首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
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.  相似文献   

2.

Objective

The differentiation of oligodendroglial tumors from astrocytic tumors is important clinically, because oligodendroglial tumors are more chemosensitive than astrocytic tumors. This study was designed to clarify the usefulness of 3 T MR perfusion imaging (PWI) in the histopathological differentiation between astrocytic and oligodendroglial tumors. This is because there is a growing interest in the diagnostic performance of 3 T MR imaging, which has the advantages of a higher signal-to-noise ratio (SNR) and greater spatial and temporal resolution.

Materials and methods

This study retrospectively included 24 consecutive patients with supratentorial, WHO grade II and III astrocytic and oligodendroglial tumors (7 astrocytic, 10 oligoastrocytic, and 7 oligodendroglial tumors) that were newly diagnosed and resected between November 2006 and December 2009 at Hiroshima University Hospital. These patients underwent dynamic susceptibility contrast-enhanced (DSC) PWI relative cerebral blood volume (rCBV) measurements before treatment. Astrocytic tumors were designated as the astrocytic group, and oligoastrocytic and oligodendroglial tumors as the oligodendroglial group. The regions of interest with the maximum rCBV values within the tumors were normalized relative to the contra-lateral white matter (rCBVmax).

Results

The average rCBVmax of astrocytic tumors (2.01 ± 0.68) was significantly lower than that of the oligoastrocytic (4.60 ± 1.05) and oligodendroglial tumors (6.17 ± 0.867) (P < 0.0001). A cut-off value of 3.0 allowed to differentiate the oligodendroglial group from the astrocytic group at 100% sensitivity and 87.5% specificity.

Conclusion

The rCBVmax values obtained from 3 T MR PWI may be useful as an adjunct to the postoperative histopathological diagnosis of glioma patients.  相似文献   

3.
The objective of this study was to evaluate the potential role of newly developed, advanced magnetic resonance (MR) imaging techniques (spectroscopy, diffusion and perfusion imaging) in diagnosing brain gliomas, with special reference to histological typing and grading, treatment planning and posttreatment follow-up. Conventional MR imaging enables the detection and localisation of neoplastic lesions, as well as providing, in typical cases, some indication about their nature. However, it has limited sensitivity and specificity in evaluating histological type and grade, delineating margins and differentiating oedema, tumour and treatment side-effects. These limitations can be overcome by supplementing the morphological data obtained with conventional MR imaging with the metabolic, structural and perfusional information provided by new MR techniques that are increasingly becoming an integral part of routine MR studies. Incorporation of such new MR techniques can lead to more comprehensive and precise diagnoses that can better assist surgeons in determining prognosis and planning treatment strategies. In addition, the recent development of new, more effective, treatments for cerebral glioma strongly relies on morphofunctional MR imaging with its ability to provide a biological interpretation of these characteristically heterogeneous tumours.  相似文献   

4.
Magnetic resonance imaging (MRI) has developed dramatically in the 25 years since its clinical introduction. Advances in hardware design have included the development of high field magnets and more sophisticated and sensitive coils. Improvements in sequences, data sampling, and postprocessing software have benefited the attainable spatial and temporal resolution to the point at which the fine depiction of anatomical structure and pathological processes is now routine. As in other radiological areas, the most recent advances in MRI have proven highly valuable in the field of musculoskeletal radiology where the lack of radiation, high soft tissue contrast, and capacity for multiplanar or three-dimensional imaging have made MRI the imaging modality of choice. Particular benefits are seen in diagnostic imaging of the spine where MRI is clearly superior to both conventional radiography and computed tomography. In this article, we discuss the impact of the most recent technological advance in MRI, namely the advent of 3 Tesla (3-T) imaging, on diagnostic imaging of the spine. Comparisons are drawn with imaging at 1.5 T, and emphasis is placed on MR physics and on the benefits and principal difficulties associated with spine imaging at high field strength.  相似文献   

