Chan Chung, Harris Mark, Le Max, Biondi James, Grobshtein Yariv, Liu Yi-Hwa, Sinusas Albert J, Liu Chi
Department of Diagnostic Radiology, Yale University School of Medicine, PO Box 208048, New Haven, CT 06520, USA.
Phys Med Biol. 2014 Oct 21;59(20):6267-87. doi: 10.1088/0031-9155/59/20/6267. Epub 2014 Sep 26.
Respiratory and cardiac motions can degrade myocardial perfusion SPECT (MPS) image quality and reduce defect detection and quantitative accuracy. In this study, we developed a dual respiratory and cardiac gating system for a high-resolution fully stationary cardiac SPECT scanner in order to improve the image quality and defect detection. Respiratory motion was monitored using a compressive sensor pillow connected to a dual respiratory-cardiac gating box, which sends cardiac triggers only during end-expiration phases to the single cardiac trigger input on the SPECT scanners. The listmode data were rebinned retrospectively into end-expiration frames for respiratory motion reduction or eight cardiac gates only during end-expiration phases to compensate for both respiratory and cardiac motions. The proposed method was first validated on a motion phantom in the presence and absence of multiple perfusion defects, and then applied on 11 patient studies with and without perfusion defects. In the normal phantom studies, the end-expiration gated SPECT (EXG-SPECT) reduced respiratory motion blur and increased myocardium to blood pool contrast by 51.2% as compared to the ungated images. The proposed method also yielded an average of 11.2% increase in myocardium to defect contrast as compared to the ungated images in the phantom studies with perfusion defects. In the patient studies, EXG-SPECT significantly improved the myocardium to blood pool contrast (p < 0.005) by 24% on average as compared to the ungated images, and led to improved perfusion uniformity across segments on polar maps for normal patients. For a patient with defect, EXG-SPECT improved the defect contrast and definition. The dual respiratory-cardiac gating further reduced the blurring effect, increased the myocardium to blood pool contrast significantly by 36% (p < 0.05) compared to EXG-SPECT, and further improved defect characteristics and visualization of fine structures at the expense of increased noise on the patient with defect. The results showed that the proposed methods can effectively reduce motion blur in the images caused by both respiratory and cardiac motions, which may lead to more accurate defect detection and quantifications. This approach can be easily adapted in routine clinical practice on currently available commercial systems.
呼吸和心脏运动可降低心肌灌注单光子发射计算机断层扫描（MPS）图像质量，并降低缺损检测及定量准确性。在本研究中，我们为高分辨率全固定式心脏SPECT扫描仪开发了一种呼吸和心脏双门控系统，以提高图像质量及缺损检测能力。使用连接到呼吸-心脏双门控盒的压缩感应枕监测呼吸运动，该双门控盒仅在呼气末期向SPECT扫描仪上的单一心脏触发输入发送心脏触发信号。列表模式数据被回顾性重排为呼气末期帧以减少呼吸运动，或仅在呼气末期重排为八个心动周期门控以补偿呼吸和心脏运动。所提出的方法首先在存在和不存在多个灌注缺损的运动模型上进行验证，然后应用于11例有或无灌注缺损的患者研究。在正常模型研究中，与非门控图像相比，呼气末期门控SPECT（EXG-SPECT）减少了呼吸运动模糊，并使心肌与血池对比度提高了51.2%。在有灌注缺损的模型研究中，与非门控图像相比，所提出的方法还使心肌与缺损对比度平均提高了11.2%。在患者研究中，与非门控图像相比，EXG-SPECT平均使心肌与血池对比度显著提高了24%（p<0.005），并使正常患者极坐标图上各节段的灌注均匀性得到改善。对于有缺损的患者，EXG-SPECT改善了缺损对比度和清晰度。与EXG-SPECT相比，呼吸-心脏双门控进一步降低了模糊效应，使心肌与血池对比度显著提高了36%（p<0.05），并进一步改善了缺损特征及精细结构的可视化，但代价是有缺损患者的图像噪声增加。结果表明，所提出的方法可有效减少由呼吸和心脏运动引起的图像运动模糊，这可能会带来更准确的缺损检测和定量。这种方法可轻松应用于当前可用商业系统的常规临床实践中。
