超声造影定量评价动脉粥样硬化斑块新生血管及其与组织病理学的相关性

目的 应用CEUS技术定量评价动脉粥样硬化斑块增强强度及其与病理染色所示的新生血管密度的相关性。方法 选取新西兰白兔25只,高脂饲养4周后,以球囊扩张腹主动脉,再高脂饲养16周,建立动脉粥样硬化模型;行常规超声及CEUS检查,观察不同类型斑块的增强情况,应用时间-强度曲线定量分析动脉粥样硬化斑块的增强强度,以CD31染色观察斑块内新生血管的密度。应用非配对t检验比较软斑与硬斑造影强度及新生血管密度的差异;Pearson相关分析动脉粥样硬化斑块CEUS增强强度与斑块新生血管密度的相关性。结果 二维超声诊断为软斑的斑块在CEUS中的增强强度明显高于硬斑(P<0.05);软斑的新生血管密度明显高于硬斑(P<0.05);斑块内新生血管密度与斑块造影增强强度存在明显相关性(r=0.75,P<0.001),与斑块增强强度/管腔增强强度亦存在明显相关性(r=0.68,P<0.001)。结论 CEUS可定量评价兔动脉粥样硬化斑块的增强情况;斑块增强强度与斑块内新生血管密度具有良好的相关性。     

高分辨MRI检测兔小管径动脉粥样斑块的可靠性

目的 探讨高分辨MRI(HRMRI)技术评价大白兔模型小管径动脉粥样斑块的价值。方法 通过高脂饮食和球囊损伤新西兰大白兔(12只)腹主动脉内膜制作模拟小管径动脉的粥样硬化模型,行高分辨FSE T2WI成像和病理分析。病理切片严格与MRI匹配,分析包括HE染色、Masson及免疫组化染色。以病理分析结果为标准,评价MRI在显示动脉斑块形态、成分以及定量测量方面的价值。结果 模型腹主动脉可见以脂质沉积和纤维增生为特征的斑块。不同组织成分的斑块表现为不同的T2WI信号特点,有大量炎性细胞浸润的疏松纤维帽表现为近管腔的高信号带,脂质聚集区多表现为高信号带下的低信号区,致密和薄的纤维帽不能显示。T2WI测量管腔面积和管壁面积与组织学测量值有较高的相关性(管腔r=0.7503,管壁r=0.8666,P均<0.05)。结论 高分辨MR T2WI可准确显示小管径动脉粥样斑块的形态学特征,提供斑块负荷和主要组织成分的信息。     

99Tcm-3PEG4-RGD用于家兔易损斑块分子显像

目的 探讨通过探测兔新生微血管活体评价动脉易损斑块的可行性。方法 将15只雄性新西兰大白兔随机分成普食对照组（A组）、易损斑块组（B组）和稳定斑块组（C组）,每组5只。于喂养2周后分别进行股动脉分离假手术（A、C组）和腹主动脉球囊拉伤术（B组）,之后喂养不同成分饲料。于4、8、12周末静脉注射⁹⁹Tc^m-3PEG4-RGD,注射后0.5 h、1 h、2 h行SPECT/CT显像及同机CT平扫。4、8周末显像后对3组各处死1只实验兔,12周末处死剩余动物,行离体血管SPECT显像、病理及免疫组化染色分析。结果 3组实验兔注射⁹⁹Tc^m-3PEG4-RGD后0.5 h SPECT/CT图像显示,4周后3组兔腹主动脉区均未见放射性摄取增高,T/NT值差异无统计学意义（F=2.515,P=0.122）;8周后B、C组局部放射性摄取增高（F=17.037,P=0.001）;12周后B组腹主动脉局部放射性摄取明显高于A、C组（F=43.710,P<0.001）。8、12周末,B、C组腹主动脉中均含有新生微血管,且B组数量明显高于C组。B组兔腹主动脉斑块的AHA动脉粥样硬化分型为Ⅲ型及Ⅳ型,C组为AHA Ⅱ型。A组腹主动脉中无新生微血管及易损斑块。结论 ⁹⁹Tc^m-3PEG4-RGD分子显像对无创性评价兔动脉斑块稳定性具有一定价值。     

