磁共振功能成像在脑肿瘤诊断中的应用

目前,MRI因软组织分辨率高、无辐射及多平面成像等优势已成为脑肿瘤疾病的一种常规检查手段。近年来,随着磁共振技术的发展及磁场强度的增加,一些新的MR功能成像技术已开始越来越多的应用于临床,如磁共振波谱、脑功能成像、灌注成像、磁敏感加权成像、弥散张量成像等,主要用于脑肿瘤之间及脑肿瘤与非肿瘤性疾病的鉴别、肿瘤的分级、指导外科术式的选择、放疗方案的制订等。     

功能磁共振成像在脑肿瘤诊断中的应用

功能磁共振成像是一种新的影像学检查方式，主要包括弥散加权成像、灌注加权成像及血氧水平依赖成像三种成像方法。同以往影像学检查只能依赖于被检查组织形态学的改变不同，弥散加权成像主要研究脑组织内水分子的弥散情况，灌注加权成像主要研究脑组织血液动力学的情况，而血氧水平依赖成像则可对脑内的重要功能区进行准确定位。所以，功能磁共振成像可对人脑在生理和病理状态下的脑功能活动进行有效的评价，可准确地对肿瘤进行早期诊断、区别肿瘤组织成分、预测肿瘤恶性程度及为临床提供治疗方案。本文主要综述脑功能磁共振成像方式的基本原理及主要临床应用，以提高临床工作者对此项检查技术的认识。     

功能磁共振成像在神经外科应用的初步经验

背景与目的：位于脑中央沟附近的肿瘤在外科手术中易造成运动功能损伤。本研究拟运用功能磁共振成像（functional magnetic resonance imaging,fMRI）的方法术前确定手运动功能皮层的位置及其与肿瘤的关系。探索fMRI在神经外科的应用价值。方法：31例位于中央沟附近的脑肿瘤患者接受常规和功能磁共振检查,其中转移瘤10例,胶质瘤11例,脑膜瘤6例,动静脉畸形2例,蛛网膜囊肿2例。功能成像方法采用在手静止和开合运动中,行快速梯度平面回波连续成像,以平行胼胝体前后联合的连线为基线,连续16层,层厚为4mm,层距为零,共获得1280幅功能原始图像,并经处理获得统计学Z-score图。结果：除2例患者头运动较明显外。其余患者都显示了手运动功能皮层活化兴奋区。并测得了功能皮层区与肿瘤的最短距离。功能皮层活化区表现出3种不同类型,包括：病灶内或边缘散在的活化小斑点;功能皮层活化区受挤压、移位;功能皮层活化区形态,位置正常。此外,在其他区域亦出现了不同例数的活化现象。结论：fMRI能帮助确定中央沟附近的脑肿瘤与手运动功能区位置的关系,从而为外科手术提供参考。     

功能磁共振成像在胶质瘤精确诊断中的研究

目的 应用多种功能磁共振成像对胶质瘤进行评估,术前对脑胶质瘤进行较精准的诊断。方法 收集35例经病理诊断证实的胶质瘤患者,均行常规磁共振成像(Magnetic resonance imaging,MRI)及功能MRI检查,对体素内不相干运动扩散加权成像(Intravoxel incoherent motion diffusion weighted imaging,IVIM-DWI)中快速扩散系数(D*)、慢扩散系数(D)、灌注分数(f)和分布扩散系数(DDC)的值进行统计学分析。结果 高级别胶质瘤患者病灶侧IVIM的D、D*、DDC值较对侧正常脑白质增高(D:0.71±0.05×10^-3mm²/s vs.0.14±0.03×10^-3mm²/s;D*:0.06±0.04mm²/s vs.0.03±0.02mm²/s;DDC:1.29±0.33×10^-3mm²/s vs.0.43±0.14×10^-3mm²/s)、f值较对侧正常脑白质降低(f:0.41±0.11 vs.0.51±0.05),差异均具有统计学意义(P＜0.05)。结论 多种磁共振功能成像序列协同分析胶质瘤,可以避免肿瘤的异质性,显著提高了磁共振检查对高级别脑胶质瘤实性部分的识别能力及精确性。     

磁共振弥散加权成像在胶质瘤分级中的价值

目的 探讨磁共振弥散加权成像(DWI)及表观弥散系数(ADC)在鉴别胶质瘤瘤体区、瘤周区和正常组织中的应用及鉴别胶质瘤良、恶性的价值.方法 采用Philips 1.5T Achieva超导型磁共振成像仪,对46例胶质瘤患者行常规MRI及DWI,弥散系数b值分别取0和1 000 s/mm2,测量瘤体区、瘤周区及对侧正常组...     

