Dynamic susceptibility contrast perfusion weighted imaging in grading of nonenhancing astrocytomas

Purpose

To evaluate if the relative tumor blood volume (rTBV) using dynamic susceptibility contrast magnetic resonance imaging (DSC‐MRI) can aid in distinguishing low‐ from high‐grade nonenhancing astrocytomas.

Materials and Methods

Seventeen patients with histologically proven astrocytomas underwent MRI including DSC‐MRI. Maximum TBV regions of interest were recorded from each neoplasm and normalized to contralateral normal white matter. Demographic features, diagnostic MRI findings including tumor volumes, and the normalized rTBV ratios were compared between low‐grade (I and II, LGA, n = 6) and high‐grade (III) astrocytomas (HGA, n = 11) using Mann–Whitney's U‐test and receiver operating characteristic (ROC) analysis.

Results

Maximum rTBV ratios were statistically higher for HGA (1.11 ± 0.13) than LGA (0.66 ± 0.17, P < 0.005) with the best cutoff threshold at 0.94 (sensitivity of 90.9%, specificity of 100%). Differences in mean age and tumor volume on fluid‐attenuated inversion recovery (FLAIR) imaging between the two groups did not reach statistical difference (P = 0.22, 0.36).

Conclusion

The addition of DSC‐MRI can aid in accurate grading of nonenhancing astrocytomas with high sensitivity and specificity. J. Magn. Reson. Imaging 2010;32:803–808. © 2010 Wiley‐Liss, Inc.     

Evaluation of different cerebral mass lesions by perfusion-weighted MR imaging

PURPOSE: To investigate the contribution of perfusion-weighted MR imaging (PWI) by using the relative cerebral blood volume (rCBV) ratio in the differential diagnosis of various intracranial space-occupying lesions. MATERIALS AND METHODS: This study involved 105 patients with lesions (high-grade glioma (N=26), low-grade glioma (N=11), meningioma (N=23), metastasis (N=25), hemangioblastoma (N=6), pyogenic abscess (N=4), schwannoma (N=5), and lymphoma (N=5)). The patients were examined with a T2*-weighted (T2*W) gradient-echo single-shot EPI sequence. The rCBV ratios of the lesions were obtained by dividing the values obtained from the normal white matter. Statistical analysis was performed with the Mann-Whitney U-test. A P-value less than 0.05 was considered statistically significant. RESULTS: The rCBV ratio was 5.76+/-3.35 in high-grade gliomas, 1.69+/-0.51 in low-grade gliomas, 8.02+/-3.89 in meningiomas, 5.27+/-3.22 in metastases, 11.36+/-4.41 in hemangioblastomas, 0.76+/-0.12 in abscesses, 1.10+/-0.32 in lymphomas, and 3.23+/-0.81 in schwannomas. The rCBV ratios were used to discriminate between 1) high- and low-grade gliomas (P<0.001), 2) hemangioblastomas and metastases (P<0.05), 3) abscesses from high-grade gliomas and metastases (P<0.001), 4) schwannomas and meningiomas (P<0.001), 5) lymphomas from high-grade gliomas and metastases (P<0.001), and 6) typical meningiomas and atypical meningiomas (P<0.01). CONCLUSION: rCBV ratios can help discriminate intracranial space-occupying lesions by demonstrating lesion vascularity. It is possible to discriminate between 1) high- and low-grade gliomas, 2) hemangioblastomas and other intracranial posterior fossa masses, 3) abscesses from high-grade gliomas and metastases, 4) schwannomas and meningiomas, 5) lymphomas and high-grade gliomas and metastases, and 6) typical and atypical meningiomas.     