比较MSCT与MRI在结直肠癌术前分期诊断中的价值

目的 结合术后病理结果比较MSCT与MRI在结直肠癌术前分期诊断中的价值。方法 对经手术病理证实的结直肠癌患者53例,分别进行MSCT和MR平扫、增强扫描。结果 MR对T1-2分期的敏感度明显高于MSCT(P<0.05);MRI对T3、T4分期的敏感度与MSCT相比差异无统计学意义(P>0.05)。MSCT、常规MRI和DWI三种扫描方法诊断淋巴结分期的准确率分别为56.60%、58.49%、73.58%。DWI的敏感度及阴性预测值最高,分别为92.31%和88.24%;与组织病理结果具有中等相关性,Kappa值为13.927(P=0.001)。MSCT和常规MRI诊断结果与组织病理结果无相关性,Kappa值分别为1.128(P=0.288)和1.585(P=0.208)。结论 在结直肠癌T分期方面,MRI较MSCT具有一定优势;DWI能更准确地预测结直肠癌区域淋巴结转移情况。     

颈动脉粥样硬化斑块MDCT定量分析

目的 探讨采用颈动脉粥样硬化斑块平扫CT值和强化幅度预测脑血管症状的价值。方法 纳入87例拟诊为颈动脉粥样硬化接受MDCT平扫及CTA的患者,根据有无脑血管症状分为有症状组(n=38)及无症状组(n=49),通过手动勾画ROI的方法测量CT平扫及CTA图像上斑块非钙化部分的CT值,采用独立样本t检验比较组间差异。应用ROC曲线分析采用平扫CT值及强化幅度判定是否引起脑血管症状的效能,并采用Z检验对曲线下面积进行比较。结果 有症状组和无症状组颈动脉斑块平扫CT值分别为(45.58±8.94)HU和(31.09±6.83)HU,二者差异有统计学意义(t=-8.569,P<0.001);有症状组颈动脉斑块强化增幅大于无症状组(t=-3.421,P=0.001)。ROC曲线阈值分析显示,平扫CT值最佳临界值为37.20 HU,判定是否引起脑血管症状的敏感度为92.10%(35/38),特异度为81.63%(40/49),准确率86.21%(75/87),ROC曲线下面积为0.937。强化幅度最佳临界值为10.1 HU,其敏感度为76.32%(29/38),特异度为63.27%(31/49),准确率为68.97%(60/87),曲线下面积为0.735;二者曲线下面积的差异有统计学意义(Z=3.613,P<0.01)。结论 颈动脉斑块非钙化部分平扫CT值和强化幅度与脑血管症状有关;斑块平扫CT值对判断是否引起脑血管症状的效能优于斑块强化幅度。     

原发性中枢神经系统淋巴瘤ADC值与预后的相关性

目的 探讨原发性中枢神经系统淋巴瘤(PCNSL)患者DWI的ADC值与无进展生存期(PFS)、Ki-67标记指数之间相关性。方法 分析经临床和病理证实的28例PCNSL的MRI和免疫组化结果。分别测量肿瘤的ADC值并记录最小ADC值(ADC_min)、平均ADC值(ADC_mean)及最大ADC值(ADC_max),并进行统计学分析。结果 28例中15例单发,13例多发。PFS与ADC_min呈正相关(r=0.565,P=0.002),PFS与Ki-67呈负相关(r=-0.627,P<0.001)。PFS与ADC_mean、ADC_max均无相关性(r=0.324、-0.056,P=0.093、0.776)。Ki-67与ADC_min呈负相关(r=-0.575,P=0.001),Ki-67与ADC_mean和ADC_max间均无相关性(r=-0.273、-0.094,P=0.159、0.636)。强化灶单发与多发患者间Ki-67和PFS以及≥60岁和<60岁间PFS差异均无统计学意义(P均>0.05)。结论 DWI可在治疗前初步判断PCNSL的PFS。     

