基于超声多普勒组织成像的人工起搏状态下心肌运动速度特征研究

目的定量分析希氏束 (His)人工起搏状态下的心肌运动速度特征 ,探索心肌运动模式。方法采用二维彩色超声组织多普勒速度成像模式 ,观察、记录 5条犬在His以 1 2 0次心率人工起搏状态下的His周和室间隔 (interventricularseptum ,IVS)心肌运动 ,对保存的图像序列进行后处理以得到心肌速度值序列 ,然后对此序列值进行分析。结果得到心肌连续时间—速度曲线 ,根据曲线得到 :His周心肌收缩舒张时间 ( 2 0 9.75± 1 9.41 )ms和 ( 2 94.5 0± 1 7.87)ms、收缩速度 (S) ( 5 .43± 1 .5 3)cm/s、舒张早期速度 (E)( 3.95± 1 .1 8)cm/s、舒张末期速度 (A) ( 1 .72± 0 .77)cm/s、E/A为 2 .0 6± 0 .95 ;IVS心肌收缩舒张时间( 1 91 .33± 1 7.2 3)ms和 ( 2 94.70± 1 7.91 )ms、S为 ( 3.1 7± 1 .34)cm/s、E为 ( 2 .1 7± 0 .64)cm/s、A为 ( 1 .48± 0 .5 2 )cm/s、E/A为 1 .30 5± 0 .2 87。结论在His人工起搏状态下 ,心肌运动的初步特征为 :1 )His周比IVS心肌运动速度大。 2 )E/A大于 1。     

肝肿瘤MR弹性成像评价肿瘤黏弹性的特性

目的 MR弹性成像评价肝肿瘤的特性黏弹性参数的价值。资料与方法 94例肝肿瘤>1cm的病人按预期进行MR弹性成像,使用50Hz的机械波和一个完整的三维运动敏感序列。计算72个除外囊性、已处理的或组织病理学未确定的肿瘤病变的无模型弹性参数(复数切变模量和它的真实和虚数部分,即储能模量和损耗模量)。结果观察到恶性肿瘤与良性肿瘤相比有较高的绝对剪切模量和损耗模量[分别为(3.38±0.26)kPa、(2.41±0.15)kPa,P<0.01和(2.25±0.26)kPa、(1.05±0.13)kPa,P<0.001]。此外,肝细胞癌的损耗模量显著高于良性肝肿瘤。恶性肿瘤和良性肿瘤的储能模量之间没有显著差异。当恶性和良性病变进行比较时损耗模量受试者操作特征曲线下的面积显著大于绝对剪切弹性模量和储能模量。结论损耗模量增加比储能模量或剪切模量绝对值的增加更有助于鉴别良性与恶性肿瘤。     

肝脏撞击伤后血液黏弹性变化及对机体影响的实验研究

目的探讨兔肝脏撞击伤后血液黏弹性变化的特点及其临床意义和对机体的影响,为临床在肝损伤后早期采用降黏措施提供实验研究依据。方法建立兔肝脏撞击伤的动物模型,分别在伤前、伤后10、30、60、120分钟及死亡即时等几个时相点各抽血2ml,24小时内全部送检并完成测定,并按血液黏弹性计算方法得出结果。结果肝撞击伤后当时间一定,血液黏度(η)随剪切率的增大而降低;当剪切率一定,η随时间的延长而升高。剪切率(ω)一定,血液黏度分量(η’)、血液弹性分量(G’)随时间的延长而升高;时间一定,η’随ω的增大先降低后升高,在ω为1．627时增大到最高峰后再降低;G’随ω的增大先升高,在ω为3．000时,增大到最高峰后再降低。结论在家兔肝撞击伤后的早期抗休克救治过程中,积极输血扩容的同时,还应采取措施降低血液黏度及黏弹性,以达到改善微循环,有效纠正组织缺血缺氧的不良状况,防止全身并发症的发生,     

