Sommer Wieland H, Johnson Thorsten R, Becker Christoph R, Arnoldi Elisabeth, Kramer Harald, Reiser Maximilian F, Nikolaou Konstantin
Department of Clinical Radiology, University Hospitals-Grosshadern, Ludwig-Maximilians University, Munich, Germany.
Invest Radiol. 2009 May;44(5):285-92. doi: 10.1097/RLI.0b013e31819b70ba.
Dual-energy computed tomography (CT) makes it possible to remove bones and intraluminal plaques from angiography datasets on the basis of spectral differentiation separating iodine from calcium. The objective of this study was to evaluate the feasibility and efficiency of this technique by comparing maximum intensity projections (MIP) created with different bone removal techniques: (a) dual-energy bone removal (DEBR); (b) purely software-based bone removal without manual corrections (SBBR - MC); and (c) manually corrected software-based bone removal (SBBR + MC). A further aim was to evaluate the dual-energy-based plaque removal tool.
Fifty-one patients underwent dual-energy CT angiography of the lower-extremity arteries on a dual-source CT scanner. CT parameters were tube potentials, 140 and 80 kVp; exposure, 80 and 340 mAs/rot; and collimation, 14 x 1.2 mm. Bolus tracking was used in the descending aorta for timing (Ultravist 370). Bones were removed from the datasets using the 3 techniques and MIP datasets were generated. Two experienced radiologists assessed image quality ((1) correct removal of bones and preservation of vessels without artificial truncation, stenoses or occlusions of arteries; (2) minor errors with residual bone in the dataset or removal of side branches; (3) significant errors impeding diagnostic evaluation), number of vessel segmentation errors, and number of nonremoved bones. Additionally, time for MIP-generation was measured. The plaque removal tool was applied to DEBR MIPs and the outcome was rated as positive, neutral, or negative.
DEBR showed better image quality than SBBR (P < 0.05; median image quality DEBR: 1; SBBR - MC: 3; SBBR + MC: 2). Less vessel segmentation errors occurred in DEBR (P < 0.05; median DEBR: 0; SBBR - MC: 5; SBBR + MC: 1). The number of nonremoved bones was not significantly different between DEBR and SBBR + MC, but significantly higher in SBBR - MC (median DEBR: 1; SBBR - MC: 2; SBBR + MC: 0). Time for generation of MIPs was lowest for SBBR - MC (P < 0.05), but also DEBR was significantly faster than manually corrected SBBR (DEBR: 160 +/- 16 seconds; SBBR - MC: 95 +/- 12 seconds; SBBR + MC: 373 +/- 69 seconds). The plaque removal tool lead to an improvement of image quality of the MIPs and a better depiction of the residual lumen in 43%.
DEBR provides significant advantages, even over manually corrected SBBR. As it works completely automatically, it can effectively help to cope with the data load of CT angiography exams. Furthermore, it enables the removal of intraluminal plaques, which provides a benefit for the estimation of the residual lumen.
双能计算机断层扫描（CT）能够基于将碘与钙分离的光谱差异，从血管造影数据集中去除骨骼和腔内斑块。本研究的目的是通过比较使用不同骨骼去除技术创建的最大强度投影（MIP）来评估该技术的可行性和效率：（a）双能骨骼去除（DEBR）；（b）无需手动校正的纯软件骨骼去除（SBBR - MC）；以及（c）手动校正的软件骨骼去除（SBBR + MC）。另一个目的是评估基于双能的斑块去除工具。
51例患者在双源CT扫描仪上接受了下肢动脉双能CT血管造影。CT参数为管电压140和80 kVp；曝光量80和340 mAs/旋转；准直14×1.2 mm。在降主动脉使用团注追踪进行计时（碘克沙醇370）。使用这3种技术从数据集中去除骨骼并生成MIP数据集。两名经验丰富的放射科医生评估图像质量（（1）骨骼正确去除且血管保留，无动脉的人为截断、狭窄或闭塞；（2）数据集中有残留骨骼或侧支去除的小误差；（3）严重误差妨碍诊断评估）、血管分割误差数量和未去除骨骼数量。此外，测量生成MIP的时间。将斑块去除工具应用于DEBR MIP并将结果评为阳性、中性或阴性。
DEBR显示出比SBBR更好的图像质量（P < 0.05；DEBR的图像质量中位数：1；SBBR - MC：3；SBBR + MC：2）。DEBR中发生的血管分割误差较少（P < 0.05；DEBR中位数：0；SBBR - MC：5；SBBR + MC：1）。DEBR和SBBR + MC之间未去除骨骼的数量无显著差异，但SBBR - MC中显著更高（DEBR中位数：1；SBBR - MC：2；SBBR + MC：0）。SBBR - MC生成MIP的时间最短（P < 0.05），但DEBR也明显比手动校正的SBBR快（DEBR：160 ± 16秒；SBBR - MC：95 ± 12秒；SBBR + MC：373 ± 69秒）。斑块去除工具使MIP的图像质量得到改善，43%的情况下对残余管腔的显示更好。
即使与手动校正的SBBR相比，DEBR也具有显著优势。由于它完全自动运行，能有效帮助应对CT血管造影检查的数据量。此外，它能够去除腔内斑块，这对评估残余管腔有益。
