非增强多层螺旋CT低剂量扫描探查尿路微小结石的研究

目的：研究应用低剂量多层螺旋CT（MSCT）检查尿路微小结石的可行性扫描方案。方法：参照228例体质量75kg以下成人腹盆部骶髂关节水平的体径值制作含有各种组织成分的模型,在其中植入2-5mm的微小草酸钙结石和管径为7mm的水管;使用GE lightspeed16CT机扫描,在管电压120kv和扫描速度0.5s.rot-1不变的情况下,分别逐渐降低管电流和改变螺距对模型进行扫描;对获得的图像资料,由2位医师独立判断结石的有无;评价图像质量是否满足结石诊断的需要。结果：当管电流为60mA时,对结石能做出正确判断,准确率为100%。随着辐射剂量的降低,噪声增加,图像质量也随之下降,当辐射剂量CTDIvol降低到2mGy及以下时,图像质量不能用于诊断;当辐射剂量CTDIvol在2-4mGy时,图像质量基本可满足诊断需要。结论：应用合适的低剂量MSCT扫描序列探查成人尿路微小结石是可行、可靠的。

Study on Low Dosage Multi-Slice Spiral Computed Tomography for Detecting Microcalculi of Urinary Tract

Objective：To study the feasible depiction program for detecting urinary microcalculi with low dosage multi-slice spiral computed tomography（MSCT）.Methods： A total of 228 adults with average body mass below 75 kg were enrolled for establishment of abdominal pelvic models consisted with all kinds of the localized tissue at the circumscribed level of sacroiliac joint;and then we took meat（pig fresh）as the equivalence for implantation of tube（7 mm in diameter）filled with water and 2-5mm oxalic acid calcium in side the soft tissues.GE lightspeed 16 CT scan with stable 120kV,speed of 0.5s·rot-1 was performed with splitting step down of X-ray tube current and change of pitch for the model scanning.The image acquisition information were separately investigated by 2 different experienced doctors to detective whether these calculi or not and thus also outcoming the evaluation of all the elements presented on the images.Results： The presence of calculi could be precisely diagnosed at tube current 60mA with 100% accuracy.Image quality would decrease with increase of signal noise along with decrease of radiation dose.The image quality could not fulfill the diagnostic requirement while the radiation dose CTDIvol lowered down to 2mGy or even merely down.Image quality could be basically satisfied for the diagnosis with radiation dose CTDIvol at 2–4mGy.Conclusions：The adult urinary microcalculi could be feasibly and reliably detected though the application of proper low dosage MSCT.