胃癌的MRI检查技术和正常胃及胃癌的表现

MRI在胃肠道的应用相对迟后于其它脏器,近年来,随着MRI扫描技术的发展,如快速扫描、脂肪抑制、屏息快速动态增强技术的应用,使MRI在胃肠道方面的应用开展起来,胃癌诊断和分期方面的研究逐渐引起人们的重视。 一、胃肠道MRI检查技术 (一)口服对比剂 胃肠道MRI检查和胃的CT检查一样,胃肠道口服对比剂非常重要,其目的为将胃肠道与其它结构区分开来,并能很好将胃肠道壁的轮廓予以显示。尽管目前对胃肠道的口服对比剂有较多的研究,但至今尚未有公认的、广泛应用于临床的胃肠道特别是胃的专用对比剂面市。理想的口服对比剂应符合下列要求     

口服钆喷酸葡胺在磁共振胰胆管成像中的应用

目的：探讨口服钆喷酸葡胺在磁共振胰胆管成像（MRCP）中的应用价值。方法：把40例黄疸患者分为服对比剂和未服对比剂2组进行扫描，比较MRCP定位诊断的正确率。结果：服对比剂组胃肠道内的高信号液体大部分或完全被钆喷酸葡胺抑制，胰胆管显示清晰，有利于诊断，未服对比剂组胃肠道内的液体为高信号，当其有较多液体时，胰胆管背景区的高信号对图像干扰较大，严重影响胰胆管的显示。结论：口服钆喷酸葡胺后行MRCP检查，可有效抑制胃肠道内液体，明显提高MRCP图像的质量。     

口服枸橼酸铁铵在3.0T高场强MR上腹部检查中的初步研究

目的通过使用3.0T磁共振扫描仪对口服枸橼酸铁铵前后进行上腹部成像,研究该对比剂在高场强磁共振上腹部检查中的临床应用价值。方法对9例健康志愿者在服用浓度为7.55mmol/L的枸橼酸铁铵前后使用相同的扫描参数进行横轴位常规T1WI、T2WI成像和磁共振胰胆管成像(MRCP),按不同解剖部位显示情况分别进行评分并进行统计学分析。结果口服对比剂后胃、十二指肠降部及肝左叶边缘的显示在不同序列的横轴位图像上都有显著改善,MRCP对胰胆管的显示也有显著改善,配对秩和检验的结果P<0.05。结论在上腹部高场强磁共振检查中使用枸橼酸铁铵对比剂可以明显改善胃肠道内液体对MRCP图像的影响,对横轴位图像的显示也有明显的改善作用。     

探讨口服对比剂在腹盆腔螺旋CT检查中的运用价值

目的：腹盆腔CT检查在临床应用相当广泛,本文探讨口服对比剂在腹盆腔螺旋CT检查中的诊断价值。材料与方法：收集我院检查前未口服对比剂和分别口服阳性和阴性对比剂病例共40例。其中10例口服阳性对比剂,15例口服阴性对比剂。未口服对比剂15例。结肠病例检查前用水灌肠,进行平扫和增强检查后回顾性分析其影像表现。结果：阴性、阳性对比剂的运用螺旋CT均能显示腹盆腔内胃肠道病变的形态、大小、内腔的狭窄程度。阳性对比剂清晰显示囊性病灶及与周围脏器和组织的关系、增大的淋巴结和转移情况,但胃肠道壁的结构显示不清。阴性对比剂显示胃肠道壁的层次、壁的增厚情况较好,但下腹部和盆腔内增大的淋巴结和软组织肿块显示不满意,并且不能用于显示腹盆腔内的囊性病变。未口服对比剂的病例由于胃肠道未充盈,腹盆腔内的实性占位和囊性病灶及增大的淋巴结显示均不满意。结论：阳性对比剂能更好地区分肠腔和周围增大的淋巴结或软组织肿块,显示并区分肠腔内外的囊性病变,适用于常规检查;阴性对比剂在实际工作中应用更方便,显示胃肠道壁效果较好,适用于上腹部和胃肠道检查。结合病史根据具体病情和患者的实际情况合理使用口服对比剂,可以扩大检查的范围,增加图像的分辨率,有效提高腹盆腔内疾病的螺旋CT诊断水平,提高病变的检出率。     

