Vasconcelos K F, Nicolielo L F P, Nascimento M C, Haiter-Neto F, Bóscolo F N, Van Dessel J, EzEldeen M, Lambrichts I, Jacobs R
OMFS IMPATH Research Group, Department of Imaging & Pathology, Faculty of Medicine, University of Leuven and Oral & Maxillofacial Surgery, University Hospitals Leuven, Leuven, Belgium.
Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, State University of Campinas, Piracicaba, Brazil.
Int Endod J. 2015 Oct;48(10):994-1000. doi: 10.1111/iej.12395. Epub 2014 Nov 15.
To evaluate the characteristic artefact patterns associated with teeth root filled with Gutta-percha when scanned with four cone-beam CT devices.
Whilst using soft tissue simulation, ten root filled human premolars were placed in empty sockets in a dry human skull. Subsequently, the skull was scanned using 3D Accuitomo 170(®) , WhiteFox(®) , Cranex 3D(®) and Scanora 3D(®) following clinical protocols with the highest resolution and artefact reduction. After proper image registration in OnDemand3D(®) software (Cybermed, Seoul, Korea), each image slice was evaluated by three trained and calibrated dentomaxillofacial radiologists, which scored absence (0) and presence (1) of cupping artefact, hypodense halos and streak artefacts. Kappa test was performed for intra- and interobserver agreement.
A moderate to perfect agreement for each observer (intra-observer κ = 0.5-1.0) was found. Agreement between the different observers was moderate to almost perfect for the different artefact patterns (interobserver κ = 0.55-0.9). Cupping artefact was the most prevalent (70%), followed by a hypodense halo (35%) and streak artefacts (16%). The Chi-squared test revealed significantly more streaks in axial slices (P < 0.0001), with some CBCT systems yielding significantly inferior results to others (P < 0.05). The dedicated EndoMode and artefact reduction did not improve the result significantly.
The variation of artefact expression was significantly different amongst CBCT machines for root filled teeth. Continuous efforts are needed to improve CBCT reconstruction algorithms, with a specific focus on reducing artefacts induced by dense dental materials, whilst striving for enhanced image quality at low-radiation doses.
评估使用四种锥形束CT设备扫描时，与牙胶充填牙根相关的特征性伪影模式。
在使用软组织模拟的情况下，将十颗牙胶充填的人类前磨牙置于干燥人类颅骨的空牙槽中。随后，按照具有最高分辨率和伪影减少功能的临床方案，使用3D Accuitomo 170(®)、WhiteFox(®)、Cranex 3D(®)和Scanora 3D(®)对颅骨进行扫描。在OnDemand3D(®)软件（韩国首尔Cybermed公司）中进行适当的图像配准后，由三名经过培训和校准的口腔颌面放射科医生对每个图像切片进行评估，对杯状伪影、低密度晕和条纹伪影的有无（0表示无，1表示有）进行评分。对观察者内和观察者间的一致性进行kappa检验。
发现每位观察者的一致性为中度至完美（观察者内κ = 0.5 - 1.0）。不同观察者之间对于不同伪影模式的一致性为中度至几乎完美（观察者间κ = 0.55 - 0.9）。杯状伪影最为常见（70%），其次是低密度晕（35%）和条纹伪影（16%）。卡方检验显示轴向切片中的条纹明显更多（P < 0.0001），一些锥形束CT系统的结果明显不如其他系统（P < 0.05）。专用的牙髓模式和伪影减少功能并未显著改善结果。
在锥形束CT机器中，充填牙根的牙齿伪影表现的差异显著。需要持续努力改进锥形束CT重建算法，特别关注减少由致密牙科材料引起的伪影，同时在低辐射剂量下努力提高图像质量。
