扩散加权成像在超急性、急性脑梗死中的诊断价值

目的通过与T2加权成像(T2-weighted imaging,T2WI)、T1加权成像(T1-weighted imaging,T1WI)进行比较,探讨磁共振扩散加权成像(diffusion-weighted imaging,DWI)及表观扩散系数(apparentdiffusion coeffecient,ADC)在超急性、急性脑梗死诊断中的应用价值。材料与方法应用单次激发SE-EPI(echoplanar imaging)序列进行DWI扫描和常规MR扫描,对临床40例脑梗死患者进行检查,观察病灶在DWI上的信号特点并测定病灶的ADC值。结果40例病例中超急性期(0~6h)脑梗死6例、急性期(7~24h)脑梗死34例均在DWI上呈高信号,在ADC图上呈低信号,平均ADC值为(0.689±1.04)×10-3mm2/s。结论DWI及ADC对急性、超急性脑梗死的诊断较常规MR更早、更准确,尤其是对超急性脑诊断,而且能准确反应出缺血半暗带的相应病理生理变化。     

怎样产生氢核密度ρ和T1、T2加权图像

磁共振成像(magnetic resonance imaging, MRI)的主要成像参数是自旋核密度ρ、T1、T2,但ρ、T1、T2并不能在磁共振(magnetic resonance,MR)中直接测得,它们是隐含在弛豫过程(relaxation process)样品的磁化强度矢量M在感应线圈中感应出的电压信号中.成像参数ρ、T1、T2只能通过人为手段提高权重,以MR信号的形式表现出来,这种获得成像参数的方法与其它成像有很大不同.     

MRI技术中T1、T2的物理学意义及临床应用

磁共振成像(magnetic resonance imaging,MRI)是利用射频(radio frequency,RF)电磁波对置于磁场中的含有自旋不为零的原子核的物质进行激发,发生核磁共振(nuclear magnetic resonance,NMR),用感应线圈采集共振信号,经计算机处理,建立的数字图像.本文介绍MRI技术中,决定图像质量的组织特性重要参数T1、T2的物理学意义及临床应用.     

大脑中动脉供血区脑缺血后同侧丘脑继发性损害的MR实验研究

本文应用磁共振(magnetic resonance,MR)成像在体观察大脑中动脉(middle cerebral artery,MCA)供血区脑缺血后同侧丘脑的信号变化。结果显示:(1)通过MRA(magnetic resonance angiography)可以观测到单侧MCA的闭塞与血流再通,而供应丘脑的大脑后动脉信号无变化;(2)脑缺血后1d MR T2WI(T2weighted imaging)显示单侧MCA供血区原发病灶呈高信号,3d、7d时此原发病灶信号增高程度有所降低,至14d信号强度再次明显增高;(3)脑缺血后1d和3d时双侧丘脑T2信号无差别,7d和14d时脑缺血同侧丘脑T2信号减低,T2值降低;(4)MCA供血区脑缺血后原发病灶和同侧丘脑T2值的变化不同步。上述结果证实MR能够在活体显示MCA供血区脑缺血后同侧丘脑的继发性损害。     

3.0TMRI增强扫描对恶性乳腺非肿块样强化病变的评估价值研究

目的:分析3.0T超导磁共振成像(3.0TSuperconducting magnetic resonance imaging,3.0TMRI)增强扫描对恶性乳腺非肿块样强化病变(Non mass like enhancement of breast,NME)的评估价值.方法:选取2019年6月至2020年7月在本院行X线或B超检查为可疑病变者后,接受3.0TMRI乳腺确诊为NME患者87例,以病理检查结果为标准,计算3.0TMRI对NME良、恶性鉴别准确性,并对比不同性质NME 3.0TMRI影像征像.结果:3.0TMRI对恶性NME检出准确性94.23％,良性NME为94.28％,与病理结果比较无差异(P>0.05);良性、恶性NME在中分布方式、内部强化情况等征象中比较并无差异(P>0.05),恶性NME脂肪抑制T2加权像(T2 weighted imaging,T2WI)信号以等信号为主,时间强度曲线(Time intensity curve,TIC)类型以Ⅲ型为主;良性NME脂肪抑制T2WI信号以稍等信号为主,TIC类型以I-Ⅱ型为主,恶性NME与良性NME在脂肪抑制T2WI信号、TIC类型上比较有差异(P<0.05);恶性NME MRI定量参数中Ktrans、Kep值明显高于良性NME、(P<0.05),Ve比较则无差异(P>0.05).结论:3.0TMRI征象、半定量参数在恶性NME病变诊断鉴别中有较高的使用价值.     

