新型冠状病毒肺炎心血管并发症的影像学研究进展

新型冠状病毒肺炎（COVID-19）可累及心血管系统引起心肌炎或其他心血管并发症,导致病人死亡率显著增加。超声心动图、心脏MR（CMR）、CT等多种无创性影像技术在COVID-19心血管并发症的诊断、治疗指导和预后评估中发挥了重要作用,特别是CMR不仅能评估心脏形态、结构方面的变化,还能判断COVID-19病人的心肌组织学异常,为预后提供新的影像学指标。就COVID-19心血管并发症的影像学研究进展予以综述。     

儿童心脏良性肿瘤的CMR影像特征分析

目的 研究儿童心脏良性肿瘤的心脏MR（CMR）特征及其对儿童良性肿瘤的诊断价值。方法 回顾性收集2006年9月-2018年3月于我院进行CMR检查的心脏肿瘤病例资料,共38例心脏良性肿瘤患儿纳入研究,其中男21例,女17例,年龄0.2~153.3个月,中位年龄13个月。分析各病理类型肿瘤在CMR上的特征,包括累及部位、大小、信号特点、血流动力学改变等,以及是否伴发心包和胸腔积液。通过与病理结果对照,计算CMR对心脏良性肿瘤诊断的敏感度和准确度。结果 肿瘤累及心肌、心腔、心包、心室流出道及纵隔,形态大小不一,临床症状与肿瘤发生部位有一定相关性而不具有特异性,但各类肿瘤具有一定的影像特征。所有的心脏肿瘤均被CMR清晰显示,CMR的诊断与病理结果相符的有32例,诊断的敏感度及准确度分别为100%（38/38）和84.21%（32/38）。结论 CMR能够同时提供心脏良性肿瘤的形态学特征及组织学信号特征,对心脏良性肿瘤诊断的敏感性及准确性均较高,是评估心脏肿瘤的重要检查方法。     

Assessment of ventricular function and mass by cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging is currently the technique of choice for precise measurements of ventricular volumes, function and left ventricular (LV) mass. The technique is 3D and hence independent of geometrical assumptions; this, along with its excellent definition of endocardial and epicardial borders, makes it highly accurate and reproducible. Cardiac magnetic resonance (CMR) is particularly useful in research, as it is highly sensitive to small changes in ejection fraction and mass, and only a small number of subjects are required for a study. The excellent reproducibility makes temporal follow-up of any individual patient in the clinical setting a realistic possibility. This review examines the merits of CMR and describes the techniques used.     

Transesophageal cardiac pacing during magnetic resonance imaging: Feasibility and safety considerations

The feasibility and safety of transesophageal cardiac pacing during clinical MRI at 1.5 Tesla is considered. An MRI compatible pace catheter was developed. In vitro testing showed a normal performance of the pulse generator, image artifacts that extended less than 11 mm from the catheter, and a less than 5% increase in noise. Cardiac stimulation induced by MRI was not observed and, theoretically, is not expected. Potentially, tissue around the catheter tip may become heated. This heating (ΔT) was monitored. Eight dogs were exposed to MRI during pacing. For low RF radiation exposure, a time-averaged squared B₁ field below 0.08 pT² (SAR < 0.03 W/kg), ΔT was below 1°C. For high RF radiation exposure, but at normal RF radiation specific absorption rate (0.4 W/kg), ΔT was 5°C. Thus, transesophageal atrial pacing during MRI at low RF exposure seems to be possible to perform cardiac stress studies or to correct unstable heart rates.     