Correlation between dynamic susceptibility contrast perfusion MRI and methionine metabolism in brain gliomas: preliminary results

PURPOSE: To evaluate in brain gliomas the relationship between tumor vascularity measured by MR-based maximum regional cerebral blood volume (rCBV) and tumor amino-acid metabolism based on maximum carbon-11 methionine (MET) uptake on positron emission tomography (PET). MATERIALS AND METHODS: Eighteen patients with histologically proven primary brain gliomas were included in the study. In addition to conventional MR sequences, dynamic MR images, including a first-pass gadopentetate dimeglumine T2*-weighted echo-planar perfusion sequence and a PET study using MET, were acquired. Eleven patients had low-grade gliomas, and seven had high-grade gliomas. rCBV ratios and MET uptake ratios normalized to the contralateral white matter (WM) corresponding values were measured in each tumor. Both maximum rCBV ratios and maximum MET uptake ratios were correlated to histopathology. The maximum rCBV ratios were correlated to the maximum MET uptake ratios. RESULTS: Both the maximum rCBV ratios and maximum MET uptake ratios of high-grade gliomas were significantly higher than those of low-grade gliomas (P<0.05). There was a significant positive correlation between maximum rCBV ratios and maximum MET uptake ratios (Spearman: r=0.89, P<0.00001). CONCLUSION: The maximum rCBV ratio and maximum MET uptake ratio are significantly correlated in gliomas, reflecting a close link between amino acid uptake and vascularity in these tumors.     

3.0TMR3D-PCASL技术在脑胶质瘤微灌注研究

目的：评价3D 伪连续动脉自旋标记技术(3D-PCASL)在脑胶质瘤术前分级价值。方法回顾性分析经组织病理学证实的20例低级别脑胶质瘤及21例高级别脑胶质瘤的3D-PCASL 图像,应用感兴趣区(ROI)分别得到肿瘤实体(TBF)、肿瘤边缘1 cm 内水肿区、肿瘤边缘1~2 cm 内水肿区以及对侧正常灰质、白质的脑血流量(CBF),对各参数值进行统计学分析。结果在高、低级别脑胶质瘤组间,除了肿瘤边缘1~2 cm 水肿区的 CBF 无统计学意义外(P >0.05),其他参数值均有统计学意义(P <0.001);在高级别胶质瘤组中,不同区域 CBF 值两两比较均有统计学意义(P <0.05),而在低级别胶质瘤组中肿瘤边缘1 cm 水肿区与肿瘤边缘1~2 cm 水肿区的 CBF 无统计学意义(P >0.05),其他区域两两相比均有统计学意义(P <0.05)。受试者工作特征曲线(ROC)曲线下面积(AUC)最大的为 TBF/对侧灰质 rCBF 值,AUC 为0.96,当阈值为2时,其敏感性和特异性也最高,分别为85.7%和100%。配对χ2检验常规序列的诊断准确率为76%,结合3D-PCASL 技术后诊断正确率为93%,2种方法比较有统计学意义(χ2=6.61,P =0.01)。结论3D-PCASL 有助于提高脑胶质瘤术前分级准确率,TBF/对侧灰质的 rCBF 值为分级最佳参数值。     

Diffusion- and perfusion-weighted MR imaging in a patient with acute demyelinating encephalomyelitis (ADEM).

To monitor changes of brain tissue metabolism in acute demyelinating encephalitis (ADEM), we examined a patient with suspected ADEM by serial MRI including diffusion- and perfusion-weighted imaging (DWI, PWI). Within the inflammatory tissue, the apparent diffusion coefficients were reduced, normal, and increased. Perfusion varied between reduced and normal values, except for small hyperperfused regions. Combining standard MRI with DWI and PWI may elucidate different overlapping phases in cerebral inflammation.     

