摘要
SCT(helical或spiral CT)又称螺旋容积CT,是一种通过快速连续扫描法采集螺旋体积数据的新技术,它的出现标志着CT成像技术的又一次飞跃。尽管其临床应用时间不长,但已经从根本上改变了我们对常规CT扫描的看法。本文综述了SCT的技术、基本原理、特点和临床应用。 最初由Kalender等和Vock等报道的容积扫描,是指当患者以恒定的速度进动通过扫描野时,X线管进行连续曝光,计算机连续地采集数据。SCT的优点是在一次性扫描完成原始数据采集后,可进行任意层面、任意间隔、任意层厚、不同方式的图像重建,因此SCT特别适用于活动性器官的检查,且不会漏掉小的病变,临床上以胸、腹部应用最多。与常规CT比较,SCT具有以下优点:①检查时间缩短,采集时间为30s或稍长,大多数患者不到1min即可扫描完;②进行增强扫描检查时,可减少造影剂的用量,SCT扫描能在一次屏气时间内获得数据,并能最佳显示血管结构;③提高多平面和三维图像质量,不受不同呼吸时相的影响,可对任意感兴趣的层面进行优质的多平面重建,没有常规扫描的层间中断现象。
Spiral CT (helical CT、SCT), alsocalled spiral volumetric CT, is a new kind of tech-nique which acquire the Spiral volumetric data in onecontinuous scan. The advent of SCT indicates anotherleap of CT imaging technology. Despite its recent in-troduction, SCT has already altered our basic con-cepts of routine CT scanning of the thorax. In thisarticle, we will review the technology and basic prin-ciple of SCT and its characteristics and clinical ap-plication. Initially reported by Kalender and Vock et al, volu-metric scanning involves continuous data acquisition whilethe patient is advanced at a constant rate through the CTgantry. Scans may be either prospectively or retrospective-ly reconstructed at arbitrary operator - selected levels usinga variety of interpolation algorithms. Therefore, spiral CTis especially suitable to the examination of moving organsand will not miss the small lesion. In comparison withroutine axial imaging, a number of important advantagesresult from helical scanning. These include: (1) reduced time of examination. With scan acquisition times of30 seconds or greater, it is possible to scan the en-tire site of examination in most patients in less than1 minute; (2) reduced volume of contrast media. Theability to acquire data in a single breath - hold allowsmore precise delivery of contrast media and optimalvisualization of vascular structures; (3) improved multipla-nar and three - dimentional (3 - D) imaging. The absenceof respiratory misregistration allows superb multiplanar re-constructions to be generated in any desired imaging planewithout the steplike discontinuities that so commonly resultfrom conventional axial imaging.
关键词
三维成像
螺旋CT
临床应用
呼吸道疾病
computed tomography
spiral scanning
three - dimentional imaging