T1 mapping cardiovascular magnetic resonance imaging to detect myocarditis—Impact of slice orientation on the diagnostic performance

BackgroundT1 mapping is a promising diagnostic tool to improve the diagnostic accuracy of cardiovascular magnetic resonance (CMR) in patients with suspected myocarditis. However, there are currently no data on the potential influence of slice orientation on the diagnostic performance of CMR. Thus, we compared the diagnostic performance of global myocardial T1 and extracellular volume (ECV) values to differentiate patients with myocarditis from healthy individuals between different slice orientations.MethodsThis study included 48 patients with clinically defined myocarditis and 13 healthy controls who underwent CMR at 1.5 T. A modified Look-Locker inversion-recovery (MOLLI) sequence was used for T1 mapping before and 15 min after administration of 0.075 mmol/kg Gadolinium-BOPTA. T1 mapping was performed on three short and on three long axes slices, respectively. Native T1, post-contrast T1 and extracellular volume (ECV) −BOPTA maps were calculated using a dedicated plug-in written for the OsiriX software and compared between the mean value of three short-axes slices (3SAX), the central short-axis (1SAX), the mean value of three long-axes slices (3LAX), the four-chamber view (4CH), the three-chamber view (3CH) and the two-chamber view (2CH).ResultsThere were significantly lower native T1 values on 3LAX (1081 ms (1037–1131 ms)) compared to 3SAX (1107 ms (1069–1143 ms), p = 0.0022) in patients with myocarditis, but not in controls (1026 ms (1009–1059 ms) vs. 1039 ms (1023–1055 ms), p = 0.2719). The areas under the curve (AUC) to discriminate between myocarditis and healthy controls by native myocardial T1 were 0.85 (p < 0.0001) on 3SAX, 0.85 (p < 0.0001) on 1SAX, 0.76 (p = 0.0002) on 3LAX, 0.70 (p = 0.0075) on 4CH, 0.72 (p = 0.0020) on 3CH and 0.75 (p = 0.0003) on 2CH. The AUCs for ECV-BOPTA were 0.83 (p < 0.0001) on 3 SAX, 0.82 (p < 0.0001) on 1SAX, 0.77 (p = 0.0005) on 3LAX, 0.71 (p = 0.0079) on 4CH, 0.69 (p = 0.0371) on 3CH and 0.75 (p = 0.0006) on 2CH.ConclusionNative T1 and ECV-BOPTA on short axes slices provide a better diagnostic performance in myocarditis than long axes slices since long axes slices seem to underestimate native myocardial T1 in myocarditis. T1 mapping in suspected myocarditis can be restricted to a single mid-ventricular short-axis slice without a significant loss in diagnostic performance.     

心脏淀粉样变性的CMR评估及研究进展

心脏淀粉样变性(CA)是系统性淀粉样变性累及心脏引起心脏损害的一种严重的疾病。心脏磁共振(CMR)具有多方位、多参数、无创、无辐射、高软组织分辨力的检查优势,在CA的早期诊断及不同亚型的鉴别、临床风险分层、治疗后的心肌反应监测、心肌淀粉样蛋白负荷评估和预后评估中具有重要价值。就CMR在CA的心脏形态结构和功能、心肌应变、组织特征评估方面的应用研究进展进行综述。     

CMR对急性心肌炎诊断价值的Meta分析

目的 通过Meta 分析评价心脏磁共振（CMR）各参数对急性心肌炎（AM）的诊断效能。方法 检索Embase、PubMed、Cochrane、中国知网、万方、维普数据库的CMR诊断AM的中英文文献,按照纳入排除标准筛选CMR对AM的诊断价值的研究,检索时间从建库至2020年7月31日。根据QUADAS-2条目评价纳入文献的质量,采用RevMan5.4评价偏倚风险及临床适用性,采用Meta-disc 1.4软件对纳入研究的合并敏感度、合并特异度、合并阳性似然比、合并阴性似然比和合并诊断比值比进行分析。绘制森林图和综合受试者操作特征（SROC）曲线,并计算相应曲线下面积（AUC）。采用不一致指数（I²）和Chochrane Q指数评价异质性,采用阈值效应、Meta回归、敏感性分析探讨异质性来源。采用Stata 15.1绘制漏斗图,评估是否存在发表偏倚,并进行Begg和Egger检验。结果 最终纳入21篇中英文文献,包括1 678例病人。路易斯湖标准（LLC）和native T₁ mapping的合并敏感度、合并特异度分别为77%、88%和85%、85%,两参数的合并敏感度、合并特异度相当;native T₁ mapping的AUC（0.941 9）大于LLC的（0.868 1）。T₂r、EGE、LGE、LLC、native T₁ mapping、T₂ mapping和ECV参数均存在中度以上异质性,阈值效应是EGE异质性的重要来源,Meta回归分析显示设备、场强、研究方法和确诊标准均不是异质性来源（均P>0.05）。Begg和Egger检验结果显示纳入研究的以上参数均不存在明显的发表偏倚（均P>0.05）。结论 native T₁ mapping具有良好的诊断效能,且只需评估单一参数,可优化检查流程。     

