磁共振T1mapping在心脏疾病中的应用

心脏磁共振T1mapping技术能够直接定量心肌组织的T1值和细胞外间质容积分数(ECV),可以无创的评估许多不同的心脏疾病.尽管传统的钆剂延迟增强(LGE)技术能鉴别某些疾病状态下的局限性心肌纤维化,但对弥漫性心肌纤维化则并不可靠,而T1mapping技术则能够对LGE上不显示或显示不明显的心肌病变进行量化评估.本文简述了T1mapping技术在多种心脏疾病中的研究进展,在不同心肌病变(特别是弥漫性心肌纤维化)的定性评估和鉴别诊断上,利用T1mappping进行T1值和ECV定量检测可能是一种更加可靠和准确的方法.     

心肌纵向弛豫时间和细胞外容积定量MR成像

磁共振心肌纵向弛豫时间定量成像(T1 mapping)和细胞外容积(extracellular volume,ECV)的测量可在活体水平定量心肌的T1值和细胞外间隙的大小,能够无创性评估局限性和弥漫性心肌病变,具有广泛的临床应用价值.本文就T1 mapping和ECV定量的相关MRI原理及其影响因素进行综述.     

心脏磁共振T1mapping技术评估肥厚型心肌病心肌纤维化

目的 基于心脏磁共振(CMR)T1 mapping技术定量评估肥厚型心肌病(HCM)心肌纤维化.资料与方法 回顾性收集2019年6月—2021年7月昆明医科大学第一附属医院45例HCM患者(HCM组)及44例CMR结果正常者(对照组)的临床及CMR资料,所有患者均行CMR检查,包括T1 mapping序列、延迟强化(L...     

CMR新技术在心肌纤维化的研究进展及与 LGE-MRI的比较

心肌纤维化（MF）是心室重塑及恶性心律失常发生的根本原因，最终可导致心功能不全、猝死等主要心脏不良事件的发生。延迟增强MRI（LGE-MRI）是既往心肌梗死后局限性MF检测的临床应用标准，而当今T1mapping技术在对心肌弥漫性MF的检测和定量评价中更具优势，心脏功能MRI技术如扩散张量成像（DTI）和扩散加权成像（DWI）无需对比剂即可定量评估心肌微细结构，在MF检测方面亦表现出较大的应用潜能。综述T1mapping、DTI、DWI等技术进展并与LGE-MRI进行比较。     

心肌纤维化、心肌瘢痕与心电图的影响:动脉粥样硬化多种族研究(MESA)

正摘要目的对4个不同种族、前期无冠心病病人的弥漫性心肌纤维化、瘢痕与心电图(ECG)参数进行相关性研究。材料与方法本前瞻性研究采用交叉性列表分析法,由伦理委员会批准,志愿者均知情同意。共有1 669名志愿者参与动脉粥样硬化多种族研究(MESA),行ECG检查及MRI心肌扫描均无前期心肌梗死。无延迟钆强化确定的心肌瘢痕病人有1 131例,采用T1mapping评估左心室(LV)间质弥漫性纤维化。采用多因素回归分析研究LV心肌纤维化、心肌瘢痕与ECG参数[QRS电压、QRS持续时间、校正QT间期(QTc)]相     

MR纵向弛豫时间定量成像评价肥厚型心肌病心肌纤维化的初步研究

目的 探讨纵向弛豫时间定量(T1mapping)成像对肥厚型心肌病(HCM)纤维化的诊断价值.方法 按诊断标准入选48例HCM患者和18名健康志愿者,分别行常规延迟强化(LGE)检查与T1 mapping成像,按HCM LGE有无及程度,分为LGE远处正常区、LGE边缘区、LGE区(分为晕状LGE与典型斑片状LGE),分别测量2组心肌对比剂增强后T1值的变化率并进行卡方检验、两两对比及ROC曲线分析.结果 健康志愿者T1值变化率与HCM远离LGE区差异无统计学意义(3.98 ±3.19和3.36 ±2.77,=0.98,p＞0.05),与LGE周边区(13.51±5.67)、晕状区(17.70±5.57)、斑片区(36.62±8.03)比较差异有统计学意义(t值分别为15.28、17.13和47.48,P值均＜0.01);远处正常区(3.36 ±2.77)与LGE周边区、晕状区及斑片区比较差异均有统计学意义(t值分别为19.64、20.76和56.64,P值均＜0.01);LGE周边区与LGE晕状区和斑片区比较差异均有统计学意义(t值分别为6.12和39.90,P值均＜0.01);LGE晕状区与斑片区比较差异有统计学意义(t=25.63,P＜0.01).ROC曲线提示T1 mapping成像较传统LGE成像有更大的曲线下面积(0.974±0.050和0.751±0.180).结论 HCM纤维化常见,且受累心肌的纤维化程度不一,T1 mapping成像能对HCM患者心肌纤维化的严重程度进行评价,能够发现处于纤维化早期的病变.     

