脑膜瘤瘤周水肿的64层螺旋CT灌注成像定量研究

目的:应用64层螺旋CT灌注成像定量估计脑膜瘤瘤周水肿的灌注状况.方法:对15例脑肿膜瘤伴瘤周水肿患者进行MSCT灌注成像,经灌注软件处理分别计算近瘤周水肿区及远瘤周水肿区局部脑血流量(rCBF)、局部脑血容量(rCBV)、表面通透性(PS),并与对侧脑白质灌注参数进行比较;测量并计算水肿指数EI[(V水肿+V肿瘤)/V肿瘤],并与rrCBV(rCBV水肿平均/rCBV对侧脑白质)的进行相关性分析.结果:脑膜瘤近瘤周水肿区、远瘤周水肿区的rCBF和rCBV明显低于对侧脑白质(rCBF:t=5.78和4.34,P=0.001,0.005; rCBV:t=6.46和8.46,P=0.001,0.003),近瘤周水肿区的rCBF和rCBV低于远瘤周水肿区(rCBF:t=3.49,P=0.013;rCBV:t=4.10,P=0.006),三组间PS值的差异均没有统计学意义(P值均＞0.05);水肿指数跟瘤周水肿区的rrCBV值呈负相关(r=-0.72,P＜0.01);2例恶性脑膜瘤近瘤周水肿区的rCBV、rCBF、PS值的均数明显高于良性脑膜瘤近瘤周水肿区.结论:脑膜瘤瘤周水肿区的灌注具有一定特征,有助于鉴别肿瘤良恶性,优化手术方案及相关辅助治疗、评价手术疗效、鉴别肿瘤复发和坏死.     

CT灌注成像对脑肿瘤瘤周水肿的评价

目的　应用CT灌注成像半定量估计脑肿瘤瘤周水肿的灌注状况。方法　应用SomatomPlus4螺旋CT机,对21例脑肿瘤瘤周水肿患者[脑膜瘤4例,胶质瘤(Ⅲ~Ⅳ级)7例、转移瘤10例]进行CT灌注成像,经灌注软件处理分别计算瘤周水肿区局部脑血流量(rCBF)、局部脑血容量(rCBV)、对比剂平均通过时间(MTT),并与对侧脑白质和不同肿瘤瘤周水肿间的灌注参数进行比较。结果　脑膜瘤和转移瘤瘤周水肿的rCBF和rCBV明显低于对侧脑白质(rCBF:t=2 .92和3 .82,P值均<0. 05, 0. 005;rCBV:t=2 .42和3. 53, P<0 .05, 0 .01),胶质瘤瘤周水肿的rCBF和rCBV与正常脑白质无明显差别(t=1 .00和1 .33, P值均>0 .05)。瘤周水肿区与对侧正常脑白质rCBF、rCBV比值,脑膜瘤和转移瘤之间差异无统计学意义(t=0 .23和0. 73, P值均>0 .05),胶质瘤明显大于脑膜瘤和转移瘤(t=3 .05和3. 37, P<0 .01, 0 .005)。结论　脑膜瘤和转移瘤瘤周水肿区的rCBF、rCBV显著降低,而胶质瘤瘤周水肿区接近或高于对侧脑白质,CT灌注能定量脑肿瘤瘤周水肿血流灌注状况,有助于肿瘤的鉴别和随访。     

Alterations in diffusion and perfusion in the pathogenesis of peritumoral brain edema in meningiomas

