多层螺旋CT动态三期扫描对肾囊肿CT值变化的观察研究

目的观察多层螺旋CT(MSCT)三期扫描下肾囊肿的CT值变化,分析"伪强化"现象及相关因素.方法对28例患者共48处肾囊肿病变进行MSCT三期扫描,测量囊肿CT值,计算强化差值并绘制散点分布图.结果平扫、皮质期、均衡期CT平均值分别为14.5 Hu、17.8 Hu、18.8 Hu,两增强组与平扫组对比均具有显著差异性(P＜0.05).皮质期(C-P)平均增强3.27±3.30)Hu;均衡期(N-P)(4.29±3.98)Hu.直径＞1 cm组平均强化(3.19±2.9)Hu,直径＜1 cm组(3.4±4.0)Hu,P=0.96.结论MSCT下肾囊肿会出现"伪强化"现象,一般＜10 Hu,"伪强化"强化程度与肾囊肿体积无显著的相关性,部分直径＜1.0 cm的病变"伪强化"可以大于10 Hu.

Analysis of changes in attenuation of renal cyst on triphasic multi-slice CT

Objective To observe the changes in attenuation values on triphasic multi-slice CT (MSCT) of proven cystic renal lesions. Methods Twenty-eight patients with 48 renal cystic lesions who underwent triphasic MSCT were retrospectively studied. The attenuation values of each cyst were measured on three phase images. Mean changes in attenuation between phases were calculated and correlated with sizes. The scatter plot was created. Results The mean attenuation of cysts in precontrast phase, cortical phase and nephrographic phase was 14.5 Hu, 17.8 Hu, and 18.8 Hu, respectively. It was significantly different in CT value between precontrast and the two contrast enhanced phase (P<0.05). The attenuation increased (3.27±3.30) Hu from precontrast phase to cortical phase; (4.29±3.98) Hu from precontrast phase to nephrographic phase. The mean increasing attenuation (3.4±4.0) Hu of small cysts (D<1.0 cm) was higher than that (3.19±2.9) Hu of bigger cyst (D<1.0 cm), but no significant difference was seen (P=0.96). Conclusion Attenuation values in the renal cysts increased artifactually on contrast-enhanced images, but this pseudoenhancement was not substantial and were mostly less than 10 Hu when the cysts were larger than 1.0 cm in diameter.