磁共振成像3种增强新技术在颅内肿瘤诊断中的应用

目的:比较增强后FLAIRMRI(CEFLAIR)、磁共振动态增强(DCEMRI)和灌注加权磁共振成像(PWI)3种MRI增强新技术诊断颅内肿瘤的应用价值。方法:43例脑肿瘤患者先后分别行DCEMRI、CEFLAIR和PWI检查。研究内容包括①造影增强病灶个数及强化病灶所在的部位;②不同部位、不同大小病灶的显示率、强化率;③病变大小:在增强后3种序列图像上分别测量肿瘤3个方向的最大径之乘积。结果:43例中,有5例因颅底伪影很重,PWI无法观察,余38图像质量可。38例中,病理证实有47个病灶,CEFLAIR、DCEMRI和PWI分别发现了41、42和45个病灶。3个病灶(2例位于皮层下、1例位于脑室旁)仅在CEFLAIR发现,4个病灶(均位于基底节区)仅在DCEMRI发现,7个位于大脑半球的病灶仅在PWI发现,表明3种方法对不同部位病灶的显示有显著差异(P<0.05)。强化程度上,68.4%(26/38)的病例DCEMRI强于CEFLAIR,3例CEFLAIR强于DCEMRI。PWI显示强化36例,未见强化2例。三者所显示的病灶体积(cm3)依次为DCEMRI:4.4±1.0、CEFLAIR:5.5±0.8、PWI:5.7±1.3(P<0.05)。14例CEFLAIR和DCEMRI显示的强化区与PWI及手术不一致。结论:3种新技术所显示的病灶强化数无明显差异,强化部位及大小差异显著,CEFLAIR对位于脑沟、脑室旁的病灶显示能力强,DCEMRI对基底节区的病灶显示率高,PWI     

胶质瘤恶性程度分级的功能性磁共振成像研究进展

胶质细胞瘤是最常见的颅内恶性肿瘤,其生长特点为浸润性生长,与正常脑组织无明显界限,偏良性者生长缓慢,病程较长,恶性者瘤体生长快,病程短。因此,对于临床治疗而言,胶质瘤的准确分级是非常必要的。目前,随着影像学技术的快速发展,功能磁共振成像不仅可为临床提供精细解剖信息,还可以提供肿瘤功能及代谢等方面的信息。因此,该文综述了扩散加权成像（DWI）、磁共振波谱成像（MRS）、扩散张量成像（DTI）、灌注加权成像（PWI）、磁敏感加权成像（SWI）等功能MRI技术在胶质瘤恶性程度分级诊断中的应用,从而更准确地指导临床个体化治疗。     

磁共振功能成像在胰腺癌诊断中的应用及新进展

胰腺癌恶性程度高、预后差，早期诊断及鉴别诊断困难。MR功能成像作为无创性检查方法能为其诊断及鉴别诊断提供重要信息。MR功能成像包括扩散加权成像、灌注成像及波谱分析。本文分别对它们的原理及在胰腺癌诊断及鉴别诊断中的应用与进展进行综述。     

氢质子磁共振波谱联合磁共振成像对脑胶质瘤的诊断价值

目的探讨氢质子磁共振波谱(1H-MRS)联合磁共振成像(MRI)对脑胶质瘤的诊断价值。方法选取2015年10月至2016年10月间哈尔滨医科大学附属第二医院收治的48例脑胶质瘤患者,其中低级别脑胶质瘤30例,高级别脑胶质瘤18例。均在行MRI基础上行1H-MRS检查,检测N-乙酰天门冬氨酸(NAA)、肌酸(Cr)和胆碱(Cho),分析患者肿瘤实质区与瘤周水肿区的低级别脑胶质瘤和高级别脑胶质瘤Cho/Cr和Cho/NAA的差异。结果 MRI扫描显示低级别脑胶质瘤和高级别脑胶质瘤的瘤周水肿区的水肿和肿瘤实质区的强化程度对比,差异均无统计学意义(均P>0.05)。1H-MRS扫描显示高级别脑胶质瘤的肿瘤实质区的Cho/Cr和Cho/NAA值与瘤周围水肿区的Cho/Cr值均高于低级别脑胶质瘤,差异均有统计学意义(均P<0.05)。而高级别脑胶质瘤和低级别脑胶质瘤瘤周水肿区的Cho/NAA值比较,差异无统计学意义(P>0.05)。结论在传统MRI扫描的基础上联合使用1H-MRS,可以提供定量的检测结果来评价肿瘤的恶性度,为脑胶质瘤做出准确的分级诊断。     

