儿童先天性心脏病磁共振成像

先天性心脏病(先心病)相当常见,在每1000个新生儿中就有7人左右.儿童先心病通常首选超声心动图枪查,如明确诊断,即行治疗,如不能明确诊断,则做心脏磁共振或多层螺旋CT.CT的主要问题是有大量射线.磁共振对手术前后的儿童先心病人可成为解剖和功能的一站式检查手段.本文介绍磁共振对儿童先心病人的扫描技术和临床应用.自旋同波...     

Sex Differences in the Risk of Coronary Heart Disease Associated With Type 2 Diabetes: A Mendelian Randomization Analysis

OBJECTIVEObservational studies have demonstrated that type 2 diabetes is a stronger risk factor for coronary heart disease (CHD) in women compared with men. However, it is not clear whether this reflects a sex differential in the causal effect of diabetes on CHD risk or results from sex-specific residual confounding.RESEARCH DESIGN AND METHODSUsing 270 single nucleotide polymorphisms (SNPs) for type 2 diabetes identified in a type 2 diabetes genome-wide association study, we performed a sex-stratified Mendelian randomization (MR) study of type 2 diabetes and CHD using individual participant data in UK Biobank (251,420 women and 212,049 men). Weighted median, MR-Egger, MR-pleiotropy residual sum and outlier, and radial MR from summary-level analyses were used for pleiotropy assessment.RESULTSMR analyses showed that genetic risk of type 2 diabetes increased the odds of CHD for women (odds ratio 1.13 [95% CI 1.08–1.18] per 1-log unit increase in odds of type 2 diabetes) and men (1.21 [1.17–1.26] per 1-log unit increase in odds of type 2 diabetes). Sensitivity analyses showed some evidence of directional pleiotropy; however, results were similar after correction for outlier SNPs.CONCLUSIONSThis MR analysis supports a causal effect of genetic liability to type 2 diabetes on risk of CHD that is not stronger for women than men. Assuming a lack of bias, these findings suggest that the prevention and management of type 2 diabetes for CHD risk reduction is of equal priority in both sexes.     

A primer for fetal cardiac imaging: a stepwise approach for 2-dimensional imaging

Detection of congenital heart disease (CHD) remains problematic, even with advances in imaging. Imaging modalities, such as magnetic resonance imaging, have been helpful in better understanding certain abnormalities, such as the fetal central nervous system. However, because of cardiac motion, screening and detection of CHD are best performed by sonography. Although newer technical advances in sonography, including 3-dimensional (3-D) dynamic multiplanar imaging and Doppler techniques, are extremely helpful in better delineating CHD, the mainstay of detection of CHD remains 2-D real-time imaging. Understanding 2-D imaging of the heart, using multiple views, is necessary to perform any type of multiplanar imaging as both require basic understanding of the same basic views. Although it is beyond the scope of this article to review all facets of fetal cardiac imaging, we will present a stepwise approach using 2-D imaging in the detection of CHD.     

彩色多普勒诊断非瓣膜病二尖瓣返流及临床意义

目的评价彩色多普勒诊断非瓣膜病二尖瓣返流的意义。方法用彩色多普勒超声对冠心病、高心病、扩心病、肺心病、甲亢及糖尿病、尿毒症性心脏病进行检查。测量返流程度（Ｈｅｌｍｃｋｅ法）和左室内径（ＬＶ）。从中选出１１５例具有病理性返流而无瓣膜病患者进行分析、对比。结果有返流的ＣＨＤ患者，３７％ＬＶ增大（５２．７±４．０），其增大程度比高心病（６１．７±４．２）、ＤＣＭ（６９．１±６．８）、尿毒症心脏病（６２．７±６．８）有显著差异（Ｐ＜０．０５），增大百分率亦显著不同（Ｐ＜０．０５）。结论根据返流可以判断各病变时期，ＣＨＤ多出现在病变早期，返流程度可轻可重。高心病，ＤＣＭ，尿毒症、甲亢、糖尿病心脏病多出现在病变晚期，左室扩大后，且多为轻度返流     

Intra-observer and interobserver variability of biventricular function, volumes and mass in patients with congenital heart disease measured by CMR imaging

Cardiovascular magnetic resonance (CMR) imaging provides highly accurate measurements of biventricular volumes and mass and is frequently used in the follow-up of patients with acquired and congenital heart disease (CHD). Data on reproducibility are limited in patients with CHD, while measurements should be reproducible, since CMR imaging has a main contribution to decision making and timing of (re)interventions. The aim of this study was to assess intra-observer and interobserver variability of biventricular function, volumes and mass in a heterogeneous group of patients with CHD using CMR imaging. Thirty-five patients with CHD (7–62 years) were included in this study. A short axis set was acquired using a steady-state free precession pulse sequence. Intra-observer and interobserver variability was assessed for left ventricular (LV) and right ventricular (RV) volumes, function and mass by calculating the coefficient of variability. Intra-observer variability was between 2.9 and 6.8% and interobserver variability was between 3.9 and 10.2%. Overall, variations were smallest for biventricular end-diastolic volume and highest for biventricular end-systolic volume. Intra-observer and interobserver variability of biventricular parameters assessed by CMR imaging is good for a heterogeneous group of patients with CHD. CMR imaging is an accurate and reproducible method and should allow adequate assessment of changes in ventricular size and global ventricular function.     