Magnetic resonance perfusion and diffusion studies were undertaken to clarify the significance of ischemia in the pathogenesis of peritumoral brain edema in patients with meningiomas. Included in this study were 26 patients with 27 meningiomas and 5 gliomas. Perfusion-weighted imaging (PWI) was performed using a gradient-echo, echo-planar-imaging (EPI) sequence for calculation of the relative regional cerebral blood volume (rrCBV) and the relative regional cerebral blood flow index (rrCBFi). Furthermore, multi-slice spin-echo EPI sequences were applied in order to obtain anisotropic and isotropic diffusion-weighted imaging (DWI). Apparent diffusion coefficient (ADC) values were then calculated for peritumoral brain parenchyma from tumors, with and without edema, using various diffusion sensitivities. Meningiomas without edema demonstrated a minimal increase of perfusion parameters in the peritumoral brain tissue. In contrast, cases with brain edema had highly significant ( p<0.0005) lower rrCBV and rrCBFi. The edema index (EI) correlated strongly with the rrCBV. A fitting procedure resulted into the following mathematical relation: EI=0.1/rrCBV(2). The DWI showed a significantly larger ADC value within areas of brain edema, compared with the normal white matter (0.74 x 10(-3) vs 1.55 x 10(-3) mm(2)/s; p<0.0001). Increases in EI correlated with increases in ADC values. In 31% of the meningiomas associated with edema, areas with increased signal, probable ischemia, demonstrated significantly lower ADC values, in comparison with the rest of the edematous areas. These areas were confined to tissue immediately adjacent to the tumor. In general, the decrease in rrCBV in brain edema represents a consequence from, rather than a cause of, vasogenic edema. Ischemic alterations can be regarded as secondary, facultative phenomena in the pathogenesis of meningioma-related brain edema.     

Perfusion MR imaging for differentiation of benign and malignant meningiomas

INTRODUCTION: Our purpose was to determine whether perfusion MR imaging can be used to differentiate benign and malignant meningiomas on the basis of the differences in perfusion of tumor parenchyma and/or peritumoral edema. METHODS: A total of 33 patients with preoperative meningiomas (25 benign and 8 malignant) underwent conventional and dynamic susceptibility contrast perfusion MR imaging. Maximal relative cerebral blood volume (rCBV) and the corresponding relative mean time to enhance (rMTE) (relative to the contralateral normal white matter) in both tumor parenchyma and peritumoral edema were measured. The independent samples t-test was used to determine whether there was a statistically significant difference in the mean rCBV and rMTE ratios between benign and malignant meningiomas. RESULTS: The mean maximal rCBV values of benign and malignant meningiomas were 7.16+/-4.08 (mean+/-SD) and 5.89+/-3.86, respectively, in the parenchyma, and 1.05+/-0.96 and 3.82+/-1.39, respectively, in the peritumoral edema. The mean rMTE values were 1.16+/-0.24 and 1.30+/-0.32, respectively, in the parenchyma, and 0.91+/-0.25 and 1.24+/-0.35, respectively, in the peritumoral edema. The differences in rCBV and rMTE values between benign and malignant meningiomas were not statistically significant (P>0.05) in the parenchyma, but both were statistically significant (P<0.05) in the peritumoral edema. CONCLUSION: Perfusion MR imaging can provide useful information on meningioma vascularity which is not available from conventional MRI. Measurement of maximal rCBV and corresponding rMTE values in the peritumoral edema is useful in the preoperative differentiation between benign and malignant meningiomas.     

High-grade gliomas and solitary metastases: differentiation by using perfusion and proton spectroscopic MR imaging

PURPOSE: To determine whether perfusion-weighted and proton spectroscopic MR imaging can be used to differentiate high-grade primary gliomas and solitary metastases on the basis of differences in vascularity and metabolite levels in the peritumoral region. MATERIALS AND METHODS: Fifty-one patients with a solitary brain tumor (33 gliomas, 18 metastases) underwent conventional, contrast material--enhanced perfusion-weighted, and proton spectroscopic MR imaging before surgical resection or stereotactic biopsy. Of the 33 patients with gliomas, 22 underwent perfusion-weighted MR imaging; nine, spectroscopic MR imaging; and two underwent both. Of the 18 patients with metastases, 12 underwent perfusion-weighted MR imaging, and six, spectroscopic MR imaging. The peritumoral region was defined as the area in the white matter immediately adjacent to the enhancing (hyperintense on T2-weighted images, but not enhancing on postcontrast T1-weighted images) portion of the tumor. Relative cerebral blood volumes in these regions were calculated from perfusion-weighted MR data. Spectra from the enhancing tumor, the peritumoral region, and normal brain were obtained from the two-dimensional spectroscopic MR acquisition. The Student t test was used to determine if there was a statistically significant difference in relative cerebral blood volume and metabolic ratios between high-grade gliomas and metastases. RESULTS: The measured relative cerebral blood volumes in the peritumoral region in high-grade gliomas and metastases were 1.31 +/- 0.97 (mean +/- SD) and 0.39 +/- 0.19, respectively. The difference was statistically significant (P <.001). Spectroscopic imaging demonstrated elevated choline levels (choline-to-creatine ratio was 2.28 +/- 1.24) in the peritumoral region of gliomas but not in metastases (choline-to-creatine ratio was 0.76 +/- 0.23). The difference was statistically significant (P =.001). CONCLUSION: Although conventional MR imaging characteristics of solitary metastases and primary high-grade gliomas may sometimes be similar, perfusion-weighted and spectroscopic MR imaging enable distinction between the two.     