亚临床期糖尿病心肌病的CMR应用进展

亚临床期糖尿病心肌病（DCM）的早期诊断对改善糖尿病病人预后至关重要。心脏磁共振（CMR）作为心肌疾病无创诊断的“金标准”,可通过形态学变化、功能学变化、微循环障碍、心肌纤维化、心肌脂肪变性等方面对亚临床期DCM进行早期诊断。就CMR在亚临床期DCM应用的研究进展予以综述。     

Utility of cardiac magnetic resonance in the diagnosis of suspected “MINOCA”: a case series and literature review

Myocardial infarction with nonobstructive coronary artery (MINOCA) is a common condition in clinical practice with multiple specific causes, such as plaque rupture, plaque erosion, and epicardial coronary vasospasm. There must be an ischemic mechanism responsible for the myocyte injury and an exclusion of nonischemic mechanisms that can mimic myocardial infarction, and then a diagnosis of MINOCA can be made. Cardiac magnetic resonance (CMR) plays an essential role in the diagnosis and differential diagnosis of MINOCA, which cannot only exclude myocarditis, Takotsubo syndrome, and cardiomyopathies, but also provide imaging confirmation of acute myocardial infarction. In this study, we presented 2 typical cases with the clinical presentation of acute myocardial infarction but normal or nonobstructive epicardial coronary arteries. Further CMR examinations showed different patterns of late gadolinium enhancement (LGE) in these 2 cases, one case with subendocardial LGE of the anterolateral wall and the other one with subepicardial LGE of the lateral wall, which indicated 2 different mechanisms for the myocyte injury. Subsequently, these 2 patients received different treatment regimens and were discharged with improved symptoms. In conclusion, CMR should be a mandatory test in patients with suspected MINOCA, because it can not only make a clear diagnosis, but also play an important role in guiding clinical decision-making.     

Central nervous system aspergillosis: magnetic resonance imaging, diffusion-weighted imaging, and magnetic resonance spectroscopy features

Aspergillus infection is invasive in nature in the immunosuppressed population and disseminates throughout the body, with the brain being a common site. Conventional magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) play a life-saving role in the early diagnosis and treatment monitoring of this potentially fatal infection. We present MRI, DWI, and MRS findings of a case of central nervous system aspergillosis with treatment follow-up.     

Society of Cardiovascular Computed Tomography guidance for use of cardiac computed tomography amidst the COVID-19 pandemic Endorsed by the American College of Cardiology

The world is currently suffering through a pandemic outbreak of severe respiratory syndrome coronavirus 2 (SARS-CoV-2) known as Coronavirus Disease 2019 (COVID-19). The United States (US) Centers for Disease Control and Prevention (CDC) currently advises medical facilities to “reschedule non-urgent outpatient visits as necessary”. The European Centre for Disease Prevention and Control, the United Kingdom National Health Service and several other international agencies covering Asia, North America and most regions of the world have recommended similar “social distancing” measures. The Society of Cardiovascular Computed Tomography (SCCT) offers guidance for cardiac CT (CCT) practitioners to help implement these international recommendations in order to decrease the risk of COVID-19 transmission in their facilities while deciding on the timing of outpatient and inpatient CCT exams. This document also emphasizes SCCT's commitment to the health and well-being of CCT technologists, imagers, trainees, and research community, as well as the patients served by CCT.     

