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1.
目的 通过致痫性局灶性脑皮质发育不良(FCD)的MR影像与病理对照研究,分析FCD的发病特点,探讨最佳MR扫描方案.方法 回顾性分析经手术病理证实的36例(40个病灶)FCD患者的MR表现及扫描方法.根据Palmini病理分型,将FCD的病理结果分为FCD Ⅰ型及FCDⅡ型.观察各型病灶在脑内分布及合并海马硬化的比例,采用Fisher精确概率法比较FCD各型在脑内分布的差异性.将轴面FSE T2WI、SE T1WI、液体衰减反转恢复(FLAIR)序列定义为常规扫描,在常规扫描的基础上增加斜冠状面FSE T2WI及FLAIR定义为优化扫描.患者均进行常规扫描和优化扫描,评价FCD主要征象在各扫描方位、序列的显示情况,应用McNemar检验比较2种扫描方法对不同部位FCD及海马硬化显示的差异性.结果 36例(40个病灶)FCD患者中,病变位于颞叶29个(72.5%),额叶9个(22.5%),顶叶2个(5.0%).FCD Ⅰ型27例(29个病灶),颞叶病灶25个;FCDⅡ型10例(11个病灶),颞叶病灶4个,2种类型在病灶分布上差异有统计学意义(P=0.002).合并海马硬化者共14例,其中,FCD Ⅰ型13例,FCDⅡ型1例.优化扫描对于颞叶FCD、海马硬化的显示优于常规扫描,颞叶FCD的阳性率从44.8% (13/29)提高到65.5% (19/29),合并海马硬化FCD的阳性率从42.9%( 6/14)提高到85.7%(12/14),差异有统计学意义(颞叶FCD x2=4.167,P=0.031;海马硬化x2=4.167,P=0.031),对额叶FCD病灶的显示2种扫描方式间差异无统计学意义(x2 =0.304,P=1.000).结论 FCD好发于颞叶,其次是额叶,FCDⅠ型好发于颞叶,且更容易合并海马硬化.垂直于海马长轴的全颞叶优化扫描是针对FCD发病特点的优化扫描序列组合,有助于病灶的显示.  相似文献   

2.
MR imaging of the brain: tumors   总被引:1,自引:0,他引:1  
K. Sartor 《European radiology》1999,9(6):1047-1054
The radiologic modality that most likely provides the imaging information needed in a patient suspected of having a brain tumor is MR imaging. A brain tumor can be reliably ruled out if the MR examination is performed properly and experts interpret the results as negative. If there is a tumor, however, its exact location and topography must be determined. Important for therapy and prognosis are also tumor properties such as histologic type and grade, as well as effects on adjacent brain structures. Although potentially a noninvasive method of in vivo neuropathology, MR is still far from being sufficiently specific, as dissimilar lesions may look the same despite the use of refined imaging protocols. The evolution of MR imaging continues, however, making further methodologic improvement likely. Presently, advanced methods, such as diffusion- and perfusion-weighted MR imaging, functional MR imaging, neuronavigation based on MR imaging data, and the use of MR imaging during surgery (intraoperative MR imaging), influence the way patients are treated. Likewise, follow-up imaging (monitoring) of tumor patients by MR has become more effective, and experience has shown how to distinguish reactive changes from recurrent tumor. In the future, MR imaging may gain importance in the development of novel therapeutic concepts.  相似文献   

3.

Purpose

To evaluate the feasibility of automatic planning and scanning of brain MR imaging (MRI) protocols on a clinical 3 Tesla system in tumor patients before and after neurosurgical intervention.

Materials and Methods

Twenty‐nine patients with intra‐axial lesions were examined with automated planscan software pre‐ and postoperatively. MR section geometries were determined using intensity‐based three‐dimensional registration and an extraction of landmarks. The technique involved an active shape model to match the boundaries of anatomical structures and typical shape variations. Insufficient geometries were corrected manually by a trained operator.