胃肠道疾病CT检查中口服对比剂的运用价值

目的初步探讨胃肠道疾病CT检查中口服对比剂的运用及诊断价值。方法收集本院145例检查前口服多种对比剂的胃肠道CT扫描病例,回顾性分析其影像表现及部分病理追踪结果;其中食道病18例,胃病67例,空、回肠病5例,阑尾病3例,结肠病16例,直肠病22例,其它14例。结果阳性、阴性对比剂的运用CT均能显示胃肠道的病变形态、大小的改变,壁的增厚,内腔的狭窄程度以及与周围组织的关系和转移情况。结论胃肠道疾病的CT诊断关健在于扫描前做好充分的胃肠道准备,阳性、阴性对比剂各有其优劣势,口服对比剂的正确选择及运用能有效的提高胃肠道的CT诊断水平,增加检出率。     

胃肠道水成像技术在低场MRI的应用

低场磁共振装机分布较广，开展胃肠道低场MRI水成像的临床应用研究具有实用价值。作者1999年完成了小肠MRI水成像的研究，将该技术经过改进应用于低场MRI，效果好，特别是肠梗阻患者不必口服任何对比剂可以及时作出诊断。现作一介绍。     

口服静脉用钆喷酸葡胺改善MRCP图像质量研究

目的:选择出静脉用钆喷酸葡胺(Gd-DTPA)作为MRCP口服胃肠道阴性对比剂的最佳浓度及容量;评价口服Gd-DTPA对比剂在抑制胃肠道高信号、改善MRCP图像质量中的作用。方法:体外实验,对不同浓度Gd-DTPA稀释液及温开水空白对照组行T1WI、T2WI、单层TSE序列及HASTE序列扫描,测量不同成像序列上的信号强度并计算增强率,选择出最佳浓度。临床实验,分别配制不同容量的最佳浓度Gd-DTPA稀释液作为MRCP口服胃肠道阴性对比剂,选择出最佳容量;以最佳浓度和容量Gd-DTPA对比剂对24例临床疑有胰胆管病变的患者行口服前及口服后5～10min、10～15minMRCP扫描,分析图像质量。结果:T1WI上对照组均为低信号,Gd-DTPA浓度≤0.01mol/L时为完全高信号;T2WI上对照组为明亮高信号,Gd-DTPA浓度≥0.015mol/L为完全低信号;2DTSE单层MRCP图像上对照组为明亮高信号,Gd-DTPA浓度在0.0025～0.03mol/L之间均为低信号;3DHASTEMRCP图像上对照组为明亮高信号,Gd-DTPA浓度≥0.01mol/L时为完全低信号;容量≥100mL浓度为0.01mol/L的Gd-DTPA对比剂对胃及十二指肠内液体高信号的抑制效果完全;24例患者口服100mL浓度为0.01mol/L的Gd-DTPA对比剂5～10min、10～15min后MRCP图像上胰胆管树各解剖结构的平均等级分数差异无显著性(P>0.05),而口服对比剂后肝内三级胆管、胆总管、胰管的平均等级分数高于口服对比剂前并差异有显著性(P<0.05)。结论:100mL浓度0.01mol/L的Gd-DTPA对比剂能使胃及十二指肠内潴留液高信号抑制完全,可作为MRCP理想的胃肠道阴性对比剂;口服该对比剂后5～10min行MRCP扫描,图像质量效果最佳。     

超顺磁性Fe2O3用作磁共振胃肠对比剂

目的 制备一种由Fe2O3为主要原料的口服磁共振胃肠造影混悬剂,研究Fe2O3在磁共振磁场中保持超顺磁性和稳定悬浮的临界尺寸.方法 根据超顺磁性理论,推导出Fe2O3微粒显示超顺磁现象的临界尺寸理论值和在1.5T磁共振磁场中的临界值;根据磁学理论,分析磁共振对比剂稳定的机制,推导在磁共振磁场中,Fe2O3微粒在对比剂中稳定悬浮的极限尺寸.以小于该尺寸的Fe2O3微粒作主料制备对比剂,并进行磁共振成像对比增强实验研究.结果 在1.5T磁共振磁场中,Fe2O3微粒在对比剂中既能稳定悬浮又具有超顺磁性的极限尺寸为11.1 nm,Fe3O4为7.1 nm.用尺寸为10 nm的Fe2O3微粒制备的对比剂,具有稳定、超顺磁性、安全、不沉降、不团聚的特性,且在磁共振成像上呈现明显的阴性对比作用.结论 从微粒尺寸角度考虑,用Fe2O3微粒作对比剂中的磁性粒子比Fe3O4更有优势.     

