法对经手术病理和/或临床证实的73例脑肿瘤、3例脑脓肿及2例炎性肉芽肿患者进行常规MRI序列扫描、DWI和/或1H-MRS检查,对照分析病变的实质部分、周围水肿区以及正常脑组织的ADC值、EDC值以及1H-MRS的各种代谢物比值,包括Cho/NAA、Cho/Cr、Cho/nCho。为观察距离肿瘤增强部分不同区域在DWI及MRS的变化,对于瘤周水肿直径>1cm者我们还对瘤周异常信号区进行划分。距肿瘤强化外缘1cm以内的区域定义为近侧瘤周,距肿瘤强化外缘1cm以外的区域为远侧瘤周。全部数据经过SPSS(11.5)统计分析软件处理,各区域的瘤间差异用单因素ANOVA方差分析。同种病变不同区域之间的差异采用配伍组方差分析。统计结果均以x±s表示,P<0.05为显著性意义。结果①DWI:颅内肿瘤及炎性病变周围水肿区在DWI图上呈等(66.67%)或稍低(33.33%)信号。颅内肿瘤及炎性病变的近、远侧瘤周水肿的ADC(EDC)值明显高于(低于)对侧正常脑白质(P<0.02)。高级别胶质瘤与低级别胶质瘤、转移瘤、脑膜瘤、炎性病变之间的近侧瘤(灶)周水肿ADC(EDC)值存在差异(P<0.05)。各病变远侧水肿区之间的ADC(EDC)值无差别。高级别胶质瘤的近侧瘤周水肿区ADC(EDC)值低于(高于)远侧(P(0.05),且近侧瘤周水肿区ADC(EDC)值与瘤体接近(P>0.05);低级别胶质瘤瘤体与近、远侧瘤周水肿的ADC(EDC)均不能区分(P>0.05);脑膜瘤、炎性病变近侧瘤(灶)周水肿区ADC(EDC)值高于远侧(P<0.05)。若近侧瘤(灶)周水肿ADC值取14.85为阈值,则对区分高级别胶质瘤和其他颅内肿瘤及炎性病变而言,敏感性为87.5%。特异性为73.17%,阳性预测值(positive predictive value,PPV)为71.79%,阴性预测值(negative pre-dictive value,NPV)为88.24%。若近侧瘤周水肿ADC值取15.20作为高、低级别胶质瘤分级的阈值,则敏感性为93.75%,特异性为80.00%,PPV为96.77%,NPV为66.67%。②1H-MRS:在高级别胶质瘤瘤周水肿仍可见到异常谱线,表现为Cho升高、NAA接近正常或降低,这与正常脑组织和肿瘤瘤体波形均有明显区别。高级别胶质瘤近侧瘤周水肿的Cho/NAA值高于低级别胶质瘤、脑膜瘤、转移瘤和炎性病变相应区域(P≤0.001)。高级别胶质瘤近侧瘤周水肿处Cho/NAA值高于远侧瘤周水肿(P<0.05)。低级别胶质瘤、脑膜瘤和转移瘤近、远侧瘤周水肿之间Cho/NAA值无统计学差异(P>0.05)。若以近侧瘤(灶)周水肿处Cho/NAA值1.70为阈值,用于区别高级别胶质瘤和转移瘤、脑膜瘤及炎性病变,则敏感性为76.92%,特异性为86.36%,PPV为86.96%,NPV为76.00%。若选取近侧瘤周水肿区Cho/NAA值1.35为阈值,用于高、低级别胶质瘤的鉴别,则敏感性为96.15%,特异性为75.00%,PPV为96.15%,NPV为75.00%。高级别胶质瘤近侧、远侧瘤周水肿处的Cho/Cr值高于低级别胶质瘤、脑膜瘤和炎性病变(P<0.05),但和转移瘤之间差异不显著(P>.05)。高级别胶质瘤近侧瘤周水肿的Cho/Cr值高于远侧(P<0.001)。在低级别胶质瘤、脑膜瘤和炎性病变,近、远侧之间的Cho/Cr值则无统计学差异(P>0.05)。近侧瘤周水肿Cho/Cr值若取1.65为阈值,对于区分高级别胶质瘤和脑膜瘤、炎性病变而言,其敏感性为88.46%,特异性为81.82%,PPV为92.00%,NPV为75.00%。若以近侧瘤周水肿区Cho/Cr进行胶质瘤分级,取1.56为阈值,则敏感性为92.31%,特异性为75.00%,PPV为96.00%,NPV为60.00%。结论近侧瘤周水肿区ADC(EDC)值可用于高级别胶质瘤与转移瘤、脑膜瘤及炎性病变之间的鉴别诊断,但用于鉴别胶质瘤的肿瘤组织和瘤周水肿不可靠。高级别胶质瘤近侧瘤周水肿区ADC(EDC)值低于(高于)远侧,而在低级别胶质瘤、转移瘤、脑膜瘤和炎性病变却相反。近侧瘤周水肿区ADC(E1)C)值有助于高、低级别胶质瘤之间的分级诊断。近侧瘤周水肿区的Cho/NAA、Cho/Cr-值对高级别胶质瘤同转移瘤、脑膜瘤及炎性病变之间的鉴别诊断很有意义。同时对高、低级别胶质瘤的分级诊断也有一定的临床应用价值。1H-MRS可以较早并准确地显示胶质瘤瘤周浸润情况,有很高的临床应用价值。本研究支持“强化周边区域”(perienhancing region)概念的提出,有助于更合理的解释T2加权像上肿瘤及其周围的异常信号区域。更多还原

【Abstract】 Objective To evaluate the potential of DWI and 1H-MRS in diagnosing of intracranial tumors and defining the tumor boundary by analysing the parameters obtained from peritumoral edema. Methods Seventy-eight patients with clinically and /or histologically proved brain diseases(73 brain tumors,3 brain abscesses,2 inflammatory granulomas) underwent routine, diffusion-weighted and/or proton spectroscopic MR imaging. Comparisons of apparent diffusion coefficients (ADC), exponential diffusion coefficients (EDC) and metabolic ratios including of Cho/NAA,Cho/Cr,Cho/nCho were done among normal, peritumoral edematous and tumoral tissues. The peritumoral signal abnormality was divided into two regions to allow investigation of whether ADC (EDC) and metabolic ratios varies with distance of from the enhancing portion of the tumor. The immediate peritumoral area was defined to be within a 1 cm distance from the outer enhancing tumor margin) the distant peritumoral region was defined as greater than 1 cm from the tumor. ADCs (EDCs) and metabolic ratios obtained from the peritumoral regions among intracranial diseases were compared by using the one-way ANOVA. The two-way ANOVA was used to determine if there was a significant difference in the intracranial diseases a-mong different peritumoral regions. All the statistical data were displayed as x±s, a P value of less than 0. 