Schwarz Annette, Hofmann Christian, Dickmann Jannis, Simon Arndt, Maier Andreas, Wacker Frank K, Raatschen Hans-Jürgen, Gleitz Stephan, Schmidbauer Martina
From the Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany (A. Schwarz, A. Simon, A.M.); Siemens Healthineers AG, Forchheim, Germany (A. Schwarz, C.H., J.D., A. Simon); Institute for Diagnostic and Interventional Radiology, Hannover Medical School, Hannover, Germany (F.K.W., S.G., M.S.); and Institut for Radiology, Pediatric and Neuroradiology, Helios Hospital, Schwerin, Germany (H.-J.R.).
Invest Radiol. 2025 Aug 1;60(8):517-525. doi: 10.1097/RLI.0000000000001157. Epub 2025 Jan 24.
Respiratory motion can affect image quality and thus affect the diagnostic accuracy of CT images by masking or mimicking relevant lung pathologies. CT examinations are often performed during deep inspiration and breath-hold to achieve optimal image quality. However, this can be challenging for certain patient groups, such as children, the elderly, or sedated patients. The study aimed to validate a dedicated triggering algorithm for initiating respiratory-triggered high-pitch computed tomography (RT-HPCT) scans in end inspiration and end expiration in complex and irregular respiratory patterns using an anthropomorphic dynamic chest phantom. Additionally, a patient study was conducted to compare the image quality and lung expansion between RT-HPCT and standard HPCT.
The study utilized an algorithm that processes the patient's breathing motion in real-time to determine the appropriate time to initiate a scan. This algorithm was tested on a dynamic, tissue-equivalent chest motion phantom to replicate and simulate 3-dimensional target motion using 28 breathing motion patterns taken from patient with irregular breathing. To evaluate the performance on human patients, prospective RT-HPCT was performed in 18 free-breathing patients. As a reference, unenhanced HPCT of the chest was performed in 20 patients without respiratory triggering during free-breathing. The mean CTDI was 1.73 mGy ± 0.1 mGy for HPCT and 1.68 mGy ± 0.1 mGy for RT-HPCT. For phantom tests, the deviation from the target position of the phantom inlay is known. Image quality is approximated by evaluating stationary versus moving acquisitions. For patient scans, respiratory motion artifacts and inspiration depth were analyzed using expert knowledge of lung anatomy and automated lung volume estimation. Statistical analysis was performed to compare image quality and lung volumes between conventional HPCT and RT-HPCT.
In phantom scans, the average deviation from the desired excursion phase was 1.6 mm ± 4.7 mm or 15% ± 24% of the phantom movement range. In patients, the overall image quality significantly improved with respiratory triggering compared with conventional HPCT ( P < 0.001). Quantitative average lung volume was 4.0 L ± 1.1 L in the RT group and 3.6 L ± 1.0 L in the control group.
This study demonstrated the feasibility of using a patient-adaptive respiratory triggering algorithm for high-pitch lung CT in both phantom and patients. Respiratory-triggered high-pitch CT scanning significantly reduces breathing artifacts compared with conventional nontriggered free-breathing scans.
呼吸运动可影响图像质量，进而通过掩盖或模拟相关肺部病变影响CT图像的诊断准确性。CT检查通常在深吸气和屏气时进行，以获得最佳图像质量。然而，这对某些患者群体（如儿童、老年人或接受镇静的患者）可能具有挑战性。本研究旨在使用拟人化动态胸部模型验证一种专用触发算法，用于在复杂和不规则呼吸模式下的吸气末和呼气末启动呼吸触发的高分辨率计算机断层扫描（RT-HPCT）扫描。此外，还进行了一项患者研究，以比较RT-HPCT和标准HPCT之间的图像质量和肺扩张情况。
本研究采用一种算法，实时处理患者的呼吸运动，以确定启动扫描的合适时间。该算法在动态、组织等效的胸部运动模型上进行测试，使用从呼吸不规则患者获取的28种呼吸运动模式来复制和模拟三维目标运动。为了评估在人类患者身上的性能，对18名自由呼吸的患者进行了前瞻性RT-HPCT检查。作为对照，对20名在自由呼吸时未进行呼吸触发的患者进行了胸部非增强HPCT检查。HPCT的平均CTDI为1.73 mGy±0.1 mGy，RT-HPCT为1.68 mGy±0.1 mGy。对于模型测试，模型镶嵌物相对于目标位置的偏差是已知的。通过评估静态与动态采集来近似图像质量。对于患者扫描，使用肺部解剖学专业知识和自动肺容积估计来分析呼吸运动伪影和吸气深度。进行统计分析以比较传统HPCT和RT-HPCT之间的图像质量和肺容积。
在模型扫描中，与期望偏移阶段的平均偏差为1.6 mm±4.7 mm，或模型运动范围的15%±24%。在患者中，与传统HPCT相比，呼吸触发显著改善了整体图像质量（P<0.001）。RT组的定量平均肺容积为4.0 L±1.1 L，对照组为3.6 L±1.0 L。
本研究证明了在模型和患者中使用患者自适应呼吸触发算法进行高分辨率肺部CT检查的可行性。与传统的非触发自由呼吸扫描相比，呼吸触发的高分辨率CT扫描显著减少了呼吸伪影。