葡萄糖酸亚铁溶液在磁共振胰胆管成像中的应用

目的评价口服葡萄糖酸亚铁糖浆溶液在磁共振胰胆管成像(MRCP)中的应用价值。方法实验部分:将不同浓度医用硫酸钡和葡萄糖酸亚铁糖浆两种溶液装入不同试管中,行MRT2WI和singleshot扫描,改变TE时间,观察信号强度和不同反转时间(TI)信噪比的变化。临床试验:把100位患者随机分成两组行不服对比剂和口服钡或铁剂5、10、15min分别进行检查,观测胃肠道图像信噪比变化及以胰胆管解剖结构为对象的MRCP图像的改善情况。结果60%硫酸钡和14%葡萄糖酸亚铁溶液将水信号基本抑制;当TI时间为130ms左右时,铁剂溶液的信噪比强度降低明显;钡剂和铁剂的信号随TE时间的延长而降低。服用钡剂和铁剂后胃内信噪比平均值降至1.043±0.456,P<0.001;服用对比剂后十二指肠的平均信噪比降至1.930±2.315,1.933±2.320,P<0.001。口服对比剂前与口服对比剂后10minMRCP成像比较,对胆总管、胰管、胆囊结构的显示,钡剂和铁剂均具有显著性差异(P=0.012,0.010,0.014;P=0.013,0.011,0.015);与口服对比剂后15min成像比较,对胆总管、胰管、胆囊结构的显示,钡剂和铁剂均具有显著性差异(P=0.006,0.018,0.024;P=0.007,0.019,0.025),但后者图像更佳。结论口服阴性胃肠道对比剂(V/V)14%葡萄糖酸亚铁糖浆溶液约500ml后,15min进行MPCP检查,将获得极佳的MRCP图像。葡萄糖酸亚铁溶液是MRCP成像时良好的胃肠液抑制剂,使MRCP图像更加清楚,使对胰胆系疾病的定位、定性及定量诊断更加准确。     

胃肠道磁共振水成像方法研究

目的探讨胃肠道磁共振水成像方法.方法 36名健康自愿者,随机分为胃组16名、小肠组20名.依检查部位和目的不同,扫描前口服水或2%～4%安其格纳芬水溶液.选用单次激发厚层投射2D FASE 序列和3D FASE序列进行胃肠道磁共振水成像.结果 36例均获得较为满意的2D胃肠道磁共振水成像图像.图像无运动伪影,胃肠道内液体信号与周围组织信号对比良好,结构清晰.10例3D MIP图像有运动伪影,胃肠道轮廓模糊,黏膜皱襞显示不清,2D与3D图像质量有明显差异(P<0.01).水能很好充盈胃,胃磁共振水成像能勾勒出胃大体轮廓,区分胃底、胃体和胃窦.水在小肠内易被吸收而不易到达远段小肠,2%～4%安其格纳芬水溶液使小肠各段充盈扩张良好.结论单次激发厚层投射2D FASE序列是胃肠道磁共振水成像简便有效的序列,2%～4%安其格纳芬水溶液是较理想的小肠磁共振水成像口服造影剂.     

Effect of size and charge on pharmacokinetics and in vivo MRI contrast enhancement of biodegradable polydisulfide Gd(III) complexes.

The purpose of this study is to investigate how the structures of polydisulfide Gd(III) complexes affect their pharmacokinetics and in vivo contrast enhancement as biodegradable macromolecular MRI contrast agents. A negatively charged polydisulfide Gd(III) complex, (Gd-DTPA)-cystine copolymers (GDCP), and a neutral agent, (Gd-DTPA)-cystine diethyl ester copolymers (GDCEP), with different molecular weights were prepared and characterized. The MRI contrast enhancement of the agents was studied in mice. Neutral GDCEP showed more rapid degradation than negatively charged GDCP in the blood plasma. Consequently, GDCP resulted in more significant and prolonged contrast enhancement in the blood pool and liver than GDCEP. The size of GDCEP did not significantly affect its in vivo contrast enhancement due to rapid degradation and clearance from the blood circulation. The increase in the molecular weight of GDCP resulted in prolonged in vivo contrast enhancement in the blood pool. The structural modification of polydisulfide Gd(III) complexes resulted in biodegradable macromolecular MRI contrast agents with different degradability and in vivo contrast enhancement.     