Normal spinal anatomy on magnetic resonance imaging

Over the past few decades, spinal magnetic resonance imaging (MR imaging) has largely replaced computed tomography (CT) and CT myelography in the assessment of intraspinal pathology at institutions where MR imaging is available. Given its high contrast resolution, MR imaging allows the differentiation of the several adjacent structures comprising the spine. This article illustrates normal spinal anatomy as defined by MR imaging, describes commonly used spinal MR imaging protocols, and discusses associated common artifacts.     

Functional MR imaging of the lung

Recent development of MR techniques has overcome many problems, such as susceptibility artifacts or motion artifact, allowing both static and dynamic MR lung imaging and providing quantitative information of pulmonary function, including perfusion, ventilation, and respiratory motion. Dynamic contrast-enhanced MR perfusion imaging is suitable for the evaluation of angiogenesis of pulmonary solitary nodules. (129)Xe MR imaging is potentially a robust technique for the evaluation of various pulmonary function and may replace (3)He. The information provided by these new MR imaging methods is proving useful in research and in clinical applications in various lung diseases.     

硝酸甘油~(99m)Tc-MIBI心肌断层显像对冠心病的诊断价值

目的 :探讨硝酸甘油99m Tc -甲氧基异丁基异腈 (MIBI)心肌断层显像对冠心病的诊断价值。方法 :对 80例疑冠心病 (CHD)患者进行静息和硝酸甘油99m Tc -MIBI心肌显像 ,并以冠状动脉造影 (CAG)对照。结果 :硝酸甘油99m Tc -MIBI心肌显像诊断CHD的敏感性为 95 2 % ,特异性为 86 8% ;诊断单支、双支及三支病变的敏感性分别为 92 6%、10 0 %、10 0 %。结论 :99mTc -MIBI心肌断层显像对CHD诊断准确率较高 ,值得临床广泛应用     

Breast MR imaging in assessing extent of disease

Breast MR imaging is valuable in assessment of extent of disease in the ipsilateral and contralateral breast in women who have breast cancer. In the ipsilateral breast, MR imaging depicts otherwise unsuspected sites of cancer in 16% (range, 6%-34%). In the contralateral breast, MR imaging depicts otherwise unsuspected sites of cancer in 6% (range, 3%-24%). MR imaging is most likely to depict additional sites of cancer in women with invasive lobular cancer and a family history of breast cancer. MR imaging can also assist in evaluating involvement of skin, pectoral muscle, and chest wall. Disadvantages of breast MR imaging include cost and additional procedures (follow-up and biopsy); furthermore, no data as yet show that breast MR imaging in the extend of disease evaluation improves disease-free or overall survival. If breast MR imaging is used in evaluating extent of disease, it is necessary to have the capability to perform biopsy of lesions detected by MR imaging only.     

Multi-institutional evaluation of the indications and radiation dose of functional cardiovascular computed tomography (CCT) imaging in congenital heart disease

Ventricular volumes and ejection fraction are often used in clinical decision making in patients with congenital heart disease (CHD). The referral diagnosis, radiation exposure and image quality of functional cardiac computed tomography (CT) in a relatively large cohort of patients of CHD has not been reported. This is a retrospective evaluation of functional CT studies performed in CHD patients from three institutions (1/2007–3/2013). Patient and scanner characteristics, radiation dose estimates and image quality were compared. Two hundred ninety-eight functional CT studies were evaluated. The most common referral diagnosis were tetralogy of Fallot (33 %), transposition complexes (24 %) single ventricle heart disease (15 %), and left sided obstruction (15 %). The reason for cardiac CT was presence of pacemaker (60 %), need for detailed coronary artery imaging (18 %), metallic artifact in CMR (12 %), evaluation of prosthetic valve function (4 %), and claustrophobia or BMI too large for the available MR scanner (6 %). 266 (89.3 %) scans allowed quantification of ventricular function, 25 (8.4 %) scans allowed qualitative assessment of function, and 7 (2.3 %) of the scans were non-diagnostic for functional analysis. Median DLP was 399 mGy cm (186, 614), and median effective dose was 5.5 mSv (2.6, 8.5). Radiation dose and image quality varied across institutions. Cardiac CT function imaging can be performed in patients with congenital heart disease when CMR is contraindicated or has poor image quality. Radiation dose and image quality varies across institutions.     

