Division of Cardiology, Department of Medicine, University of California, San Francisco, CA, USA.
Department of Radiology and Biomedical Imaging, University of California, 185 Berry St., Suite 350, San Francisco, CA, 94143-0946, USA.
J Nucl Cardiol. 2019 Jun;26(3):763-771. doi: 10.1007/s12350-017-1016-7. Epub 2017 Aug 3.
SPECT myocardial perfusion imaging (MPI) is a clinical mainstay that is typically performed with static imaging protocols and visually or semi-quantitatively assessed for perfusion defects based upon the relative intensity of myocardial regions. Dynamic cardiac SPECT presents a new imaging technique based on time-varying information of radiotracer distribution, which permits the evaluation of regional myocardial blood flow (MBF) and coronary flow reserve (CFR). In this work, a preliminary feasibility study was conducted in a small patient sample designed to implement a unique combined static-dynamic single-dose one-day visit imaging protocol to compare quantitative dynamic SPECT with static conventional SPECT for improving the diagnosis of coronary artery disease (CAD).
Fifteen patients (11 males, four females, mean age 71 ± 9 years) were enrolled for a combined dynamic and static SPECT (Infinia Hawkeye 4, GE Healthcare) imaging protocol with a single dose of Tc-tetrofosmin administered at rest and a single dose administered at stress in a one-day visit. Out of 15 patients, eleven had selective coronary angiography (SCA), 8 within 6 months and the rest within 24 months of SPECT imaging, without intervening symptoms or interventions. The extent and severity of perfusion defects in each myocardial region was graded visually. Dynamically acquired data were also used to estimate the MBF and CFR. Both visually graded images and estimated CFR were tested against SCA as a reference to evaluate the validity of the methods.
Overall, conventional static SPECT was normal in ten patients and abnormal in five patients, dynamic SPECT was normal in 12 patients and abnormal in three patients, and CFR from dynamic SPECT was normal in nine patients and abnormal in six patients. Among those 11 patients with SCA, conventional SPECT was normal in 5, 3 with documented CAD on SCA with an overall accuracy of 64%, sensitivity of 40% and specificity of 83%. Dynamic SPECT image analysis also produced a similar accuracy, sensitivity, and specificity. CFR was normal in 6, each with CAD on SCA with an overall accuracy of 91%, sensitivity of 80%, and specificity of 100%. The mean CFR was significantly lower for SCA detected abnormal than for normal patients (3.86±1.06 vs 1.94±0. 0.67, P < 0.001).
The visually assessed image findings in static and dynamic SPECT are subjective, and may not reflect direct physiologic measures of coronary lesion based on SCA. The CFR measured with dynamic SPECT is fully objective, with better sensitivity and specificity, available only with the data generated from the dynamic SPECT method.
单光子发射型计算机断层扫描（SPECT）心肌灌注显像是一种临床常用的技术，通常采用静态成像方案，并根据心肌区域的相对强度，通过视觉或半定量评估来判断灌注缺损。动态 SPECT 是一种新的成像技术，基于放射性示踪剂分布的时变信息，可评估局部心肌血流（MBF）和冠状动脉血流储备（CFR）。本研究在小样本患者中进行了初步可行性研究，旨在实施一种独特的静态-动态单剂量一日就诊成像方案，比较定量动态 SPECT 与静态常规 SPECT 对冠心病（CAD）的诊断价值。
15 名患者（11 名男性，4 名女性，平均年龄 71±9 岁）接受了 Tc-四氮茂单剂量静息和单剂量负荷的 SPECT（Infinia Hawkeye 4，GE Healthcare）成像方案，在一日就诊中进行。15 名患者中，11 名进行了选择性冠状动脉造影（SCA），8 名在 SPECT 成像后 6 个月内进行，其余在 24 个月内进行，期间没有出现症状或干预措施。通过视觉评估对每个心肌区域的灌注缺损程度和严重程度进行分级。动态采集的数据还用于估计 MBF 和 CFR。将视觉分级图像和估计的 CFR 与 SCA 进行对比，以评估方法的有效性。
总体而言，10 名患者的常规静态 SPECT 正常，5 名患者异常；12 名患者的动态 SPECT 正常，3 名患者异常；9 名患者的 CFR 正常，6 名患者异常。在 11 名接受 SCA 的患者中，5 名患者的常规 SPECT 正常，3 名患者有 SCA 证实的 CAD，总体准确性为 64%，灵敏度为 40%，特异性为 83%。动态 SPECT 图像分析也产生了类似的准确性、灵敏度和特异性。6 名患者的 CFR 正常，均有 SCA 证实的 CAD，总体准确性为 91%，灵敏度为 80%，特异性为 100%。SCA 检测异常患者的平均 CFR 明显低于正常患者（3.86±1.06 比 1.94±0.067，P<0.001）。
静态和动态 SPECT 的视觉评估图像结果是主观的，可能无法反映基于 SCA 的冠状动脉病变的直接生理测量值。通过动态 SPECT 测量的 CFR 是完全客观的，具有更好的灵敏度和特异性，只能通过动态 SPECT 方法生成的数据获得。
