猪食管异物低剂量多排螺旋CT检查的实验性应用研究

摘要

Objective To assess the feasibility of multi-slice spiralCT (MSCT) with low radiation dose in detecting foreign body in esophagus in pigs.Methods The fish and chicken bones were fixed in one section of pig esophagus, which was inserted in one piece of pork to establish a model of foreign body in esophagus.The pork was scanned using MSCT with different scanning conditions (tube current: 50, 100, 200, 400 mA;tube voltage: 80, 100, 120 kV).The subjective and objective image quality, radiation dose and detection rate of forgeign body were compared among different scanning condition groups.Results The subjective evaluation of image quality had good consistency between two valuators for all the scanning condition groups and different layer thickness.With increase of layer thickness, the border of the forgeign body was gradually evasive and fuzzy, the surround structure of esophagus was gradually smooth and distinct.Under the same voltage, the CT value of forgeign body was not significantly changed, the signal-to-noise ratio (SNR) and contrast-to-noise (CNR) were significantly changed with reduction of the current in 2 mm image;under the same current, the CT value of forgeign body was significantly increased, while the SNR and CNR were significantly decreased along with reduction of the current.Under the same voltage, the effective radiation dose was decreased by 48.8％-50.0％ in one group than that in the adjacent group along with reduction of the current;under the same current, the effective radiation dose was decreased by 37.7％-50.0％ in one group than that in the adjacent group reduction of the voltage.Combination of low tube voltage and low tube current most greatly reduced the effective radiation dose.The detect rate of foreign body were 100％ in all the groups.Condusion MSCT with low tube voltage and low tube currents can effectively diagnose the foreign body in esophagus in pigs.%目的 探讨猪食管异物低剂量多排螺旋CT扫描及后处理技术应用的可行性.方法 利用猪食管、块状猪肉、鱼刺及鸡碎骨模拟人颈段食管异物模型,在不同扫描条件(管电流50、100、200、400 mA与管电压80、100、120 kV相互组合)进行多排螺旋CT扫描,比较各组的主、客观图像质量、有效辐射剂量和异物检出率.结果 不同层厚的各组图像主观评价一致性良好,随图像重建层厚增加异物边缘显示圆滑、模糊,食管周围结构平滑、清晰.重建层厚为2 mm时,相同管电压下,随管电流降低,异物CT值变化不明显,信噪比、对比信噪比变化明显;而相同管电流下,随管电压降低,异物CT值呈升高趋势、信噪比及对比信噪比呈下降趋势;相同管电压条件下,随着管电流的降低,有效辐射剂量相邻组间降低48.8％～50.0％;而相同管电流条件下,随着管电压的降低,有效辐射剂量相邻组间降低37.7％～50.0％;低管电压/管电流组合能更大幅度地降低有效辐射剂量.各组对异物的检出率均为100％.结论 联合降低管电压及管电流的低剂量MSCT扫描能用于猪食管异物的诊断.