低场MR动态增强对肝脏占位病变的诊断价值探讨

目的：探讨低场MR动态增强对肝脏占位病变的应用价值。方法：应用0．2T永磁型磁共振仪对24例肝脏占位性病变先行TIW1、T2WI平扫，再使用FMPSPGR(快速多层面扰相位梯度回波)序列，进一步对其中28个占位灶作同层块动态增强扫描。造影剂为磁显葡胺(Gd-DTPA)0．2mmol／kg。结果：在上下5～8cm范围内可显示肝脏占位病变的动态强化方式，有助于定性诊断。结论：低场MR动态增强可作为肝脏占位病变定性诊断的补充方法。     

MR imaging of the pancreas

MR imaging is a valuable tool in the assessment of the full spectrum of pancreatic diseases. MR imaging techniques are sensitive for the evaluation of pancreatic disorders in the following settings: (1) TI-weighted fat-suppressed and dynamic gadolinium-enhanced SGE imaging for the detection of chronic pancreatitis, ductal adeno-carcinoma, and islet-cell tumors; (2) T2-weighted fat-suppressed imaging and T2-weighted breath-hold imaging for the detection of islet-cell tumors;and (3) precontrast breath-hold SGE imaging for the detection of acute pancreatitis. Relatively specific morphologic and signal intensity features permit characterization of acute pancreatitis,chronic pancreatitis, ductal adenocarcinoma, insulinoma, gastrinoma, glucagonoma, microcystic cystadenoma, macrocystic cystadenoma, and solid and papillary epithelial neoplasm. MR imaging is effective as a problem-solving modality because it distinguishes chronic pancreatitis from normal pancreas and chronic pancreatitis with focal enlargement from pancreatic cancer in the majority of cases.MR imaging studies should be considered in the following settings: (1) in patients with elevated serum creatinine, allergy to iodine contrast, or other contraindications for iodine contrast administration; (2) in patients with prior CT imaging who have focal enlargement of the pancreas with no definable mass; (3) in patients in whom clinical history is worrisome for malignancy and in whom findings on CT imaging are equivocal or difficult to interpret; and (4) in situations requiring distinction between chronic pancreatitis with focal enlargement and pancreatic cancer. Patients with biochemical evidence of islet-cell tumors should be examined by MR imaging as the first-line imaging modality because of the high sensitivity of MR imaging for detecting the presence of islet-cell tumors and determining the presence of metastatic disease.     

New techniques in MR imaging of brain tumors

The past decade has seen many new MR imaging techniques that have been applied to brain tumor imaging. As MR imaging is applied further to cellular and molecular imaging (e.g., imaging of gene transfer and expression), more possibilities for brain tumor diagnosis and treatment will become evident. The superior contrast, resolution, and lack of need for image coregistration suggest that MR imaging techniques may displace PET as the preeminent modality for studying brain and tumor physiology and chemistry for indications other than receptor-based imaging. Nevertheless, the new MR imaging techniques require further histologic, physiologic, and intraoperative validation in suitable animal models and in clinical studies, and should be used to complement PET. Application of echo-planar imaging and other fast imaging sequences can permit the merger of several MR imaging studies (e.g., perfusion imaging, DWI, and MRS(I) into a typical (1-hour) clinical time slot). Synergistic information provided by these new techniques might soon enable physicians to reach the ultimate goals of noninvasive tumor grading and avoidance of having to obtain a biopsy.     

Ischemic heart disease: value of MR techniques

Background. The cardiovascular applications of magnetic resonance (MR) techniques in coronary artery disease have increased considerably in recent years. Technical advantages of MR imaging are the excellent spatial resolution, the characterization of myocardial tissue, and the potential for three-dimensional imaging. These characteristics allow the accurate assessment of left ventricular mass and volume, the differentiation of infarcted from normal tissue, and the determination of systolic wall thickening and regional wall motion abnormalities. Methods. In addition to the conventionally used spin-echo and cine-echo techniques, newer techniques such as myocardial tagging, ultrafast MR imaging and MR coronary angiography have been developed. These newer techniques allow a more accurate assessment of ventricular function (tagging), myocardial perfusion (ultrafast imaging), and evaluation of stenosis severity (MR coronary angiography). Particularly early detection and flow assessment of stenosed coronary arteries and bypasses by MR angiography would constitute a major breakthrough in cardiovascular MR imaging. Apart from the MR imaging techniques, cardiac metabolism may be well assessed using MR spectroscopy. This provides unique information on the metabolic behaviour of the myocardium under conditions stress-induced ischemia. However, the definite niche of cardiac MR spectroscopy has still to be settled. Conclusion. Currently, MR techniques allow the evaluation of anatomy and function (accepted use), perfusion and viability (development phase), and coronary angiography (experimental phase). A particular strength of MR imaging is that one single MR test may encompass cardiac anatomy, perfusion, function, metabolism and coronary angiography. The replacement of multiple diagnostic tests with one MR test may have major effects on cardiovascular healthcare economics and would outweigh the cost inherent to the MR angiography procedure.     