动态增强MR成像在肿瘤血管生成功能成像中的应用

通过静脉注射细胞外对比剂(Gd-DTPA)后,磁共振成像(MRI)可以描述肿瘤的血管特征.由于不同组织对造影剂药物动力学的影响不同,因而动态增强磁共振成像(DCE-MRI)具有展示组织内在差异的功能.大量研究结果表明,DCE-MRI数据结果与肿瘤血管生成免疫组织标记物间具有相关性,可以用于监测各种肿瘤治疗方法的效果,如:放疗、化疗、激素治疗以及新的抗血管生成治疗等.本文就DCE-MRI基本方法和数据处理方法作一简要回顾.     

A novel technique for modeling susceptibility-based contrast mechanisms for arbitrary microvascular geometries: the finite perturber method

Recently, we demonstrated that vessel geometry is a significant determinant of susceptibility-induced contrast in MRI. This is especially relevant for susceptibility-contrast enhanced MRI of tumors with their characteristically abnormal vessel morphology. In order to better understand the biophysics of this contrast mechanism, it is of interest to model how various factors, including microvessel morphology contribute to the measured MR signal, and was the primary motivation for developing a novel computer modeling approach called the Finite Perturber Method (FPM). The FPM circumvents the limitations of traditional fixed-geometry approaches, and enables us to study susceptibility-induced contrast arising from arbitrary microvascular morphologies in 3D, such as those typically observed with brain tumor angiogenesis. Here we describe this new modeling methodology and some of its applications. The excellent agreement of the FPM with theory and the extant susceptibility modeling data, coupled with its computational efficiency demonstrates its potential to transform our understanding of the factors that engender susceptibility contrast in MRI.     

MRI在直肠癌诊疗中的发展过程与应用

直肠癌是胃肠道常见的恶性肿瘤之一,其治疗与预后主要取决于分期。目前对直肠癌分期最为准确的检查方法是MRI。初期,MRI常规序列对直肠癌的T、N分期准确率偏低,为了提高诊断准确性、为临床提供更多的信息,学者们运用了直肠腔内线圈,局部高分辨T2WI序列,增强及动态增强(dynamic contrast enhancement,DCE)扫描以及扩散加权成像(diffusion-weighted imaging,DWI)序列等进行扫描。作者就上述MRI新序列或技术的临床应用及其意义展开综述。     

Magnetic resonance safety

Magnetic resonance imaging (MRI) has a superior soft-tissue contrast compared to other radiological imaging modalities and its physiological and functional applications have led to a significant increase in MRI scans worldwide. A comprehensive MRI safety training to protect patients and other healthcare workers from potential bio-effects and risks of the magnetic fields in an MRI suite is therefore essential. The knowledge of the purpose of safety zones in an MRI suite as well as MRI appropriateness criteria is important for all healthcare professionals who will work in the MRI environment or refer patients for MRI scans. The purpose of this article is to give an overview of current magnetic resonance safety guidelines and discuss the safety risks of magnetic fields in an MRI suite including forces and torque of ferromagnetic objects, tissue heating, peripheral nerve stimulation, and hearing damages. MRI safety and compatibility of implanted devices, MRI scans during pregnancy, and the potential risks of MRI contrast agents will also be discussed, and a comprehensive MRI safety training to avoid fatal accidents in an MRI suite will be presented.     

Three‐dimensional contrasted visualization of pancreas in rats using clinical MRI and CT scanners

The purpose of this work was to visualize the pancreas in post‐mortem rats with local contrast medium infusion by three‐dimensional (3D) magnetic resonance imaging (MRI) and computed tomography (CT) using clinical imagers. A total of 16 Sprague Dawley rats of about 300 g were used for the pancreas visualization. Following the baseline imaging, a mixed contrast medium dye called GadoIodo‐EB containing optimized concentrations of Gd‐DOTA, iomeprol and Evens blue was infused into the distally obstructed common bile duct (CBD) for post‐contrast imaging with 3.0 T MRI and 128‐slice CT scanners. Images were post‐processed with the MeVisLab software package. MRI findings were co‐registered with CT scans and validated with histomorphology, with relative contrast ratios quantified. Without contrast enhancement, the pancreas was indiscernible. After infusion of GadoIodo‐EB solution, only the pancreatic region became outstandingly visible, as shown by 3D rendering MRI and CT and proven by colored dissection and histological examinations. The measured volume of the pancreas averaged 1.12 ± 0.04 cm³ after standardization. Relative contrast ratios were 93.28 ± 34.61% and 26.45 ± 5.29% for MRI and CT respectively. We have developed a multifunctional contrast medium dye to help clearly visualize and delineate rat pancreas in situ using clinical MRI and CT scanners. The topographic landmarks thus created with 3D demonstration may help to provide guidelines for the next in vivo pancreatic MRI research in rodents. Copyright © 2015 John Wiley & Sons, Ltd.     