Results

In 29/29 of the preoperative and 47/58 MRI sessions in total, no manual interaction was necessary. Predominantly minor corrections were necessary in 11/29 postoperative sessions, with critical corrections (≥ 3‐mm offcenter change or ≥ 5° in alignment of the stacks) in 3/58 sessions. Mean offcenter correction was 1.41 mm (range, 0–7.33 mm), mean angle change toward the midline or commissural line was 1.43° (range, 0–8.05°).

Conclusion

Automatic planning and scanning before and after brain surgery yields robust results in most of the patients with substantial shape deviations. The dimensions of necessary geometry corrections are predominantly small. These results are promising to minimize interscan variability in longitudinal studies. J. Magn. Reson. Imaging 2009;30:672–677. © 2009 Wiley‐Liss, Inc.  相似文献   

4.
For optimizing MR of the joints, a sophisticated knowledge of MR system hard-and software condition, and coil technologies, sequence and contrast preparation techniques, and the use of paramagnetic contrast agents is necessary. This review article discusses the basic principles of the appropriate use of surfacecoilsas well as the different conventional and fast imagingsequences, including three-dimensional (3D)MR imaging. In addition, the applications of contrast agents as well as the most important contrast prepaation techniques are reviewed.  相似文献   

5.
Fluid-attenuated inversion-recovery (FLAIR) imaging has shown to be a valuable imaging modality in the assessment of intra-axial brain tumors; however, no data are available about the role of this technique in the clinically important postoperative stage. The purpose of this study was to evaluate the diagnostic potential of FLAIR MR imaging in residual tumor after surgical resection of cerebral gliomas. Fifteen patients with residual cerebral gliomas were examined within the first 18 days after partial surgical resection of cerebral gliomas. The imaging protocol included T1-weighted spin echo, T2- and proton-density-weighted fast spin echo, and FLAIR imaging with identical slice parameters. T1 and FLAIR were repeated after contrast media application. Detection and delineation of residual tumor were the primary parameters of the image analysis. Additionally, the influence of image artifacts on the image interpretation was assessed. On FLAIR images residual signal abnormalities at the border of the resection cavities were observed in all patients, whereas T2- and T1-weighted images present residual abnormalities in 13 of 15 and 10 of 15 patients, respectively. The FLAIR imaging was found to be superior to conventional imaging sequences in the delineation of these changes and comparable to contrast enhanced T1-weighted imaging in the delineation of residual enhancing lesions. Because of protein cell components and blood byproducts within the resection cavity, FLAIR imaging was unable to suppress the cerebrospinal fluid (CSF) in 4 patients. After the decomposition of proteins and blood, CSF could again be completely suppressed and residual or recurrent tumors were clearly identified. Our preliminary study has shown that FLAIR may be a valuable diagnostic modality in the early postoperative MR imaging after resection of cerebral gliomas due to its better delineation of residual pathologic signal at the border of the resection cavity. It should therefore be integrated into the early and/or intraoperative MR imaging protocol.  相似文献   

6.
目的 线栓法制作小鼠缺血性脑梗死模型,小动物专用高场MR(7T)观察其不同时间段成像特点.方法 线栓法制作小鼠脑梗死模型30只,术前及术后不同时间应用MR进行扫描,以出现神经症状及弥散加权像(DWI)高信号判断为模型成功,并将MR影像与病理切片对照分析.结果 模型成功率为90%(27/30,1只术中死亡,2只未见明显病灶);DWI于术后40min即可见高信号区,范围随时间延长而扩大,6h后T2加权像(T2WI)出现高信号改变,T1WI相应区域脑组织肿胀,表现为稍低信号;12h内T2 WI高信号区域面积较DWI高信号区域面积小(P<0.05);病理TCC染色证实病变区为梗死区,该区域细胞溶解.结论 线栓法制作小鼠缺血性脑梗死模型稳定可行,7T MR扫描反映脑组织改变具有高度的敏感性及特异性,与病理具有良好的一致性,为脑梗死范围的评价、后期治疗评价提供实验基础.  相似文献   