5.
Balanced steady-state free precession (SSFP) techniques provide excellent contrast between myocardium and blood at a high signal-to-noise ratio (SNR). Hence, SSFP imaging has become the method of choice for assessing cardiac function at 1.5T. The expected improvement in SNR at higher field strength prompted us to implement SSFP at 3.0T. In this work, an optimized sequence protocol for cardiac SSFP imaging at 3.0T is derived, taking into account several partly adverse effects at higher field, such as increased field inhomogeneities, longer T(1), and power deposition limitations. SSFP contrast is established by optimizing the maximum amplitude of the radiofrequency (RF) field strength for shortest TR, as well as by localized linear or second-order shimming and local optimization of the resonance frequency. Given the increased SNR, sensitivity encoding (SENSE) can be employed to shorten breath-hold times. Short-axis, long-axis, and four-chamber cine views obtained in healthy adult subjects are presented, and three different types of artifacts are discussed along with potential methods for reducing them.  相似文献   

6.

Objectives

To compare ultra-high field, high-resolution bilateral magnetic resonance imaging (MRI) of the hips at 7 Tesla (T) with 3 T MRI in patients with avascular necrosis (AVN) of the femoral head by subjective image evaluations, contrast measurements, and evaluation of the appearance of imaging abnormalities.

Materials and Methods

Thirteen subjects with avascular necrosis treated using advanced core decompression underwent MRI at both 7 T and 3 T. Sequence parameters as well as resolution were kept identical for both field strengths. All MR images (MEDIC, DESS, PD/T2w TSE, T1w TSE, and STIR) were evaluated by two radiologists with regard to subjective image quality, soft tissue contrasts, B1 homogeneity (four-point scale, higher values indicating better image quality) and depiction of imaging abnormalities of the femoral heads (three-point scale, higher values indicating the superiority of 7 T). Contrast ratios of soft tissues were calculated and compared with subjective data.

Results

7-T imaging of the femoral joints, as well as 3-T imaging, achieved “good” to “very good” quality in all sequences. 7 T showed significantly higher soft tissue contrasts for T2w and MEDIC compared with 3 T (cartilage/fluid: 2.9 vs 2.2 and 3.6 vs 2.6), better detailed resolution for cartilage defects (PDw, T2w, T1w, MEDIC, DESS?>?2.5) and better visibility of joint effusions (MEDIC 2.6; PDw/T2w 2.4; DESS 2.2). Image homogeneity compared with 3 T (3.9–4.0 for all sequences) was degraded, especially in TSE sequences at 7 T through signal variations (7 T: 2.1–2.9); to a lesser extent also GRE sequences (7 T: 2.9–3.5). Imaging findings related to untreated or treated AVN were better delineated at 3 T (≤1.8), while joint effusions (2.2–2.6) and cartilage defects (2.5–3.0) were better visualized at 7 T. STIR performed much more poorly at 7 T, generating large contrast variations (1.5).

Conclusions

7-T hip MRI showed comparable results in hip joint imaging compared with 3 T with slight advantages in contrast detail (cartilage defects) and fluid detection at 7 T when accepting image degradation medially.  相似文献   

7.
Parallel imaging of knee cartilage at 3 Tesla   总被引:1,自引:0,他引:1  
PURPOSE: To evaluate the feasibility and reproducibility of quantitative cartilage imaging with parallel imaging at 3T and to determine the impact of the acceleration factor (AF) on morphological and relaxation measurements. MATERIALS AND METHODS: An eight-channel phased-array knee coil was employed for conventional and parallel imaging on a 3T scanner. The imaging protocol consisted of a T2-weighted fast spin echo (FSE), a 3D-spoiled gradient echo (SPGR), a custom 3D-SPGR T1rho, and a 3D-SPGR T2 sequence. Parallel imaging was performed with an array spatial sensitivity technique (ASSET). The left knees of six healthy volunteers were scanned with both conventional and parallel imaging (AF = 2). RESULTS: Morphological parameters and relaxation maps from parallel imaging methods (AF = 2) showed comparable results with conventional method. The intraclass correlation coefficient (ICC) of the two methods for cartilage volume, mean cartilage thickness, T1rho, and T2 were 0.999, 0.977, 0.964, and 0.969, respectively, while demonstrating excellent reproducibility. No significant measurement differences were found when AF reached 3 despite the low signal-to-noise ratio (SNR). CONCLUSION: The study demonstrated that parallel imaging can be applied to current knee cartilage quantification at AF = 2 without degrading measurement accuracy with good reproducibility while effectively reducing scan time. Shorter imaging times can be achieved with higher AF at the cost of SNR.  相似文献   

