椎动脉型颈椎病的MRI分析

目的 探讨椎动脉型颈椎病的ＭＲＩ诊断价值及其限度。材料与方法 选取我院近２年来经临床诊断为椎动脉型颈椎病患者４２例,全部行颈部ＭＲＡ检查,其中２３例同时行颈椎ＭＲＩ,观察椎动脉全段ＭＲＡ表现及颈椎横突孔以及钩椎关节的变化情况。选择２６例正常人作为对照组。全部行颈椎ＭＲＩ及椎动脉ＭＲＡ检查,方法条件和观察内容同病例组。结果 （１）４２例中７例椎动脉ＭＲＡ正常,其余３５例（３５／４２）分别显示不同程度     

Arterial spin labeling MRI: Clinical applications in the brain

Visualization of cerebral blood flow (CBF) has become an important part of neuroimaging for a wide range of diseases. Arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) sequences are increasingly being used to provide MR‐based CBF quantification without the need for contrast administration, and can be obtained in conjunction with a structural MRI study. ASL MRI is useful for evaluating cerebrovascular disease including arterio‐occlusive disease, vascular shunts, for assessing primary and secondary malignancy, and as a biomarker for neuronal metabolism in other disorders such as seizures and neurodegeneration. In this review we briefly outline the various ASL techniques including advantages and disadvantages of each, methodology for clinical interpretation, and clinical applications with specific examples. J. Magn. Reson. Imaging 2015;41:1165–1180. © 2014 Wiley Periodicals, Inc.     

肺动脉疾病的MRI检查技术及影像学表现

MRI作为一种无创、无辐射的检查手段临床应用已非常广泛,它在人体各个部位疾病的诊断中都占有重要地位。随着MRI技术的提高,扫描速度的加快,胸部MRI成像及对疾病的诊断在某些方面已经具有优势。本文旨在对肺动脉疾病的MRI检查技术及其影像学表现作一综述,以提高对MRI扫描在肺动     

MRI和心导管检查同步测定肺动脉舒张压的相关性研究

目的　探索MRI无创性测量肺动脉舒张压 (PADP)的新途径。材料与方法　应用MR相位速度图测量 40例具有肺动脉瓣返流 (PR)患者的最大返流速度并计算出舒张末期肺动脉与右心室间的压差 (PVDG) ,同时 ,与右心导管检查结果进行比较 ,通过直线相关与回归分析MRI测量PADP的敏感性和特异性。结果　MRI测定的PADP为 4.82± 1.2 4mmHg(1mmHg =0 .133kPa) ,右心导管的测值为 4.5 2± 2 .0 0mmHg ,二者之间无明显差异 (t=1.45 ,P >0 .0 5 ) ,但具有高度相关性 (r =0 .94,P <0 .0 1)。回归方程y =0 .82x + 4.5 8,其敏感性和特异性高达 90 %。结论　MRI是评价PR患者PADP的较可靠的新技术。     

磁共振成像对内皮素-1在犬迟发脑血管痉挛模型中作用的评价

目的 应用MR评价内皮素-1(ET-1)在蛛网膜下腔出血(SAH)后迟发脑血管痉挛(DCVS)中的作用.材料与方法健康家犬9只,经环枕缝向蛛网膜下腔注入自体动脉血制成SAH动物模型.于术后第2、4、6、8、10、12和第14天行MRI及DSA检查.抽取静脉血及脑脊液(CSF)进行ET-1放射免疫测定.造模后第4天和第14天,处死动物,行大体标本观察、常规光镜观察及免疫组织化学染色.采用方差分析法比较痉挛前后CSF和血浆中ET-1水平、痉挛前后免疫组织化学结果.将磁共振血管成像(MRA)结果与ET-1水平对照.结果 大体标本见基底动脉周围,脑干腹侧面有近似黑色血块包绕,造模后第4天基底动脉管腔变小,厚薄不均匀,内弹力膜皱缩呈不规则锯齿状,管壁周围有大量红细胞包围.免疫组织化学片显示造模后第4天基底动脉内膜阳性细胞多,着色深.正常和造模后第14天基底动脉内膜阳性细胞较造模后第4天者少,着色较前者浅.MRA显示基底动脉痉挛发生于造模后2～4天,平均3天.各组血浆及CSF中ET-1值差异无统计学意义(P值分别为0.052、0.404).结论 (1)将ET-1看作是SAH后DCVS所致颅内缺血性改变的一种产物,并将其视为SAH后导致DCVS的诱因更能准确地反映它在SAH后的作用;(2)MRA图像能比较准确地显示血管痉挛的程度,扩散加权成像(DWI)能尽早地显示颅内缺血性改变.因此,M1KI是评价SAH后DCVS程度和DCVS导致神经病变的重要影像检查手段.     

Arterial spin labeling perfusion MRI in pediatric arterial ischemic stroke: Initial experiences

Purpose

To investigate the feasibility and utility of arterial spin labeling (ASL) perfusion MRI for characterizing alterations of cerebral blood flow (CBF) in pediatric patients with arterial ischemic stroke (AIS).

Materials and Methods

Ten children with AIS were studied within 4 to 125 hours following symptom onset, using a pulsed ASL (PASL) protocol attached to clinically indicated MR examinations. The interhemisphere perfusion deficit (IHPD) was measured in predetermined vascular territories and infarct regions of restricted diffusion, which were compared with the degree of arterial stenosis and volumes of ischemic infarcts.