心脏磁共振延迟强化技术进展

心脏磁共振（CMR）延迟强化是诊断心肌梗死、心肌病及评估病变范围最重要的检查技术。目前临床应用的单次激发相位敏感反转恢复（SS-PSIR）序列、自由呼吸运动伪影校正PSIR（MOCO-PSIR）序列和非血流依赖黑血延迟强化（FIDDLE）序列,相比常规采用的PSIR序列能够实现呼吸、心脏运动伪影及血池信号抑制,可明显改善影像质量,有利于更好地指导治疗并进行预后评价。就多种CMR延迟强化技术原理及应用作一综述。     

Nuclear magnetic resonance imaging of the heart

NMR imaging is a noninvasive technique that has been shown to provide high-quality images of the heart. Due to the signal characteristics of flowing blood, inherent contrast between blood pool and myocardium is achieved without the use of contrast media. This paper briefly describes technical aspects of NMR imaging of the heart, normal cardiovascular anatomy, applications of the technique in patients with ischemic heart disease, and the potential of NMR imaging for functional studies in various forms of heart disease.Dedicated to Prof. Heinz Hundeshagen on the occasion of his 60th birthday     

Appropriateness of cardiovascular computed tomography and magnetic resonance imaging in patients with conotruncal defects

BackgroundTo promote the rational use of cardiovascular imaging in patients with congenital heart disease, the American College of Cardiology developed Appropriate Use Criteria (AUC), but its clinical application and pre-release benchmarks have not been evaluated. We aimed to evaluate the appropriateness of indications for cardiovascular magnetic resonance (CMR) and cardiovascular computed tomography (CCT) in patients with conotruncal defects and to identify factors associated with maybe or rarely appropriate (M/R) indications.MethodsTwelve centers each contributed a median of 147 studies performed prior to AUC publication (01/2020) on patients with conotruncal defects. To incorporate patient characteristics and center-level effects, a hierarchical generalized linear mixed model was used.ResultsOf the 1753 studies (80% CMR, and 20% CCT), 16% were rated M/R. Center M/R ranged from 4 to 39%. Infants accounted for 8.4% of studies. In multivariable analyses, patient- and study-level factors associated with M/R rating included: age <1 year (OR 1.90 [1.15–3.13]), truncus arteriosus (vs. tetralogy of Fallot, OR 2.55 [1.5–4.35]), and CCT (vs. CMR, OR 2.67 [1.87–3.83]). None of the provider- or center-level factors reached statistical significance in the multivariable model.ConclusionsMost CMRs and CCTs ordered for the follow-up care of patients with conotruncal defects were rated appropriate. However, there was significant center-level variation in appropriateness ratings. Younger age, CCT, and truncus arteriosus were independently associated with higher odds of M/R rating. These findings could inform future quality improvement initiatives and further exploration of factors resulting in center-level variation.     

异位妊娠的MRI诊断及鉴别诊断

目的：以手术病理为金标准对照,回顾性分析异位妊娠的 MRI 特征。方法收集11例手术证实的异位妊娠病例：宫角妊娠 l 例,间质部妊娠6例,输卵管峡部妊娠2例,输卵管壶腹妊娠1例,原发性腹腔妊娠1例。其中6例仅行 MR 平扫,5例行平扫及增强扫描。评价胎囊可视度,胎囊位置、大小,胎囊内部信号特点,胎囊周围血管情况,输卵管扩张,输卵管积血、腹腔积血,以及子宫内膜厚度,卵巢内黄体、功能性囊肿等改变。结果11例病例中,10例可见异位妊娠病灶的直接征象,位置判断均同手术一致。1例输卵管妊娠未见胎囊,存在输卵管积血和盆腔积血。结论MRI 可全面观察胎囊同周围结构的解剖关系明确定位,根据胎囊的自身信号特点及异位妊娠的常见征象帮助诊断和鉴别诊断。     

Inter- and intra-rater reproducibility of semiautomatic determination of volume parameters in cardiac magnetic resonance imaging

Purpose

The purpose of this study was to evaluate inter- and intra-rater reproducibility in volume assessment using cardiac magnetic resonance imaging (CMRI).