MR脑血流灌注成像在星形细胞肿瘤中的应用研究

目的　评价MR脑血流灌注成像在星形细胞肿瘤中的应用价值。方法　经手术及病理证实的星形细胞肿瘤共 2 6例。行常规MR及MR灌注成像检查。构建局部脑血容量 (rCBV)图 ,并计算肿瘤最大相对局部脑血容量 (rrCBV)值。评价星形细胞肿瘤的rCBV图表现 ,并分析平均最大rrCBV值与肿瘤病理学级别之间的关系。结果　 9例Ⅱ级星形细胞瘤的rCBV分布较均匀 ,接近或略高于对侧脑白质。 7例Ⅲ级和 10例Ⅳ级星形细胞肿瘤的rCBV分布明显不均匀 ,肿瘤实性区rCBV多有不同程度的升高 ;瘤内囊变坏死区和瘤周水肿区rCBV降低。增强MRI上 ,2例Ⅲ级和 2例Ⅳ级肿瘤内无明显强化区域 ,在rCBV图上脑血容量明显升高。Ⅱ～Ⅳ级肿瘤最大rrCBV的平均值分别为 0 91±0 18、3 5 1± 1 0 1和 4 75± 1 2 3;Ⅱ级与Ⅲ级 (t=6 79,P <0 0 1)、Ⅱ级与Ⅳ级 (t=9 75 ,P <0 0 1)、Ⅲ级与Ⅳ级之间 (t=2 19,P <0 0 5 )平均最大rrCBV值差异均有显著性意义。结论　MR脑血流灌注成像可观察星形细胞肿瘤的血流灌注变化 ,对判断星形细胞肿瘤的病理学分级有重要临床意义。     

Effects of tracer arrival time on flow estimates in MR perfusion-weighted imaging.

A common technique for calculating cerebral blood flow (CBF) and mean transit time (MTT) is to track a bolus of contrast agent using perfusion-weighted MRI (PWI) and to deconvolve the change in concentration with an arterial input function (AIF) using singular value decomposition (SVD). This method has been shown to often overestimate the volume of tissue that infarcts and in cases of severe vasculopathy to produce CBF maps that are inconsistent with clinical presentation. This study examines the effects of tracer arrival time differences between tissue and a user-selected global AIF on flow estimates. CBF and MTT were calculated in both numerically simulated and clinically acquired PWI data where the AIF and tissue signals were shifted backward and forward in time with respect to one another. Results show that when the AIF leads the tissue, CBF is underestimated independent of extent of delay, but dependent on MTT. When the AIF lags the tissue, flow may be over- or underestimated depending on MTT and extent of timing differences. These conditions may occur in practice due to the application of a user-selected AIF that is not the "true AIF" and therefore caution must be taken in interpreting CBF and MTT estimates.     

Proton MR spectroscopy in predicting the increase of perfusion MR imaging for WHO grade II gliomas

Purpose:

To investigate the correlation between the metabolite ratios obtained from proton magnetic resonance (MR) spectroscopy and those obtained from MR perfusion parameters (relative cerebral blood volume [rCBV]) in a cohort of low‐grade glioma (LGG).

Materials and Methods:

Patients underwent prospectively conventional MR, proton magnetic resonance spectroscopy (¹HMRS), and perfusion‐weighted images (PWI). Statistical analyses were performed to determine the correlative and independent predictive factors of rCBVmax and the metabolite ratio thresholds with optimum sensitivity and specificity.

Results:

Thirty‐one patients were included in this study. Linear correlations were observed between the metabolic ratios (lactate [Lac]/creatine [Cr], choline [Cho]/N‐acetyl‐aspartate [NAA], free‐lipids/Cr) and rCBVmax (P < 0.05). These metabolic ratios were determined to be independent predictive factors of rCBVmax (P = 0.027, 0.011 and 0.032, respectively). According to the receiver operating characteristic curves, the cutoff values of the metabolic ratios to discriminate between the two populations of rCBVmax (<1.7 versus = 1.7) were 1.72, 1.54, and 1.40, respectively, with a sensitivity = 75% and a specificity >95% for Lac/Cr.

Conclusion:

This study demonstrated consistent correlations between the data from ¹HMRS and PWI. The Lac/Cr ratio predicts regional hemodynamic changes, which are themselves a useful biomarker of clinical prognosis in patients with LGG. As such, this ratio may provide a new parameter for making improved clinical decisions. J. Magn. Reson. Imaging 2012;35:543‐550. © 2011 Wiley Periodicals, Inc.     

