磁共振扩散加权成像技术在肝纤维化检查中的应用价值

肝纤维化是各种病因引起的肝脏纤维结缔组织的过度沉积,是纤维增生和分解不平衡的结果,也是各类慢性肝损伤→肝纤维化→肝硬化→肝癌渐进发展的必经的特征性病理过程。因肝纤维化是唯一可逆的过程,如何早期诊断肝纤维化、有效地阻断或干预肝纤维化的进程,正是当今研究的难点。弥散加权磁共振成像（DWI）是能反映活体组织内水分子扩散运动的成像技术,应用DWI对肝脏病变分析也是目前影像研究的热点之一。     

MR扩散加权及相位对比法成像评价肝纤维化及肝硬化的应用现状

我国慢性病毒性肝炎和肝硬化病人在逐年增多,评价病人肝纤维化及肝硬化的严重程度是当前研究的热点之一。这一领域的磁共振功能成像研究正在开展。就磁共振扩散加权及相位对比法成像在评价慢性病毒性肝炎肝纤维化、肝硬化的严重程度中的应用现状予以综述。     

磁敏感加权成像技术在脑肿瘤中的研究现状

磁敏感加权成像(SWI)是一种相对新兴的核磁序列,通过组织之间的磁敏感差异成像.磁敏感加权成像对血液产物、小静脉和铁沉积十分敏感,因此可用于脑肿瘤中微出血、静脉成像、血氧饱和度水平等的检测及评估.     

磁共振扩散加权成像在肝纤维化诊断中的应用

肝炎-肝纤维化-肝硬化-肝细胞癌是逐渐发展的病理过程,其中肝纤维化是唯一可逆性阶段。有关肝纤维化早期诊断和治疗的研究是当今临床及医学影像学研究的热点和难点。磁共振扩散加权成像(DWI)是近年开发并趋向成熟的功能成像技术,尤其对肝纤维化有望成为其早期诊断无创而有效的手段。现就DWI的成像方法及其对肝纤维化病理分级、分期等应用现状予以综述。     

磁共振扩散加权成像在肝纤维化诊断中的应用

肝炎-肝纤维化-肝硬化-肝细胞癌是逐渐发展的病理过程,其中肝纤维化是唯一可逆性阶段。有关肝纤维化早期诊断和治疗的研究是当今临床及医学影像学研究的热点和难点。磁共振扩散加权成像（DWI）是近年开发并趋向成熟的功能成像技术,尤其对肝纤维化有望成为其早期诊断无创而有效的手段。现就DWI的成像方法及其对肝纤维化病理分级、分期等应用现状予以综述。     

MR磁敏感加权成像在肝纤维化分级中的可行性研究

正目的本研究以组织病理结果为参考标准,探讨应用MR磁敏感加权(SW)成像信号强度(SI)来评估慢性肝病(CLD)病人肝纤维化分级的可行性。材料与方法本回顾性     

磁敏感加权成像在中枢神经系统的临床应用和前景

磁敏感加权成像是利用不同组织间磁化率不同而产生图像对比的一项新技术.和磁共振的其他技术相比,磁敏感加权成像最大的优势在于清晰显示颅内静脉结构及铁沉积,因此目前最多应用于中枢神经系统血管病变及变性疾病的诊断和研究.但在外伤、肿瘤等疾病中的价值也在不断被挖掘.     