Preoperative subtyping of meningiomas by perfusion MR imaging

Introduction  This paper aims to evaluate the value of perfusion magnetic resonance (MR) imaging in the preoperative subtyping of meningiomas by analyzing the relative cerebral blood volume (rCBV) of three benign subtypes and anaplastic meningiomas separately. Materials and methods  Thirty-seven meningiomas with peritumoral edema (15 meningothelial, ten fibrous, four angiomatous, and eight anaplastic) underwent perfusion MR imaging by using a gradient echo echo-planar sequence. The maximal rCBV (compared with contralateral normal white matter) in both tumoral parenchyma and peritumoral edema of each tumor was measured. The mean rCBVs of each two histological subtypes were compared using one-way analysis of variance and least significant difference tests. A p value less than 0.05 indicated a statistically significant difference. Results  The mean rCBV of meningothelial, fibrous, angiomatous, and anaplastic meningiomas in tumoral parenchyma were 6.93 ± 3.75, 5.61 ± 4.03, 11.86 ± 1.93, and 5.89 ± 3.85, respectively, and in the peritumoral edema 0.87 ± 0.62, 1.38 ± 1.44, 0.87 ± 0.30, and 3.28 ± 1.39, respectively. The mean rCBV in tumoral parenchyma of angiomatous meningiomas and in the peritumoral edema of anaplastic meningiomas were statistically different (p < 0.05) from the other types of meningiomas. Conclusion  Perfusion MR imaging can provide useful functional information on meningiomas and help in the preoperative diagnosis of some subtypes of meningiomas.     

PC机辅助MR脑灌注成像初步研究

目的:研究PC机辅助MR脑灌注成像软件,探讨其临床应用价值。方法:在PC机上使用MR脑灌注成像软件,对5例健康人和18例脑缺血患者的灌注图像进行后处理,计算出有关脑灌注参数图,包括相对脑血流量(rrCBF)图、相对脑血容量(rrCBV)图、局部灌注达峰时间(TTP)图和团注平均通过时间(bMTT)图。结果:应用MR脑灌注成像软件可以在PC机上实现灌注图像的后处理,脑灌注参数图能够为脑缺血患者提供有价值的脑血液动力学信息,显示灌注异常的范围。结论:PC机辅助MR脑灌注成像软件简单易行,可显示常规MR无法显示的血流动力学异常,对临床和科研具有重要价值。     

Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging

Introduction We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging. Methods The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P < 0.05 was taken as indicating statistical significance. Results The mean MD values (×10⁻³ mm²/s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 ± 0.057 and 0.820 ± 0.094, the mean MD ratios were 220.3 ± 22.6 and 193.1 ± 23.4, the mean FA values were 0.146 ± 0.026 and 0.199 ± 0.052, and the mean FA ratios were 32.3 ± 5.9 and 46.0 ± 12.1. All the values were significantly different between metastases and meningiomas (MD values P = 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002). Conclusion The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging.     

