全模型迭代重建联合256层iCT低剂量扫描评估慢性鼻窦炎

目的 观察以全模型迭代重建（IMR）联合256层iCT低剂量扫描评估慢性鼻窦炎的可行性。方法 对20例临床拟诊慢性鼻窦炎患者先后行标准剂量和低剂量鼻窦CT扫描。根据剂量指数（DRI）和重建算法分为SD-FBP组、LD-IMR-L1组、LD-IMR-L2组和LD-IMR-L3组，记录不同扫描方案下容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP），计算有效剂量（ED），测量图像客观噪声值，评价图像噪声、伪影及窦口鼻道复合体解剖结构和病变显示情况。结果 4组图像噪声值自低到高依次为SD-FBP组、LD-IMR-L3组、LD-IMR-L2组和LD-IMR-L1组。LD-IMR-L3组平均噪声与SD-FBP组差异无统计学意义（P>0.05）；LD-IMR-L2组及LD-IMR-L1组噪声均高于SD-FBP组（P均<0.001）。LD-IMR各组伪影及显示病变评分与SD-FBP组差异均无统计学意义（P均>0.05），均满足诊断需求；其显示解剖结构细节较SD-FBP组欠清晰，但评分均>3分，能满足诊断需求。LD-IMR组CTDIvol、DLP、ED较SD-FBP组分别减少89.20%、89.37%和89.36%。结论 降低ED条件下，IMR低剂量鼻窦CT扫描图像质量可满足显示窦口鼻道复合体解剖结构及诊断慢性鼻窦炎所需。

Feasibility of assessment of chronic sinusitis using iterative model reconstruction combined with 256-slice iCT low-dose scan

Objective To explore the feasibility of iterative model reconstruction (IMR) combined with 256-slice iCT low-dose scan in assessment of chronic sinusitis. Methods Twenty patients with clinically diagnosed chronic sinusitis were examined with conventional dose CT scan and low-dose CT scan. According to dose right index (DRI) and reconstruction algorithms, CT data were divided into SD-FBP group, LD-IMR-L1 group, LD-IMR-L2 group and LD-IMR-L3 group. The volume CT dose index (CTDIvol), dose-length product (DLP) and the effective dose (ED) were recorded under different scanning schemes. The objective noise value of images were measured. The differences of image noise, artifacts and displaying of anatomical structures of ostiomeatal complex and lesions were analyzed. Results SD-FBP group, LD-IMR-L3 group, LD-IMR-L2 group and LD-IMR-L1 group were in a descending order of image noise values. No significant difference of average noise value between LD-IMR-L3 group and SD-FBP group was found(P>0.05). The noise value of LD-IMR-L2 group and LD-IMR-L1 group were higher than that of SD-FBP group (both P<0.001). There was no significant difference of scoring of artifacts and lesion displaying between LD-IMR groups and SD-FBP group (all P>0.05), which would both satisfy diagnostic requirements. The displaying of anatomical details was better in SD-FBP group groups than that in LD-IMR, but the scores in LD-IMR groups were all above 3 points and able to satisfy diagnostic requirements. CTDIvol, DLP and ED in LD-IMR groups reduced by 89.20%, 89.37% and 89.36% compared with those in SD-FBP group, respectively. Conclusion IMR low-dose sinus CT can satisfy the requirements of displaying important bone structures of ostiomeatal complex and diagnosing chronic sinusitis with reduced ED.