8.
Patients with epilepsy often have a structural cause for their seizures and may benefit from surgical resection. As recommended in the National Institute of Health and Clinical Excellence (NICE) guidelines, magnetic resonance imaging (MRI) is used to screen for structural abnormalities in these patients and there is increasing evidence that 3T MRI has better sensitivity and specificity than 1.5T. This article reviews the imaging findings of many of the common diseases that can cause epilepsy.  相似文献   

9.
The aim of this study was to assess the feasibility of diffusion tensor imaging (DTI) of the prostate and to determine normative fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of healthy prostate with a 3-Tesla magnetic resonance imaging (MRI) system. Thirty volunteers with a mean age of 28 (25–35) years were scanned with a 3-Tesla MRI (Intera Achieva; Philips, The Netherlands) system using a six-channel phased array coil. Initially, T2-weighted turbo spin-echo (TSE) axial images of the prostate were obtained. In two subjects, a millimetric hypointense signal change was detected in the peripheral zones on T2-weighted TSE images. These two subjects were excluded from the study. DTI with single-shot echo-planar imaging (ssEPI) was performed in the remaining 28 subjects. ADC and FA values were measured using the manufacturer supplied software by positioning 9-pixel ROIs on each zone. Differences between parameters of the central and peripheral zones were assessed. Mean ADC value of the central (1.220 ± 0.271 × 10−3 mm2/s) was found to be significantly lower when compared with the peripheral gland (1.610 ± 0.347 × 10−3 mm2/s) (P < 0.01). Mean FA of the central gland was significantly higher (0.26), compared with the peripheral gland (0.16) (P < 0.01). This study shows the feasibility of prostate DTI with a 3-Tesla MR system and the normative FA and ADC values of peripheral and central zones of the normal prostate. The results are compatible with the microstructural organization of the gland. An erratum to this article can be found at  相似文献   

10.
A spin echo‐based MRSI sequence was developed to acquire edited spectra of γ‐aminobutyric acid in an entire slice. Water and lipid signals were suppressed by a dual‐band presaturation sequence, which included integrated outer volume suppression pulses for additional lipid suppression. Experiments in three normal volunteers were performed at 3 T using a 32‐channel head coil. High signal‐to‐noise ratio spectra and metabolic images of γ‐aminobutyric acid were acquired from nominal 4.5 cm3 voxels (estimated actual voxel size 7.0 cm3) in a scan time of 17 min. The sequence is also expected to co‐edit homocarnosine and macromolecules, giving a composite γ‐aminobutyric acid+ resonance. The γ‐aminobutyric acid+ to water ratio was measured using a companion water MRSI scan and was found to correlate linearly with the % gray matter (GM) of each voxel (γ‐aminobutyric acid+/water = (1.5 × GM + 3.2) × 10?5, R = 0.27), with higher γ‐aminobutyric acid+ levels in gray matter compared with white. In conclusion, high signal‐to‐noise ratio γ‐aminobutyric acid‐MRSI is possible at 3 T within clinically feasible scan times. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.  相似文献   

