不同浓度钆喷替酸葡甲胺体外实验及MR直接法膝关节造影的临床研究

目的 探讨不同浓度钆喷替酸葡甲胺(Gd-DTPA)MRI体外信号的变化规律及MR直接法膝关节造影的最佳浓度。方法 配制不同浓度的Gd-DTPA溶液各50ml，采用1．5T MR设备SE序列扫描、观察、测量。然后，选择2mmol／L和100mmol/L浓度Gd-DTPA分别进行直接膝关节造影。结果 Gd-DTPA浓度为2mmol/L时，TlWI信号强度最高；浓度为1．5mmoL／L时，T1WI信号强度最高。T1、T2浓度与信号强度曲线呈“L形”曲线样变化。膝关节直接造影，100mmoL／L浓度Gd-DTPA呈低信号且关节软骨显示清晰，2mmoL／L浓度Gd-DTPA呈高信号且半月板显示清晰。结论 不同浓度Gd-DTPA MRI体外信号变化规律呈“L形”曲线，MR直接法关节造影时，应根据关节病变不同，选择不同浓度的Gd-DTPA。     

肝脏MR动态增强扫描：Gd-EOB-DTPA与Gd-DTPA的个体内对照研究

目的：比较钆塞酸二钠（Gd-EOB-DTPA）及钆喷酸葡胺（Gd-DTPA）肝脏 MR动态增强扫描腹腔脏器及血管的强化特点,重点比较Gd-EOB-DTPA移行期与Gd-DTPA平衡期的图像特点。方法：本研究为前瞻性、个体内随机对照研究。25例病理证实为原发直肠癌或结肠癌、怀疑肝转移的患者,3天内行2次肝脏 MR 动态增强检查,分别使用 Gd-EOB-DTPA及Gd-DTPA两种对比剂。动态增强扫描的序列相同,包括平扫、动脉期、门静脉期、平衡期（Gd-DTPA）／移行期（Gd-EOB-DTPA）。图像客观评估中,测量各期相图像上血管及肝脾实质的信号强度。以椎旁肌肉的信号为参考,计算相对信号强度（RS）并比较两组间的差异,以及不同期相时肝实质RS的差异。主观评估：读片者主观评价增强扫描各期相图像上,主动脉、门静脉及肝静脉与肝实质的相对信号强度。结果：肝实质的RS：在动脉期Gd-DTPA 组明显高于Gd-EOB-DTPA组（t＝3．006,P＝0．005）;在门静脉期及平衡期／移行期,两组检查的差异无统计学意义（t＝1．788,P＝0．086;t＝0．781,P＝0．442）。Gd-EOB-DTPA检查时,门静脉期肝实质RS明显高于动脉期（t＝－3．014,P＝0．006）,移行期RS与门静脉期的差异无统计学意义。Gd-DTPA检查时,平衡期肝实质RS明显低于门静脉期（t＝5．827,P＝0．000）。主观评估：Gd-DTPA增强扫描平衡期图像上所有患者的主动脉、门静脉、肝静脉均为高信号（100％）;Gd-EOB-DTPA 增强扫描移行期图像上主动脉、门静脉、肝静脉均以低或等信号为主（84％,92％,92％）。结论：Gd-EOB-DTPA动态增强 MR 检查,肝脏实质在门静脉期及移行期呈持续强化,其移行期的图像特征与Gd-DTPA平衡期的图像特征有明显不同,在影像诊断时应予以关注。     

骨髓基质细胞移植联合应用脑源性神经营养因子促进大鼠脊髓损伤修复

1材料与方法 取Wistar大鼠（鼠龄2～4个月）股骨和胫骨骨髓组织，采用Percoll分离液（比重1．077）分离法获取骨髓基质细胞（BMSCs）进行培养纯化。细胞传3代，移植前72h按20μmol／L终浓度加入5溴-2脱氧尿嘧啶（BrdU）标记细胞核。采用大鼠T12．13脊髓半横断损伤模型。选择Wistar大鼠48只，体重250～300g，雌雄不拘。随机分成Ⅰ组：脊髓半横断后明胶内给予DMEM10μl；Ⅱ组：明胶内给予脑源性神经营养因子（BDNF）10μl（33μg／m1）。     