心梗部位对超声多普勒左室舒张功能测定的影响

目的 :观察心梗患者缺血部位不同对常规超声多普勒左室舒张功能检测指标的影响。资料与方法 :以核素心肌扫描显像为定位标准 ,将 84例急性、陈旧性心肌梗塞患者按缺血部位不同分成 :(1)前壁心梗 ,(2 )间壁心梗 ,(3 )下 (后 )壁心梗 ,(4 )侧壁心梗 ,(5 )广泛前壁 ,(6)前壁伴下壁及侧壁心梗 ,(7)心尖部室壁瘤形成 7组 ;观察了描述左室舒张功能的超声多普勒二尖瓣口血流速度指标 E/A比值和核素心血池造影左室峰值充盈率 LVPFR在各分组中的变化。结果 :缺血范围较局限的左室前壁、间壁及侧壁心梗组之间的 L VPFR测值无明显差别 ,分别为 (1.82± 0 .48)、(2 .0 7± 0 .79)、(2 .18± 0 .90 ) EDV/S,但多明显高于下 (后 )壁、广泛前壁、室壁瘤及左室壁多个部位缺血组 ,其 LVPFR分别为 (1.63± 0 .3 3 )、(1.2 2± 0 .68)、(1.45± 0 .43 )、(1.15± 0 .3 8) EDV/S,而后 4组之间的 L VPFR测值差别不显著 ;单有左室前壁、间壁缺血的心梗组的 E/A比值也高于左室下 (后 )壁、广泛前壁、多部位心肌缺血的心梗组 ,其 E/A比值分别为 1.17± 0 .3 1、1.0 9±0 .2 6、0 .78± 0 .2 8、0 .80± 0 .5 1、0 .81± 0 .3 1;除下 (后 )壁心梗组外 ,其它各组的 E/A比值与室壁瘤形成组差别不显著 ,后者的 E/A比值为 1.0 2± 0 .     

运动201Tl肺/心比值对高血压合并冠状动脉疾病的临床价值

目的评价运动201Tl肺/心比值对高血压合并冠状动脉疾病(CAD)患者冠状动脉病变严重程度的诊断价值及其与左室舒张功能的相关性.方法 19例正常对照者.102例经冠状动脉造影确诊的CAD患者,分为3组无高血压、高血压无心肌肥厚和高血压心肌肥厚组.受检者均行运动-延迟心肌灌注断层显像,取运动断层显像上的前位显像计算肺/心比值.结果无高血压组(0.43±0.09,t=3.01)、高血压无心肌肥厚组(0.42±0.12,t=2.10)和高血压心肌肥厚组(0.47±0.09,t=4.76)的肺/心比值均较对照组(0.36±0.05,P<0.05～0.01)显著为高,但3组间相比差异均无显著性(P均>0.05);上述3组单支和多支病变的肺/心比值分别为0.40±0.09和0.46±0.10、0.38±0.11和0.48±0.12及0.46±0.11和0.48±0.10.前2组单支与多支相比差异均有显著性(P均<0.05),后组差异无显著性(P>0.05);3组患者肺/心比值≥0.45时对多支病变的诊断灵敏度和特异性分别为82%和75%、90%和75%及40%和45%.无高血压组(r=0.402,P<0.01)和高血压无心肌肥厚组(r=0.408,P<0.05)的肺/心比值与半定量评分均呈显著正相关,但高血压心肌肥厚组(r=0.114,P>0.05)与半定量评分无相关性.无高血压组(r=-0.413,P<0.01)、高血压心肌肥厚组(r=-0.662,P<0.01)和高血压无心肌肥厚组的肺/心比值(r=-0.408,P<0.05)与早期(E)和晚期(A)充盈速率比值均呈显著负相关.结论运动肺/心比值对伴和不伴高血压CAD患者的冠状动脉多支病变及左室舒张功能异常均有较好的诊断价值,但对高血压心肌肥厚CAD患者多支病变的诊断价值不大.     