11.
PURPOSE: To estimate cerebral blood perfusion in areas of strong magnetic susceptibility changes with high spatial and temporal resolution using a flow-sensitive alternating inversion recovery (FAIR) arterial spin labeling (ASL) method. MATERIALS AND METHODS: We implemented an ASL method that is capable of imaging perfusion in areas of high magnetic susceptibility changes by combining a FAIR spin preparation with a true fast imaging in steady precession (TrueFISP) data acquisition strategy. A TrueFISP readout sequence was applied especially in regions with magnetic field inhomogeneities and compared with corresponding FAIR measurements obtained with a standard echo-planar imaging (EPI) readout. Quantitative perfusion images were obtained at 1.5 Tesla (1.5T) from eight healthy volunteers (24-42 years old) and one patient (23 years old). FAIR-TrueFISP perfusion images were compared with FAIR echo-planar images. T1 maps, which are necessary for quantitative perfusion estimation, were obtained with inversion recovery (IR) TrueFISP and IR EPI. Additionally, high-resolution perfusion measurements were performed on four volunteers at 3T. RESULTS: The two ASL perfusion imaging modalities yielded comparable diagnostic image quality in brain areas with low susceptibility differences at 1.5T. Cerebral perfusion of gray matter (GM) areas was 105.7 +/- 5.2 mL/100 g/minute for FAIR-TrueFISP and 88.8 +/- 14.6 mL/100 g/minute for FAIR-EPI at 1.5T, and 70.4 +/- 7.1 mL/100 g/minute for FAIR-TrueFISP and 63.5 +/- 6.9 mL/100 g/minute for FAIR-EPI at 3.0T. Higher perfusion values at 1.5T were due to more pronounced partial-volume effects from fast moving spins at lower spatial resolution. The FAIR-TrueFISP sequence showed no significant distortions and markedly reduced signal void artifacts in areas of high susceptibility changes (e.g., near brain-bone transitions and close to metallic clips) compared to FAIR-EPI. At 3T, highly resolved FAIR-TrueFISP perfusion images were acquired with an in-plane resolution of up to 1.3 mm. CONCLUSION: FAIR-TrueFISP allows for assessment of cerebral perfusion in areas of critically high susceptibility changes with conventional ASL methods.  相似文献   

12.

Purpose:

To investigate whether quantitative MRI measures of cervical spinal cord white matter (WM) using diffusion tensor imaging (DTI) in neuromyelitis optica (NMO) differed from controls and correlated with clinical disability.

Materials and Methods:

Ten referred patients and 12 healthy volunteers were imaged on a 3 Tesla scanner and patients were clinically assessed on the Expanded Disability Status Scale (EDSS). Two raters quantified DTI‐derived indices from all participants, including fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (lambda[parallel]) and perpendicular diffusivity (lambda[perpendicular]) at C1–C6 for lateral and dorsal columns. After the inter‐rater reliability test, univariate correlations between DTI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analysis was performed to investigate which DTI measures independently correlated with the clinical score.

Results:

Statistical test results indicated high reliability of all DTI measurements between two raters. NMO patients showed reduced FA, increased MD and lambda[perpendicular] compared with controls while lambda[parallel] did not show any significant difference. The former three DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO (EDSS ≤ 3)

Conclusion:

FA is a potentially useful quantitative biomarker of otherwise normal appearing WM damage in NMO. Such damage is associated with clinical disability. J. Magn. Reson. Imaging 2011;33:1312–1320. © 2011 Wiley‐Liss, Inc.  相似文献   