心血管磁共振成像临床应用和新进展

近年来由于MRI的进展,现已成为医学成像技术的主要组成部分,心血管MRI已广泛、有效地应用于心脏、大血管、内脏和外周血管成像及诊治工作.本文简要叙述心血管MRI临床应用概况,如对胸主动脉疾患、缺血性心脏病、心肌病、心脏肿瘤、先心病、心包疾患和心脏瓣膜病的诊断评价等.重点讨论一些新进展,如MR心肌灌注成像和心肌存活的评价;MR冠脉造影和斑块成像;深静脉血栓和肺栓塞的MR诊断以及MR血管造影对腹主-髂股-下肢动脉狭窄性病变的诊断及效果分析.     

MR imaging of degenerative diseases in the cervical spine

This article reviews three topics of fundamental importance in MR imaging of degenerative diseases in the cervical spine: (1) common clinical presentations that determine whether an MR examination is ordered and the ultimate significance ascribed to MR imaging results; (2) imaging techniques; and (3) MR imaging of the major types of cervical spine degeneration.     

Imaging at higher magnetic fields: 3 T versus 1.5 T

Clinical hepatobiliary magnetic resonance (MR) imaging continues to evolve at a fast rate. However, three basic requirements must still be satisfied if novel high-field MR imaging techniques are to be included in the hepatobiliary imaging routine: improvement of parenchymal contrast, suppression of respiratory motion artifact, and anatomic coverage of the entire hepatobiliary system. This article outlines the various arenas involved in MR imaging of the hepatobiliary system at 3 Tesla (T) compared with 1.5 T by (1) highlighting magnetic field-dependent MR contrast phenomena that contribute to the overall appearance of high-field hepatobiliary imaging; (2) summarizing the biodistributions of different gadolinium chelates used as MR contrast agents and their effectiveness regarding the static magnetic field; (3) showing the?implementation of advanced imaging techniques such as three-dimensional acquisition schemes and parallel acceleration techniques used in T1-, T2-, and diffusion-weighted hepatobiliary imaging; and (4) addressing artifact mechanisms exacerbated by, or originating from, increase of the static magnetic field.     

MRI in the evaluation of hepatocellular nodules: role of pulse sequences and contrast agents

Magnetic resonance (MR) imaging is more useful than computed tomography (CT) in the evaluation of hepatocellular nodules based on the excellent soft-tissue image contrast of MR imaging. In addition, recent MR units have allowed various fast MR imaging techniques (i.e., parallel imaging or echo-planar imaging) to dramatically improve image quality and image contrast. A variety of liver-specific MR contrast agents are also currently available or have been evaluated in clinical trials to improve the contrast between the liver parenchyma and hepatocellular nodules.     

Hepatocellular nodules in liver cirrhosis: MR evaluation

Liver cirrhosis is a major public health problem worldwide. Common causes of cirrhosis include hepatitis C virus, hepatitis B virus, alcohol consumption, and nonalcoholic steatohepatitis. Cirrhotic livers are characterized by advanced hepatic fibrosis and the development of hepatocellular nodules such as regenerative nodules, dysplastic or neoplastic nodules. Cirrhosis is the strongest predisposing factor for hepatocellular carcinoma (HCC). For example, viral hepatitis is the main risk factor for cirrhosis and is associated with the increased incidence (1%–4% per year) of HCC after development of cirrhosis. Currently, a variety of imaging modalities, including ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET) are used in noninvasive evaluation of patients with chronic liver disease and suspected HCC. With technological development of MR scanners, MR imaging has emerged as an important imaging modality for assessing cirrhosis and its complications such as HCC. The recent advance in MR is the introduction of faster sequences which have allowed high-quality imaging of the entire liver with high intrinsic soft-tissue contrast, and also multiphasic dynamic MRI that is essential for the detection and characterization of HCC. In addition, functional MRI including diffusion-weighted MRI, MR elastography, and new MR contrast agent with dual function have been investigated for the clinical utility of detection and characterization of HCCs. In this article, we provide an overview of the state-of-the-art MR imaging techniques being used for noninvasive assessment of hepatocellular nodules including conventional dynamic imaging, liver-specific contrast-enhanced MR imaging, diffusion-weighted imaging, MR spectroscopy, and MR elastography.