MR-Perfusions- und spektroskopische Bildgebung bei WHO-Grad-II-Astrozytomen

BACKGROUND: This study evaluates whether MR perfusion imaging and spectroscopic imaging (MRSI) can depict anaplastic areas in WHO grade II astrocytomas, whether these areas are co-localized, and whether the prognosis can be better predicted. MATERIAL AND METHODS: Fifteen patients (nine female, six male, aged 42+/-14 years) with WHO grade II astrocytomas but without preceding radio- or chemotherapy were examined every 3 months with MR perfusion imaging and MRSI (mean follow-up 18 months). Using a region of interest analysis, the regional relative cerebral blood volume (rrCBV) and blood flow (rrCBF) were measured in tumor tissue. In the same areas, choline/creatine (Cho/Cr) and choline/N-acetyl-aspartate (Cho/NAA) ratios were quantified. RESULTS: During follow-up, nine patients had stable disease. In six patients, the tumor showed progression and contrast-enhancement. The progressing tumors had already had higher perfusion (rrCBF 2.1+/-1.4; rrCBV 1.9+/-1.1) parameters than the stable astrocytomas (rrCBF 1.2+/-0.6, p=0.01; rrCBV 1.4+/-0.8, p=0.05) at first examination. However, the Cho/NAA and Cho/Cr ratios only tended to be higher than in stable astrocytomas (Cho/NAA 2.4+/-1.0 vs. 2.0+/-1.5, p=0.23; Cho/Cr 1.7+/-0.6 vs. 1.4+/-0.5, p=0.06). In all six progressing tumors, areas of maximum perfusion and maximum Cho/NAA and Cho/Cr ratio were co-localized. During follow-up, contrast-enhancement was observed in these areas. CONCLUSIONS: MR perfusion imaging can depict anaplastic areas in WHO grade II astrocytomas earlier than conventional MRI and thus enables a better prediction of prognosis.     

DTI多参数值及DTT技术在颅内肿瘤中的应用研究

目的 探讨MR扩散张量成像(DTI)多参数值在脑肿瘤中的诊断和鉴别诊断价值;评价扩散张量纤维柬成像(DTT)在显示脑肿瘤与周围脑白质纤维束关系中的应用.资料与方法 搜集经手术病理证实的星形细胞瘤(低级别、高级别)、脑膜瘤、转移瘤患者资料(低级别星形细胞瘤15例,高级别星形细胞瘤18例,脑膜瘤16例,转移瘤10例)共59例.行常规T_1WI、T_2WI、增强T_1WI及DTI.测量病灶肿瘤实质区、瘤周水肿区、囊变坏死区、水肿邻近正常白质区及对侧正常白质区的平均扩散系数(DCavg)值、部分各向异性分数(FA)值、1-容积比(1-VR)值及相对各向异性(RA)值,分析各测量值在肿瘤的诊断及良恶性鉴别诊断中的作用.利用DTI数据进行DTT重组病变周围脑白质纤维束,观察肿瘤与脑白质纤维束的关系.结果 低级别星形细胞瘤、高级别星形细胞瘤、脑膜瘤及转移瘤的肿瘤实体、瘤周水肿区的FA值、1-VR值及RA值差异均具有统计学意义(P<0.05);对侧正常白质区DCavg值、FA值、1-VR值及RA值差异均具有统计学意义(P<0.5).FA图、FA彩色编码图、DTT图均能显示脑白质纤维受累情况,而常规MRI难以显示;脑白质纤维束与脑肿瘤的位置关系可分为四型,即推挤型、水肿型、浸润型和破坏型.低级别星形细胞瘤及脑膜瘤良性肿瘤周围的白质纤维束多呈推挤水肿改变,而高级别星形细胞瘤及转移瘤恶性肿瘤周围的白质纤维束多表现为以浸润破坏为主.结论 DTI较常规MRI能更确切、直观地显示脑内肿瘤与周围脑白质的关系,结合FA值、1-VR值及RA值能为肿瘤的诊断及鉴别诊断提供更多的依据;DTT可以为临床提供更多的肿瘤及其周围白质纤维束的信息,指导术前计划的制定和术后的评估.     

Effects of dexamethasone on cerebral perfusion and water diffusion in patients with high-grade glioma

BACKGROUND AND PURPOSE: The mechanisms by which the glucocorticoid dexamethasone produces its therapeutic action in patients with intracranial tumors still remain unclear. The purpose of this study was to investigate whether dexamethasone affects cerebral perfusion and water molecule diffusion by using quantitative dynamic susceptibility contrast perfusion MR imaging (DSC-MR imaging) and diffusion tensor MR imaging (DT-MR imaging). METHODS: Ten consecutive patients with glioblastoma multiforme underwent DSC-MR imaging and DT-MR imaging before and 48-72 hours after dexamethasone treatment (16 mg/day). Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and water mean diffusivity () were measured for enhancing tumor, nonenhancing peritumoral edematous brain, and normal-appearing contralateral white matter before and after steroid therapy. The percentage change in CBF, CBV, MTT, and for the 3 tissue types was calculated for each patient, a mean value obtained for the population, and the statistical significance determined by using a paired-samples Student t test. RESULTS: After dexamethasone treatment, there was no significant change in tumor CBF, CBV, or MTT. Edematous brain CBV and MTT were also unchanged. There was, however, an increase in edematous brain CBF (11.6%; P = .05). was reduced in both enhancing tumor (-5.8%; P = .001) and edematous brain (-6.0%; P < .001). There was no significant change in CBF, CBV, MTT, or for normal-appearing contralateral white matter after treatment. CONCLUSION: These data suggest that dexamethasone does not significantly affect tumor blood flow but may, by reducing peritumoral water content and local tissue pressure, subtly increase perfusion in the edematous brain.     

