Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacherstraße 6, 97080, Würzburg, Germany.
Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076, Tübingen, Germany.
Eur Radiol. 2023 Nov;33(11):7818-7829. doi: 10.1007/s00330-023-09790-y. Epub 2023 Jun 7.
While established for energy-integrating detector computed tomography (CT), the effect of virtual monoenergetic imaging (VMI) and iterative metal artifact reduction (iMAR) in photon-counting detector (PCD) CT lacks thorough investigation. This study evaluates VMI, iMAR, and combinations thereof in PCD-CT of patients with dental implants.
In 50 patients (25 women; mean age 62.0 ± 9.9 years), polychromatic 120 kVp imaging (T3D), VMI, T3D, and VMI were compared. VMIs were reconstructed at 40, 70, 110, 150, and 190 keV. Artifact reduction was assessed by attenuation and noise measurements in the most hyper- and hypodense artifacts, as well as in artifact-impaired soft tissue of the mouth floor. Three readers subjectively evaluated artifact extent and soft tissue interpretability. Furthermore, new artifacts through overcorrection were assessed.
iMAR reduced hyper-/hypodense artifacts (T3D 1305.0/-1418.4 versus T3D 103.2/-46.9 HU), soft tissue impairment (106.7 versus 39.7 HU), and image noise (16.9 versus 5.2 HU) compared to non-iMAR datasets (p ≤ 0.001). VMI ≥ 110 keV subjectively enhanced artifact reduction over T3D (p ≤ 0.023). Without iMAR, VMI displayed no measurable artifact reduction (p ≥ 0.186) and facilitated no significant denoising over T3D (p ≥ 0.366). However, VMI ≥ 110 keV reduced soft tissue impairment (p ≤ 0.009). VMI ≥ 110 keV resulted in less overcorrection than T3D (p ≤ 0.001). Inter-reader reliability was moderate/good for hyperdense (0.707), hypodense (0.802), and soft tissue artifacts (0.804).
While VMI alone holds minimal metal artifact reduction potential, iMAR post-processing enabled substantial reduction of hyperdense and hypodense artifacts. The combination of VMI ≥ 110 keV and iMAR resulted in the least extensive metal artifacts.
Combining iMAR with VMI represents a potent tool for maxillofacial PCD-CT with dental implants achieving substantial artifact reduction and high image quality.
• Post-processing of photon-counting CT scans with an iterative metal artifact reduction algorithm substantially reduces hyperdense and hypodense artifacts arising from dental implants. • Virtual monoenergetic images presented only minimal metal artifact reduction potential. • The combination of both provided a considerable benefit in subjective analysis compared to iterative metal artifact reduction alone.
虽然已经在能量整合探测器 CT 中建立了虚拟单能量成像（VMI）和迭代金属伪影减少（iMAR），但在光子计数探测器（PCD）CT 中，VMI 和 iMAR 的效果仍缺乏深入的研究。本研究评估了 VMI、iMAR 及其在有牙种植体的患者的 PCD-CT 中的组合应用。
在 50 名患者（25 名女性；平均年龄 62.0 ± 9.9 岁）中，对多色 120 kVp 成像（T3D）、VMI、T3D 和 VMI 进行了比较。VMIs 以 40、70、110、150 和 190 keV 进行重建。在最高密度和低密度伪影以及口腔底部受影响的软组织中，通过衰减和噪声测量来评估伪影减少。三位读者主观评估了伪影程度和软组织的可解读性。此外，还评估了因过度校正而产生的新伪影。
与非 iMAR 数据集相比，iMAR 降低了高密度/低密度伪影（T3D 为 1305.0/-1418.4 与 T3D 为 103.2/-46.9 HU）、软组织损伤（106.7 与 39.7 HU）和图像噪声（16.9 与 5.2 HU）（p ≤ 0.001）。VMI ≥ 110 keV 可在 T3D 基础上进一步增强伪影减少（p ≤ 0.023）。没有 iMAR，VMI 没有表现出可测量的伪影减少（p ≥ 0.186），并且没有比 T3D 更好的降噪效果（p ≥ 0.366）。然而，VMI ≥ 110 keV 可减轻软组织损伤（p ≤ 0.009）。VMI ≥ 110 keV 产生的过度校正比 T3D 少（p ≤ 0.001）。高密度（0.707）、低密度（0.802）和软组织伪影（0.804）的读者间可靠性为中等/良好。
虽然 VMI 本身具有最小的金属伪影减少潜力，但 iMAR 后处理能够显著减少高密度和低密度伪影。VMI ≥ 110 keV 和 iMAR 的组合使用可使金属伪影最小化。
将 iMAR 与 VMI 结合使用是一种强大的工具，可用于有牙种植体的颌面 PCD-CT，可实现金属伪影的大量减少和高质量的图像。
光子计数 CT 扫描的后处理使用迭代金属伪影减少算法可显著减少源自牙种植体的高密度和低密度伪影。
虚拟单能量图像仅表现出最小的金属伪影减少潜力。
与单独使用迭代金属伪影减少相比，两者的组合在主观分析中提供了相当大的益处。
