腹膜后肿瘤位置深在，往往无明显临床症状。腹部超声常首先发现肿物，但对肿瘤定位、定性诊断，更多依赖于CT和MRI检查，后两者检查方法优缺点明确，但CT的应用更加普及。腹膜后肿瘤的定位、定性需仔细观察影像特点，增强CT、CT重建技术有助于明确肿物对邻近脏器及血管的累及。

Application of CT and MRI in the diagnosis of retroperitoneal tumor        YANG Li, XING Ning. Department of Radiology, PLA General Hospital, Beijing 100853, China
Corresponding author: YANG Li, E-mail:yangli301@yahoo.com
Abstract    Located deeply and having no symptoms in early stage, the retroperitoneal neoplasm can be detected more often on the abdominal study with ultrasound for the routine healthy care. The definition of tumor location and property depends on the cross-imaging, such as CT and MRI imaging. Clinically, the CT is the fist choice modality for its high spatial resolution and more powerful ability with 3D imaging technique. Enhanced CT and CT reconstruction technique are necessary for the definite diagnosis. The characteristics of tumor and tumor adjacent structure are key points for the definition of tumor location, property and discovery of the involving of the vessels and organs.