Glucocorticoid treatment of brain tumor patients: changes of apparent diffusion coefficient values measured by MR diffusion imaging

Glucocorticoids (GCC) generally are administered to patients with brain tumors to relieve neurological symptoms by decreasing the water content in a peritumoral zone of edema. We hypothesized that diffusion imaging and apparent diffusion coefficient (ADC) values could detect subtle changes of water content in brain tumors and in peritumoral edema after GCC therapy. The study consisted of 13 patients with intra-axial brain tumor, and ADC was measured in the tumor, within peritumoral edema, and in normal white matter remote from the tumor before and after GCC therapy. ADC also was measured in normal white matter in four control patients with no intracranial disease who were treated with GCC for other indications. Conventional MR images showed no visually evident interval change in tumor size or the extent of peritumoral edema in any subject after GCC therapy, which nonetheless resulted in a decrease in mean ADC of 7.0% in tumors (P<0.05), 1.8% in peritumoral edema (P>0.05, not significant) and 5.8% in normal white matter (P<0.05). In patients with no intracranial disease, GCC therapy decreased mean ADC in white matter by 5.4% (P<0.05). ADC measurement can demonstrate subtle changes in the brain after GCC therapy that cannot be observed by conventional MR imaging. Measurement of ADC proved to be a sensitive means of assessing the effect of GCC therapy, even in the absence of visually discernible changes in conventional MR images.     

大脑胶质瘤弥散张量磁共振成像定量研究

目的:应用弥散张量磁共振成像定量分析大脑胶质瘤的特点。方法:11例经病理证实的大脑胶质瘤患者,行弥散张量磁共振成像检查,在ADC图和FA图上分别测量肿瘤周围水肿区域、肿瘤强化区域、囊变区域、脑脊液及对侧正常大脑白质ADC值和FA值。结果:肿瘤周围水肿区域的ADC值和FA值与肿瘤囊变区域、脑脊液及对侧大脑白质相比较均有显著性差异(P<0.05),而与肿瘤强化区域相比较无显著性差异。肿瘤囊变区域的ADC值及FA值与脑脊液、对侧正常大脑白质相比较有显著性差异(P<0.05);肿瘤囊变区域与肿瘤强化区域相比较,ADC值无显著性差异,FA值却有显著性差异(P<0.05)。肿瘤强化区域的ADC值及FA值与对侧大脑白质相比较具有显著性差异(P<0.05)。高、低级别胶质瘤肿瘤周围水肿区域、肿瘤强化区域、肿瘤囊变区域的ADC值及FA值均无统计学显著差异。结论:磁共振弥散张量成像对定量分析大脑胶质瘤本身及其周围脑组织具有重要价值。     

磁共振灌注成像在脑膜瘤术前分型中的价值

目的探讨磁共振灌注成像(PW I)在脑膜瘤术前分型中的价值。方法39例经手术和病理证实的脑膜瘤患者,术前行PW I检查,计算并比较各型脑膜瘤的相对局部脑血流容积(rrCBV)和相对平均通过时间(rMTT)。结果血管瘤型脑膜瘤的rrCBV和rMTT分别平均为11.8、1.8,明显高于其他组织亚型。上皮细胞型和过渡型的rrCBV分别为8.3和7.5,之间无统计学意义;两者的rMTT则分别平均为1.5、1.3,统计学意义显著。纤维细胞型的rrCBV为4.0,明显低于其他组织亚型。结论PW I在脑膜瘤术前分型中具有重要价值。     

Discrimination of an infected brain tumor from a cerebral abscess by combined MR perfusion and diffusion imaging.

