评估两种用于减少 CT 金属伪影的迭代技术。
Evaluation of two iterative techniques for reducing metal artifacts in computed tomography.
机构信息
Department of Radiology, Stanford University Medical Center, 300 Pasteur Dr, Room H-1307, Stanford, CA 94305, USA.
出版信息
Radiology. 2011 Jun;259(3):894-902. doi: 10.1148/radiol.11101782. Epub 2011 Feb 25.
PURPOSE
To evaluate two methods for reducing metal artifacts in computed tomography (CT)--the metal deletion technique (MDT) and the selective algebraic reconstruction technique (SART)--and compare these methods with filtered back projection (FBP) and linear interpolation (LI).
MATERIALS AND METHODS
The institutional review board approved this retrospective HIPAA-compliant study; informed patient consent was waived. Simulated projection data were calculated for a phantom that contained water, soft tissue, bone, and iron. Clinical projection data were obtained retrospectively from 11 consecutively identified CT scans with metal streak artifacts, with a total of 178 sections containing metal. Each scan was reconstructed using FBP, LI, SART, and MDT. The simulated scans were evaluated quantitatively by calculating the average error in Hounsfield units for each pixel compared with the original phantom. Two radiologists who were blinded to the reconstruction algorithms used qualitatively evaluated the clinical scans, ranking the overall severity of artifacts for each algorithm. P values for comparisons of the image quality ranks were calculated from the binomial distribution.
RESULTS
The simulations showed that MDT reduces artifacts due to photon starvation, beam hardening, and motion and does not introduce new streaks between metal and bone. MDT had the lowest average error (76% less than FBP, 42% less than LI, 17% less than SART). Blinded comparison of the clinical scans revealed that MDT had the best image quality 100% of the time (95% confidence interval: 72%, 100%). LI had the second best image quality, and SART and FBP had the worst image quality. On images from two CT scans, as compared with images generated by the scanner, MDT revealed information of potential clinical importance.
CONCLUSION
For a wide range of scans, MDT yields reduced metal streak artifacts and better-quality images than does FBP, LI, or SART.
SUPPLEMENTAL MATERIAL
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101782/-/DC1.
目的
评估两种用于减少计算机断层扫描（CT）金属伪影的方法——金属消除技术（MDT）和选择性代数重建技术（SART）——并将这些方法与滤波反投影（FBP）和线性内插（LI）进行比较。
材料与方法
本研究经机构审查委员会批准，符合 HIPAA 规定；患者同意豁免。模拟投影数据是为一个包含水、软组织、骨和铁的体模计算的。回顾性地从 11 例连续识别的带有金属条纹伪影的 CT 扫描中获得临床投影数据，共包含 178 个含金属节段。每个扫描均使用 FBP、LI、SART 和 MDT 进行重建。模拟扫描通过计算与原始体模相比每个像素的平均 CT 值误差进行定量评估。两名对重建算法不了解的放射科医生对临床扫描进行了定性评估，对每种算法的总体伪影严重程度进行了排名。图像质量等级比较的 P 值由二项式分布计算得出。
结果
模拟结果表明，MDT 可减少因光子饥饿、束硬化和运动引起的伪影，且不会在金属与骨之间引入新的条纹。MDT 的平均误差最低（比 FBP 低 76%，比 LI 低 42%，比 SART 低 17%）。对临床扫描的盲法比较显示，MDT 始终具有最佳的图像质量（95%置信区间：72%，100%）。LI 的图像质量次之，SART 和 FBP 的图像质量最差。在两个 CT 扫描的图像中，与来自扫描仪的图像相比，MDT 揭示了具有潜在临床意义的信息。
结论
对于广泛的扫描，MDT 产生的金属条纹伪影和图像质量优于 FBP、LI 或 SART。
补充材料
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101782/-/DC1.
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