MR diffusion imaging and ADC measurement in solid and cystic mediastinal masses for differentiating benign from malignant lesions

Purpose

The purpose of this study is to evaluate the role of MR diffusion imaging (DWI) and apparent diffusion coefficient (ADC) measurement of solid and cystic mediastinal masses to differentiate benign from malignant lesions.

MR灌注成像在鉴别胶质瘤复发与放射性脑损伤中的价值

目的 分析MR灌注成像在鉴别胶质瘤复发与放射性脑损伤中的作用.方法 选取15例脑胶质瘤术后、放疗后并出现新强化灶的患者.所有患者均经二次手术病理或随访(随访时间＞6个月)证实为胶质瘤复发或放射性脑损伤.15例患者均行常规MR平扫、增强扫描和MR脑灌注成像.灌注成像采用梯度回波-回波平面成像(GRE-EPI)序列,ROI放置在横断面T1WI异常强化区域和对侧相对正常的脑白质内,大小为20～40 mm2,每个病灶测量10～15次,取平均值,计算异常强化区与对侧正常区的参数比值,包括相对脑血容量(rCBV)、相对脑血流量(rCBF)及相对平均通过时间(rMTT),采用秩和检验比较胶质瘤复发和放射性脑损伤各灌注参数.并采用ROC曲线评价rCBV、rCBF及MTT鉴别诊断两者的灵敏度及特异度.结果 15例患者最终经手术和随访证实有9例胶质瘤复发,6例放射性脑损伤.胶质瘤复发rCBV、rCBF比值的M分别为2.87(范围0.70～4.91)、1.89(范围0.64～3.96),明显高于放射性脑损伤比值[rCBV 0.70(范围0.12～1.62)、rCBF 0.56(范围0.12～2.08)],差异有统计学意义(Z值分别为-2.55、-2.08,P值均＜0.05).rCBV和rCBF比值鉴别诊断为胶质瘤复发或放射性脑损伤的ROC曲线下面积为0.893和0.821.rCBV比值≤0.77时诊断放射性脑损伤灵敏度为100.0%,rCBV比值≥2.44时诊断胶质瘤复发特异度为100.0%.结论 MR灌注成像是鉴别胶质瘤复发和放射性脑损伤的有效方法,rCBV比值和rCBF比值在鉴别诊断中具有重要价值.

Abstract：

Objective To evaluate the feasibility of perfusion weighted imaging (PWI) in the differentiation of recurrent glioma and radiation-induced brain injuries. Methods Fifteen patients with previously resected and irradiated glioma, presenting newly developed abnormal enhancement, were included in the study. The final diagnosis was determined either histologically or clinicoradiologically. PWI was obtained with a gradient echo echo-planar-imaging (GRE-EPI) sequence. The normalized rCBV ratio[CBV(abnormal enhancement)/CBV(contralateral tissue)], rCBF ratio[CBF(abnormal enhancement)/CBF(contralateral tissue)]and rMTT ratio[(MTT abnormal enhancement)/MTT(contralateral tissue)]were calculated, respectively. The regions of interest (ROIs) consisting of 20-40 mm2 were placed in the abnormal enhanced areas on postcontrast T1-weighted images. Ten to fifteen ROIs measurements were performed in each lesion and the mean value was obtained. Mann-Whitney test was used to determine whether there was a difference in the rCBV/rCBF/MTT ratios between glioma recurrence and radiated injuries. Results Nine of the 15 patients were proved recurrent glioma,6 were proved radiation-induced brain injuries. The mean rCBV ratio[2.87(0.70-4.91)]in glioma recurrence was markedly higher than that[0.70(0.12-1.62)]in radiation injuries (Z=-2.55,P＜0.05). The mean rCBF ratio[1.89(0.64-3.96)]in glioma recurrence was markedly higher than that[0.56(0.12-2.08)]in radiation injuries (Z=-2.08,P＜0.05). The areas under rCBV and rCBF ROC curve were 0.893 and 0.821. If the rCBV ratio ≤0.77, the diagnosis sensitivity of radiation-induced brain injuries was 100.0%;If ≥2.44, the diagnosis specificity of recurrent glioma was 100.0%. Conclusion PWI was an effective technique in distinguishing glioma recurrence from radiation injuries and rCBV and rCBF ratios were of great value in the differentiation.     