Methods

Twenty-five healthy volunteers and 106 patients were included into this retrospective study and received CMRI. The patients were divided in three groups (group I, 80 patients with arrhythmia; group II, 20 patients with cardiomyopathy; group III, 6 patients after correction of septum defects). Therefore, the images were semiautomatically segmented by an experienced and an unexperienced radiologists. The analysis of end-diastolic volume (EDV), end-systolic volume (ESV) and stroke volume (SV) as well as ejection fraction (EF) and myocardial mass (MM) were performed twice by an experienced and an unexperienced radiologists. The intra-class correlation coefficients (ICC) were determined for the evaluation of inter- and intra-rater variance.

Results

The intra-rater reproducibility for determination of EF, ESV, EDV and MM was excellent with ICCs ranging from 0.88 to 0.99 (all p < 0.001). The inter-observer reproducibility for these parameters was also excellent with ICCs ranging from 0.91 to 0.98 (all p < 0.001). The assessment of the SV showed an excellent intra-rater agreement with ICCs of 0.96 and 0.92 (both p < 0.001), but only a moderate ICC for the inter-rater reproducibility (0.54, p < 0.001).

Conclusions

Our study shows that assessment of cardiac volumes can be performed on CMRIs with an excellent reproducibility by both experienced and unexperienced investigators.     

COVID-19 Associated leukoencephalopathy in a term neonate: imaging findings and clinical presentation

A 5-day old neonate presented with several episodes of seizure-like activity associated with hypoxia. The episodes were responsive to anti-epileptic medications and the infant was given empiric antibiotics and antiviral coverage. Cerebrospinal fluid polymerase chain reaction (PCR), culture, and gram stain were negative for viral or bacterial etiology. However, a nasopharyngeal PCR of the infant was positive for SARS-COV-2. While head computed tomography (CT) was negative, magnetic resonance imaging (MRI) showed evidence of white matter injury in the subcortical and periventricular regions and corpus callosum. With supportive therapies, the infant made a full neurologic recovery and was discharged following a 5-day admission. This case highlights the growing evidence of SARS-COV-2 associated leukoencephalopathy in neonates, and physicians should consider this diagnosis in neonates with similar presentation.     

Quantification of cardiac function by conventional and cine magnetic resonance imaging

Magnetic resonance imaging (MRI) has been effective for depicting cardiac anatomy and is already established as a technique for the evaluation of some structural abnormalities of the heart and pericardium. With recent advances, MRI can now be used to quantitate cardiac function. Multiphasic ECG-gated spin-echo imaging has been used to quantitate right and left ventricular volumes and ejection fraction. left ventricular mass, and regional myocardial wall thickening. The new technique of cine MRI acquires frames during the cardiac cycle with a time resolution corresponding to 20 msec up to approximately 40 frames for an average cardiac cycle. This technique uses narrow flip angle (30°) and gradient refocused echoes. Cine MRI has been used to measure ventricular volumes and ejection fraction and regional myocardial wall thickening. It is also sensitive to the detection of valvular regurgitation and can provide quantitation of regurgitant volume. This article reviews the current status of MRI for quantitating cardiac function. Research fellow in magnetic resonance imaging supported by grant SE 441-2 from Deutsche Forschungsgenmeinschaft, Bonn, West Germany. Research fellow in magnetic resonance imaging supported by a grant from the Canadian Heart Foundation.