A novel stepwise thresholding for fuzzy image segmentation

INTRODUCTION　　 In some imaging system,such as laser scanning confocal microscopy( LSCM)imaging,computerised tomography ( CT ) imaging,magnetic resonance ( RM )imaging,etc.,the image acquisition produces sometimes fuzzy images.The fuzzyimage can be described as the follows.( 1 ) Objects may appearto fuse together.( 2 )Objects in the same class can have different intensities and individual objects canthemselves have a wide range of intensity values.( 3) Intensity will be lower deepwith…     

小粒径磁共振成像超敏感纳米对比剂的研制及初步动物实验

Objective To synthesize a small size and super-sensitive magnetic resonance imaging (MRI) nano-contrast agent for preliminary animal experiment and to explore the feasibility for its use in molecular imaging studies.Methods Polyethylene glycol (PEC) was used for ring-opening polymerization of ε-caprolactone(CL), and amphiphilic PEG-b-PCL block polymer was prepared by self-assembly technique.Single particle superparamagnetic iron oxide (SPIO) was loaded at the hydrophobic core of PEG-b-PCL to develop a nano-contrast agent.The particle diameter and SPIO-loading density were respectively determined by transmission electron microscope and atomic absorption spectroscopy.Echo multiplanar sequence was used for T2 value test, with transverse relaxation rate R2 computed.Meanwhile, magnetic properties were tested.After intravenous injection via caudal vein of Balb/c nude mice, the distributions and circulation time of this nano- particle were analyzed using MRI scanner at before injection and lh, 3h, 6 h, 12 h and 24 h after injection.Results The micelle diameter was around (38+3) nm and the content of Fe3O4 (wt%) was 37.0%.The transverse relaxation rate R2 was 110 Fe(mmol/L)-1 ·s-1.Superparamagnetism was observed in magnetic property test.After intravenous injection, the nano-particles were mainly distributed in the liver with a long circulation time.Signal intensity at 1 h decreased significantly when compared with that of before injection (120±32 vs 4986±0, P＜0.05) , and then decreased to (88±28) at 24 h (P＜0.05).Conclusion The nanometer micelle loaded with single SPIO particle demonstrates its potential as a powerful MRI contrast agent for molecular imaging studies because of its small size and high sensitivity.     

Application of functional peptides for biomedical diagnosis北大核心

BACKGROUND: As a class of biomaterials with excellent biocompatibility and biodegradability, functional peptides are becoming a research hotspot in the field of biomedicine. OBJECTIVE: To review the current development and future prospects of functional peptides in the field of biomedical diagnosis. METHODS: Search words were “peptides, self-assembly force, medicine imaging, biomaterials, medical diagnosis” in English and Chinese. Computer was used to retrieve relevant articles on self-assembled peptide medical diagnosis in VIP, Wanfang, CNKI, Web of Science, and PubMed databases from 2000 to 2020, and systematic induction, summary and analysis were conducted. RESULTS AND CONCLUSION: (1) The bonding forces for constructing self-assembled structures include van der Waals forces, hydrophobic interactions, electrostatic interactions, as well as the biological recognition of peptides. (2) The application of functional peptides in the field of biomedical diagnosis includes optical imaging, photoacoustic imaging, magnetic resonance imaging, computer tomography, and radionuclide imaging. (3) Functional peptides specifically target tumor sites in vivo for tumor imaging and treatment, with good targeting, high specificity, and strong binding affinity to receptors. (4) The functional peptides can be activated in situ by temperature and light to activate aggregation, complete multifunctional diagnosis of specific parts, good imaging effect, no toxic side effects, and fast metabolism in the body. (5) Functional peptides are labeled to enhance the detection signal in the body, monitor small changes, and perform disease diagnosis and preventive treatment. (6) It can be found that functional peptides have very broad application prospects in biomedical diagnosis, such as tumor detection and treatment, imaging of specific parts, and enhancement of detection signals. © 2023, Chinese Journal of Tissue Engineering Research. All rights reserved.     

癫痫病灶检测技术的研究进展

癫痫病灶检测技术已成为治疗难治性癫痫的一种重要手段,病灶的准确检测是保证手术安全、取得良好疗效的关键。本文综述了癫痫病灶检测技术的新进展,包括脑电图(electroencephalogram,EEG)、常规磁共振(magnetic resonance imaging,MRI)、功能性磁共振(functional magnetic resonance imaging,f-MRI)、同步脑电联合功能磁共振成像(electroencephalogram-functional magnetic resonance imaging,EEG-f MRI)、磁共振波谱分析(magnetic resonance spectroscopy,MRS)、脑磁图(magnetoencephalogram,MEG)、磁源性影像(magnetic source imaging,MSI)、单光子发射计算机断层扫描(single photon emission computed tomography,SPECT)、正电子发射断层扫描-计算机断层成像(positron emission tomography-computed tomography,PET-CT)以及偶极子定位(dipole localization method,DLM)等检测方法,并分析了每种方法的优缺点及发展方向。     

大脑锥体束华勒氏变性影像学研究进展

原发性脑损伤可导致病灶远端的锥体束发生华勒氏病变,基于磁共振技术(magnetic resonance imaging,MRI)的弥散加权成像(diffusion weighted imaging,DWI)、弥散张量成像(diffusion tensor imaging,DTI)等成像技术对于华勒氏变性的检测有不同的特点和优势,本文针对华勒氏变性各个阶段不同的影像学表现进行了综述,并对临床检测早期华勒氏变性做出了指导。