低剂量MSCT尿路造影对非扩张性输尿管的显示与测量

The Display and Measurement for Non-dilated Ureter with Low-dose Multi-slice CT Urography

目的：探讨多层螺旋CT尿路造影对非扩张性输尿管图像质量的影响，并测量输尿管管径大小正常值范围。方法：根据螺旋CT扫描时管电流的设置，将38例行MSCTU患者中的72侧非扩张性输尿管分为常规剂量组和低剂量组，分别测量辐射剂量值；采用评分法观察图像质量，并进行统计学检验；在MSCTU条件下，测量输尿管正常管径的大小。结果：在其它扫描参数为默认设置的条件下，将管电流由常规mA（180—250mA）降至低mA（50，120mA）时，患者所接受的平均辐射剂量由15．19mGy降至5．66mGy（P〈0．05），而MSCTU图像质量无明显下降（P〉0．05）。在MSCTU条件下正常输尿管平均管径大小为5．23mm，95百分位数值为6．93mm。结论：单纯降低管电流，能在保证图像质量的前提下，有效降低辐射剂量。MSCTU状态下正常输尿管管径的上限值为7mm。

Objective： To determine the display effect of non- dilated ureter with reducing mA on the image quality in patients undergoing multi - slice CT urography, and to measure the normal ureter size. Methods： Seventy - two sides of non - dilated ureters in thirty - eight patients were divided into routine - dose and low- dose groups according to the fixed kv set. The radiation dose was measured and image quality was evaluated by twelve - points method. Measure the normal size of ureter with MSCTU. Results： Mean radiation dose to the patients was significantly reduced from 15.19mGy （ 180 - 250mA） to 5.66 mGy （50 - 120mA） （ P 〈 0.05）. No significant difference of the image quality was found between the two groups （ P 〉 0.05）. The mean normal size of ureter is 5.23mm on MSCTU. On 95% patients, the normal ureter diameter is 6,93mm or smaller; Conclusion： MSCTU scanning of the ureters can be performed at greatly reduced lose without loss the image quality. The upper limit of normal ureter size on MSCTU is 7mm.