肿瘤组织99Tcm-EC-甲硝唑显像与乏氧诱导因子-1α表达水平的相关性研究

目的探讨肿瘤组织^99Tc^m-双半胱氨酸（EC）-甲硝唑SPECT显像与乏氧诱导因子-1α（HIF-1α）表达水平的相关性。方法建立昆明小鼠S180肉瘤肿瘤模型12个，对其进行^99Tc^m-EC-甲硝唑SPECT乏氧显像，测定其肿瘤／对侧肌肉放射性比值（T／M）。显像结束后即刻断颈处死小鼠，取出瘤体，用免疫组织化学法分别测定肿瘤组织HIF-1α及其调控的下游基因血管内皮生长因子（VEGF）表达水平。结果12只荷S180肉瘤昆明小鼠注射^99Tc^m-EC-甲硝唑后3hSPECT显像的T／M为1．93～4．46（中位值3．13）。免疫组织化学结果显示表达HIF-1α的细胞占31．2％～60．8％（中位值50．4％），与T／M呈直线相关（t=2．732，r=0．654，P=0．021）；表达VEGF的细胞占33．8％．57．5％（中位值53．1％），与HIF-1α表达细胞亦呈直线相关（t=3．011，r=0．690，P=0．0131）。结论肿瘤组织^99Tc^m-EC-甲硝唑SPECT显像与其HIF-1α的表达水平呈线性相关，两者结合能较可靠地反映肿瘤组织的乏氧状况。     

Spred2基因对人肝癌细胞凋亡韵影响

目的观察Spred2对人肝癌细胞（HepG2）凋亡的影响。方法用阳离子脂质体瞬时转染pcDNA3．0,pcDNA3．0-Spred2到HepG2细胞,建立过表达Spred2的细胞模型。膜联蛋白（annexlFl）V．FITC／PI（7．AAD）双标通过流式细胞仪检测细胞凋亡;蛋白质印迹检测SprcdZ的表达水平。结果特柒Spred2基因能明显诱导HepG2细胞凋亡。另外,转染Spred2基因能显著地增强5一FU诱导HepG2细胞凋亡。结论Spred2对人肝癌细胞凋亡有调控作用。     

18F—FB—RGD的自动化制备及其生物学评价

目的研究18F标记RGD多肽的自动化合成方法,并探讨标记物在荷瘤鼠体内的生物学分布情况。方法在研究了自动化制备N-琥珀酰亚胺-4-18F-氟苯甲酸酯（18F—SFB）的基础上,通过向18F—SFB乙腈溶液中加入RGD多肽、无水DMSO和无水N,N-二异丙基乙胺（DIPEA）,充分反应得到18F-氟苯甲酰基（FB）-C（RGDyK）,即18F—FB—RGD的粗产品,经HPLC系统梯度分离和固相萃取得到纯品18F—FB—RGD,研究其在荷瘤鼠体内的生物学分布和竞争实验。结果18F—FB—RGD的标记率为（33．6±3．5）％,合成时间约为110min,放化纯大于98％。荷瘤小鼠注射18F—FB—RGD后30,60,90和120min,肿瘤摄取放射眭分别为（3．43±0．15）、（2．61±0．14）、（211±0．13）、（1．79±O．18）％ID／g,肿瘤／肌肉放射性比值为4．26±0．69至5．80±0,78。用RGD阻断后,肿瘤摄取放射性明显下降,阻断后60min,阻断组放射性摄取[（0．46±0．21）％ID／g]为非阻断性组[（2．87±0．59）％ID／g]的1／6。结论18F—FB—RGD是一种有希望的肿瘤显像剂,用国产模块可自动化合成。     