用99Tcm-MIBI心肌显像评价犬急性心肌梗死后早期左室重构

目的 使用99Tcm-甲氧基异丁基异腈(MIBI)心肌显像观察犬实验性急性心肌梗死(AMI)后6 h内左心室形态、功能等早期重构变化.方法 杂种犬24条,分为手术组16条,假手术组8条.手术组犬在麻醉下开胸打开心包,结扎冠状动脉左前降支(LAD)主干建成AMI模型.即刻按体重静脉注射99Tcm-MIBI 37～55.5 MBq/kg.结扎LAD后[21.87±11.03(14～48)]min开始行首次显像,并连续采集6 h.假手术组手术过程同上,但不结扎冠状动脉LAD.仪器为ADAC VertexDual-head SPECT仪.结果 结扎后首次显像即可观察到左心室前壁、心尖部放射性缺损或明显减低,左室整体扩张变形、梗死区膨胀无室壁运动.QGS软件计算手术组舒张末期容积(EDV)、收缩末期容积(ESV)分别为(48.73±12.74)、(32.57±8.10)ml,与假手术组[分别为(36.88±11.12)、(24.93±7.25)ml]相比差异有显著性(t=5.24、3.50,P＜0.01);左室射血分数(LVEF)为(33.64±6.05)%与假手术组[(32.40±9.20)%]比较差异无显著性(t=0.95,P＞0.05).结扎LAD后6 h内EDV、ESV仍增大,而LVEF无明显变化.结论 99Tcm-MIBI心肌显像可在AMI后早期(最早14min)就观察到左心形态、大小及功能改变等早期左室重构的发生,并可随时间进展了解AMI后心功能受损情况,是研究AMI后左室重构的有用方法.     

甲状腺素对胸部火器伤后心功能不全治疗作用的实验研究

目的　观察胸部火器伤后甲状腺激素 (FT3)变化及其对伤后心功能不全的治疗作用。方法 :　家兔 18只 ,随机分为 3组。A组 :正常对照组 6只 ;B组 :火器伤组 6只 ;C组 :FT3治疗组 6只。监测平均动脉压、左室舒张末压、中心静脉压、FT3及心肌肌钙蛋白T(cTnT) ,观察心肌病理及超微结构。结果　B组伤后6小时平均动脉压 (6 1.1± 15 .4)mmHg,明显低于A组 (10 1.3± 17.5 )mmHg ,左室舒张末压 (39.6± 7.7)mmHg及中心静脉压 (2 0 .93± 1.97)cmH2 O ,显著高于A组 [(16 .3± 11.0 )mmHg ,(6 .5 4± 0 .5 2 )cmH2 O],cTnT漏出较A组增加明显 ,血FT3(1.32± 0 .37)ng/ml浓度明显低于A组 (5 .16± 1.45 )ng/ml,心肌间质大量红细胞浸润。治疗组平均动脉压明显高于B组 ,中心静脉压及左室舒张末压明显低于B组 ,FT3浓度接近正常水平 ,明显高于B组。心肌肿胀减轻 ,间质出血、肌丝断裂和溶解减轻现象明显。结论　胸壁心前区切线位火器伤后造成心肌病理损害及心功能不全 ;甲状腺激素明显减低 ,与心功能减退有一致性关系 ;纠正伤后低T3状态 ,有显著的治疗效果。     

超声弹性成像技术在天芪降糖胶囊治疗糖尿病患者下肢动脉血管壁弹性的评价

目的 探讨超声弹性成像技术评价天芪降糖胶囊对2型糖尿病(T2DM)患者下肢动脉血管壁弹性的影响.方法 研究时间为2013年9月到2017年1月,选择收治的健康成人30例作为对照组,将初诊T2DM患者60例(糖尿病组)随机双盲实验方法分为两组,治疗组(30例)给予天芪降糖胶囊治疗,观察组(30例)给予安慰剂治疗;记录所有入选者的下肢动脉血管壁弹性状况,记录与随访糖尿病组患者的预后情况.结果 糖尿病组足背动脉的 B/A、β、AC值分别为1.92 ± 0.56、26.70 ± 8.29和0.01 ± 0.01 mm2,对照组分别为1.09 ± 0.14、14.53 ± 4.40和0.05 ± 0.02 mm2,对比差异明显(P<0.05);治疗组足背动脉的B/A、β、AC值与观察组对比无明显差异(P<0.05).治疗组与观察组的总有效率为96.7%和83.3%,治疗组明显优于观察组(P<0.05).随访至今,治疗组的脑梗死、下肢静脉血栓、周围神经病变等终点事件发生率为6.7%,观察组为30.0%,治疗组低于观察组(P<0.05).直线相关分析显示治疗组的足背动脉B/A、β、AC值与总有效率和终点事件发生率都有明显相关性(P<0.05).结论 天芪降糖胶囊治疗T2DM有很好的效果,超声弹性成像技术能有效评价T2DM患者的下肢动脉血管壁弹性,且血管壁弹性的评价能有效反映治疗效果.     