巨噬细胞MRI检测兔早期腹主动脉粥样硬化斑块

目的 观察巨噬细胞MRI在检测兔早期动脉粥样硬化斑块中的应用价值。方法 将10只健康新西兰兔随机均分为模型组及对照组,对模型组通过球囊拉伤联合高脂饲料建立腹主动脉粥样硬化模型,对照组不予任何干预。对两组动物行MR扫描,检测静脉注射葡聚糖四氧化三铁纳米颗粒（DCIONP）对比剂前及注射后45 min、24 h、48 h、72 h、96 h和120 h 血管壁信号强度（SI）及信号强度变化值（ΔSI）。之后处死动物,病理观察动脉粥样硬化斑块。结果 模型组斑块注射DCIONP后45 min SI升至最高,48 h开始低于注射前水平,96 h降至最低;对照组管壁于注射DCIONP后45 min均匀强化,24 h后SI基本恢复至注射前水平,其后SI无明显变化。两组间各时间点ΔSI差异均有统计学意义（P均<0.05）。病理结果表明血管壁信号衰减区与斑块内铁蓝染区及巨噬细胞分布相符。结论 巨噬细胞MRI可检测兔早期动脉粥样硬化斑块,可能具有潜在临床应用价值。     

声触诊组织量化技术无创动态评估兔耳增生性瘢痕硬度

探讨声触诊组织量化(VTQ)技术无创评估兔耳增生性瘢痕(HS)形成过程中的硬度变化。方法 运用VTQ技术在兔耳HS模型形成过程的不同时间点(术前1天,术后第1、3、5、7、11、16、20、28、36、45、60、90、120天)测量其剪切波速度(SWV),比较相邻时间点的SWV值,同时测量二维图灰阶值,对HS剪切波速度值(HSSWV)及灰阶值进行对比分析。结果 HS形成过程中SWV值比较:除术前1天与术后第1天(P=0.099)、术后第60天与术后第90天(P=0.053)差异无统计学意义外,其余相邻时间点差异均有统计学意义(P均<0.05)。兔耳HS形成过程中,HSSWV值与灰阶值呈正相关(r=0.568,P<0.001);而在兔耳HS增生期(术后11~45天),HSSWV值与灰阶值高度相关(r=0.813,P<0.001)。结论 应用VTQ技术测得的HSSWV值在量化评估HS硬度改变方面有重要应用价值。     

定量CT和双回波MRI评价骨质疏松

目的 探讨定量CT(QCT)和双回波MR成像评价骨质疏松的价值。方法 对74名志愿者行前瞻性队列研究,分别采用双能X线骨密度测量仪(DXA)和QCT检测腰椎骨密度,MR扫描仪及后处理软件检测腰椎椎体内骨髓脂肪组织。根据腰椎DXA结果分为骨量正常组、低骨量组和骨质疏松组,采用单因素方差分析比较3组间信号强度比值(SIR)的差异;采用Pearson相关分析分别检验双回波MRI技术所测SIR与DXA的T值及QCT所测骨量的相关性;采用ROC曲线分析SIR值对骨质疏松的诊断效能。结果 骨量正常组SIR值0.41±0.11,低骨量组SIR值0.55±0.12,骨质疏松组SIR值0.62±0.15,三组间差异有统计学意义(F=18.5,P=0.002),骨量正常组与骨质疏松组间、骨量正常组与低骨量组间SIR差异有统计学意义(P均<0.01),而低骨量组与骨质疏松组间SIR差异无统计学意义(P=0.194),QCT所测骨量与DXA所测T值呈正相关(r=0.675,P<0.01),SIR值与T值呈负相关(r=-0.587,P<0.01)。SIR值与QCT所测骨量呈负相关关系(r=-0.599,P<0.001)。采用SIR评价骨质疏松的ROC分析显示,SIR=0.54时,ROC曲线下面积最大,为0.833,诊断的敏感度为83.3%,特异度为75.7%。结论 QCT可直接精确测量骨质密度;双回波MRI技术可通过检测骨髓脂肪组织间接反映骨代谢情况。     