模拟失重条件下骨形态发生蛋白-2诱导的成骨细胞蛋白激酶MEK1活性的变化

目的观察模拟失重条件下由骨形态发生蛋白-2（BMP-2）诱导的大鼠骨肉瘤成骨样细胞（ROS17／2．8）中丝裂原激活的蛋白激酶／细胞外信号调节激酶的激酶1（MAPK／ERK kinase1，MEK1）活性的变化。方法在地面1G和回转器模拟失重条件下培养ROS17／2．8细胞，培养时间分别为24h、48h和72h。培养结束前1h加入BMP-2（500ng／ml），1h后提取细胞蛋白，应用Western Blotting法检测细胞中的总细胞外信号调节激酶1／2（总ERK1／2）和磷酸化细胞外信号调节激酶（p-ERK1／2）的含量。另设一空白对照组，即1G条件下不加BMP-2的培养组。结果7个实验组细胞的总ERK1／2蛋白表达量无明显差异；空白对照组p-ERK1／2的表达量极低，明显低于其他6组（P〈0．01）；各时间点模拟失重组p-ERK1／2表达量均低于1G对照组（P〈0．01）；随着失重时间延长p-ERK1／2表达量呈逐渐降低的趋势（P〈0．01）。结论模拟失重条件下BMP-2诱导的成骨细胞MAPK信号通路中蛋白激酶MEK1的活性下降。     

增强MRI评价抗青光眼药物对血-房水屏障的影响

目的：探讨增强 MRI评估抗青光眼药物滴眼后对血-房水屏障影响的可行性。方法：将12只健康洁净新西兰白兔分为两组,A组采用单眼滴注1％盐酸匹鲁卡品滴眼液,B组采用单眼滴注0．25％噻吗心安滴眼液,以对侧眼作为对照。静脉注射Gd-DTPA 0．2 mL后行 MR动态增强扫描,共扫描10次（1 h内每间隔10 min行1次 MRI,1 h以后间隔15 min行1次 MRI）。测量各时间点前房、睫状体和后房的平均信号强度,绘制时间-信号增强率曲线,观察对比剂在眼内的分布情况。结果：在注射对比剂后2组中实验眼睫状体信号迅速增高,15 min后达到最高峰,信号增强率为109．0％±5．8％,此后信号强度逐渐下降;前房信号呈缓慢增高,50～60 min到达峰值,信号增强率为98．0％±6．3％,高于对照眼（59．0％±4．6％）,差异有统计学意义（P＜0．05）;双眼后房均未见信号增强,始终为低信号。结论：血浆蛋白进入前房途径与房水分泌途径是分别独立的通道,眼的前后房之间存在着屏障,使用抗青光眼药物后并没有破坏血-房水屏障;增强MRI可用于评估眼的房水循环情况。     

乳腺纤维腺瘤的MRI表现及与病理对照

目的观察乳腺纤维腺瘤的多种MRI表现，分析其病理基础，从而加深对纤维腺瘤的认识，提高MRI诊断准确率。方法对33例乳腺纤维腺瘤患者（38个病灶），行常规MR平扫和动态增强检查。所有病例均经病理证实，分析比较病灶的MRI形态学、信号强度及其动态增强特点等。结果33例38个乳腺纤维腺瘤的形态学表现以分叶状、类圆形为主，占89．5％（34／38）。MRI显示内部信号多较均匀，T1WI呈等、低信号，T2WI信号多样化，高信号者的黏液样变明显（平均指数1．9），间质细胞丰富（平均指数2．2）；呈低信号者间质多硬化，间质细胞分布稀疏。不同信号强度的2种指数差异有统计学意义（x^2值分别为11．267、10．415，P值均〈0．05）。肿瘤有完整的包膜，边界多清晰者占86．8％（33／38）。增强后无或轻度强化（5／38）、明显强化（33／38）；不同强化曲线的2种指数差异无统计学意义（x^2=1．171、2．861，P〉0．05）。强化程度与患者的年龄构成有一定的相关性，年龄较轻者，强化多明显。无强化分隔者（9／33），是由于瘤体内部间质纤维组织胶原化形成。结论乳腺纤维腺瘤的MR T2WI信号及强化程度表现多样化，和其瘤体内黏液硬化程度及间质细胞含量相关。认识纤维腺瘤的特征性MRI表现有助于鉴别诊断。     

采用磁共振扩散加权成像和动态增强T_2~*加权灌注成像评价腮腺恶性肿瘤

目的：采用磁共振扩散加权成像和动态增强T2^＊加权灌注成像评价腮腺恶性肿瘤，探讨其最佳参数。方法：45例经病理证实为腮腺肿瘤的患，其中男26例，女19例，平均55岁。采用单次激发EPI进行扩散加权成像和动态增强T2^＊加权首过灌注成像，得到b值为0、500、1000s／mm^2的扩散加权图像，重组出表观扩散系数图（ADC图），计算肿瘤的ADC值。团注Gd-DTPA（0．3mlmol／kg BW）后进行磁共振动态增强成像，得到肿瘤的信号-时间曲线及最大信号强度衰减曲线。进行多变量的logistic回归分析，得出判断恶性肿瘤的阈值，计算其诊断符合率、敏感度、特异度、阳性预测值（PPV）、阴性预测值（NPV）。     