川芎嗪对急性心肌梗死急诊冠状动脉介入治疗后"心肌无复流"的影响

目的 利用SPECT心肌灌注显像观察川芎嗪对急性心肌梗死(AMI)急诊冠状动脉介入治疗(PCI)后患者心肌微循环的影响,以探讨"心肌无复流"治疗的新途径.方法 行PCI的AMI患者82例,分为川芎嗪组(治疗组,40例)和对照组(42例).受检患者分别于梗死相关血管(IRA)再通即刻、川芎嗪治疗24 h内及第15天分别注射99Tcm-tetrofosmin 555、1110和740 MBq,1 h后用SPECT行门控静息心肌灌注显像.用Cequal和Qgspect软件分别处理,得到3个断面断层图像及左室射血分数(LVEF)、左室收缩末期容积(LVESV)、左室舒张末期容积(LVEDV).并分别计算心肌显像总积分.结果 治疗组与对照组PCI后即刻LVEF(%)(47.5±7.1和48.4±8.6)、LVEDV(ml)(91.1±24.5和89.1±23.4)、LVESV(ml)(48.7±16.4和45.9±16.7)和心肌显像积分(7.8±2.9和7.5±3.1)差异无显著性(P＞0.05);PCI后24 h内,治疗组LVEF(%)(43.5±8.0)较对照组(44.7±8.3)减少更为明显(P＜0.05),而LVEDV(ml)(93.5±24.9和99.2±24.8)、LVESV(ml)(52.9±16.1和54.5±14.4)呈增加趋势,2组间差异无显著性(P＞0.05);PCI后15 d,治疗组与对照组比较,LVEF(%)(45.5±6.9和45.6±7.6)、LVEDV(ml)(92.8±24.9和99.9±22.3)及LVESV(ml)(51.2±17.0和54.8±16.1)均明显改善(P＜0.05).治疗组与对照组PCI后24 h内及15 d心肌显像积分比较,治疗组积分减少更为明显(4.5±2.6,3.0±2.5和6.0±2.6,4.2±2.7;P＜0.05).结论 SPECT心肌灌注显像能准确反映川芎嗪对"心肌无复流"的改善.     

冠心病舒张性心力衰竭与左房扩大的相关分析

目的对冠心病舒张性心力衰竭患者左房内径变化及其临床意义进行研究.方法用彩色多普勒超声心动图仪测定44例冠心病舒张性心力衰竭患者(DHF组)左房内径(LAD)、左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)、左心室射血分数(LVEF)、E峰、A峰及E/A比值,并与30例冠心病心功能正常者(对照组)比较.结果DHF组左房内径(33.5±4.5)mm较对照组(28.4±4.4)mm显著增加(P＜0.01),左房内径扩大者(＞30 mm)36例,占80.0%.DHF组中,E/A＞1(伪正常化)患者LAD(35.93±9.78)mm较E/A＜值的增加和降低与NYHA心功能分级相关性不明显,左房扩大程度与心功能分级相关性不明显.结论DHF患者存在左房扩大,左房扩大是舒张性心功能不全的病情发展标志.     