MRI评价兔动脉粥样硬化模型

目的 探讨1.5T MR仪检测兔颈动脉粥样硬化模型中粥样硬化斑块的形成。 方法 用动脉球囊扩张法损伤兔一侧颈总动脉血管内膜后高脂饲养15周,行MRI及损伤血管的病理学检查。 结果 15周后,MRI表现为损伤血管壁高信号区增厚并管腔狭窄,对应病理学检查显示:血管腔狭窄;损伤侧颈总动脉明显粥样斑块形成,符合动脉粥样硬化特点。MR成像与病理学所测血管壁厚度之间有相关关系(r＝0.953)。 结论 临床应用型1.5T MRI可成功检测兔颈动脉粥样硬化的形成。     

3.0T MRI观察兔腹主动脉粥样硬化斑块演变过程

目的 探讨MRI在识别兔动脉粥样硬化斑块中的诊断价值.方法 20只新西兰白兔,随机设置实验组16只,对照组4只,结合球囊拉伤腹主动脉和间断高脂饲料喂养,建立动脉粥样硬化模型;在建模后2、3、4个月分别行高分辨MR成像.通过测量腹主动脉管壁厚度和面积、管腔面积、管壁信号增强程度等指标,观察腹主动脉壁的重构过程,并对模型最终的斑块成分进行MRI和组织病理结果对照研究.结果 对17只兔(实验组14只,对照组3只)完成3次MR检查,并获得组织病理学结果.MRI显示,实验组腹主动脉管壁厚度和面积逐渐增厚,且与同期对照组相比差异均有统计学意义(P＜0.01);实验组腹主动脉管腔进行性扩张,管壁强化程度较对照组增加明显,但演变过程不明显.另外,MRI对兔腹主动脉硬化斑块的成分判别限制在纤维、脂质和钙化斑块,对纤维斑块、脂质斑块识别率较高.结论 高分辨MRI可以无创性地观察动脉粥样硬化动物模型腹主动脉管壁重构的演变过程,有助于对动脉硬化斑块的预后和药物干预进行探索.     

MRI定量分析颈动脉粥样硬化斑块脂质坏死核:与手术病理对照

目的 探讨MRI定量分析颈动脉斑块内脂质坏死核心（LRNC）的准确性。方法 对19例颈动脉内膜剥脱术（CEA）患者术前行MR颈动脉检查,于MRI图像和病理组织学切片上分别测量LRNC的大小,计算其所占总管壁面积的百分比,分析两者的相关性。结果 共151个MRI图像层面与患者的病理组织学区域相匹配,MRI与组织学测得LRNC占总管壁面积的百分比分别为（20.64±9.03）%和（18.65±9.49）%,两者具有中-高度相关性（r=0.69,P<0.001）。结论 MRI可定量测量颈动脉斑块内LRNC,有助于预测斑块的稳定性。     

兔动脉粥样硬化易损斑块的磁共振成像特

目的探讨易损斑块与稳定斑块的MRI表现差异。方法选取20只雄性新西兰大白兔,以高脂饲料喂养加球囊拉伤主动脉的方法建立动脉粥样硬化模型。药物诱发斑块破裂前、后各进行1次MR扫描,之后处死动物,获得主动脉病理资料。对扫描所得数据与病理所见进行对比。结果 11只实验兔存活,MRI显示主动脉均呈不同程度的粥样硬化改变。其中7只成功诱发斑块破裂和血栓形成,共检出75个斑块,其中14个为易损斑块,61个为稳定斑块。MRI表现与病理学所见在纤维帽厚度、斑块面积、脂核面积方面相关度较高。与稳定斑块相比,易损斑块具有薄纤维帽、大脂核以及高脂核/斑块面积比等特点。脂核/斑块面积比是斑块易损性的较强预测因子。结论 MRI能够区分兔易损斑块和稳定斑块,可作为无创检测易损斑块的工具。     

Detection of thrombus size and protein content by ex vivo magnetization transfer and diffusion weighted MRI

Background

To utilize a rabbit model of plaque disruption to assess the accuracy of different magnetic resonance sequences [T1-weighted (T1W), T2-weighted (T2W), magnetization transfer (MT) and diffusion weighting (DW)] at 11.7 T for the ex vivo detection of size and composition of thrombus associated with disrupted plaques.