广义磁共振功能成像在肿瘤非手术治疗早期评价中的应用

肿瘤非手术治疗技术的发展对评定治疗效果的方法提出了新的要求。磁共振弥散成像(DWI)、磁共振灌注成像(PWI)、磁共振波谱(MRS)等磁共振功能成像技术的进步提供了明显超前于形态学变化的评价手段,为肿瘤非手术治疗的早期评价提供了客观的指标。     

Magnetic Resonance Imaging of Ethyl-nitrosourea-induced Rat Gliomas: A Model for Experimental Therapeutics of Low-grade Gliomas

Human low-grade gliomas represent a population of brain tumors that remain a therapeutic challenge. Preclinical evaluation of agents, to test their preventive or therapeutic efficacy in these tumors, requires the use of animal nobreak models. Spontaneous gliomas develop in models of chemically induced carcinogenesis, such as in the transplacental N-ethyl-N-nitrosourea (ENU) rat model. However, without the ability to detect initial tumor formation, multiplicity or to measure growth rates, it is difficult to test compounds for their interventional or preventional capabilities. In this study Fisher-334 rats, treated transplacentally with ENU, underwent magnetic resonance imaging (MRI) examination in order to evaluate this approach for detection of tumor formation and growth. ENU-induced intracranial cerebral tumors were first observable in T2-weighted images beginning at 4 months of age and grew with a mean doubling time of 0.487 ± 0.112 months. These tumors were found histologically to be predominately mixed gliomas. Two therapeutic interventions were evaluated using MRI, vitamin A (all-trans retinol palmitate, RP), as a chemopreventative agent and the anti-angiogenic drug SU-5416. RP was found to significantly delay the time to first tumor observation by one month (P = 0.05). No differences in rates of tumor formation or growth rates were observed between control and RP-treated groups. MRI studies of rats treated with SU-5416 resulted in reduction in tumor growth rates compared to matched controls. These results show that MRI can be used to provide novel information relating to the therapeutic efficacy of agents against the ENU-induced tumor model.     

Functional Magnetic Resonance Imaging in Cervical Cancer Diagnosis and Treatment

Cervical Cancer is the fourth most common cancer in women worldwide. Treatment with chemoradiotherapy followed by brachytherapy achieves high local control, but recurrence with metastatic disease impacts survival. This highlights the need for predictive and prognostic biomarkers identifying populations at risk of poorer treatment response and survival. Magnetic resonance imaging (MRI) is routinely used in cervical cancer and is a potential source for biomarkers. Functional MRI (fMRI) can characterise tumour beyond anatomical MRI, which is limited to the assessment of morphology. This review summarises fMRI techniques used in cervical cancer and examines the role of fMRI parameters as predictive or prognostic biomarkers. Different techniques characterise different tumour factors, which helps to explain the variation in patient outcomes. These can impact simultaneously on outcomes, making biomarker identification challenging. Most studies are small, focussing on single MRI techniques, which raises the need to investigate combined fMRI approaches for a more holistic characterisation of tumour.     

前列腺磁共振扩散张量成像研究进展

扩散张量成像（DTI）是一种可以无创反映活体组织内水分子扩散的各向异性程度的磁共振功能成像方法,在前列腺的应用尚处于初步研究阶段。DTI能够提供前列腺的组织微观结构信息,并直观显示前列腺纤维走形,有助于前列腺疾病的诊断及鉴别诊断。文章就DTI在前列腺的研究进展及临床应用近况进行综述。     

Dynamic Contrast-enhanced Magnetic Resonance Imaging: Applications in Oncology

Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) allows functional characterisation of tissue perfusion characteristics and acts as a biomarker for tumour angiogenesis. It involves serial acquisition of MRI images before and after injection of contrast, as such, tissue perfusion and permeability can be assessed based on the signal enhancement kinetics. The ability to evaluate whole tumour volumes in a non-invasive manner makes DCE MRI especially attractive for potential oncological applications. Here we provide an overview of the current research involving DCE MRI as a biomarker for the diagnosis and characterisation of malignancies, prediction of the therapeutic response and survival outcomes, as well as radiation therapy planning.     