3.0T磁共振扩散加权成像在肝硬化与肝癌的应用研究

目的 探讨3.0T磁共振扩散加权成像(DWI)对肝硬化与肝癌的诊断价值.方法 对10例健康志愿者、21例肝硬化患者及30例肝癌患者于3.0T磁共振成像系统行磁共振扩散加权成像检查,分析正常肝脏、肝硬化与肝癌扩散加权成像的特点,并测量正常肝脏、肝硬化与肝癌的ADC值,分析三者ADC值范围及不同b值时,ADC值对正常肝脏、肝硬化及肝癌的诊断灵敏度与特异性.结果 当b值为100 s/mm2时,正常肝脏ADC值分别与肝硬化、肝癌存在显著差异(P＜0.05),但肝硬化与肝癌ADC值之间无差异(P＞0.05);当b值分别为300 s/mm2和1000 s/mm2时,正常肝脏、肝硬化及肝癌的ADC值有显著性差异(P＜0.01).当b值为300 s/mm2时,ADC值对肝硬化的诊断灵敏度及特异性分别为82.6%和100%;对肝细胞癌的诊断灵敏度及特异性分别为95.2%和90.4%.当b值为1000 s/mm2时,ADC值对肝硬化的诊断灵敏度及特异性分别为86.9%和100%;对肝细胞癌的诊断灵敏度及特异性分别为95.2%和66.7%.结论 在3.0T磁共振成像系统进行肝脏DWI,通过综合及量化分析肝硬化与肝癌ADC值的变化规律,能为肝硬化及肝癌的诊断提供更有力的依据.     

定量磁敏感加权成像在急性缺血性脑卒中的应用进展

磁敏感加权成像(SWI)对显示静脉、血液成分、钙化、铁沉积等非常敏感,已广泛应用于脑血管病的诊断。近年来,定量SWI对急性缺血性脑卒中进行早期诊断及评估成为热点。SWI优势在于显示急性缺血性脑卒中血栓、不对称显著皮质静脉征、不对称深髓质静脉以及对急性缺血性脑卒中后血氧饱和度变化的判断,进而指导临床治疗及提示预后。主要综述定量磁敏感加权成像在急性缺血性脑卒中的应用。     

肝纤维化的MR扩散张量成像定量诊断与分期研究进展

肝纤维化是各种慢性肝病向肝硬化发展的必经过程,该过程是潜隐渐进的,且肝纤维化早期阶段是可逆的。早期定量诊断肝纤维化对其治疗效果、预后评估及促进其逆转具有重要意义。随着功能MRI技术,特别是MR扩散加权成像及扩散张量成像技术的发展,肝纤维化的无创性定量诊断取得一定进展。着重就MR扩散张量成像对肝纤维化的定量诊断与分期研究进展予以综述。     

Primary hepatocellular lesions: imaging findings on state-of-the-art magnetic resonance imaging, with pathologic correlation

Magnetic resonance imaging is routinely used for the workup of patients with focal or diffuse liver disease, including primary hepatocellular lesions, storage diseases, metastatic liver disease, and diseases of the hepatobiliary tree. The most important magnetic resonance imaging sequences used for diagnostic imaging of the liver consist of T1-weighted sequences, T2-weighted sequences, and at least the arterial and delayed phases of dynamic gadolinium-enhanced imaging. This article provides an overview of magnetic resonance imaging of primary hepatocellular lesions and will describe the following: (1) the classification and etiology of primary hepatocellular lesions, including focal nodular hyperplasia, hepatocellular adenoma, and hepatocellular carcinoma; (2) the stepwise carcinogenesis of hepatocellular carcinoma in cirrhosis on magnetic resonance imaging; and (3) the typical imaging findings of primary hepatocellular lesions on magnetic resonance imaging, with differential diagnoses.     

体素内不相干运动扩散加权成像在肝纤维化定量诊断与分期中的研究进展

肝纤维化是指在各种致病因素作用下肝内结缔组织异常增生。肝脏的任何损伤在修复过程中都有肝纤维化过程,但是如果损伤因素长期存在,纤维化将持续进展,并发展成肝硬化。早期肝纤维化通过干预可逆转。因此,早期定量诊断肝纤维化对其临床治疗方案的选择及促进其逆转具有重要意义。随着MRI技术的发展,肝纤维化无创定量诊断及分期取得了较大进展。着重就MRI体素内不相干运动扩散加权成像在肝纤维化的定量诊断与分期中的研究进展予以综述。     

DWI及声辐射力脉冲成像在肝纤维化诊断中的价值

目的对比DWI和声辐射力脉冲成像(acoustic radiation force impulse imaging,ARFI)对肝纤维化的诊断价值。方法对50例肝纤维化患者(观察组)及16例健康志愿者(正常对照组)行DWI(b=0、600s/mm 2)扫描,并测量ADC值;2组同时行ARFI检查,检测指标为低频剪切波传播速度(shear wave velocity,SWV)。分析并对比不同组间ADC值和SWV的变化规律。结果SWV波速随肝脏纤维化分期(从S0~S4期)升高而递增,而ADC值则呈降低趋势(P<0.05)。肝纤维化各组与正常对照组间比较差异均有统计学意义,肝纤维化各组组间比较差异均有统计学意义。结论在肝纤维化定量中,ARFI和DWI均具备一定的检测能力。在诊断肝纤维化敏感度方面,ARFI高于DWI;而在特异度方面,DWI优于ARFI,两者皆可检测重度肝纤维化及肝硬化。     

