MRI可提供有效的非侵袭性的肝脏诊断

两项最新的研究表明核磁共振组织弹性成像(MRE)，一种新的成像技术，是一种非侵袭性诊断肝脏疾病的工具。

肝脏可由于很多疾病造成其细胞破坏并发展成瘢痕组织或纤维化。MRE是MRI基础上发展而来的，并且可以有效测量肝脏的硬度和弹性。对肝脏振动的同时，MRE可获得机械波穿透器官后所成的像。图像经过处理后就可得到相应组织有关硬度的信息。

健康肝脏组织是非常柔软的，而纤维化的肝脏是比较硬的，而硬化后的肝脏像岩石一样坚硬。

Mayo诊所Richard Ehman博士解释道。如果发现得较早，肝纤维化是可以逆转的，但一旦发展成肝硬化，就不可逆转了。

Ehman博士和他的研究团队并在胃肠道医师的帮助下，研究MRE是否可在不同肝脏疾病水平提供可信和准确的信息。这项研究涉及57名慢性肝脏疾病患者和20例健康志愿者。研究表明，MRE在诊断肝纤维化上具有灵敏性和特异性。研究还表明脂肪变性，脂肪酸和甘油三脂在肝细胞内沉积所造成，这是一种肝脏疾病普遍性病变，并不影响MRE对纤维化的检测。

第二项Mayo研究检测MRE是否能准确检测门静脉高压、或者门静脉高血压所致血液从消化道流入肝脏，典型的肝硬化结果。这项研究涉及35例慢性肝硬化病人和12例健康志愿者。研究人员通过MRE检测肝脏和脾脏的硬度发现肝脏和脾脏硬度与门静脉高压有显著的相关性。

根据Ehman博士的看法，许多可导致组织改变的疾病在未来都可通过MRE来检测。他的研究团队正在评估使用MRE检测乳腺癌和老年痴呆的可行性。

这些研究成果在2007年5月柏林举行的核磁共振年会以及今年在华盛顿举行的消化疾病会议上分别作了展示。


MRI Elastrography Provides Effective Noninvasive Liver Diagnoses 
     
Two recent studies have found that magnetic resonance elastography (MRE), a new imaging technique, is an accurate tool for noninvasive diagnosis of liver disease.
 
The liver responds to many diseases that damage its cells by developing scar tissue or fibrosis. MRE, developed at the Mayo Clinic (Rochester, MN, USA), uses a modified form of magnetic resonance imaging (MRI) to effectively measure the hardness or elasticity of the liver. By applying vibrations to the liver, MRE obtains images of the mechanical waves passing through the organ. The wave images are then processed to generate a quantitative image of tissue stiffness. 

ealthy liver tissue is very soft, while a liver with fibrosis is firmer, and a liver with cirrhosis is almost rock-hard,?stated Richard Ehman, M.D., lead Mayo Clinic researcher on the MRE project. f detected early, fibrosis of the liver can be treated, but once the disease has progressed to cirrhosis, the condition is irreversible.

Dr. Ehman and his imaging research team collaborated with Mayo Clinic gastroenterologists to study whether MRE could provide reliable and accurate diagnoses in patients with varying levels of liver disease. One study involved MRE examinations of 57 individuals with chronic liver disease and 20 healthy volunteers. The researchers confirmed that MRE accurately detects fibrosis with high sensitivity and specificity. Researchers also found that steatosis, which is deposits of fatty acids and triglycerides in liver cells and a common condition in patients with liver disease, did not interfere with detection of fibrosis with MRE. 

The second Mayo study looked at whether MRE can accurately measure portal hypertension, or high-blood pressure in the portal vein that carries blood from the digestive track to the liver, typically as a result of cirrhosis of the liver. This study involved 35 individuals with differing degrees of chronic liver disease and 12 healthy volunteers. Researchers assessed MRE examinations of liver and spleen stiffness and discovered that a highly significant correlation exists between liver and spleen stiffness in patients with portal hypertension. 

According to Dr. Ehman, many disorders cause the characteristics of tissue to change and will be likely candidates for diagnosis using MRE in the future. His research team is now evaluating the use of MRE in detecting breast cancer and Alzheimer disease. 

The findings were presented in May 2007 at the International Society for Magnetic Resonance in Medicine annual meeting in Berlin, Germany, and Digestive Disease Week 2007 in Washington, DC, USA.