The aim of this study was to investigate the signal characteristics of the abscess wall and tumor wall on diffusion-weighted and perfusion-weighted images and thus to evaluate the feasibility of using combined MR diffusion and perfusion imaging to differentiate pyogenic cerebral abscess from infected brain tumor. The tumor wall of various types of cystic or necrotic brain tumor was significantly hyperintense relative to that of cerebral abscess wall on both diffusion-weighted images and regional cerebral blood volume maps.Sixteen patients who had cerebral masses with large cystic or necrotic cavities were imaged to generate diffusion-weighted images and regional cerebral blood volume maps using single-shot echoplanar imaging (EPI) pulse sequences. Apart from qualitative analysis, apparent diffusion coefficients (ADC) as well as regional cerebral blood volume (rCBV) ratios were calculated from the abscess wall and peripheral tumor wall and comparison was made by using Student's t-test. The tumor wall of various types of cystic or necrotic brain tumor had significantly lower ADCs relative to those of the abscess wall (P<0.005) and thus appeared relatively hyperintense on diffusion-weighted images. The mean rCBV ratio relative to normal white matter (2.90+/-0.62) of the peripheral tumor wall of various types of cystic or necrotic brain tumor were significantly larger than the mean rCBV ratio (0.45+/-0.11) of the pyogenic cerebral abscess wall (P<0.001) by Student's t-test. It is concluded that the combined MR diffusion and perfusion imaging might be capable of differentiating an infected brain tumor from a pyogenic cerebral abscess.     

CT sign of brain swelling without concomitant parenchymal hypoattenuation: comparison with diffusion- and perfusion-weighted MR imaging

PURPOSE: To retrospectively evaluate the apparent diffusion coefficient (ADC) on magnetic resonance (MR) images and the perfusion parameters of lesions that show brain swelling without concomitant parenchymal hypoattenuation on computed tomographic (CT) scans. MATERIALS AND METHODS: Review board approval was obtained, and informed consent was waived. A total of 14 patients (seven men and seven women; mean age, 64 years +/- 11) were retrospectively selected from the consecutive 172 patients with acute cerebral ischemia who underwent CT within 6 hours of symptom onset. All patients had brain swelling without parenchymal hypoattenuation, including loss of gray-white matter distinction on CT scans, and they underwent diffusion- and perfusion-weighted MR imaging shortly after CT. CT attenuation, ADC, and perfusion parameters of relative cerebral blood volume (CBV), time to peak (TTP), and relative cerebral blood flow (CBF) were calculated for gray and white matter of the lesion. The measured values were compared with those of the contralateral hemisphere by using the paired t test; comparison of values of perfusion parameters among three subgroups was performed with the Kruskal-Wallis test. Arterial occlusions were determined with MR angiography or conventional angiography. RESULTS: The mean interval between initial CT and MR imaging was 2.4 hours +/- 0.9 (range, 0.4-3.4 hours). The ADC of lesions was similar to that of contralateral normal tissue (mean ADC ratio for gray matter and white matter, 0.99 and 0.97, respectively) (P > .05). Lesions had an increased relative CBV (P < .001), a mild to moderate TTP delay (P < .001), and a variable but not statistically significant reduction of relative CBF. The mean relative CBF of gray matter was less in patients who had complete infarction (0.81 +/- 0.16) than that in patients with partial infarction (0.99 +/- 0.16) or those with a normal radiologic outcome (1.12 +/- 0.22), but this difference was not statistically significant (P > .05). Proximal cerebral artery occlusions were found in all patients. In five (36%) patients, the lesion did not progress to infarction at follow-up. CONCLUSION: The CT sign of brain swelling without concomitant parenchymal hypoattenuation in patients with acute cerebral ischemia does not represent severe ischemic damage and may suggest ischemic penumbral or oligemic tissue.     

