Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland.
Ann Nucl Med. 2019 May;33(5):305-316. doi: 10.1007/s12149-019-01335-y. Epub 2019 Jan 24.
Correction for respiratory motion in myocardial perfusion imaging requires sorting of emission data into respiratory windows where the intra-window motion is assumed to be negligible. However, it is unclear how much intra-window motion is acceptable. The aim of this study was to determine an optimal value of intra-window residual motion.
A custom-designed cardiac phantom was created and imaged with a standard dual-detector SPECT/CT system using Tc-99m as the radionuclide. Projection images were generated from the list-mode data simulating respiratory motion blur of several magnitudes from 0 (stationary phantom) to 20 mm. Cardiac defect contrasts in six anatomically different locations, as well as myocardial perfusion of apex, anterior, inferior, septal and lateral walls, were measured at each motion magnitude. Stationary phantom data were compared to motion-blurred data. Two physicians viewed the images and evaluated differences in cardiac defect visibility and myocardial perfusion.
Significant associations were observed between myocardial perfusion in the anterior and inferior walls and respiratory motion. Defect contrasts were found to decline as a function of motion, but the magnitude of the decline depended on the location and shape of the defect. Defects located near the cardiac apex lost contrast more rapidly than those located on the anterior, inferior, septal and lateral wall. The contrast decreased by less than 5% at every location when the motion magnitude was 2 mm or less. According to a visual evaluation, there were differences in myocardial perfusion if the magnitude of the motion was greater than 1 mm, and there were differences in the visibility of the cardiac defect if the magnitude of the motion was greater than 9 mm.
Intra-window respiratory motion should be limited to 2 mm to effectively correct for respiratory motion blur in myocardial perfusion SPECT.
心肌灌注成像中的呼吸运动校正需要将发射数据分类到呼吸窗口中，其中窗口内的运动被认为是可以忽略的。然而，尚不清楚可接受的窗口内运动幅度是多少。本研究旨在确定窗口内残余运动的最佳值。
使用 Tc-99m 作为放射性核素，使用标准的双探测器 SPECT/CT 系统创建并对定制的心脏模型进行成像。从模拟从 0（静止的心脏模型）到 20mm 不同程度呼吸运动模糊的列表模式数据中生成投影图像。在每个运动幅度下，测量六个解剖位置不同的心脏缺陷对比度以及心尖、前壁、下壁、间隔壁和侧壁的心肌灌注。将静止的心脏模型数据与运动模糊的数据进行比较。两位医生查看图像并评估心脏缺陷可见度和心肌灌注的差异。
在前壁和下壁心肌灌注与呼吸运动之间观察到显著的相关性。发现缺陷对比度随运动而下降，但下降幅度取决于缺陷的位置和形状。位于心脏心尖附近的缺陷比位于前壁、下壁、间隔壁和侧壁的缺陷更快地失去对比度。当运动幅度为 2mm 或更小，每个位置的对比度下降幅度小于 5%。根据视觉评估，如果运动幅度大于 1mm，则心肌灌注存在差异，如果运动幅度大于 9mm，则心脏缺陷的可见度存在差异。
为了有效校正心肌灌注 SPECT 中的呼吸运动模糊，窗口内呼吸运动应限制在 2mm 以内。
