双源CT单能谱成像减少脊柱金属固定器伪影的研究

目的：探讨双源CT单能谱成像技术减少脊柱金属内固定器伪影的可能性。方法：31例后路脊柱金属内固定植入术后复查患者行双源CT双能量扫描，获得100、140和120kV图像。其中颈椎9例，胸椎7例，腰椎l5例。扫描数据采用双能量软件内的单能谱技术（Monoenergetic）处理，每例患者数据分别重建成64、69、88、105keV共4组图像以及主观目测图像质量最好的keV图像。由2位有经验的放射诊断医师分别对上述4组图像和主观目测最佳keV（OPT-keV）图像，以及平均加权120kV等图像共6组图像按照4分法进行图像质量评分。采用Kruskal—wallis检验分别对上述各组不同keV图像的质量进行统计学分析；采用Kappa检验评价2位医师评分的一致性。结果：单能谱最佳图像评分在3分及以上者27例，平均加权120kV图像3分及以上者仅3例，两者之间差异有统计学意义（F=118．139，P〈0．01）。金属固定器CT值在不同脊柱节段问存在统计学差异（P〈0．01）；与120kV图像相比，较高单能谱值组（105keV组）图像质量改善明显（V=0．62，P〈0．001）；脊柱金属内固定成像最佳单能谱值为123～144keV。结论：双能量CT单能谱技术能够有效减少脊柱内固定器金属伪影，明显改善脊柱金属内固定术后的CT图像质量，此外还可根据脊柱金属内固定所在不同脊柱节段，采用个性化的单能谱值进行后处理，使图像质量进一步提高。

Metallic artifact reduction with monoenergetic imaging technique of dual-energy CT..systematic evaluation of posterior spinal fusion implants

Objective：To evaluate optimal monoenergetic dual-energy computed tomography （DECT） settings for ar tifact reduction of posterior spinal fusion implants. Methods： Posterior spinal fusion implants for cervical, thoracic and lum- bar spine were examined with DECT （140/100kV）. Extrapolated monoenergetic DECT images at 64,69,88,105keV and in dividually adjusted monoenergy for optimised image quality （OPT-keV） and average weighted 120kV images were genera ted. Two independent radiologists assessed quantitative and qualitative image parameters for each device,according to the following 4-score scale. Kruskal-Wallis was used to perform statistical analysis of image quality for total fixations. Results： For total fixations,monoenergetic imaging of dual energy CT had 27 fixations with score 3 and 4. but 120kV has only 3 fixa tions with score 3 and 4. Monoenergetic imaging of dual energy CT improved image quality of fractures with metal fixation compared to average weighted 120kV images （F 118. 139 ,P〈0.01）. CT values of spinal fusion implants were significant ly different among different spine levels （P〈0.01） and among 120kV, monoenergetic DECT of 64,69,88,105keV and OPT-keV （P〈0. 01 ）. hnage quality was significantly different between datasets and improved with higher monoenergies （105 keV） of DECT compared with 120kV（V=0.62,P〈0. 001）. OPTkeV values ranged from 123-144keV. OPT-keV according to vendor and spine level were presented herein. Conclusion： Monoenergetic DECT provides significantly better image quality and less metallic artifacts from implants than traditional CT scan. Use of individual keV values for metal in- plants located at different spine level is recommended.