13.
14.
15.
PURPOSE: To determine whether imaging at 3 T could improve and prolong the tag contrast compared to images acquired at 1.5 T in normal volunteers, and whether such improvement would translate into the ability to perform strain measurements in diastole. MATERIALS AND METHODS: Normal volunteers (N = 13) were scanned at 1.5 T (GE Signa CV/i) and 3.0 T (GE VH/i). An ECG-triggered, segmented k-space, spoiled-gradient-echo grid-tagged sequence was used during cine acquisition. Tag contrast was determined by the difference of the mean signal intensity (SI) of the tagline to the mean SI of the myocardium divided by the standard deviation (SD) of the noise (CNR(tag)). Matched short-axis (SA) slices were analyzed. Strain measurements were performed on images using a 2D strain analysis software program (harmonic phase (HARP)). RESULTS: The average CNR(tag) over the cardiac cycle was superior at 3 T compared to 1.5 T for all slices (3 T: 23.4 +/- 12.1, 1.5 T: 9.8 +/- 8.4; P < 0.0001). This difference remained significant at cycle initiation, end-systole, and the end R-R interval (at cycle termination: 3 T = 14.0 +/- 11.0 vs. 1.5 T = 4.4 +/- 3.5; P < 0.01). Strain measures were obtainable only in early systole for 1.5 T images, but were robust throughout the entire R-R interval for 3 T images. CONCLUSION: Imaging at 3 T had a significant benefit for myocardial tag persistence through the cardiac cycle. The improvement allowed strain analysis to be performed into diastole.  相似文献   

16.
MR灌注成像在脑胶质瘤术前分级中的价值   总被引:2,自引:1,他引:1       下载免费PDF全文
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。  相似文献   

17.
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.  相似文献   

18.
Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla.   总被引:2,自引:0,他引:2  
A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner.  相似文献   

19.
RATIONALE AND OBJECTIVES: To qualitatively compare the image quality of torso phased-array 3-Tesla (3T) imaging of the prostate with that of endorectal 1.5-Tesla imaging. MATERIALS AND METHODS: Twenty cases of torso phased-array prostate imaging performed at 3-Tesla with FSE T2 weighted images were evaluated by two readers independently for visualization of the posterior border (PB), seminal vesicles (SV), neurovascular bundles (NVB), and image quality rating (IQR). Studies were performed at large fields of view(FOV) (25 cm) (14 cases) (3TL) and smaller FOV (14 cm) (19 cases) (3TS). A comparison was made to 20 consecutive cases of 1.5-T endorectal evaluation performed during the same time period.Results. 3TL produced a significantly better image quality compared with the small FOV for PB (P = .0001), SV (P =.0001), and IQR (P = .0001). There was a marginally significant difference within the NVB category (P = .0535). 3TL produced an image of similar quality to image quality at 1.5 T for PB (P = .3893), SV (P = .8680), NB (P = .2684), and IQR (P = .8599). CONCLUSION: Prostate image quality at 3T with a torso phased-array coil can be comparable with that of endorectal 1.5-T imaging. These findings suggest that additional options are now available for magnetic resonance imaging of the prostate gland.  相似文献   

20.

Purpose

To assess the feasibility of black‐blood turbo spin‐echo imaging of the left anterior descending coronary artery wall at 3 Tesla under free‐breathing and breath‐hold conditions.

Materials and Methods

Proton density‐weighted black‐blood turbo spin‐echo imaging of the left anterior descending coronary artery was performed on 15 volunteers on a 3 T whole body scanner with an eight channel phased array coil. Volunteers were imaged during free‐breathing (with navigators, N = 5), or with breath‐hold (N = 5), or both (N = 2). Imaging was not possible in three volunteers due to either gradient or radiofrequency (RF) coupling with the electrocardiogram (ECG). Images were analyzed to determine coronary artery wall thickness, wall area, lumen diameter, and lumen area. Signal‐to‐noise and contrast‐to‐noise ratios were calculated.

Results

Coronary artery wall thickness, wall area, lumen diameter, and lumen area measurements were consistent with previous magnetic resonance (MR) measurements of the coronary wall at 1.5 Tesla.

Conclusion

Coronary wall imaging using free‐breathing and breath‐hold two‐dimensional black‐blood TSE is feasible at 3 T. Further improvement in resolution and image quality is required to detect and characterize coronary plaque. J. Magn. Reson. Imaging 2005;21:128–132. © 2005 Wiley‐Liss, Inc.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号