Wang Zhen J, Coakley Fergus V, Fu Yanjun, Joe Bonnie N, Prevrhal Sven, Landeras Luis A, Webb Emma M, Yeh Benjamin M
Department of Radiology, University of California-San Francisco, 505 Parnassus Ave, Box 0628, C-372C, San Francisco, CA 94143-0628, USA.
Radiology. 2008 Sep;248(3):910-6. doi: 10.1148/radiol.2482071583. Epub 2008 Jul 15.
To determine the effect of the number of detectors and peak tube voltage on renal cyst pseudoenhancement in a phantom model.
This study on computed tomographic (CT) phantoms did not require institutional review board approval. The renal compartments of a CT phantom were filled with iodinated contrast material diluted to attain attenuations of 40, 140, and 240 HU. Saline-filled cylinders simulating cysts of varying diameters (range, 0.7-3.0 cm) were serially suspended in the renal compartments and scanned at 80, 90, 100, 120, and 140 kVp in 16-detector (n = 3) and 64-detector (n = 2) CT scanners. Generalized estimating equations were used to determine predictors of cyst pseudoenhancement (defined as a >10 HU increase in cyst attenuation when the background renal attenuation increased from 40 to 140 or 240 HU).
Pseudoenhancement was seen with higher frequency (59 [61%] of 96 cysts vs 52 [39%] of 132 cysts, P < .05) and magnitude (17 vs 13 HU, P < .005) with 64- rather than with 16-detector scanners. Pseudoenhancement was also seen with higher frequency (25 [42%] of 60 cysts vs 11 [18%] of 60 cysts, P < .005) and magnitude (18 vs 13 HU, P < .05) at 140 kVp than at 80 or 90 kVp. Cyst pseudoenhancement increased with higher background renal enhancement (P < .005) and smaller cyst diameter (P < .05). The number of detectors, peak tube voltage, renal parenchymal enhancement level, and cyst diameter were independent predictors of cyst pseudoenhancement.
Lower tube voltage settings may be useful when accurate differentiation between small renal cysts and solid masses is critical, particularly for 64-detector CT scanners.
在体模模型中确定探测器数量和峰值管电压对肾囊肿假性强化的影响。
本项关于计算机断层扫描（CT）体模的研究无需机构审查委员会批准。CT体模的肾区填充有稀释后的碘化对比剂，以达到40、140和240 HU的衰减值。模拟不同直径（范围为0.7 - 3.0 cm）囊肿的盐水填充圆柱体依次悬浮于肾区，并在16排探测器（n = 3）和64排探测器（n = 2）CT扫描仪上分别于80、90、100、120和140 kVp进行扫描。采用广义估计方程确定囊肿假性强化的预测因素（定义为当背景肾衰减值从40 HU增加到140或240 HU时，囊肿衰减值增加>10 HU）。
与16排探测器扫描仪相比，64排探测器扫描仪的假性强化出现频率更高（96个囊肿中有59个[61%]，而132个囊肿中有52个[39%]，P <.05），强化幅度更大（17 HU对13 HU，P <.005）。与80或90 kVp相比，140 kVp时假性强化出现频率也更高（60个囊肿中有25个[42%]，而60个囊肿中有11个[18%]，P <.005），强化幅度更大（18 HU对13 HU，P <.05）。囊肿假性强化随背景肾强化程度增加（P <.005）和囊肿直径减小（P <.05）而增加。探测器数量、峰值管电压、肾实质强化水平和囊肿直径是囊肿假性强化的独立预测因素。
当准确区分小肾囊肿和实性肿块至关重要时，较低的管电压设置可能有用，尤其是对于64排探测器CT扫描仪。