软组织肿瘤MR扩散成像与灌注成像的比较研究

目的 通过分析一组软组织肿瘤同一病例相同ROI的MR DWI及PWI的影像信息,比较这2种MR功能成像技术用于软组织肿瘤的定性诊断价值.方法 对50例软组织肿瘤(良性24例,恶性26例)同时行DWI及PWI.通过扩散及灌注软件分析DWI及PWI参数在良、恶性肿瘤中的表现,进行差异的t检验,对所获两法的诊断符合率进行x2检验.采用受试者操作特征曲线(ROC曲线)分析曲线下面积(AUC),确定诊断阈值并对2种诊断方法进行评价.结果 良、恶性软组织肿瘤的ADC值[(良、恶性分别为(2.03±0.36)和(1.52±0.39)×10-3mm2/s]、首过灌注(FP)期信号强度丢失率[良、恶性分别为(13.54±3.37)%和(47.57±5.21)%]的差异均有统计学意义(t值分别为2.515和2.938,P值均<0.05),时间-信号强度曲线(TIC)最大线性斜率[良、恶性分别为(5.51±2.54)%和(7.94±3.33)%]的差异无统计学意义(t值为1.272,P>0.05);以ADC值1.866×10-3mm2/s为阈值,DWI诊断恶性肿瘤的敏感度为84.6%(22/26),特异度为83.3%(20/24);以FP期最大信号丢失率40.33%为阈值,PWI诊断恶性肿瘤的敏感度为88.5%(23/26),特异度为75.0%(18/24);TIC类型的Ⅰa型在良性肿瘤中占3/24,在恶性肿瘤中占20/26;Ⅰb型在良性肿瘤中占14/24,在恶性肿瘤中占3/26;Ⅰc型在恶性肿瘤中占3/26.Ⅱ型TIC在良性肿瘤中占7/24.在DWI上用ADC值、PWI上用FP期最大信号强度丢失率作诊断,诊断符合率分别为84.0%(42/50)和82.0%(41/50),两者的差异无统计学意义(x2=0.8,P>0.05);AUC测得的准确度分别为81.7%和83.6%,PWI诊断恶性软组织肿瘤的敏感度高.结论 以DWI和PWI的ADC值、FP期信号强度丢失率分别为1.866×10-3mm2/s和40.33%为阈值时,均有利于软组织肿瘤良、恶性的鉴别;TIC最大线性斜率对于软组织肿瘤良、恶性的鉴别意义不大;软组织肿瘤的TIC形态有助于肿瘤良、恶性的鉴别.DWI和PWI用于诊断恶性软组织肿瘤的准确性均为中等,在DWI与PWI用于诊断恶性软组织肿瘤的准确性相近时,应选择诊断敏感度较高的PWI.     

磁共振成像在牙根尖周病变中的临床应用价值

目的探讨磁共振成像（MRI）在诊断牙根尖周炎性病变中的临床应用价值。方法选取8名有牙髓及牙周病变的病例,对口腔上下颌牙进行MRI检查,分析牙根尖周病变的MRI表现,并与X线牙片进行对照。结果 8例均有牙根尖周炎症水肿表现,T1WI上信号减低,T2WI信号稍增高,脂肪抑制像上呈明显高信号,其中3例病变范围显示较普通X线牙片大,2例普通X线牙片显示正常而MRI显示有炎性病变,2例显示牙根尖与上颌窦囊肿的关系。结论 MRI可敏感地显示牙根尖周的炎性病理改变,MRI在显示病变的大小、范围及其与周围结构关系方面比X线片优越,并能显示普通X线牙片所不能显示的病理改变,MRI在牙根尖周炎性病变诊断中具有重要的临床应用价值。     

