Vasconcelos Taruska Ventorini, Bechara Boulos B, McMahan Clyde Alex, Freitas Deborah Queiroz, Noujeim Marcel
Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
Department of Comprehensive Dentistry, Division of Oral and Maxillofacial Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
Oral Surg Oral Med Oral Pathol Oral Radiol. 2017 Feb;123(2):265-272. doi: 10.1016/j.oooo.2016.10.021. Epub 2016 Nov 1.
To evaluate zirconium implant artifact production in cone beam computed tomography images obtained with different protocols.
One zirconium implant was inserted in an edentulous mandible. Twenty scans were acquired with a ProMax 3D unit (Planmeca Oy, Helsinki, Finland), with acquisition settings ranging from 70 to 90 peak kilovoltage (kVp) and voxel sizes of 0.32 and 0.16 mm. A metal artifact reduction (MAR) tool was activated in half of the scans. An axial slice through the middle region of the implant was selected for each dataset. Gray values (mean ± standard deviation) were measured in two regions of interest, one close to and the other distant from the implant (control area). The contrast-to-noise ratio was also calculated.
Standard deviation decreased with greater kVp and when the MAR tool was used. The contrast-to-noise ratio was significantly higher when the MAR tool was turned off, except for low resolution with kVp values above 80. Selection of the MAR tool and greater kVp resulted in an overall reduction of artifacts in images acquired with low resolution.
Although zirconium implants do produce image artifacts in cone-bean computed tomography scans, the setting that best controlled artifact generation by zirconium implants was 90 kVp at low resolution and with the MAR tool turned on.
评估在不同扫描方案下获得的锥形束计算机断层扫描图像中锆植入物产生的伪影。
将一枚锆植入物植入无牙颌下颌骨。使用ProMax 3D设备（普兰梅卡公司，芬兰赫尔辛基）进行20次扫描，采集设置包括峰值千伏（kVp）从70到90，体素大小为0.32和0.16毫米。在一半的扫描中激活金属伪影减少（MAR）工具。为每个数据集选择穿过植入物中间区域的轴向切片。在两个感兴趣区域测量灰度值（平均值±标准差），一个靠近植入物，另一个远离植入物（对照区域）。还计算了对比度噪声比。
随着kVp增加以及使用MAR工具时，标准差降低。当MAR工具关闭时，对比度噪声比显著更高，但kVp值高于80时的低分辨率情况除外。选择MAR工具和更高的kVp可使低分辨率采集图像中的伪影总体减少。
尽管锆植入物在锥形束计算机断层扫描中确实会产生图像伪影，但在低分辨率且开启MAR工具的情况下，90 kVp是最能控制锆植入物产生伪影的设置。