Assessment of liver viscoelasticity using multifrequency MR elastography

MR elastography (MRE) allows the noninvasive assessment of the viscoelastic properties of human organs based on the organ response to oscillatory shear stress. Shear waves of a given frequency are mechanically introduced and the propagation is imaged by applying motion‐sensitive gradients. An experiment was set up that introduces multifrequency shear waves combined with broadband motion sensitization to extend the dynamic range of MRE from one given frequency to, in this study, four different frequencies. With this approach, multiple wave images corresponding to the four driving frequencies are simultaneously acquired and can be evaluated with regard to the dispersion of the complex modulus over the respective frequency. A viscoelastic model based on two shear moduli and one viscosity parameter was used to reproduce the experimental wave speed and wave damping dispersion. The technique was applied in eight healthy volunteers and eight patients with biopsy‐proven high‐grade liver fibrosis (grade 3–4). Fibrotic liver had a significantly higher (P < 0.01) viscosity (14.4 ± 6.6 Pa · s) and elastic moduli (2.91 ± 0.84 kPa; 4.83 ± 1.77 kPa) than the viscosity (7.3 ± 2.3 Pa · s) and elastic moduli (1.16 ± 0.28 kPa; 1.97 ± 0.30 kPa) of normal volunteers. Multifrequency MRE is well suited for the noninvasive differentiation of normal and fibrotic liver as it allows the measurement of rheologic material properties. Magn Reson Med 60:373–379, 2008. © 2008 Wiley‐Liss, Inc.     

Energetic differences between viable and non-viable myocardium in patients with recent myocardial infarction are not an effect of differences in wall thinning— a multivoxel <Superscript>31</Superscript>P-MR-spectroscopy and MRI study

To evaluate multivoxel ³¹P-MR spectroscopy (MRS) for assessment of energy metabolism in patients with myocardial infarction (MI) in correlation to left ventricular (LV) wall thickness and the outcome of revascularization. Thirty patients with subacute anterior myocardial infarction and planned revascularization were enrolled. 3D–chemical shift imaging was applied to determine PCr/ATP ratios in two areas: infarcted/anterior and noninfarcted/septal myocardium. MRI was used to evaluate LV function and wall thickness, and was repeated 6 months after revascularization to assess myocardial viability. Fifteen volunteers were controls. Fifteen patients showed normalization of wall motion abnormalities after revascularization (Group 1; viable), 15 not (Group 2; non-viable). Regarding infarcted/anterior myocardium, Group 2 had lower PCr/ATP ratios (0.81 ± 0.60 vs 1.17 ± 0.25), and PCr/ATP ratios were reduced in both groups compared to controls (1.45 ± 0.29). Regarding noninfarcted/septal myocardium, again Group 2 had lower ratios (0.93 ± 0.53 vs 1.31 ± 0.38); however, compared to controls (1.51 ± 0.32) a reduction of PCr/ATP ratios was only found in Group 2. For both myocardial regions, no correlations between PCr/ATP ratios and LV wall thickness were detected. The more severe energetic alteration in irreversibly damaged myocardium is not an effect of differences of wall thinning. Additional alterations of noninfarcted, adjacent myocardium can be detected.     

Altered energy metabolism after myocardial infarction assessed by 31P-MR-spectroscopy in humans

The value of ³¹P-magnetic resonance spectroscopy (MRS) as a possible tool to distinguish viable from non-viable tissue after myocardial infarction was analysed in humans. Fifteen patients 3 weeks after anterior myocardial infarction were studied with breath-hold cine MRI and 3D-CSI MRS (1.5 T system). ³¹P-spectra were obtained from infarcted as well as non-infarcted myocardium (voxel size 25 cm³ each). Gold standard for viability was recovery of regional function, as determined by a control MRI 6 months after revascularization. Ten age-matched healthy volunteers served as control group. No significant difference was found between the phosphocreatine to adenosinetriphosphate (PCr/ATP) ratio of volunteers (SD 1.72 ± 0.31) and non-infarcted septal myocardium of patients. Cine MRI demonstrated recovery of regional function in 10 patients, i. e. 10 patients showed viable and 5 non-viable myocardium. In viable myocardium, the PCr/ATP ratio was 1.47 ± 0.38 (non-significant vs volunteers; p > 0.05). In the 5 patients with akinetic myocardium, PCr peaks could not be detected. Therefore, calculation of PCr/ATP ratios was not possible. However, a significant reduction of the ATP signal-to-noise ratio (SNR) was observed (2.92 ± 0.73 vs 6.68 ± 0.80; patients vs volunteers; p <0.05). The SNR of ATP of akinetic regions may predict recovery of function after revascularization in patients with myocardial infarction. Received: 9 September 1999; Revised: 30 November 1999; Accepted: 24 December 1999     