Perfusion magnetic resonance imaging in intracerebral parenchymal tuberculosis: preliminary findings

OBJECTIVES: To study the vascular perfusion patterns of focal intracerebral tubercular lesions using echoplanar magnetic resonance (MR) imaging-derived relative cerebral blood volume (rCBV) maps. METHODS: Seventeen focal tubercular lesions were evaluated with conventional and perfusion-weighted MR imaging on a 1.5-T MR system. The rCBVs of the center, peripheral wall, and perilesional white matter were calculated from the perfusion MR-derived data. Perfusion MR imaging findings as depicted on the rCBV maps were qualitatively compared with those of conventional MR findings. RESULTS: Eleven of the 17 lesions demonstrated vascularity greater than that of the contralateral white matter on rCBV maps. The mean of the measured rCBV values of the peripheral wall and center of the lesions was 2.5 +/- 1.42 and 0.33 +/- 0.3 (mean +/- SD), respectively. Most of the hypervascular lesions (8) revealed a concentric peripheral wall having alternating hypointense and hyperintense signal intensity rims surrounding a variable intensity center on T2-weighted images. All the lesions having a nodular enhancing pattern (4) were hypervascular. CONCLUSIONS: Focal cerebral tubercular lesions can have variable vascularity as shown on perfusion MR-derived rCBV maps. It may be difficult to differentiate hypervascular lesions from cerebral tumors in some patients based on perfusion MR imaging alone.     

Contribution of dynamic contrast MR imaging to the differentiation between dural metastasis and meningioma

Purpose To determine the perfusion-sensitive characteristics of cerebral dural metastases and compare them with the data on meningiomas.Methods Twenty-two patients presenting with dural tumor underwent conventional and dynamic susceptibility-contrast MR imaging: breast carcinoma metastases, two patients; colorectal carcinoma metastasis, one patient; lung carcinoma metastasis, one patient; Merkel carcinoma metastasis, one patient; lymphoma, one patient; meningiomas, 16 patients. The imaging characteristics were analyzed using conventional MR imaging. The cerebral blood volume (CBV) maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral white matter (CBVn).Results The differentiation between a meningioma and a dural metastasis can be difficult using conventional MR imaging. The rCBVs of lung carcinoma metastasis (1 case: 1.26), lymphoma (1 case: 1.29), breast carcinoma metastasis (2 cases: 1.50,1.56) and rectal carcinoma metastasis (1 case: 3.34) were significantly lower than that of meningiomas (16 cases: mean rCBV = 8.97±4.34, range 4–18). Merkel carcinoma metastasis (1 case: 7.56) showed an elevated rCBV, not different from that of meningiomas.Conclusion Dural metastases are sometimes indistinguishable from meningiomas using conventional MR imaging. rCBV mapping can provide additional information by demonstrating a low rCBV which may suggest the diagnosis of metastasis.     

脑内转移瘤瘤周水肿相关因素的MRI研究

目的 探讨脑内转移瘤瘤周水肿的MRI表现及其相关因素。方法 回顾性分析了经手术病理及临床证实的35例脑内转移瘤患瘤周水肿的MRI表现及其相关因素。结果 MRI准确证实脑内转移瘤瘤周水肿程度与肿瘤的部位及大小有关。位于小脑半球及丘脑的瘤周水肿多较轻，而大球半径皮层及皮层下的瘤周水肿相对较重，同时，瘤周水肿的程度与肿瘤的大小成正相关，肿瘤愈大，瘤周水肿愈严重。结论 瘤周水肿的发生机制与转移瘤的形成过程和脑的解剖结构特点有关。MRI有助于评价瘤周水肿的进展程度。     

MRS和DTI对放疗前后脑胶质瘤瘤周水肿的观察与分析

目的:应用MRS和DTI观察脑胶质瘤放疗前、后肿瘤周围水肿区变化。方法:31例病理诊断明确的脑胶质瘤术后患者,分别在放疗前、后行MRI平扫+增强+MRS+DTI检查。分析肿瘤瘤周水肿区代谢物比值的变化[胆碱(Cho)/肌酐(Cr)、Cho/N-乙酰天门冬氨酸(NAA)、NAA/Cr]及部分各向异性(fractional anisotropy,FA)值、ADC值变化。结果:放疗后瘤周水肿区Cho/Cr、Cho/NAA、NAA/Cr值较放疗前下降,其中Cho/Cr差异有统计学意义(P<0.05),Cho/NAA、NAA/Cr值差异无统计学意义(P>0.05);瘤周水肿区域放疗后FA值升高(P>0.05),ADC值下降(P<0.05)。结论:MRS及DTI能显示肿瘤水肿区放疗后的早期变化,较早反映放疗效果。