Widmann Gerlig, Al-Shawaf Reema, Schullian Peter, Al-Sadhan Ra'ed, Hörmann Romed, Al-Ekrish Asma'a A
Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria.
Department of Oral Medicine and Diagnostic Sciences, College of Dentistry, King Saud University, P. O. Box 56810, Riyadh, 11564, Kingdom of Saudi Arabia.
Eur Radiol. 2017 May;27(5):2225-2234. doi: 10.1007/s00330-016-4588-8. Epub 2016 Sep 21.
Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR.
Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures.
Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel).
Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used.
• Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.
使用超低剂量结合滤波反投影（FBP）、自适应统计迭代重建（ASIR）和模型迭代重建（MBIR）获得的MDCT图像中的噪声和密度值差异可能会影响种植位点密度分析。本研究的目的是比较使用超低剂量结合FBP、ASIR和MBIR记录的牙种植位点的密度和噪声测量值。
使用标准方案和四种低剂量方案对尸体进行扫描。扫描图像使用FBP、ASIR-50、ASIR-100和MBIR重建，并使用骨或标准重建内核。记录所有数据集中牙槽骨的密度（平均亨氏单位[HU]）和噪声水平（HU的平均标准差），并通过配对t检验和重复测量的双向方差分析比较测量值。
在参考剂量/FBP方案与几乎所有测试组合之间发现密度和噪声存在显著差异。HU的最大平均差异为178.35（骨内核）和273.74（标准内核），噪声的最大平均差异为243.73（骨内核）和153.88（标准内核）。
无论重建技术和内核如何，降低辐射剂量都会增加密度和噪声。重建技术对密度和噪声的影响取决于所使用的重建内核。
•超低剂量MDCT方案可使剂量降低90%以上。•降低剂量通常会增加密度和噪声。•迭代重建技术（IRT）对密度和噪声的影响因重建内核而异。•低剂量方案对骨解剖结构解释的准确性尚不清楚。•低剂量对计算机辅助设计模型准确性的影响未知。
