【作者】 李晓；

【导师】 徐卓东； 李春卫；

【作者基本信息】 山东大学 ， 影像医学与核医学， 2011， 硕士

【摘要】 目的①探讨多层螺旋CT后处理技术在眶骨正常相关结构中的应用及标准断面图像在对称显示眼眶相关结构中的优势。②探讨降低管电压在减少眼眶CT扫描辐射剂量中的可行性。材料与方法①收集207例无眼眶外伤史的被检者的眶部多层螺旋CT图像,对常规扫描断面图像与经MRP重建的标准断面图像对眼眶正常相关结构的对称显示情况进行对比研究及统计学分析,同时结合多种后处理技术。②另外对40例(80个眼眶)无眼眶外伤史的被检者随机分为两组,每组各20例(40个眼眶),分别进行标准条件(120Kv,100mA)和低剂量条件(100Kv,100mA)CT扫描,并对所得图像均行1.51mm、3.Omm薄层重建,层间距分别为1.Omm、2.Omm。比较不同管电压的容积CT剂量指数(CTDIvo1)、图像质量及图像噪声的差别。结果①重组后的标准化图像在双侧眼眶相关结构的对称性显示中较常规扫描图像更有优势,更有利于临床诊断。结合VR、CPR等后处理技术更能立体、直观地观察眼眶细微结构的全貌。本研究结果显示,标准轴位图像对颧额缝、颧骨管、眶下管、眶上切迹、视神经管及晶状体的对称性显示明显优于常规扫描轴位图像(P<0.01)；而两者对颧蝶缝的对称性显示无显著差异(P>0.05)。②管电压100Kv时与常规剂量(120Kv)比较,CTDIvol减低,即辐射剂量有所下降。本研究结果显示,两组间相应层厚图像噪声大小间都存在统计学差别(P<0.01),100Kv扫描的图像噪声均较120Kv大。虽然低Kv扫描图像噪声有所增加,但图像能够清楚显示眼环、眼直肌、视神经及晶状体等眶内各结构及眶壁骨质,图像质量与常规剂量扫描图像相比无显著差异(P>0.05)。结论①多层螺旋CT后处理技术在显示眼眶正常相关结构中有重要意义和优势,经MPR重建的标准轴位图像能够很好地对称显示双侧眼眶的相关结构,这对病变的定位和定性都有重要的意义。观察标准化图像在减轻影像医生的阅片量的同时,也提高了诊断准确率。同时,结合VR、CPR等后处理技术更能立体、直观地观察眼眶细微结构的全貌。②降低管电压(100Kv)对眼眶行CT扫描,虽然图像噪声有所增加,但是图像质量与常规剂量相比无明显差异,能满足临床诊断要求,并降低了被检者的辐射剂量。它是降低管电流之外的,另一种降低辐射剂量的可行方法更多还原

【Abstract】 Purpose①To explore the value of post-processing techniques of multi-slice spiral CT(MSCT) in normal orbital related structures,and the advantages of standard axle bits image in showing the normal orbital related structures symmetrically.②To explore the possibility of Low-Kilovoltage CT Scanning in orbit.Material and Methods①207cases with the source images of no orbital trauma history were retrospectively reviewed.The show results of conventional axel bits image and standard axle bits image after MPR reconstrution were compared and statistical analysed, also using other post-processing techniques.②In addition,forty cases(eighty orbits) of no orbital trauma history were divided into tow groups randomly,each group contains twenty cases (forty orbits).One group were scanned routinely(120Kv,100mA),and the other group was scanned with Low-Kilovoltage(100Kv,100mA).The image was reconstructed into 1.5mm and 3.0mm.The layer spacing was respectively 1.0mm and 2.0mm. The CTDvol, image quality and image noise were respectively compared between different tube voltage.Result①The standard axle bits image afer MPR reconstrution was better than conventional axel bits image in showing the orbital related structures symmetrically,and it was more advantageous to the clinical diagnosis.Combining VR,CPR,etc post-processing techniques,it can show the whole subtle orbital structures stereoscopically and intuitively. The display rate of sutura nygomaticofrontalis,the canal of temporal bone,infraorbital canal,supraorbital notch,optic canal,and crystalline lens in the standard section was significantly higher than in conventional images(P< 0.01);.There were no difference in the display rate of the sutura zygomaticosphenoidalis(P>0.05).②Comparing the conventional scanning(120Kv),the CTDvol of 100Kv is smaller,that means the radiation dosage become lower. The study showed that, there was difference between different thickness (P<0.01).The image noise of 100Kv was higher than 120Kv.Although the image noise become higher, the image of Low-Kilovoltage can show the intraorbital structures clealy,such as eye ring, eye mustle,optic nerve,crystalline lens and orbital wall. Comparing the conventional scanning,there was no difference in image quality(P>0.05).Conclusion①The post-processing techniques of multi-slice spiral CT(MSCT) has significant meanings and advantages in showing the orbital related structures. The standard axle bits after MPR reconstrution image can show the both sides orbital structures symmetrically.lt is very important for the focus’positioning and qualitative dignosis.It can reduce the doctors’ reading quantity and improve the dignosis accurancy to analy the standard images. Combining VR,CPR,etc post-processing techniques,it can show the whole subtle orbital structures stereoscopically and intuitively.②Though the image noise of Low-Kilovoltage CT Scanning(100Kv) increased, there was no difference in image quality,comparing the conventional scanning.lt can meet t the requirements of clinical diagnosis,and it’s an another avaliable method to reduce the radiation dosage,besides lessening the current.更多还原