Heneghan Joan P, Spielmann Audrey L, Sheafor Douglas H, Kliewer Mark A, DeLong David M, Nelson Rendon C
Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
J Comput Assist Tomogr. 2002 Jan-Feb;26(1):90-4. doi: 10.1097/00004728-200201000-00013.
The purpose of this work was to compare the extent of pseudoenhancement (artifactual increase in measured attenuation of a simple cyst after contrast medium administration) in a phantom model on single detector and multidetector helical CT scanners.
The phantom consisted of four water-filled spheres varying in size from 8 to 28 mm, suspended in an aqueous contrast medium bath. Iodine concentration in the bath was varied: 0, 6, 12, and 24 mg/ml corresponding to attenuation values of 0, +108, +180, and +300 HU. The phantom was scanned on single detector and multidetector helical CT scanners during the same session. Collimation (1, 3, and 5 mm) and pitch (1 and 1.5:1, single detector; 3:1 and 6:1, multidetector) were varied at each concentration. All scans were performed at 140 kVp and 170 mA. The region of interest was measured at the center of each sphere. The effects were analyzed using a linear regression model.
The degree of pseudoenhancement was more pronounced with increasing iodine concentration, decreasing cyst size, and wider collimation (all p = 0.0001). Pseudoenhancement was also more marked on the multidetector than the single detector scanner (p = 0.0001). At physiological levels of renal enhancement, the average pseudoenhancement was +18 HU for the single detector versus +23 HU for the multidetector scanner. Variation in pitch had no effect.
Pseudoenhancement is greater on a multidetector than a single detector helical CT scanner and may exceed 20 HU at physiological levels of renal enhancement.
本研究旨在比较单排探测器和多排探测器螺旋CT扫描仪在体模模型中伪强化（造影剂注入后单纯囊肿测量衰减值的人为增加）的程度。
体模由四个大小从8至28毫米不等的充水球体组成，悬浮于含造影剂的水浴中。水浴中的碘浓度各不相同：0、6、12和24毫克/毫升，分别对应0、+108、+180和+300亨氏单位的衰减值。在同一时段，对体模进行单排探测器和多排探测器螺旋CT扫描。在每个浓度下，改变准直（1、3和5毫米）和螺距（单排探测器为1和1.5:1；多排探测器为3:1和6:1）。所有扫描均在140千伏峰值电压和170毫安下进行。在每个球体的中心测量感兴趣区域。使用线性回归模型分析结果。
随着碘浓度增加、囊肿尺寸减小和准直变宽，伪强化程度更明显（所有p = 0.0001）。多排探测器扫描仪上的伪强化也比单排探测器扫描仪更显著（p = 0.0001）。在肾脏强化的生理水平下，单排探测器的平均伪强化为+18亨氏单位，而多排探测器扫描仪为+23亨氏单位。螺距变化无影响。
多排探测器螺旋CT扫描仪上的伪强化比单排探测器更大，在肾脏强化的生理水平下可能超过20亨氏单位。
