Bundschuh Ralph A, Martínez-Moeller Axel, Essler Markus, Martínez María-José, Nekolla Stephan G, Ziegler Sibylle I, Schwaiger Markus
Nuklearmedizinische Klinik und Poliklinik, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
J Nucl Med. 2007 May;48(5):758-63. doi: 10.2967/jnumed.106.035279.
One of the main degrading factors in the quality of oncologic PET images of the thorax and upper abdomen is respiratory motion of tumors. One method to reduce this effect is the acquisition of PET data in gated mode. A second method is the correction of studies for motion. Motion registration is essential in both cases. We report a method using list-mode data to detect the craniocaudal (z) movement of thoracic and abdominal lesions without using any external gating device. The aim of this study was to show the feasibility of applying this method to patient data.
For 10 patients with lesions in the lung or upper abdominal organs, images for short time bins of 250, 500, and 750 ms were reconstructed. A volume of interest, which was manually defined in a summed image around the structure of interest, was projected to each time bin. The center of mass of the activity distribution in this volume of interest was determined for each case. The curves of the z-coordinate of the center of mass (z(COM)) over the time were analyzed and compared with respiration curves obtained by a pressure-sensitive belt.
In 7 of the 10 patients, movement of the lesion was registered in good accordance with the pressure belt. In the 3 remaining patients, no changes in the center of mass due to respiration could be detected, most likely because of minimal respiratory motion. The maximal difference in z(COM) for a lesion that was detected within the 10-min acquisition was 18.5 mm. For 7 of the 10 patients, the mean value for each respiration amplitude was between 11.0 and 2.0 mm.
We have shown the feasibility of registering movement of high-uptake lesions without the use of any external device that may restrain the patient. Furthermore, unlike external sensors, this method quantifies internal motion and, thus, is a promising base for correction methods.
胸部和上腹部肿瘤PET图像质量的主要降解因素之一是肿瘤的呼吸运动。减少这种影响的一种方法是在门控模式下采集PET数据。第二种方法是对运动进行图像校正。在这两种情况下，运动配准都至关重要。我们报告了一种使用列表模式数据检测胸部和腹部病变头足向（z）运动的方法，该方法无需使用任何外部门控设备。本研究的目的是证明将该方法应用于患者数据的可行性。
对于10例肺部或上腹部器官有病变的患者，重建了250、500和750毫秒短时间间隔的图像。在感兴趣结构周围的总和图像中手动定义一个感兴趣体积，并将其投影到每个时间间隔。确定每个病例该感兴趣体积内活动分布的质心。分析质心z坐标（z(COM)）随时间的曲线，并与通过压敏带获得的呼吸曲线进行比较。
10例患者中有7例病变的运动与压力带记录良好一致。其余3例患者中，未检测到因呼吸导致的质心变化，很可能是因为呼吸运动极小。在10分钟采集时间内检测到的病变的z(COM)最大差异为18.5毫米。10例患者中有7例，每次呼吸幅度的平均值在11.0至2.0毫米之间。
我们已经证明了在不使用任何可能限制患者的外部设备的情况下记录高摄取病变运动的可行性。此外，与外部传感器不同，该方法可量化内部运动，因此是校正方法的一个有前景的基础。