Methods

Atherosclerosis was induced in the aorta of male New Zealand White rabbits (n = 17) by endothelial denudation and high-cholesterol diet. Subsequently, plaque disruption was induced by pharmacological triggering. Segments of infra-renal aorta were excised fixed in formalin and examined by ex vivo magnetic resonance imaging (MRI) at 11.7 T and histology.

Results

MRI at 11.7 T showed that: (i) magnetization transfer contrast (MTC) and diffusion weighted images (DWI) detected thrombus with higher sensitivity compared to T1W and T2W images [sensitivity: MTC = 88.2%, DWI = 76.5%, T1W = 66.6% and T2W = 43.7%, P < 0.001]. Similarly, the contrast-to-noise (CNR) between the thrombus and the underlying plaque was superior on the MTC and DWI images [CNR: MTC = 8.5 ± 1.1, DWI = 6.0 ± 0.8, T1W = 1.8 ± 0.5, T2W = 3.0 ± 1.0, P < 0.001]; (ii) MTC and DWI provided a more accurate detection of thrombus area with histology as the gold-standard [underestimation of 6% (MTC) and 17.6% (DWI) compared to an overestimation of thrombus area of 53.7% and 46.4% on T1W and T2W images, respectively]; (iii) the percent magnetization transfer rate (MTR) correlated with the fibrin (r = 0.73, P = 0.003) and collagen (r = 0.9, P = 0.004) content of the thrombus.

Conclusions

The conspicuity of the thrombus was increased on MTC and DW compared to T1W and T2W images. Changes in the %MTR and apparent diffusion coefficient can be used to identify the organization stage of the thrombus.     

Comparative evaluation of TEE, conventional MRI and contrast-enhanced 3D breath-hold MRA in the post-operative follow-up of dissecting aneurysms

Purpose: To verify the diagnostic potentialities of conventional magnetic resonance imaging (MRI), breath-hold 3D contrast enhanced MR angiography (C3D MRA) and transesophageal echocardiography (TEE) in patients surgically treated for type A aortic dissection. Materials and methods: Twenty-nine patients (21 males and 8 females), surgically treated for type A aortic dissection, were evaluated with MRI using a 1.5 T (GE Horizon Echospeed 8.2) with standard gated SE sequences and breath-hold 3D fast SPGR after intravenous Gd injection (0.2 mmol/kg). 3D MIP reconstruction was obtained. TEE evaluation was performed with a HP 2000 system and a biplane 5 MHz probe. The sizes of aortic root, distal anastomosis, descending aorta and periprosthetic thickening were measured. Regional false lumen and aortic branch involvement were also evaluated. Results: Concordance among TEE, conventional MRI and C3D MRA was observed in the evaluation of aortic root (MRI vs. C3D MRA r = 0.93; MRI vs. TEE r = 0.84; C3D MRA vs. TEE r = 0.84) and descending aorta (r = 0.94, 0.91 and 0.92, respectively). The interobserver variability was also very low. Inadequate agreement was observed for distal anastomosis. C3D MRA was inadequate in the evaluation of periprosthetic thickening; r = 0.73 was obtained between MRI and TEE. For qualitative data: TEE was inadequate in the evaluation of the abdominal aorta and branches. C3D MRA depicted supra-aortic vessel involvement in more cases than the other techniques. Conclusion: C3D MRA is a fast and accurate technique in the evaluation of the endoluminal alterations and involvement of the aortic branches. Conventional MRI allows a direct evaluation of the aortic wall and periaortic tissue. TEE is less accurate in the evaluation of aortic branches and abdominal aorta.     