05 indicated a statistically significant difference. Results (1)DWI DWI signal in peritumoral edema of intracranial diseases demonstrated iso-intensity (66. 67%) and slight hypointensity (33. 33%). ADC(EDC) in immediate and distant perifocal edema of brain tumors and inflammatory diseases were significantly higher (lower) than normal white matter (P<0. 02). ADC (EDC) of immediate perifocal edema were prominently significant for differentiating high-grade gliomas from low-grade gliomas, metastases, meningiomas and inflammation(P<0. 05), while no significantly difference was recorded among ADC(EDC) in distant peripheral edema of all diseases(P>0. 05). As for high-grade glioma, the ADC(EDC) of immediate peritumoral edema was lower (higher) than that of distant edema(P<0. 05) , and the former is similar to the contrast-enhancing portion(P>0. 05). The ADC (EDC) in immediate, distant peritumoral edema and solid portion of low-grade glioma could not distinguish from each other(P>0. 05). The ADC(EDC) of immediate peripheral edema in patients with meningioma or inflammatory disease differed significantly from those of distant peripheral edema(P<0. 05). A threshold value of 14. 85 for ADC in immediate perifocal edema provided 87. 5% ,73. 17% ,71. 19% and 88. 24% for the sensitivity, specificity, positive predictive value(PPV) and negative predictive value(NPV) for differentiation of a high-grade glioma from metastasis, meningioma and inflammation. A threshold value of 15. 20 provided 93. 75% ,80. 00% ,96. 77% and 66. 67% for the sensitivity, specificity, NPV and PPV for differentiation of a high-grade glioma from low-grade one. (2)1H-MRS High-grade glioma showed abnormal spectra outside the area of contrast enhancement, which demonstrated elevated Cho level, normal of decreased NAA level. This spectra is prominently different from normal tissue and solid tumoral tissue. The Cho/NAA in immediate peritumoral edema of patients with high-grade glioma was higher than that seen with low-grade glioma, meningioma, metastasis and inflammatory disease (P<0. 05). The Cho/NAA of immediate edema surrounding high-grade glioma is higher than that of distant edema (P<0. 05). The Cho/NAA between immediate and distant edema had no statistic significance in patients with low-grade glioma, metastasis and meningioma. A threshold of 1. 70 for Cho/NAA in immediate perifocal edema provided 76. 92% , 86. 36% , 86. 96% and 76. 00% for the sensitivity, specificity, PPV and NPV for differentiation a high-grade glioma from metastasis, meningioma and inflammation. A threshold of 1. 35 for Cho/NAA in immediate peritumoral edema provided 96. 15%, 75. 00%,96. 15% and 75. 00% for the sensitivity,specificity, P更多还原