Improving detection of siderotic nodules in cirrhotic liver with a multi-breath-hold susceptibility-weighted imaging technique

Purpose:

To evaluate the role of abdominal susceptibility‐weighted imaging (SWI) in the detection of siderotic nodules in cirrhotic liver.

Materials and Methods:

Forty patients with pathologically identified liver cirrhosis and 40 age/sex‐matched normal controls underwent T1‐, T2‐, T2*‐weighted imaging and SWI at 3T. Two radiologists prospectively analyzed all magnetic resonance imaging (MRI) studies. Siderotic nodules detected by each imaging technique were counted for comparison. The conspicuity of siderotic nodules was assessed using a scale from 1 to 3 (1, weak; 2, moderate; 3, prominent).

Results:

The number of siderotic nodules detected by SWI (3863) was significantly greater than that of T1‐weighted imaging (262, P < 0.001), T2‐weighted imaging (842, P < 0.001), and T2*‐weighted imaging (2475, P < 0.001). No suspected siderotic nodules were detected in normal controls by any imaging technique.

Conclusion:

SWI appears to provide the most sensitive method to detect siderotic nodules in cirrhotic liver. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

磁敏感加权成像在高血压脑微出血中应用价值的探讨

目的:探讨磁敏感加权成像在高血压脑微出血中的应用价值.方法:采用1.5T MR扫描仪,对48例高血压脑微出血患者分别进行常规和SWI序列扫描,比较各序列对于脑微出血灶的数量、部位、分布的显示情况.结果:T2WI序列检出低信号灶169个,T2FLAIR序列检出低信号灶273个,SWI序列检出低信号灶1335个,各序列显示...     

Magnetic resonance imaging in chronic liver disease evaluated in relation to hepatic fibrosis--clinical and experimental results

In 21 patients with chronic liver disease, the ratio of liver to muscle signal intensity on T1-weighted images was negatively correlated with the progression of hepatic fibrosis defined according to findings by laparoscopy and liver biopsy, and differentiated six patients with early chronic hepatitis from eight with liver cirrhosis. On T2-weighted images, the number of low intensity nodules comparable in size to regenerating nodules surrounded by connective tissues showed a positive correlation with stage. When hepatic fibrosis with no necrosis or fat infiltration was induced in rats, T2 values were positively correlated with hepatic hydroxyproline content, though there was no such correlation for T1 values. These results suggest that MR imaging may be useful for determining the progression of hepatic fibrosis in chronic liver disease. T2 values may directly reflect hepatic fibrosis.     

Diminished visibility of cerebral venous vasculature in multiple sclerosis by susceptibility‐weighted imaging at 3.0 Tesla

Multiple sclerosis (MS) is a disease of the central nervous system characterized by widespread demyelination, axonal loss and gliosis, and neurodegeneration; susceptibility‐weighted imaging (SWI), through the use of phase information to enhance local susceptibility or T2* contrast, is a relatively new and simple MRI application that can directly image cerebral veins by exploiting venous blood oxygenation. Here, we use high‐field SWI at 3.0 Tesla to image 15 patients with clinically definite relapsing‐remitting MS and to assess cerebral venous oxygen level changes. We demonstrate significantly reduced visibility of periventricular white matter venous vasculature in patients as compared to control subjects, supporting the concept of a widespread hypometabolic MS disease process. SWI may afford a noninvasive and relatively simple method to assess venous oxygen saturation so as to closely monitor disease severity, progression, and response to therapy. J. Magn. Reson. Imaging 2009;29:1190–1194. © 2009 Wiley‐Liss, Inc.     

Detection of hepatocellular carcinoma arising in cirrhotic livers: comparison of gadolinium- and ferumoxides-enhanced MR imaging.