肥厚型心肌病MRI T_1 mapping：对无延迟钆剂增强及血流动力学障碍病人的评价(DOI:10.19300/j.2020.r0203)

正无延迟钆剂增强(LGE)和血流动力学障碍的肥厚型心肌病(HCM)病人,其固有心肌T1mapping和细胞外容积(ECV)分数值目前尚不清楚。目的用固有心肌T1mapping     

心肌T1-mapping进展：成像技术与临床应用

【摘要】心肌T1-mapping成像作为近些年快速成长起来的心脏磁共振（CMR）技术,在心肌水肿、纤维化及浸润性疾病的诊断、治疗及预后过程中都发挥了极大的作用,可用于定量检测局灶性或弥漫性病变、评估无症状性或早期心肌改变,效果优于传统对比剂增强T1WI和T2WI。本文拟通过回顾近年来有关心肌T1-mapping成像的序列、成像技术和在水肿、纤维化及浸润性心肌病变中的临床应用价值进行系统阐述并对国际共识中有关T1-mapping的纳入情况进行更新。     

T2 mapping在周围神经疾病中的研究进展

MR T2 mapping可以通过测量组织T2值反映组织内水含量的变化,最早被应用于关节软骨和心肌病变的评估中。与传统的磁共振结构成像相比,它具有客观、精准、重复性高等优点。近年来,它在外周神经疾病中的应用越来越广泛。本文就T2 mapping的基本成像原理、在正常周围神经以及在不同种类周围神经疾病中的应用进展予以综述。     

心肌病的心脏MR T1图定量测量:与心内膜活检的对照研究

目的确定心脏MRT1图测量在定量评价弥漫性心肌纤维化中的价值,并与心内膜活检进行对照。材料与方法研究符合HIPAA原则,获得单位伦理委员会的批准。回顾同一单位5年内进行心内膜活检和心肌MRI检查的心肌病病人。47例病人(53%男性,平均年龄46.8岁)进行了诊断性心肌MRI检查和心内膜活检。13名健康志愿者(54%男性,平均年龄38.1岁)作为对照组进行了心脏MRI检查。在1.5TMR设备上团注0.2mmol/kg钆螯合物后,采用反转恢复Look-Locker序列进行心肌的T1图测量,采集时间为(10.7±2.7)min。采用梯度回波反转恢复序列评价钆对比剂的延迟强化。2名放射医师采用盲法评价,意见一致后得出心脏MRI的结论。对心内膜活检的样品进行Masson染色,采用自动分析软件对数字图像进行纤维化的定量测量。2名病理学家采用盲法进行组织病理学结果报告。统计学分析包括Mann-WhitneyU检验、方差分析和线性回归。结果心肌纤维化的中位数为8.5%(四分位距5.7%～14.4%)。对照组的T1值均大于无或伴明显的钆延迟强化病人[分别为(466±14)ms、(406±59)ms和(303±53)ms,P<0.001)。T1值与组织学纤维化负相关(r=-0.57;95%CI:-0.74～-0.34;P<0.0001)。采用T1值检测大于5%的心肌纤维化时曲线下面积为0.84,临界值为383ms。结论心脏的MRT1图定量测量可无创性评价心肌病病人心内膜弥漫性纤维化的情况。原文载于Radiology,2012,265(3):724-732.     