A monitoring,feedback, and triggering system for reproducible breath-hold MR imaging

A technique is described that provides improved reproducibility of breath-holding for MR image acquisition by monitoring the superior-inferior (S/I) position of the diaphragm. The method incorporates detection of the level of inspiration using an MR signal, rapid display to the patient of diaphragm position to enable breath-hold adjustment, and triggering of image data acquisition once appropriate position is attained. The response time of the system is short, approximately 10 ms. Studies in six volunteers using this method demonstrate a considerable decrease in the S/I range of diaphragm position over 10 consecutive periods of suspended respiration. The mean range is 1.3 mm with the system, while it is 8.3 mm without using it is expected that this method will be of assistance in many abdominal and cardiothoracic studies that use breath-hold techniques.     

DSA功能性参数的提取与利用

本文介绍了在临床实际中利用功能性参数，对冠状动脉ＤＳＡ心肌血流灌注成像、冠状动脉血流量测定、左心室功能测定、肺动脉高压程度的评价等项目研究结果。重点讨论了提取ＤＳＡ功能性参数的一般方法，认为功能性参数在现代影像诊断学中的作用是对疾病做出程度、定量、动态及功能诊断。     

RARE spiral T2-weighted imaging

Spiral imaging has a number of advantages for fast imaging, including an efficient use of gradient hardware. However, inhomogeneity-induced blurring is proportional to the data acquisition duration. In this paper, we combine spiral data acquisition with a RARE echo train. This allows a long data acquisition interval per excitation, while limiting the effects of inhomogeneity. Long spiral k-space trajectories are partitioned into smaller, annular ring trajectories. Each of these annular rings is acquired during echoes of a RARE echo train. The RARE refocusing RF pulses periodically refocus off-resonant spins while building a long data acquisition. We describe both T₂-weighted single excitation and interleaved RARE spiral sequences. A typical sequence acquires a complete data set in three excitations (32 cm FOV, 192 × 192 matrix). At a TR = 2000 ms, we can average two acquisitions in an easy breath-hold interval. A multifrequency reconstruction algorithm minimizes the effects of any off-resonant spins. Though this algorithm needs a field map, we demonstrate how signal averaging can provide the necessary phase data while increasing SNR. The field map creation causes no scan time penalty and essentially no loss in SNR efficiency. Multiple slice, 14-s breath-hold scans acquired on a conventional gradient system demonstrate the performance.     

Echo-Time-Encoded Burst Imaging (EBI): A Novel Technique for Spectroscopic Imaging

A new technique for rapid spectroscopic imaging is presented. The proposed experiment enables a complete mapping of the two-dimensional reciprocal space k_x, k_o, and thus the acquisition of a 1D spectroscopic image in a single scan. The properties of the pulse sequence, based on the use of a burst of low flip angle pulses, are analyzed in the framework of linear response theory, and it is shown that chemical shift information may be introduced into the spatially encoded echoes. First experimental results are presented demonstrating that 32 x 32 proton spectroscopic images may be acquired within less than 1 min with a conventional imaging system.     

Fast imaging of phosphocreatine in the normal human myocardium using a three-dimensional RARE pulse sequence at 4 Tesla

PURPOSE: To investigate the use of a three-dimensional rapid acquisition with relaxation enhancement (RARE) pulse sequence for direct acquisition of phosphocreatine (PCr) images of the human myocardium. MATERIALS AND METHODS: A short elliptical birdcage radiofrequency (RF) body coil was constructed to produce a uniform flip angle throughout the chest cavity. In vivo images using a spectrally-selective RARE sequence with a spatial resolution of 1.2 cm x 1.2 cm x 2.5 cm (4 cm(3)) were acquired in nine minutes and 40 seconds. RESULTS: Scans of phantoms demonstrated excellent spectral selectivity. The signal-to-noise ratio in the myocardium ranged from 12.6 in the anterior wall to 5.3 in the mid septum. CONCLUSION: This study demonstrates that PCr data can be acquired using a three-dimensional RARE sequence with greater spatial and temporal resolution than spectroscopic techniques.     