The Role of Magnetic Resonance Imaging in Brachytherapy

The application of magnetic resonance imaging (MRI) in image-guided brachytherapy has expanded rapidly over the past two decades. In cervix cancer, significant improvements in overall survival, local control and long-term morbidity have been shown in patients treated with MRI-guided brachytherapy, changing clinical practice and directing an international approach to standardise the technique; unifying adaptive target volume definition and dose reporting. MRI-guided prostate brachytherapy has significantly improved the accuracy of tumour and organ-at-risk delineation, facilitating targeted implantation and dose optimisation. It also has potential to improve clinical outcomes through enhancement of the therapeutic ratio and the identification of dominant lesions that can be the targets of sub-volume boosting and salvage therapy. However, MRI-guided brachytherapy presents a number of logistical and financial challenges in modern healthcare systems, requiring technologically advanced imaging and planning techniques, as well as robust safety and quality assurance procedures. A collaborative, multidisciplinary approach involving clinical oncologists, radiologists, medical physicists, therapy radiographers, nurses and technical staff is therefore critical to its successful incorporation into any clinical brachytherapy workflow. In this overview we evaluate the current role of MRI in image-guided brachytherapy, primarily in cervix and prostate cancer, but also in other tumour sites, and review its potential future developments in the context of both clinical and research spheres.     

Magnetic Resonance Imaging (MRI) Appearances of Syringohydromyelia

Magnetic resonance imaging (MRI) examination of the spinal cord is now a first-line in vestigation for the evaluation of suspected syringohydromyelia. It is an accurate, non-invasive means of detecting cavities within the spinal cord and for assessing spinal cord size and the position of the cerebellar tonsils. It has considerable advantages over post-myelographic computerised tomography (CT). The current study discusses our initial experience of thirteen surgically proven cases of syringomyelia with special reference to appearances on T 1 and T2 weighted images and a discussion of the apparently confusing appearances of the cavities on the T2 weighted images.     

Impact of Radiotherapy on Background Parenchymal Enhancement in Breast Magnetic Resonance Imaging

Background: While many studies have shown that hormones can influence background parenchymalenhancement (BPE) in breast magnetic resonance imaging (MRI), only few have directly address the effect ofradiotherapy. The purpose of this study was to evaluate the impact of radiotherapy on BPE in breast MRI.Materials and Methods: A retrospective search identified 62 women with unilateral breast cancer who had abreast MRI both before and after radiotherapy following breast-conserving surgery. In our study, we assumedthat systemic therapy affected both breasts equivalently. We rated the level of BPE of both breasts using a fourpointcategorical scale. A change in the level of BPE prior to and after treatment was compared in the diseasedand contralateral breasts. Results: All patients received a 4256 to 6480 cGy dose of whole breast radiotherapyover 3-7 weeks. The mean timing of the follow-up study was 6.6 months after completion of radiotherapy.Although the BPE showed a decrease in both breasts after treatment, there was a significant reduction of BPEin the irradiated breast compared with the contralateral breast (1.18 versus 0.98 average reduction in BPE level,p=0.042). Conclusions: Radiotherapy is associated with decrease in BPE with MRI.     

脑肿瘤的功能性成像

随着影像医学的发展，CT和MRI已经成为当前脑肿瘤最主要的影像学检查方法。但常规的形态学诊断方法已经不能满足临床需要。磁共振波谱成像（magnetic resonance spectroscopy，MRS）、弥散加权成像（diffusion—weighted imaging，DWI）、弥散张量成像（diffusion tensor imaging，DTI）、弥散张量纤维束成像（diffusion tensor tractography，DTT）、CT灌注成像（CT perfusion）和磁共振灌注加权成像（perfusion—weighted imaging，PWI）和血氧水平依赖效应功能磁共振成像（blood oxygen level dependent—functional MRI，BOLD—fMRI）等新技术的出现为临床医师提供了脑肿瘤的功能信息，为常规CT和MRI检查方法提供了重要的补充。