A Comparison of Conventional and Spiral CT: An Experimental Study on the Detection of Spherical Lesions
A Comparison of Conventional and Spiral CT: An Experimental Study on the Detection of Spherical Lesions
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常规CT与螺旋CT的比较：球形病灶检测的实验研究
DOI：
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发表时间：
1994
影响因子：
1.3
通讯作者：
C. Süss
中科院分区：
文献类型：
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作者：
W. Kalender;A. Polacin;C. Süss
目的螺旋CT扫描在许多临床应用中具有明显的优势。然而，由于扫描床运动导致切片灵敏度曲线略微变宽，因此仍存在一些图像质量方面的问题。我们进行了理论分析，幻影测量，和计算机模拟，以评估和比较传统的螺旋扫描的对比度和空间分辨率。特别强调了检测球形病变的任务。材料与方法对于仅测量扫描平面分辨率的标准测试对象，常规扫描和螺旋扫描之间没有观察到显著差异。因此，我们设计了一个体模设置，允许我们将任意直径和对比度的球体放置在任意位置，以测试三维（3D）分辨率。结果对于常规CT，病变对比度和观察到的病变空间分离程度取决于扫描序列的起始位置与球体或病变的随机位置的关系。螺旋CT由于其连续扫描而提供空间不变的分辨率。与传统CT相比，小病变对比度可提高1.8倍，因为切片可回顾性居中。测量和模拟结果非常一致。结论螺旋CT能提高三维对比度和空间分辨率。为了利用这些优点，应在螺旋CT中以小于一个360°管旋转期间行进距离的一半的增量重建图像。每个这样的间隔（通常等于切片宽度）有四到五个图像，可以获得非常接近理论最佳值的结果。许多提出的考虑和结果适用于其他切片成像方式，如MRI以类似的方式。
Objective It is accepted that spiral CT scanning may offer significant advantages in a number of clinical applications. There is still some concern with respect to image quality, however, since slice sensitivity profiles are slightly broadened due to the table motion. We carried out theoretical analysis, phantom measurements, and computer simulations to evaluate and to compare contrast and spatial resolution for conventional and for spiral scanning. Special emphasis was put on the task of detecting spherical lesions. Materials and Methods For standard test objects that measure only resolution in the scan plane, no significant difference between conventional and spiral scanning was observed. We therefore designed a phantom setup that allowed us to place spheres of arbitrary diameter and contrast in arbitrary positions to test three-dimensional (3D) resolution. Results For conventional CT, both lesion contrast and the degree of spatial separation of lesions observed depend on the relation of the start position of the scan series to the random location of a sphere or lesion. Spiral CT offers space-invariant resolution due to its continuous scanning. Small lesion contrast may be improved by up to a factor of 1.8 when compared with conventional CT since slices can be centered retrospectively. Measurements and simulations were in excellent agreement. Conclusion We conclude that spiral CT can offer improved 3D contrast and spatial resolution. To exploit these advantages, images should be reconstructed in spiral CT at increments of less than half the distance traveled during one 360° tube rotation. With four to five images per such interval, usually equal to the slice width, results very close to the theoretical optimum are achieved. Many of the presented considerations and results apply to other slice imaging modalities like MRI in an analogous fashion.