7.
We evaluated the usefulness of surface anatomy scanning (SAS) in intracranial tumours, comparing it with surgical findings. We examined 31 patients with brain tumours preoperatively. The tumours included 16 meningiomas, 8 gliomas, 4 metastases and 3 others. SAS clearly demonstrated the tumours, allowing them to be distinguished from the structures of the brain surface, including oedema, except in cases of metastasis. SAS clearly demonstrated large cortical veins. SAS is useful for three-dimensional delineation of the brain surface before surgery.  相似文献   

8.
The intention of this article is to provide an overview of all MR imaging techniques that are accessible on most of commercially available scanners and have the potential to be used in routine clinical applications. The techniques implemented by the major vendors are briefly explained, including a comparison of the commonly used acronyms. A classification scheme is introduced which provides a reasonable illustration of similarities and differences between various techniques. The imaging techniques are divided into two main groups, the spin-echo and gradient-echo sequences. Within each group is the basic sequence, those which require a preparation of the magnetization, those which use multiple echoes to fill the k-space and those which are performed in a single shot. For each technique the typical clinical applications are listed or the potential applications which have been published. Received: 18 August 1998; Revision received: 3 November 1998; Accepted: 4 November 1998  相似文献   

9.
Dynamic MRI has proven to be an important tool in studies of transient physiologic changes in animals and humans. High sensitivity and temporal resolution in such measurements are critical for accurate estimation of dynamic information. Fast imaging, often involving expensive hardware, has evolved for use in such cases. We demonstrate herein the possibility of accelerated data acquisition schemes on conventional machines using standard pulse sequences for dynamic studies. This is achieved by combining reduced-encoded dynamic data (typically 30 to 40 phase encodings) with a priori high-resolution data via a novel constrained image reconstruction algorithm. Such an approach reduces image acquisition time significantly (by a factor of 3 to 4 in the examples described here) without loss in the accuracy of information.  相似文献   

10.
Distributions of proton MR‐detected metabolites have been mapped throughout the brain in a group of normal subjects using a volumetric MR spectroscopic imaging (MRSI) acquisition with an interleaved water reference. Data were processed with intensity and spatial normalization to enable voxel‐based analysis methods to be applied across a group of subjects. Results demonstrate significant regional, tissue, and gender‐dependent variations of brain metabolite concentrations, and variations of these distributions with normal aging. The greatest alteration of metabolites with age was observed for white‐matter choline and creatine. An example of the utility of the normative metabolic reference information is then demonstrated for analysis of data acquired from a subject who suffered a traumatic brain injury. This study demonstrates the ability to obtain proton spectra from a wide region of the brain and to apply fully automated processing methods. The resultant data provide a normative reference for subsequent utilization for studies of brain injury and disease. Magn Reson Med, 2009. © 2008 Wiley‐Liss, Inc.  相似文献   

11.
The aim of this study was to assess blood flow in the middle cerebral artery (MCA) according to age, gender, and side. Eighty-eight subjects without carotid obstruction were measured for mean velocity, vessel area, and volume flow rates of both MCA with phase-contrast MR. A high-resolution sequence with a matrix of 300 × 512 and a double oblique localizing strategy was used for measurement. A mean velocity of 33 ± 6.8 cm/s, a mean vessel area of 6.2 ± 1.2 mm2 and a mean flow rate of 121 ± 28 ml/min were measured in the MCA. Lower volume flow rates were seen in subjects aged over 50 years (p < 0.01). When comparing women with men, a lower vessel area (p < 0.05) of the MCA was counterbalanced by a higher velocity, resulting in no significant difference of the volume flow rate. No difference occurred between the right and the left side. Flow reduction occurs in the elderly. A lower vessel area of the MCA in women is compensated by a higher velocity. Received: 3 September 1999; Revised: 17 January 2000; Accepted: 23 February 2000  相似文献   