OBJECTIVE: We prospectively compared the detectability of hepatocellular carcinoma (HCC) arising in cirrhotic livers using dynamic gadolinium-enhanced fast low-angle shot (FLASH), ferumoxides-enhanced T2-weighted turbo spin-echo, and ferumoxides-enhanced T2*-weighted FLASH MR imaging. SUBJECTS AND METHODS: Fifty-three patients with HCC (32 men and 21 women) who were 33-86 years old (mean, 63 years old) were enrolled in a prospective MR study to assess hepatic lesions using both gadopentetate dimeglumine and ferumoxides. Dynamic gadolinium-enhanced imaging was obtained before and 30, 60, and 180 sec after rapid bolus injection of gadopentetate dimeglumine (0.1 mmol/kg). Ferumoxides-enhanced T2-weighted turbo spin-echo imaging and ferumoxides-enhanced T2*-weighted FLASH imaging were performed between 30 min and 2 hr after i.v. infusion of ferumoxides (10 micromol/kg). Images were analyzed qualitatively and quantitatively. A receiver operating characteristic curve study was performed to compare the diagnostic value of gadolinium-enhanced imaging with that of ferumoxides-enhanced imaging for the detection of HCC. RESULTS: Quantitative analysis revealed a significantly higher percentage of signal-intensity loss and higher liver-lesion contrast-to-noise ratio on ferumoxides-enhanced T2*-weighted FLASH imaging than on ferumoxides-enhanced T2-weighted turbo spin-echo imaging. The percentage of signal-intensity loss and liver-lesion contrast-to-noise ratio on ferumoxides-enhanced images was significantly higher in patients with mild liver cirrhosis (Child's class A) than in patients with severe liver cirrhosis (Child's class C). Qualitative analysis showed that dynamic gadolinium-enhanced images revealed significantly higher lesion conspicuity than did ferumoxides-enhanced T2-weighted turbo spin-echo images. According to receiver operating characteristic analysis, dynamic gadolinium-enhanced FLASH imaging achieved the highest sensitivity, and ferumoxides-enhanced T2*-weighted FLASH imaging was the second most sensitive. We found that ferumoxides-enhanced turbo spin-echo imaging was the least valuable technique for revealing HCC lesions. Gadolinium-enhanced imaging revealed more HCC lesions than did ferumoxides-enhanced imaging, particularly for lesions smaller than 2 cm in diameter. CONCLUSION: Ferumoxides-enhanced imaging revealed fewer findings, such as lesion conspicuity of HCCs arising in cirrhotic livers, than did gadolinium-enhanced FLASH imaging.     

Focal manifestations of diffuse liver disease at MR imaging.

Detection and exclusion of focal liver lesions is especially difficult in patients with diffuse liver disease. Magnetic resonance (MR) imaging may be particularly valuable in these patients. By judicious comparison of appropriate pulse sequences, normal and hypertrophic liver may be distinguished from atrophic, neoplastic, or otherwise abnormal hepatic parenchyma. Chemical shift (lipid-sensitive) techniques allow definitive identification of fatty liver, including focal fatty infiltration or focal sparing. T2-weighted and T2*-weighted images allow identification of iron overload, depicting malignancies as focal masses without iron. Analysis of signal intensity and internal morphology allows confident distinction between regenerative nodules and hepatocellular carcinoma in most instances, and allows diagnosis of early carcinoma within regenerative nodules. MR imaging provides capabilities for noninvasive characterization of liver tissue beyond those available with other noninvasive modalities.     

磁共振扩散成像及磁敏感加权成像在脊髓损伤中的应用

目前,脊髓MR成像常规检查是诊断脊髓损伤的最佳手段,能清楚地显示受损伤脊髓形态及信号改变,以此明确疾病,但是当MRI常规检查出现信号改变时往往提示脊髓损伤严重,并非病变的早期,使得病人错过最佳治疗时期。而MR扩散加权成像(DWI)和磁敏感加权成像(SWI)对脊髓损伤的早期诊断、治疗和预后均具有重要价值。对DWI及SWI在急慢性脊髓损伤中的应用情况及研究进展进行综述。