Técnicas paramétricas de caracterización tisular del miocardio mediante resonancia magnética (parte 1): mapas de T1

The development of myocardial fibrosis is a common process in the appearance of ventricular dysfunction in many heart diseases. Magnetic resonance imaging makes it possible to accurately evaluate the structure and function of the heart, and its role in the macroscopic characterization of myocardial fibrosis by late enhancement techniques has been widely validated clinically. Recent studies have demonstrated that T1-mapping techniques can quantify diffuse myocardial fibrosis and the expansion of the myocardial extracellular space in absolute terms. However, further studies are necessary to validate the usefulness of this technique in the early detection of tissue remodeling at a time when implementing early treatment would improve a patient's prognosis. This article reviews the state of the art for T1 mapping of the myocardium, its clinical applications, and its limitations.     

Case report: Delayed enhancement on cardiac MRI in a patient with multiple myeloma without amyloidosis

We report the first observation of diffuse subendocardial and myocardial delayed enhancement on cardiac MRI in a 50-year-old patient with recurrent multiple myeloma but without evidence of amyloidosis. She presented with advanced heart failure and severe restrictive cardiomyopathy. Myocardial biopsy revealed endomyocardial fibrosis. The case was associated with development of multiple arterial and venous thromboses and a fatal course. Because of the fatal outcome, the prognostic significance of delayed enhancement on MRI in multiple myeloma patients may need to be further investigated.     

Non-contrast estimation of diffuse myocardial fibrosis with dual energy CT: A phantom study

BackgroundEstimation of diffuse myocardial fibrosis, substrate for adverse events such as heart failure and arrhythmias in patients with various cardiac disorders, is presently done by histopathology or cardiac magnetic resonance. We sought to develop a non-contrast method to estimate the amount of diffuse myocardial fibrosis leveraging dual energy computed tomography (DECT) in phantoms and a suitable small animal model.Methods and ResultsPhantoms consisted of homogenized bovine myocardium with varying amounts of Type 1 collagen. Fifteen mice underwent sham surgery, no procedure, or transverse aortic constriction (TAC) for 5 or 8 weeks to produce moderate or severe fibrosis, respectively. Phantoms and ex vivo mouse hearts were imaged on a single source, DECT scanner equipped with kVp switching. Monochromatic images were reconstructed at 40–140 keV. Linear discriminant analysis (LDA) was performed on mean myocardial CT numbers derived from single energy (70 keV) images as well as images reconstructed across multiple energies. Classification of myocardial fibrosis severity as low, moderate or severe was more often correct using the multi-energy CT/LDA approach vs. single energy CT/LDA in both phantoms (80.0% vs. 70.0%) and mice (93.3% vs. 33.3%).ConclusionsDECT myocardial imaging with multi-energy analysis better classifies myocardial fibrosis severity compared to a single energy-based approach. Non-contrast DECT can accurately and non-invasively estimate the extent of diffuse myocardial fibrosis in phantom and animal models. These data support further evaluation of this approach for in vivo myocardial fibrosis estimation.     

糖尿病心肌病的CMR诊断及研究进展

心脏磁共振（CMR）成像技术具有多参数、多成像序列的特点,可以对糖尿病心肌病（DbCM）进行早期诊断,评价DbCM存在的心脏结构重塑、心脏整体和局部的收缩和舒张功能障碍、心肌灌注受损、心脏局部及弥漫性纤维化及心脏能量代谢和脂质异常,为病人的早期治疗及预后评估提供重要信息。就CMR对DbCM的心脏组织特征、风险评估和远期预后方面的诊断予以综述。     

