Photon-Counting Detector CT-Based Vascular Calcium Removal Algorithm
Photon-Counting Detector CT-Based Vascular Calcium Removal Algorithm
复制标题
基于光子计数探测器CT的血管除钙算法
作者：
T. Allmendinger;T. Nowak;T. Flohr;E. Klotz;Junia Hagenauer;H. Alkadhi;B. Schmidt
目的冠状动脉严重钙化斑块的存在对冠状动脉CT血管成像的诊断性能有负面影响。在这篇文章中，评估了一种新的图像重建算法(PureLumen)的性能，该算法基于第一代双源光子计数探测器计算机断层扫描(PCD-CT)系统的光谱CT数据。PureLumen试图只删除图像中的钙化部分，而不对其余部分进行修改。材料与方法使用2个直径为4 mm的碘造影剂充填的血管模型，填充不同浓度的碘，并配备钙化的狭窄支架。每个模型有两个独立的钙化病变，直径狭窄(PDS)大小分别为25%和50%。血管模体被安装在一个连接到人工运动设备上的拟人胸腔模体中，模拟心率在每分钟50到100次之间的真实心脏运动。使用预期的心电图触发的双源序列模式在PCD-CT系统(NAEOTOM Alpha，Siemens Healthineers)上进行采集。在RR间期的80%处重建图像，使用虚拟单能图像(Mono)和附加钙去除(PureLumen)，两者均为65keV。PureLumen是基于光谱基材分解成碘和钙的，其目的是在没有钙贡献的情况下重建图像，同时保持所有其他材料贡献不变。使用2个阅读器分别对所有重建图像序列中的每个血管插入物进行狭窄等级评估。结果50%病变的PDS值中位数为56.0%(52.0%，57.0%)，PureLumen为50.0%(48.5%，51.0%)。25%病变的中位数PDS值，单声道为36.0%(29.5%，39.5%)，纯音为31.5%(30.5%，34.0%)。两种病变大小在Mono和PureLumen之间显示出显著差异(P<；0.05)，PureLumen的中位数更接近50%和25%病变的实际狭窄大小。根据心率对图像质量进行视觉评估，在PureLumen的情况下，图像质量良好，心率高达每分钟80次。结论本模型研究表明，采用第一代双源PCD-CT的新型去钙图像重建算法(PureLumen)有效地减少了钙化斑块引起的斑块状伪影，提高了图像的可解析性。它还表明，PureLumen在模拟心率高达每分钟80次的运动中仍能保持其性能。未来的活体临床研究还需要证实这种重建在冠状动脉CT血管成像质量和准确性方面的益处。
Objectives The diagnostic performance of coronary computed tomography angiography is known to be negatively affected by the presence of severely calcified plaques in the coronary arteries. In this article, the performance of a novel image reconstruction algorithm (PureLumen) based on spectral CT data of a first-generation dual-source photon-counting detector computed tomography (PCD-CT) system was assessed in a phantom study. PureLumen tries to remove only the calcified contributions from the image while leaving the rest unmodified. Materials and Methods The study uses 2 iodine contrast filled vessel phantoms (diameter 4 mm) filled with different concentrations of iodine and equipped with calcified stenosis inserts. Each phantom features 2 separate calcified lesions of 25% and 50% percentage diameter stenosis (PDS) size. The vessel phantoms were mounted inside an anthropomorphic thorax phantom attached to an artificial motion device, simulating realistic cardiac motion at heart rates between 50 beats per minute and 100 beats per minute. Acquisitions were performed using a prospectively electrocardiogram triggered dual-source sequence mode on a PCD-CT system (NAEOTOM Alpha, Siemens Healthineers). Images were reconstructed at 80% of the RR interval with virtual monoenergetic images (Mono) and with additional calcium-removal (PureLumen), both at 65 keV. PureLumen is based on a spectral base material decomposition into iodine and calcium, which aims to reconstruct images without calcium contributions, while leaving all other material contribution unchanged. Stenosis grade was assessed individually for each vessel insert in all reconstructed image series by 2 readers. Results The measured median PDS values for the 50% lesion were 56.0% (52.0%, 57.0%) for the Mono case and 50.0% (48.5%, 51.0%) for PureLumen. The 25% lesion median PDS values were 36.0% (29.5%, 39.5%) for Mono and 31.5% (30.5%, 34.0%) for PureLumen. Both lesion sizes demonstrate a significant difference between Mono and PureLumen in their result (P < 0.05) with PureLumen median values being closer to the actual true stenosis size for the 50% and 25% lesion. A visual assessment of the image quality depending on the heart rate yielded good image quality up to a heart rate of 80 beats per minute in the PureLumen case. Conclusions This phantom study shows that a novel calcium-removal image reconstruction algorithm (PureLumen) using a first-generation dual-source PCD-CT effectively decreases blooming artifacts caused by heavily calcified plaques and improves image interpretability. It also shows that PureLumen retains its performance in the presence of motion with simulated heart rates up to 80 beats per minute. Future in vivo clinical studies are needed to confirm the benefits of this type of reconstruction in terms of coronary computed tomography angiography quality and accuracy.