12.
Introduction It is important to have information on cavernous sinus extension and bony destruction in pituitary macroadenomas before surgery, but magnetic resonance (MR) imaging cannot always depict them. In the present study we sought to determine whether multidetector-row computed tomography (MDCT) could provide preoperative information in addition to that provided by MR imaging in pituitary macroadenoma. Methods The subjects comprised 33 consecutive patients (15 women, 18 men; mean age 50 years) with surgically proven macroadenoma. For MDCT, using the soft-tissue window and bone window, three orthogonal multiplanar reconstruction images were generated from venous-phase contrast-enhanced 0.5-mm isotropic voxel data. MDCT and MR images were evaluated with regard to: (1) clarity of tumor margins; (2) identification of the normal pituitary gland; (3) identification of erosion or destruction of the sellar floor; and (4) visualization of the adjacent optic pathways. Results MDCT more clearly demonstrated the lateral tumor margin than MR imaging (P = 0.002). No significant differences in visualization of the normal pituitary gland were noted between MDCT and dynamic MR imaging (P = 0.7). MDCT more clearly demonstrated sellar floor erosion or destruction at the sphenoid sinus than MR imaging (P < 0.001). MR imaging was superior to MDCT for visualizing the adjacent optic pathways (P < 0.001). Conclusion MDCT is superior to MR imaging for assessing lateral tumor margin and the sellar floor at the sphenoid sinus. MDCT offers useful preoperative information in addition to that obtained from MR imaging. Y.M. and M.K. contributed equally to this study.  相似文献   

13.
Introduction We have often encountered high signal intensity (SI) of the cingulate gyrus and insula during diffusion-weighted magnetic resonance imaging (DW-MRI) on neurologically healthy adults. To date, cortical signal heterogeneity on DW images has not been investigated systematically. The purpose of our study was to determine whether there is regional signal variation in the brain cortices of neurologically healthy adults on DW-MR images. Methods The SI of the cerebral cortices on DW-MR images at 1.5 T was evaluated in 50 neurologically healthy subjects (34 men, 16 women; age range 33–84 years; mean age 57.6 years). The cortical SI in the cingulate gyrus, insula, and temporal, occipital, and parietal lobes was graded relative to the SI of the frontal lobe. Contrast-to-noise ratios (CNRs) on DW-MR images were compared for each cortical area. Diffusion changes were analyzed by visually assessment of the differences in appearance among the cortices on apparent diffusion coefficient (ADC) maps. Results Increased SI was frequently seen in the cingulate gyrus and insula regardless of patient age. There were no significant gender- or laterality-related differences. The CNR was significantly higher in the cingulate gyrus and insula than in the other cortices (p < .01) , and significant differences existed among the cortical regions (p < .001). There were no apparent ADC differences among the cortices on ADC maps. Conclusion Regional signal variation of the brain cortices was observed on DW-MR images of healthy subjects, and the cingulate gyrus and insula frequently manifested high SI. These findings may help in the recognition of cortical signal abnormalities as visualized on DW-MR images.  相似文献   

14.
Contrast agents have greatly expanded the role of MR imaging (MRI) to allow assessment of physiologic, or “functional,” parameters. Although activation mapping generally does not require contrast agents, other forms of functional MRI, including mapping of cerebral hemodynamics (eg, perfusion imaging), are best done with the use of contrast agents. Serial echo planar images are obtained after bolus injection of lanthanide chelates. Application of susceptibility contrast physics and standard tracer kinetic principles permits generation of relative cerebral blood volume maps. Deconvolution of cerebral blood flow and mean transit time parameters is also possible within technical limitations. By using diffusion and perfusion pulse sequences, an imaging correlate to the ischemic penumbra can be identified. Functional MRI perfusion imaging of intraaxial tumors is analogous to positron emission tomography for delineation of metabolic activity, yet may be even more sensitive to neovascularity and possesses improved image quality. Clinical applications include biopsy site selection and postirradiation follow-up. Further improvements in data analysis and map generation techniques may improve diagnostic accuracy and utility.  相似文献   

15.