Current Status of Optical Imaging for Evaluating Lymph Nodes and Lymphatic System

Optical imaging techniques use visual and near infrared rays. Despite their considerably poor penetration depth, they are widely used due to their safe and intuitive properties and potential for intraoperative usage. Optical imaging techniques have been actively investigated for clinical imaging of lymph nodes and lymphatic system. This article summarizes a variety of optical tracers and techniques used for lymph node and lymphatic imaging, and reviews their clinical applications. Emerging new optical imaging techniques and their potential are also described.     

Simultaneous multislice (SMS) imaging techniques

Simultaneous multislice imaging (SMS) using parallel image reconstruction has rapidly advanced to become a major imaging technique. The primary benefit is an acceleration in data acquisition that is equal to the number of simultaneously excited slices. Unlike in‐plane parallel imaging this can have only a marginal intrinsic signal‐to‐noise ratio penalty, and the full acceleration is attainable at fixed echo time, as is required for many echo planar imaging applications. Furthermore, for some implementations SMS techniques can reduce radiofrequency (RF) power deposition. In this review the current state of the art of SMS imaging is presented. In the Introduction, a historical overview is given of the history of SMS excitation in MRI. The following section on RF pulses gives both the theoretical background and practical application. The section on encoding and reconstruction shows how the collapsed multislice images can be disentangled by means of the transmitter pulse phase, gradient pulses, and most importantly using multichannel receiver coils. The relationship between classic parallel imaging techniques and SMS reconstruction methods is explored. The subsequent section describes the practical implementation, including the acquisition of reference data, and slice cross‐talk. Published applications of SMS imaging are then reviewed, and the article concludes with an outlook and perspective of SMS imaging. Magn Reson Med 75:63–81, 2016. © 2015 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.     

Dynamic bioluminescence imaging for quantitative tumour burden assessment using IV or IP administration of <Emphasis Type="SmallCaps">d</Emphasis>-luciferin: effect on intensity,time kinetics and repeatability of photon emission

Introduction In vivo bioluminescence imaging (BLI) is a promising technique for non-invasive tumour imaging. d-luciferin can be administrated intraperitonealy or intravenously. This will influence its availability and, therefore, the bioluminescent signal. The aim of this study is to compare the repeatability of BLI measurement after IV versus IP administration of d-luciferin and assess the correlation between photon emission and histological cell count both in vitro and in vivo. Materials and methods Fluc-positive R1M cells were subcutaneously inoculated in nu/nu mice. Dynamic BLI was performed after IV or IP administration of d-luciferin. Maximal photon emission (PE_max) was calculated. For repeatability assessment, every acquisition was repeated after 4 h and analysed using Bland–Altman method. A second group of animals was serially imaged, alternating IV and IP administration up to 21 days. When mice were killed, PE_max after IV administration was correlated with histological cell number. Results The coefficients of repeatability were 80.2% (IV) versus 95.0% (IP). Time-to-peak is shorter, and its variance lower for IV (p < 0.0001). PE_max was 5.6 times higher for IV. A trend was observed towards lower photon emission per cell in larger tumours. Conclusion IV administration offers better repeatability and better sensitivity when compared to IP. In larger tumours, multiple factors may contribute to underestimation of tumour burden. It might, therefore, be beneficial to test novel therapeutics on small tumours to enable an accurate evaluation of tumour burden. Marleen Keyaerts is a Ph. D. fellow of the Research Foundation—Flanders (Belgium; FWO).     

Temporal resolution improvement in dynamic imaging

In some dynamic imaging applications, only a fraction, 1/n, of the field of view (FOV) may show considerable change during the motion cycle. A method is presented that improves the temporal resolution for a dynamic region by a factor, n, while maintaining spatial resolution at a cost of √n in signal-to-noise ratio (SNR). Temporal resolution is improved, or alternatively, total imaging time is reduced by reducing the number of phase encodes acquired for each temporal frame by 1/n. To eliminate aliasing, a representation of the signal from the static outer portion of the FOV is constructed using all the raw data. The k-space data derived from this representation is subtracted from the original data sets, and the differences correspond to the dynamic portion of the FOV. Improved resolution results are presented in phantom studies, and in vivo phase contrast quantitative flow imaging.