Results

Interpretable CBF maps were obtained in all 10 patients, showing simple lesion in nine patients (five hypoperfusion, two hyperperfusion, and two normal perfusion) and complex lesions in one patient. Both acute and follow‐up infarct volumes were significantly larger in cases with hypoperfusion than in either hyper‐ or normal perfusion cases. The IHPD was found to correlate with the degree of stenosis, diffusion lesion, and follow‐up T₂ infarct volumes. Mismatch between perfusion and diffusion lesions was observed. Brain regions presenting delayed arterial transit effects were tentatively associated with positive outcome.

Conclusion

This study demonstrates the clinical utility of ASL in the neuroimaging diagnosis of pediatric AIS. J. Magn. Reson. Imaging 2009;29:282–290. © 2009 Wiley‐Liss, Inc.     

Multi-Slice MRI of Rat Brain Perfusion During Amphetamine Stimulation Using Arterial Spin Labeling

When a single coil is used to measure perfusion by arterial spin labeling, saturation of macromolecular protons occurs during the labeling period. Induced magnetization transfer contrast (MTC) effects decrease tissue water signal intensity, reducing the sensitivity of the technique. In addition, MTC effects must be properly accounted for in acquiring a control image. This forces the image to a single slice centered between the labeling plane and the control plane. In this work, a two-coil system is presented as a way to avoid saturation of macromolecular spins during arterial spin labeling. The system consists of one small surface coil for labeling the arterial water spins, and a head coil for MRI, actively decoupled from the labeling coil by using PIN diodes. It is shown that no signal loss occurs due to MTC effects when the two-coil system is used for MRI of rat brain perfusion, enabling three-dimensional perfusion imaging. Using the two-coil system, a multi-slice MRI sequence was used to study the regional effects of amphetamine on brain perfusion. Amphetamine causes significant increases in perfusion in many areas of the brain including the cortex, cingulate, and caudate putamen, in agreement with previous results using deoxyglucose uptake to monitor brain activation.     

Arterial input functions for dynamic susceptibility contrast MRI: requirements and signal options

Cerebral perfusion imaging using dynamic susceptibility contrast (DSC) has been the subject of considerable research and shows promise for basic science and clinical use. In DSC, the MRI signals in brain tissue and feeding arteries are monitored dynamically in response to a bolus injection of paramagnetic agents, such as gadolinium (Gd) chelates. DSC has the potential to allow quantitative imaging of parameters such as cerebral blood flow (CBF) with a high signal-to-noise ratio (SNR) in a short scan time; however, quantitation depends critically on accurate and precise measurement of the arterial input function (AIF). We discuss many requirements and factors that make it difficult to measure the AIF. The AIF signal should be linear with respect to Gd concentration, convertible to the same concentration scale as the tissue signal, and independent of hematocrit. Complicated relationships between signal and concentration can violate these requirements. The additional requirements of a high SNR and high spatial/temporal resolution are technically challenging. AIF measurements can also be affected by signal saturation and aliasing, as well as dispersion/delay between the AIF sampling site and the tissue. We present new in vivo preliminary results for magnitude-based (DeltaR2*) and phase-based (Deltaphi) AIF measurements that show a linearity advantage of phase, and a disparity in the scaling of Deltaphi AIFs, DeltaR2* AIFs, and DeltaR2* tissue curves. Finally, we discuss issues related to the choice of AIF signal for quantitative perfusion imaging.     

MRI对评价肝癌Lp-TACE治疗的价值

目的 通过影像－病理对照研究,探讨ＭＲＩ尤其是动态增强ＭＲＩ（Ｄ－ＭＲＩ）在肝癌Ｌｐ－ＴＡＣＥ治疗随诊中的价值以及协助临床确定Ｌｐ－ＴＡＣＥ治疗间隔的可行性。材料与方法 １０例Ｌｐ－ＴＡＣＥ治疗后手术切除的肝癌患者,术前行ＣＴ扫描、ＭＲ平扫及早期动态增强扫描、增强晚期和延迟期扫描。术后肿瘤标本作ＭＲＩ、ＣＴ扫描和软Ｘ线照相（８例）,作影像－病理对照研究。结果 （１）病理表现：１０例均发现残留的肝癌     

Arterial spin labeling MRI study of age and gender effects on brain perfusion hemodynamics

Normal aging is associated with diminished brain perfusion measured as cerebral blood flow (CBF), but previously it is difficult to accurately measure various aspects of perfusion hemodynamics including: bolus arrival times and delays through small arterioles, expressed as arterial-arteriole transit time. To study hemodynamics in greater detail, volumetric arterial spin labeling MRI with variable postlabeling delays was used together with a distributed, dual-compartment tracer model. The main goal was to determine how CBF and other perfusion hemodynamics vary with aging. Twenty cognitive normal female and 15 male subjects (age: 23-84 years old) were studied at 4 T. Arterial spin labeling measurements were performed in the posterior cingulate cortex, precuneus, and whole brain gray matter. CBF declined with advancing age (P < 0.001). Separately from variations in bolus arrival times, arterial-arteriole transit time increased with advancing age (P < 0.01). Finally, women had overall higher CBF values (P < 0.01) and shorter arterial-arteriole transit time (P < 0.01) than men, regardless of age. The findings imply that CBF and blood transit times are compromised in aging, and these changes together with differences between genders should be taken into account when studying brain perfusion.