心血管MR T1mapping/iECV定量分析在主动脉瓣关闭不全评价中的价值

目的探讨心脏MR(CMR)定量技术纵向弛豫时间定量成像/心肌细胞外容积分数指数(T₁ mapping/iECV)对主动脉瓣关闭不全(AI)患者的临床价值,并探索其与传统心功能参数的相关性。方法回顾性收集2012年5月至2016年2月在中国医学科学院阜外医院经影像及临床资料确诊为慢性AI患者36例。所有患者均接受CMR常规扫描序列、初始及增强后T₁ mapping检查,CMR图像经后处理分析,计算主动脉瓣反流分数、钆对比剂延迟强化(LGE)质量分数、心肌细胞外容积分数(ECV)和iECV。基于CMR反流分数结果,将AI患者分为轻度组(9例)、中度组(14例)和重度组(13例)。3组AI患者初始及增强后T₁值、ECV及iECV等计量资料比较采用单因素方差分析,进一步两两比较采用LSD检验;心血管相关病史、纽约心脏协会(NYHA)心功能分级及LGE阳性率等计数资料比较采用χ2检验或Fisher确切概率法;左心室常规功能参数LVEF与iECV的相关关系采用Spearman相关分析。结果3组AI患者年龄、性别、心血管相关病史差异无统计学意义(P均>0.05)。3组不同反流程度AI患者比较:(1)3组患者LGE阳性率总体差异有统计学意义(P=0.023),随着主动脉瓣反流分级程度增高,替代性纤维化发生率增加。(2)3组患者初始T₁值、增强后T₁值及ECV总体差异均无统计学意义(H值分别为1.815、0.929、2.496,P均>0.05)。3组iECV总体差异有统计学意义(H=16.725,P<0.001),重度组iECV值明显高于其他2组(P<0.05)。iECV与LVEF呈负相关(r=-0.649,P<0.001)。结论无创性CMR定量参数技术T₁ mapping/iECV能识别不同反流程度AI患者发生弥漫性心肌纤维化的程度,并与传统心功能参数LVEF有较高的相关性,具有反映左心室功能失代偿前可逆阶段的潜力。     

Fulminant myocarditis owing to high-dose interleukin-2 therapy for metastatic melanoma

High-dose interleukin-2 (IL-2) therapy may cause acute myocarditis characterised by diffuse myocardial involvement and occasionally fulminant heart failure. Cardiac MRI (CMRI) provides a comprehensive assessment of myocardial function, inflammation and injury in a single examination and has shown value in the diagnosis of myocarditis. We report a case of a 54-year-old male with metastatic melanoma who developed acute severe myocarditis with fulminant heart failure after high-dose IL-2 therapy. CMRI using a combination of T(2) weighted imaging and T(1) weighted late post-gadolinium enhancement techniques played a key role in establishing the diagnosis. To our knowledge we present the first case report of the combined use of T(1) and T(2) weighted CMRI techniques to diagnose IL-2 induced myocarditis.     

Cardiac MR imaging of nonischemic cardiomyopathies: imaging protocols and spectra of appearances

Recent technologic advances in cardiac magnetic resonance (MR) imaging have resulted in images with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MR is a valuable imaging technique for detection and assessment of the morphology and functional characteristics of the nonischemic cardiomyopathy. It has gained acceptance as a standalone imaging modality that can provide further information beyond the capabilities of traditional modalities such as echocardiography and angiography. Black-blood fast spin-echo MR images allow morphologic assessment of the heart with high spatial resolution, while T2-weighted MR images can depict acute myocardial edema. Contrast material-enhanced images can depict and be used to quantify myocardial edema, infiltration, and fibrosis. This review presents recommended cardiac MR protocols for and the spectrum of imaging appearances of the nonischemic cardiomyopathies.     

MR relaxometry and perfusion of the myocardium in spontaneously hypertensive rat: correlation with histopathology and effect of anti-hypertensive therapy

Objectives

To investigate myocardial relaxation times and perfusion values in spontaneously hypertensive rats (SHRs) at various stages of the disease, with or without anti-fibrotic therapy, and to correlate magnetic resonance imaging (MRI) findings with histopathological myocardial fibrosis and capillary density.

Methods

Five groups of rats underwent MRI at 4.7 T. They were either untreated or treated with an aldosterone-synthase inhibitor. T1, T2 and T2* relaxation times were determined and myocardial perfusion was quantified from an arterial spin labelling sequence. MR relaxation times and perfusion values were compared with the fibrotic content and capillary density of the myocardium obtained at histology after euthanasia.

