Hollinger E F, Loncaric S, Yu D C, Ali A, Chang W
Department of Diagnostic Radiology and Nuclear Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA.
J Nucl Med. 1998 Aug;39(8):1335-44.
The objective of this study was to determine the feasibility of using a fast (short-duration) transmission computed tomogram (TCT), acquired immediately before or after the emission CT, to correct for photon attenuation in cardiac SPECT.
The asymmetric fanbeam geometry with a 99mTc line source was used to acquire TCTs after conventional cardiac emission CT imaging on a triple-head SPECT system. The TCTs were reconstructed to generate patient-specific attenuation maps, which were used with an iterative maximum likelihood algorithm to reconstruct attenuation-corrected cardiac SPECT studies. The results of attenuation correction based on TCTs as short as 1 min were compared with long-duration transmission imaging for a phantom and several human studies.
Attenuation correction based on asymmetric fanbeam TCT significantly improves the uniformity of images of a uniform tracer distribution in a cardiac-thorax phantom configured to simulate a large patient. By using a high-activity line source and a rapid camera rotation, a suitable attenuation map for this phantom can be obtained from a 4-min TCT. A similar result is obtained for patients with thorax widths of <40 cm.
A sequential imaging protocol for acquiring a fast TCT can be used for attenuation correction of cardiac SPECT imaging. The sequential TCT can be acquired without significantly extending the duration of the imaging study. This method provides a way to perform attenuation correction on existing triple-head SPECT systems without extensively modifying the system.
本研究的目的是确定在发射型计算机断层扫描（CT）之前或之后立即获取的快速（短时长）透射计算机断层扫描（TCT）用于校正心脏单光子发射计算机断层扫描（SPECT）中光子衰减的可行性。
在三头SPECT系统上，在常规心脏发射CT成像后，使用带有99m锝线源的不对称扇形束几何结构获取TCT。对TCT进行重建以生成患者特异性衰减图，该衰减图与迭代最大似然算法一起用于重建经衰减校正的心脏SPECT研究。将基于短至1分钟的TCT的衰减校正结果与用于模型和多项人体研究的长时间透射成像结果进行比较。
基于不对称扇形束TCT的衰减校正显著提高了在配置为模拟大患者的心脏-胸部模型中均匀示踪剂分布图像的均匀性。通过使用高活度线源和快速相机旋转，可从4分钟的TCT中获得该模型的合适衰减图。对于胸部宽度<40 cm的患者也获得了类似结果。
用于获取快速TCT的序贯成像方案可用于心脏SPECT成像的衰减校正。序贯TCT可在不显著延长成像研究时长的情况下获取。该方法提供了一种在不进行广泛系统修改的情况下对现有三头SPECT系统进行衰减校正的方法。