T1-relaxation kinetics of extracellular, intracellular and intravascular MR contrast agents in normal and acutely reperfused infarcted myocardium using echo-planar MR imaging

The objective of this study was to determine and compare if MR contrast agents distributed into various compartments can provide estimation of fractional distribution volume (FDV) in normal and infarcted myocardium using inversion recovery echo-planar MR imaging (IR EPI). Three different types of MR agents were investigated: (a) an extracellular agent, GdDTPA-BMA (0.1 mmol/kg); (b) an intravascular agent, GdDTPA-albumin (0.025 mmol/kg); and (c) an intracellular agent, manganese chloride (0.025 mmol/kg). The null point was determined from a series of IR EPI images in which TI was varied. Temporal changes in ΔR1 (ΔR1 = 1/T1_post-1/T1_pre) were measured during the initial 29–59 min after administration. Rats (n = 24) were subjected to 1-h coronary artery occlusion/reperfusion. Histochemical staining confirmed the presence and location of infarction. GdDTPA-BMA caused increase in ΔR1 of infarction < blood < < normal myocardium. ΔR1 ratios were 1.55 ± 0.08 for infarction and 0.33 ± 0.03 for normal myocardium, consistent with FDV of 0.82 ± 0.04 and 0.18 ± 0.01. The fractional distribution of this agent in normal myocardium approximated the extracellular space of myocardium. GdDTPA-albumin caused increase in ΔR1 of blood < < infarction < < normal myocardium. ΔR1 ratio in normal, but not infarcted, myocardium was constant at 0.10 ± 0.02 and approximated fractional blood volume. MnCl₂ caused equivalent increase in ΔR1 of normal and infarcted myocardium. ΔR1 of normal myocardium did not change overtime, whereas ΔR1 of blood rapidly decreased, leading to overestimation of FDV in normal and infarcted myocardium. In conclusion, extracellular, intravascular and intracellular MR contrast agents exhibited different T1-relaxation kinetics in both normal and infarcted myocardium. Constant ΔR1 ratio (myocardium/blood) after administration of MR contrast agent is a prerequisite for estimation of FDV of MR contrast agent in myocardium. Received: 22 December 1998; Revised: 7 April 1999; Accepted: 18 May 1999     

冠状动脉侧枝循环对STEMI患者心肌损伤影响的心血管MRI研究

目的探讨应用心血管磁共振(cardiovascular MR, CMR)多序列参数联合评价法,对急性ST段抬高型心肌梗死(ST-segment elevation myocardial infarction, STEMI)患者缺血再灌注后冠状动脉侧枝循环对心肌损伤的影响进行评估,为预后诊治提供影像支撑。方法对临床确诊的37例STEMI患者以Rentrop分级标准分为侧枝循环不良组(Rentrop:0～1级)和侧枝循环良好组(Rentrop:2～3级),比较两组患者水肿心肌、梗死心肌、梗死水肿心肌比、梗死水肿心肌差以及可挽救心肌等磁共振定量参数。结果冠状动脉侧枝循环不良组患者23例,良好组14例;不良组水肿心肌略大(31.0±8.4%LV vs. 28.7±7.9%LV,P=0.42);不良组梗死心肌显著高于良好组(6.7±3.2%LV vs. 3.9±1.7%LV,P<0.05);梗死水肿心肌比(21.7±9.8%vs. 13.8±5.8%)和可挽救心肌(78.3±9.8%vs. 86.2±5.8%),不良组均显著低于良好组(P<0.05)。结论 CMR可定量评估STEMI...     

