Coulam C H, Sheafor D H, Leder R A, Paulson E K, DeLong D M, Nelson R C
Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
AJR Am J Roentgenol. 2000 Feb;174(2):493-8. doi: 10.2214/ajr.174.2.1740493.
The purpose of our study was to evaluate renal cyst pseudoenhancement during helical CT in a phantom model and in patients.
Iodine baths containing water-filled spheres and cylinders were constructed to simulate cysts in enhancing renal parenchyma. Iodine concentration, cyst size and location, collimation, and peak kilovoltage were varied and cyst attenuation was measured. Data were analyzed with the mixed linear models and Mantel-Haenszel tests. Subsequently, a paired t test compared CT attenuation values before and after contrast material enhancement in 40 patients with 68 renal cysts (radiographic stability >3 months).
The attenuation values of phantom cysts increased when placed in a contrast media bath (p = 0.001). The increase in attenuation values became more pronounced with increasing iodine concentrations, decreasing peak kilovoltage, and smaller sphere sizes. In patients, mean cyst attenuation increased 3.4 +/- 6.2 H after administration of contrast material (p = 0.00002). The attenuation did not increase more than 10 H in any of the 37 cysts larger than 2 cm found in patients. Eight (26%) of the 31 cysts smaller than 2 cm found in patients increased by at least 10 H.
In a phantom model, at simulated physiologic levels of renal enhancement, cysts may pseudoenhance by more than 10 H. Similarly, in patients, cysts may also pseudoenhance; however, most pseudoenhancement does not exceed 10 H. In patients, pseudoenhancement of at least 10 H is more likely in cysts smaller than 2 cm.
我们研究的目的是在体模模型和患者中评估螺旋CT检查时肾囊肿的假性强化。
构建含充水球体和圆柱体的碘浴，以模拟强化肾实质中的囊肿。改变碘浓度、囊肿大小和位置、准直以及峰值千伏，并测量囊肿的衰减。采用混合线性模型和Mantel-Haenszel检验分析数据。随后，对40例患有68个肾囊肿（影像学稳定性>3个月）的患者，采用配对t检验比较对比剂增强前后的CT衰减值。
将体模囊肿置于造影剂浴中时，其衰减值增加（p = 0.001）。随着碘浓度增加、峰值千伏降低以及球体尺寸减小，衰减值的增加变得更加明显。在患者中，给予对比剂后囊肿平均衰减增加3.4±6.2 H（p = 0.00002）。在患者中发现的37个大于2 cm的囊肿中，没有一个囊肿的衰减增加超过10 H。在患者中发现的31个小于2 cm的囊肿中有8个（26%）至少增加了10 H。
在体模模型中，在模拟的肾脏强化生理水平下，囊肿可能假性强化超过10 H。同样，在患者中囊肿也可能假性强化；然而，大多数假性强化不超过10 H。在患者中，小于2 cm的囊肿更有可能出现至少10 H的假性强化。