Objective

To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods

Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results

SPACE MR imaging showed significantly greater CNR for focal liver lesions (median = 22.82) than TSE MR imaging (median = 14.15) (P < .001). No differences were found for SNR of hepatic parenchyma (P = .097), main focal hepatic lesions (P = .35), and splenic parenchyma (P = .25). SPACE sequence showed less artifacts than TSE sequence (vascular, P < .001; respiratory motion, P < .001; cardiac, P < .001) but needed a longer acquisition time (228.4 vs. 162.1 s; P < .001).

Conclusion

SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.  相似文献   

16.
"Single shot" magnetic resonance (MR) diffusion imaging was used to study the details of signal decay curves in experimental perturbations of cerebral perfusion induced by hypercapnia or death. Despite large perfusion increases observed with dynamic susceptibility-contrast MR imaging, no correlation with these changes was seen in either the diffusion coefficient or any other intravoxel incoherent motion (IVIM) model parameters in dog gray matter as arterial carbon dioxide pressure increased. Non-monoexponential signal decay in cat gray matter was seen both before and after death. In addition, cat gray matter demonstrated a steady decrease in the diffusion coefficient after death. These data are strong evidence that the fast component of the non-monoexponential diffusion-related signal decay is not due solely to perfusion. The authors believe that a second compartment of nonexchanging spins, most likely cerebrospinal fluid, accounts for the non-monoexponential decay.  相似文献   

17.
Our objective was to describe MR imaging findings of liver lesions in human fascioliasis. The MR imaging of the liver was performed in 29 patients with fascioliasis. Seventeen patients were women and 12 were men, with a mean age of 47.5 years (age range 17–75 years). Hepatic lesions were grouped into five types based on their signal characteristics. Three patients had normal imaging findings. One or more lesions were observed in the other 26 patients. The lesion types and the frequency of appearances were as follows: hyperintensity of the liver capsule on T2-weighted images (n=16, 55.2%); ill-defined slightly hyperintense areas on T2-weighted images (n=18, 62.1%); lesions which were hypointense on T1-weighted and hyperintense on T2-weighted images (n=10, 34.5%); hypointense on T1-weighted images and centrally hypo- or hyperintense, surrounded by peripherally less hyperintense area on T2-weighted images (n=4, 13.8%); and hypointense foci or ill-defined hypointense areas on T1- and T2-weighted images (n=10, 34.5%). We describe the MR imaging features of the disease. Our findings may help the differential diagnosis in which fascioliasis should be added to the list. Electronic Publication  相似文献   

18.

Purpose

The aim of this retrospective study is to evaluate the role of T2-weighted MR imaging (MRI) and MR cholangiopancreatography (MRCP) findings in the diagnosis of primary biliary cirrhosis (PBC).

Materials and methods

The following T2-weighted MRI and MRCP findings: segmental hepatic atrophy/hypertrophy, irregular liver surface, parenchymal lace-like fibrosis, rounded low signal intensity lesions centering portal vein branches (periportal halo sign), periportal hyperintensity (cuffing), splenomegaly, ascites, lymphadenopathy, venous collaterals, and the configuration of intrahepatic biliary ducts were reviewed for their diagnostic significance by two observers in 13 female patients (mean age: 49 years) with PBC. Discordant readings of the observers were resolved at consensus.

Results

When parenchymal lace-like fibrosis and periportal halo sign were seen together the sensitivity of T2-weighted MR images was 69%. In six cases periportal hyperintensity (cuffing) and periportal halo sign were seen together. Segmental hypertrophy was present in nine patients and hepatic surface irregularity due to regenerative nodules were present in 10 patients. Lymphadenopathy was seen in 10, splenomegaly was seen in 5, collateral vascular structures were seen in 2 and minimal perihepatic free fluid was seen in 2 patients. MRCP images revealed various mild irregularity in the intrahepatic bile ducts in 8 patients and focal narrowing at the common bile duct level in 1 patient.