转化生长因子-β1与乳腺病变弹性特征的相关性

目的探讨转化生长因子-β1(TGF-β1)与乳腺病变弹性特征的相关性。资料与方法选取经手术、穿刺活检或旋切活检的130例患者135个乳腺病变,其中良性84个,恶性51个。于手术或活检前对其进行剪切波弹性成像检查,记录病变的最大弹性模量、平均弹性模量、最小弹性模量,与周围组织弹性比值及“硬环征”等,采用免疫组化法检测TGF-β1的表达水平。比较良、恶性病变弹性特征及TGF-β1表达水平的差异,分析TGF-β1表达水平与上述弹性参数的相关性。结果恶性病变与良性病变的最大弹性模量[(161.9±79.5)kPa比(58.2±50.5)kPa]、平均弹性模量[(99.6±51.9)kPa比(35.9±26.4)kPa]、病变与周围组织弹性比值(6.0±4.1比2.1±1.7)、“硬环征”检出率[74.5%(38/51)比4.8%(4/84)]及TGF-β1表达水平(0.299±0.011比0.104±0.009)比较,差异均有统计学意义(P均<0.001);TGF-β1表达水平与最大弹性模量、平均弹性模量、病变与周围组织弹性比值均呈强正相关(r=0.879、0.821、0.741,P<0.001);有无“硬环征”的病变TGF-β1表达水平比较,差异有统计学意义(0.308±0.010比0.115±0.010,P<0.001)。结论乳腺病变的TGF-β1表达水平与最大弹性模量、平均弹性模量、病变与周围组织弹性比值及病变边缘“硬环征”等均具有相关性。     

Phase‐contrast MRI‐based elastography technique detects early hypertensive changes in ex vivo porcine aortic wall

Purpose

To measure the elastic properties of ex vivo porcine aortas in control and hypertensive groups using a phase contrast magnetic resonance imaging (MRI)‐based elastography technique.

Materials and Methods

Female domestic pigs were randomized to a normal control group (N; n = 5) or a renovascular hypertension group (HT; n = 5) for the duration of 3 months. Mean arterial pressure was significantly higher in the hypertension group than in the control group (173 ± 12 vs. 115 ± 11 mmHg, P ≤ 0.05). The animals were euthanized after 3 months of hypertension and abdominal aortas harvested. The ex vivo aortic samples were then examined using a phase‐contrast MRI‐based elastography technique.

Results

The Young's modulus‐wall thickness product, a reflection of vascular stiffness, was significantly higher in the hypertension group than in the control group (0.571 ± 0.080 vs. 0.419 ± 0.026, P < 0.05). Histological analysis and staining confirmed increased intima‐media thickness and collagen content in the hypertensive aorta, while elastin staining showed no difference.

Conclusion

The current study shows that MR elastography offers a method to study the physiologic changes in the arterial wall secondary to early hypertension. J. Magn. Reson. Imaging 2009;29:583–587. © 2009 Wiley‐Liss, Inc.     

Pre- and post-synaptic sympathetic function in human hibernating myocardium

Purpose Impaired pre-synaptic noradrenaline uptake-1 mechanism has been reported in a swine model of hibernating myocardium (HM). To ascertain whether adrenergic neuroeffector abnormalities are present in human HM, we combined functional measurements in vivo using cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) to assess pre- and post-synaptic sympathetic function. Methods Twelve patients with coronary artery disease and chronic left ventricular (LV) dysfunction underwent CMR at baseline and 6 months after bypass for assessment of regional and global LV function and identification of segments with reversible dysfunction. Before surgery, myocardial noradrenaline uptake-1 ([¹¹C]meta-hydroxy-ephedrine; HED) and β-adrenoceptor (β-AR) density ([¹¹C]CGP-12177) were measured with PET. Patient PET data were compared with those in 18 healthy controls. Results The volume of distribution (V_d) of HED in HM (47.95±28.05 ml/g) and infarcted myocardium (42.69±25.76 ml/g) was significantly reduced compared with controls (66.09±14.48 ml/g). The V_d of HED in normal myocardium (49.93±20.48 ml/g) of patients was also lower than that in controls and the difference was close to statistical significance (p=0.06). Myocardial β-AR density was significantly lower in HM (5.49±2.35 pmol/g), infarcted (4.82±2.61 pmol/g) and normal (5.86±1.81 pmol/g) segments of patients compared with healthy controls (8.61±1.32 pmol/g). Conclusion Noradrenaline uptake-1 mechanism and β-AR density are reduced in the myocardium of patients with chronic LV dysfunction and evidence of HM. The increased sympathetic activity to the heart in these patients is a generalised rather than regional phenomenon which is likely to contribute to the remodelling process of the whole LV rather than playing a causative role in HM.     