Imaging of cranial chordomas

The clinical, pathologic, and imaging characteristics of clival chordomas in 14 patients who underwent magnetic resonance examinations were evaluated. Magnetic resonance imaging (MRI) was compared with skull series, tomography, computed tomography (CT), and magnification angiography in the diagnosis of clival chordomas. Although all examinations were highly sensitive for the detection of clival chordomas, MRI was the best single study because of its ability to image in orthogonal planes, its excellent soft-tissue contrast, and its demonstration of the relationship between the neoplasm and regional vital structures, particularly the brainstem, cavernous sinus, cranial nerves, and neighboring vessels. The deficiencies of MRI are poor visualization of tumoral calcification and osseous destruction--findings that are better identified on CT. In all 14 cases, MRI revealed the neoplasms to be black on inversion-recovery, gray on partial-saturation, and white on T2-weighted pulse sequences. Three chordomas had a speckled signal void pattern, typical of tumor calcification.     

一种载磁微泡的超声/磁共振成像研究

目的制备一种超声/MRI双模态载磁微泡,并通过超声成像和MRI成像探讨载磁量对成像效果的影响。方法利用声振法将超顺磁纳米颗粒(SPIO)装载在微泡包膜上,制备超声/MRI双模态造影剂,并根据SPIO的浓度将样品分成Ⅰ～Ⅳ组(分别为0、19.6μg/ml、114.7μg/ml、292.0μg/ml),通过透射电子显微镜和紫外可见分光光度仪测量微泡基本特征和磁浓度,应用体外超声和体外MRI检测成像效果。结果透射电镜技术证实SPIO粒子成功附着,有较好的分散性,粒径呈正态分布,中心粒径约12 nm。体外超声成像显示除气水的声像图表现为无光团,未检测到回声信号;Ⅰ～Ⅳ组随着微泡浓度的增加,回声显著增强,超声图像表现为光团强度增加。Ⅰ～Ⅳ组微泡的组织对比度分别为(5.89±0.70)dB、(8.97±0.80)dB、(11.04±0.72)dB及(12.84±0.56)dB。体外MRI成像显示,T1模式下,随着微泡中磁性粒子浓度增加,其亮度增加;而在T2模式下,随着微泡中磁性粒子浓度增加,T2弛豫时间减小,亮度变弱;双模态微泡溶液和SPIO纳米粒子水溶液的纵向弛豫率分别为7.23 s~(-1)·mM~(-1)和5.43 s~(-1)·mM~(-1),横向弛豫率分别为193.62 s~(-1)·mM~(-1)和101.55 s~(-1)·mM~(-1)。结论载磁造影剂可以增强超声/MRI成像,可为优化多模态微泡造影剂的制备提供实验指导。     

Magnetic resonance imaging of the pediatric abdomen.

In many ways, MRI of the pediatric abdomen is in its infancy. Motion will be a problem with most of the current pulse sequences, but the problem appears manageable given many of the newer software options for motion suppression. Faster pulse sequences (approaching CT scan times) will serve to improve image quality and reduce the need for sedation. Identification of a reliable enteric contrast agent probably will expand the current utility of MRI beyond evaluation of solid abdominal viscera. Although preliminary results appear promising, controlled comparative studies are necessary to determine the exact role of MRI in diagnosis and staging of common pediatric abdominal malignancies. The addition of MRI intravenous contrast agents and MR spectroscopy are anticipated to add depth and specificity to the diagnostic potential of this exciting modality.     

兔颈动脉急性血栓的MRI分子影像学评价

目的 评价纤维蛋白靶向结合MRI对比剂(EP-2104R)对兔颈动脉急性血栓的显示能力,并与非对比增强和Gd-DTPA增强MR进行对比.方法 用颈动脉外部损伤和阻塞的方法制作5只兔颈动脉内血栓模型,在血栓诱导后急性期(6.0 h)进行对比剂EP-2104R注入前及注入后MR扫描,并与组织病理学对比.结果 纤维蛋白靶向对比剂能准确显示血栓,优于非对比增强MRI和Gd-DTPA增强MRI(P<0.001).Gd-DTPA增强后不能提高发现血栓的能力.结论 纤维蛋白靶向对比剂在显示活体内急性血栓方面优于非对比增强和Gd-DTPA增强MRI.