Effect of vascular stenosis on perfusion-weighted imaging; differences between calculation algorithms

PURPOSE: To determine the most suitable postprocessing technique for magnetic resonance (MR) perfusion imaging in patients with vascular stenosis, by comparing the cerebral blood flow (CBF) maps of single photon emission tomography (SPECT) and perfusion MR imaging (MRI). MATERIALS AND METHODS: In 15 consecutive patients (14 men and one woman, mean age 73.9 +/- 6.0 years) with stenosis of common carotid artery (CCA) or internal carotid artery (ICA) of more than 75%, both brain perfusion MRI and brain perfusion SPECT were performed. From perfusion MR images, CBF maps were calculated with the first moment, singular value decomposition (SVD), and block circulant SVD (b-SVD) methods, and CBF maps from each algorithm were compared with those from SPECT. RESULTS: The b-SVD method had the best correlation with SPECT (R = 0.814), followed by the first moment method (R = 0.776) and the SVD method (R = 0.723). The b-SVD method has the least mean difference with SPECT (0.118), the first moment method also had less difference (0.121), and the SVD had greatest mean difference (0.164). CONCLUSION: Our results suggest that in patients with vascular impairment the b-SVD method will be the technique of choice rather than SVD or first moment method.     

单侧大脑中动脉狭窄程度与磁共振血流灌注相关性研究

目的:探讨大脑中动脉(MCA)狭窄程度与脑磁共振灌注加权成像(PWI)的相关性.方法:30例短暂性脑缺血发作(TIA)患者行高分辨力MRI检查并判断单侧MCA狭窄程度,同时行磁共振PWI检查,并对MCA不同狭窄状态下得出的患侧和镜像侧灌注参数,包括相对脑血容量(rCBV)、相对脑血流量(rBCF)、相对平均通过时间(rMTT)、相对达峰时间(rTTP)进行定量分析.结果:30例患者中,高分辨力MRI均可显示不同程度MCA狭窄,灌注均出现异常,患侧灌注参数rCBV、rCBF、rMTT、rTTP与镜像侧比较,差异均有统计学意义(P＜0.05).MCA狭窄率与rMTT延长百分率之间呈正相关性(r=0.45,P＜0.05).结论:高分辨力MRI对MCA狭窄程度的评估与PWI灌注参数之间存在正相关性,MCA狭窄程度与PWI相结合对于评价脑组织供血有一定的指导意义.     

大鼠C6脑胶质瘤MR扩散加权成像及灌注成像与组织学对照研究

目的对大鼠脑胶质瘤MR扩散加权成像(DWI)及灌注成像(PWI)的实验研究,探讨两者在肿瘤生长及血管生成中的诊断价值。方法对36只颅内种植C6胶质瘤细胞的雌性Wistar大鼠分别于种植后1～4周行MRT1WI、T2WI、DWI、PWI及增强T1WI检查。处死后行脑组织HE及CD34免疫组织化学(简称免疫组化)染色。结果种植后3～4周,肿瘤实质区及肿瘤周围区表观扩散系数(ADC)值与种植后1～2周及对侧脑白质相比,差异均具有统计学意义(P<0.01)。胶质瘤实质区的ADC值随镜下肿瘤组织细胞构成比增加而降低,呈明显的负相关(r=-0.682,P<0.01)。种植后2～4周,肿瘤实质部分最大局部脑血容量(rCBVmax)与种植后1周及对侧脑白质相比,差异均具有统计学意义(P<0.01)。种植后1～2周,肿瘤周围区出现宿主血管rCBVmax值的增高,以种植后1周最为显著(t=3.88,P<0.01)。肿瘤实质区的rCBVmax值与CD34免疫组化微血管密度(MVD)计数值间具有显著的正相关(r=0.716,P<0.01)。结论DWIC6胶质瘤肿瘤实质区ADC值的减低与肿瘤恶性程度有关;C6胶质瘤的PWI肿瘤实质区rCBVmax值与组织学MVD值间具有显著的相关性,可作为1种活体评价肿瘤微血管的指标。肿瘤周围区rCBVmax值可对肿瘤的新生血管与正常脑组织原有血管扩张的鉴别有帮助。     