In vivo MR imaging of plaque disruption and thrombus formation in an atherosclerotic rabbit model

Our aim is to introduce an atherosclerotic rabbit model for inducing atherosclerosis lesions in rabbits, and to validate the model in vivo with 3T high resolution magnetic resonance imaging of the thrombosis followed a pharmacologically triggered plaque disruption. Twenty male New Zealand White rabbits were randomly allocated into an experimental group (n = 16) and a control group (n = 4). The aortic wall injuries were induced by an intravascular balloon in the experimental group rabbits after feeding them with a high cholesterol diet for 2 weeks. The pharmacological triggering with Russell’s viper venom and histamine was performed after totally 16 weeks of intermittent cholesterol feeding. All of the animals underwent both the pre-trigger and post-trigger MR examinations including TOF, T1WI, T2WI and post contrast T1WI. Euthanasia was performed in all rabbits; gross anatomy and histological specimen of aorta were obtained. MR images were analyzed and compared with histological results. Compared with the control group rabbits, the aorta of the experimental group rabbits in the pre-triggered MR images showed an increased vessel wall thickening, luminal narrowing, and vessel wall enhancement. Fourteen rabbits survived the triggering, and 8 of them developed thrombosis (58.1%). No thrombus was found in the control group. The accuracy of the multi-sequences MR including TOF, T1WI, T2WI and post contrast T1WI was 87.1% (27/31) for detecting thrombus. MR data significantly correlated with the histopathology data for both thrombus length (r = 0.94, P < 0.01) and thrombus location (r = 0.85, P < 0.01), respectively. The study demonstrated that MR reliably determined the plaque disruption and thrombus formation in the atherosclerotic rabbit model.     

Experimental evaluation of the detectability of submillimeter atherosclerotic lesions in ex vivo human iliac arteries with ultrahigh-field (7.0 T) magnetic resonance imaging

Background To evaluate the ability of ultrahigh-field magnetic resonance imaging (MRI) to accurately depict the composition of the human arterial vessel wall ex vivo and to detect early atherosclerotic lesion formation in comparison to histology. Methods Eight iliac artery specimens with low-grade atherosclerotic lesions obtained from human organ donors were studied. Three-dimensional, high-resolution MRI (spatial resolution: 79 × 79 × 109 μm) was performed using T1-, T2- and proton density (PD)-weightings (7.0 Tesla MR system, Bruker Pharmascan). A total of 36 MR slices and corresponding histological sections were matched for comparative evaluation of area measurements of lumen, media and adventitia and—if present—plaque size. Statistical correlation between histology and MR measurements was tested and a ROC-analysis was performed to determine the plaque size being predictive of correctly identifying atherosclerotic lesions with MRI. Results The areas of vessel lumen and media as measured on T1-, T2- and PD-weighted MR images showed a strong correlation with the corresponding histological measurements (r = 0.84 to r = 0.89; P < 0.01), however, a systematic overestimation of 34–41% was found. For the area of adventitia, only a moderate, though significant, correlation (r = 0.55 to r = 0.62; P < 0.01) could be demonstrated with a similar overestimation by MRI (38–43%). With T1-weighted MRI, sensitivity and specificity for the detection of plaques > 4.0 mm² were 79% and 91%, respectively. With T2- and PD-weighted MRI, however, sensitivity and specificity for the detection of plaques > 0.4 mm² were 93% and 89%. Conclusions In an experimental ex vivo setting, ultrahigh-field MRI of the human arterial vessel wall resulted in an accurate visualization of vessel wall composition when compared to histology and, thus, allowed for a quantitative assessment. T2- and PD-weighted MRI proved capable of reliably detecting submillimeter atherosclerotic lesions. Cosima Jahnke and Thore Dietrich contributed equally to the work.