RESUMO
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 P0.05), 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.