Conclusion

MRI and MRCP may support the clinical and laboratory findings of PBC even in the early stages of the disease. MRI can also be a choice of method for the recommended prolonged follow up.  相似文献   

19.
Objective. To analyse to what extent MR imaging based decisions were correct in determining the surgical procedure in patients with osteosarcoma of the distal femur. Design. We compared the findings on MR imaging that determined the surgical strategy with the actual surgical findings or histopathological specimen. We assessed to what extent MR images could be used to determine the surgical procedure in patients with osteosarcoma. Patients. Between 1985 and 1992, 34 patients with an osteosarcoma were treated. Two patients had a low-grade osteosarcoma. Thirty-two patients with a high-grade osteosarcoma of the distal femur (17 stage IIB, 15 stage III) were included in this study. Surgical options consisted of either limb salvage surgery or ablative surgery, which included the Van Nes-Borggreve rotationplasty. Limb salvage surgery consisted of extra-articular or transarticular resection, followed by reconstruction. Surgery was planned depending on the local extent of the tumour as depicted on the MR studies, coupled with data from the biopsy, age, patient compliance and histological grade. Follow-up was available in all patients. Nine of 17 patients graded as IIB were alive with an average follow-up of 68 months (range 46–109 months), of whom one has metastases. No local recurrence was encountered. Results. If no tumour involvement on MR imaging was found and this was used as a determining factor, this proved to be correct at subsequent analysis. We found that in eight of 11 cases, when MR images suggested a close relationship between tumour and nerve, an oncologically safe plane could be achieved during surgery. In three, a free plane could not be accomplished, as confirmed at histopathological examination. Hence, when nerve involvement was equivocal on MR imaging we found it valuable to reassess nerve involvement during surgery and reconsider limb salvage surgery. When the decisive factor was the vascular involvement and tumour extension was read as equivocal, it was possible to obtain a oncologically safe plane in six of 13 cases. When comprehensive tumour involvement of any structure was noted pre-operatively, it proved to be correct at histopathological examination, except for one case of assumed vascular involvement that proved to be free. Conclusions. If no tumour involvement of a structure was found on MR imaging and this was used as a determining factor, this proved to be correct. When nerve involvement was equivocal on MR imaging we found it valuable to reassess nerve involvement during surgery and reconsider limb salvage surgery. Extensive tumour involvement of any structure, as shown by MR imaging, could be used correctly as a decisive argument in planning a surgical procedure.  相似文献   

20.

Aim

Spiculation of breast masses is usually the result of significant desmoplastic reaction. Diminished neovascularization is expected due to sparsely dispersed tumor cells within the lesion. This feature can cause differences in enhancement patterns which can cause pitfalls while evaluating MR images as well. Aim of this study is to explore the enhancement characteristics of malignant spiculated masses and to correlate these findings with histopathological features.

Materials and methods

Eighteen spiculated and seventeen non-spiculated masses depicted with mammography were included in the study. MR imaging was performed with 1.5 T magnet with breast coil. In MR imaging, T2-weighted turbo spin echo (TSE) with fat suppression sequence followed by pre- and post-contrast T1-weighted 3D-fast low angle shot (FLASH) sequences were used. Lesions were evaluated according to enhancement characteristics: early phase enhancement (first 2 min; less than 50%, 50–100% and more than 100%), late phase enhancement (2–6 min; persistent, plateau and washout) and inner enhancement pattern (homogenous, heterogenous and rim). Desmoplasia and lymphocyte infiltration was classified as mild, moderate and severe. MR images and histopathological findings (desmoplasia, lymphocyte infiltration and grade) of both groups were compared.

Results

Mean ages of patients in spiculated and non-spiculated-mass groups were 55.07 (41–71) and 47.35 (31–62), respectively. Mean diameter of lesions was 17.3 mm (10–31 mm) for spiculated masses while non spiculated masses were 15.8 mm (6–40 mm). There were statistically significant differences between late phase enhancement, persistent enhancement, plateau and washout (p < 0.05). Intergroup comparison of desmoplasia revealed significant difference between severe versus and mild, moderate (p < 0.05).

Conclusion

Spiculated malignant lesions are supposed to contain intense desmoplastic reaction. On DCE-MR images they can show persistent enhancement pattern more often than non-spiculated lesions.  相似文献   

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