In vivo high-resolution magnetic resonance elastography of the uterine corpus and cervix

Objectives

To apply 3D multifrequency MR elastography (3DMMRE) to the uterus and analyse the viscoelasticity of the uterine tissue in healthy volunteers considering individual variations and variations over the menstrual cycle.

Methods

Sixteen healthy volunteers participated in the study, one of whom was examined 12 times over two menstrual cycles. Pelvic 3DMMRE was performed on a 1.5-T scanner with seven vibration frequencies (30–60 Hz) using a piezoelectric driver. Two mechanical parameter maps were obtained corresponding to the magnitude (|G ^* |) and the phase angle (φ) of the complex shear modulus.

Results

On average, the uterine corpus had higher elasticity, but similar viscosity compared with the cervix, reflected by |G ^* |_{uterine corpus}?=?2.58?±?0.52 kPa vs. |G ^* |_cervix?=?2.00?±?0.34 kPa (p?φ _{uterine corpus}?=?0.54?±?0.08, φ _cervix?=?0.57?±?0.12 (p?=?0.428). With 2.23?±?0.26 kPa, |G ^* | of the myometrium was lower in the secretory phase (SP) compared with that of the proliferative phase (PP, |G ^* |?=?3.01?±?0.26 kPa). For the endometrium, the value of |G ^* | in SP was 68 % lower than during PP (PP, |G ^* |?=?3.34?±?0.42 kPa; SP, |G ^* |?=?1.97?±?0.34 kPa; p?=?0.0061).

Conclusion

3DMMRE produces high-resolution mechanical parameter maps of the uterus and cervix and shows sensitivity to structural and functional changes of the endometrium and myometrium during the menstrual cycle.

Key Points

? MR elastography provided for the first time spatially resolved viscoelasticity maps of uterus. ? Uterine corpus had a higher elasticity, but similar viscosity compared with cervix. ? The stiffness of both endometrium and myometrium decreases during the menstrual cycle.     

Gd-BOPTA for assessment of myocardial viability on MRI: changes of T1 value and their impact on delayed enhancement

Gadobenate (Gd-BOPTA), injected at a dose of 0.1 mmol/kg body weight, was compared with gadopentetate (Gd-DTPA), injected at a dose of 0.2 mmol/kg body weight, for delineation of myocardial infarction interindividually in two groups of 26 patients each. Delayed enhancement images were assessed subjectively for image quality, and measured for regional T1 values before, 3 min after and 25 min after the injection of each contrast agent. In the 26 patients who received Gd-BOPTA, T1 values of remote myocardium were 1,070 ± 125 ms, 358 ± 78 ms and 562 ± 108 ms before, 3 min after and 25 min after injection, respectively. Infarcted myocardium values were 1,097 ± 148 ms, 246 ± 68 ms and 373 ± 84 ms and left ventricular blood pool 1,238 ± 95 ms, 194 ± 47 ms and 373 ± 72 ms. In the 26 patients who received Gd-DTPA, T1 values were 1,087 ± 96 ms, 325 ± 60 ms and 555 ± 108 ms for remote myocardium; 1,134 ± 109, 210 ± 43 ms and 304 ± 57 ms for infarcted myocardium; and 1,258 ± 104 ms, 166 ± 27 ms and 351 ± 73 ms for left ventricular blood pool. Delayed enhancement image quality showing myocardial infarction was rated good (54%) and excellent (46%) after Gd-BOPTA, and good (58%) and excellent (42%) after Gd-DTPA (no significant differences). A single dose of Gd-BOPTA compared with a double dose of Gd-DTPA causes similar changes of T1 values in infarcted and remote myocardium and provides fairly similar contrast between infarcted and remote myocardium (0.64 ± 14 versus 0.71 ± 11) and slightly higher contrast between left ventricular blood and infarcted myocardium (0.22 ± 17 versus 0.14 ± 6; p < 0.05). Administration of 0.1 mmol/kg body weight Gd-BOPTA can provide similar late enhancement images compared with the standard 0.2 mmol/kg body weight dose of Gd-DTPA due to the higher T1 relaxivity associated with the former. Peter Lodemann is an employee of Bracco Deutschland GmbH.