Results

T1 values significantly increased during the course of hypertensive disease, and correlated with myocardial fibrosis (R?=?0.71, P?<?0.001); T2 values also increased but were weakly correlated with myocardial fibrosis (R?=?0.27,P?=?0.047). Myocardial perfusion and capillary density significantly decreased with hypertensive disease but they did not correlate. Following prolonged treatment, we observed a trend associating T1 decrease and improved perfusion compared with untreated SHRs.

Conclusions

Myocardial T1 and T2 values increase with hypertensive disease, whereas myocardial perfusion decreases. The correlation between T1 values and collagen density suggests that the former could be considered as a non-invasive marker of myocardial fibrosis.

Key Points

? MR is increasingly used to assess alteration in myocardial tissue content. ? MR relaxometry and perfusion can be assessed in rats without exogenous contrast agents. ? Myocardial T1 and T2 values significantly increase during the course of hypertensive heart disease. ? T1 values correlate significantly with myocardial collagen content. ? Myocardial perfusion values decrease with hypertensive disease.     

Characterisation of peripartum cardiomyopathy by cardiac magnetic resonance imaging

Peripartum cardiomyopathy (PPCM) is a rare cause of heart failure. Only half of the patients recover normal cardiac function. We assessed the usefulness of magnetic resonance imaging (MRI) and late enhancement imaging to detect myocardial fibrosis in order to predict cardiac function recovery in patients with peripartum cardiomyopathy. Among a consecutive series of 1,037 patients referred for heart failure treatment or prognostic evaluation between 1999 and 2006, eight women had confirmed PPCM. They all underwent echocardiography and cardiac MRI for assessment of left ventricular anatomy, systolic function and detection of myocardial fibrosis through late enhancement imaging. Mean (± SD) baseline left ventricular ejection fraction (LVEF) was 28 ± 4%. After a follow-up of 50 ± 9 months, half the patients recovered normal cardiac function (LVEF = 58 ± 4%) and four did not (LVEF = 35 ± 6%). None of the eight patients exhibited abnormal myocardial late enhancement. No difference in MRI characteristics was observed between the two groups. Patients with PPCM do not exhibit a specific cardiac MRI pattern and particularly no myocardial late enhancement. It suggests that myocardial fibrosis does not play a major role in the limitation of cardiac function recovery after PPCM. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Kardiomyopathien und Myokarditis

Clinical issue

Cardiomyopathies and myocarditis are frequently challenging in clinical practice regarding differentiation, risk stratification and treatment strategy. There are various disease entities which often affect young or middle-aged adults and the course is variable from asymptomatic and irrelevant for prognosis to sudden cardiac death or severe heart failure even at an early age. Making the right diagnosis is therefore fundamental to correctly identify affected patients and to initiate treatment steps in time.

Standard treatment

Whereas causal treatment options exist for some forms of cardiomyopathy, the majority of patients receives standard heart failure and device therapy but others require lifelong careful monitoring.

Diagnostic work-up

The diagnosis of cardiomyopathy is mainly based on the cardiac phenotype; therefore, non-invasive imaging is very important. Cardiovascular magnetic resonance has become the gold standard to assess cardiomyopathy as it combines functional information (e.g. wall motion) with myocardial tissue analysis (e.g. fibrosis and edema) and in some cases it can replace invasive endomyocardial biopsies.

Performance

The importance of cardiovascular magnetic resonance to assess cardiomyopathy is based on several aspects:

accurate analysis of cardiac dimensions and function,

non-invasive tissue analysis to make the diagnosis (e.g. myocarditis),

estimation of prognosis by non-invasive tissue analysis,

high reproducibility for accurate follow-up examinations,

potential for technical improvements (e.g. quantification of extracellular volume fraction by T1 mapping).

Achievements

In all types of cardiomyopathy, cardiovascular magnetic resonance has a major impact on the differential diagnosis, risk stratification and treatment. In some entities the appropriate clinical use is already confirmed by evidence (e.g. myocarditis) and in others there are first encouraging results that indicate the future potential (e.g. risk stratification in hypertrophic cardiomyopathy).

Practical recommendations

Cardiovascular magnetic resonance has evolved as the gold standard to assess cardiomyopathy as it provides both functional and morphological information. It is recommended to use this technique in a comprehensive approach to achieve complete work-up of affected patients.