Combined spin- and gradient-echo perfusion-weighted imaging

In this study, a spin- and gradient-echo echo-planar imaging (SAGE EPI) MRI pulse sequence is presented that allows simultaneous measurements of gradient-echo and spin-echo dynamic susceptibility-contrast perfusion-weighted imaging data. Following signal excitation, five readout trains were acquired using spin- and gradient-echo echo-planar imaging, all of them with echo times of less than 100 ms. Contrast agent concentrations in brain tissue were determined based on absolute R2* and R(2) estimates rather than relative changes in the signals of individual echo trains, producing T(1)-independent dynamic susceptibility-contrast perfusion-weighted imaging data. Moreover, this acquisition technique enabled vessel size imaging through the simultaneous quantification of R2* and R(2), without an increase in acquisition time. In this work, the concepts of SAGE EPI pulse sequence and results in stroke and tumor imaging are presented. Overall, SAGE EPI combined the advantages of higher sensitivity to contrast agent passage of gradient-echo perfusion-weighted imaging with better microvascular selectivity of spin-echo perfusion-weighted imaging.     

Breath-hold MR imaging of focal liver lesions: comparison of fast and ultrafast techniques

The performance of breath-hold MR imaging using two T2-weighted hybrid sequences (TSE, TGSE), two T2-weighted single-shot sequences (HASTE, EPI-SE), and one T1-weighted gradientecho sequence (FLASH) was compared with a standard conventional T2-weighted SE sequence in 20 patients with focal liver lesions. Liver signal-to-noise ratio was highest spleen-liver contrast-to-noise ratio (54.3 ± 8.3) and thee HASTE (41.1 ± 12.5) sequence, whereas the highest spleen-liver contrast-noise-ratio was obtained by the TSE sequence (38.9 ± 20.7). Lesion-liver CNR was highest with the TSE sequence (63.9 ± 21.4). With both TSE and HASTE significantly (p < 0.01) more lesions were detected as compared with SE and EPE-SE sequences. Our results indicate that breath-hold TSE and HASTE sequences will eventually replace conventional T2-weighted SE techniques due to their insensitivity to motion artifacts, superior lesion detectability and inherently short acquisitions times.Correspondence to: J. Gaa     

MR灌注成像在脑胶质瘤术前分级中的价值

目的 :运用磁共振灌注成像 (PWI)技术 ,探讨脑血流容量 (rCBV)及其rCBV比值在脑胶质瘤术前分级中的价值。方法 :3 2例经病理证实的脑胶质瘤 ,其中Ⅰ级 2例 ,Ⅱ级 9例 ,Ⅲ级 14例 ,Ⅳ级 7例 ,行PI扫描 ,计算肿瘤最大rCBV及其rCBV比值 ,将结果与病理分级进行对照。结果 :低分级胶质瘤rCBV值为 43 .82± 15 .5 1,rCBV比值为 2 .89± 0 .83 ;高分级胶质瘤rCBV值为 12 4.3 2± 3 0 .5 4,rCBV比值为 7.82± 1.2 1;两组的rCBV值以及rCBV比值差异均有显著性意义 (P <0 .0 0 1)。结论 :不同分级的胶质瘤之间的rCBV及rCBV比值差异存在显著性意义 ,PWI技术有助于脑胶质瘤的术前分级。