Sand N P, Bøttcher M, Madsen M M, Nielsen T T, Rehling M
Department of Nuclear Medicine, The PET Center, Aarhus University Hospital, Skejby Sygehus, Denmark.
J Nucl Cardiol. 1998 Jan-Feb;5(1):4-13. doi: 10.1016/s1071-3581(98)80004-4.
Positron emission tomography (PET) scanning with 13N-ammonia and 18FDG is well established for the detection of myocardial viability. Due to the limited availability of PET facilities, recent studies have combined technetium 99m sestamibi single photon emission computed tomography (SPECT) with 18FDG PET or 18FDG SPECT. This approach enables simultaneous assessment of regional myocardial blood flow and metabolism and substantially increases the capacity for viability detection. To validate whether 99mTc-Sestamibi SPECT can replace 13N-ammonia PET, we compared these two modalities in patients with severe left ventricular dysfunction due to coronary artery disease.
Thirty-one patients (mean age 57+/-8 years; mean ejection fraction 27%+/-8%) with angiographically verified coronary artery disease were included. In random order, ammonia-PET and sestamibi-SPECT scans were performed. In a 20-segment model of the left ventricle, two blinded observers scored a total of 610 segments on a five-point scale. In a subset of 20 patients, 400 segments were scored twice to evaluate the observer variations of the two techniques. Segmental score differences were used to compare the imaging modalities. The impact on viability detection was assessed by combining the two flow tracers with FDG PET.
Segmental comparison of the PET and SPECT studies yielded similar (difference < or = 1) results in 74% of segments, reflecting regional concordance values in the lateral, apical, anterior, septal, and inferior myocardial walls of 86%, 82%, 71%, 66%, and 63%, respectively. The differences in the septal and inferior walls were primarily due to overestimation of perfusion defects by sestamibi SPECT, which yielded a higher proportion of mismatch patterns in those regions. The overall observer variations of the PET and SPECT studies were 7.5% and 5.8%.
Myocardial perfusion imaging with 13N-ammonia PET and 99mTc-sestamibi SPECT yielded similar results in patients with severe left ventricular dysfunction, except for the septal and inferior regions. In these regions, SPECT tended to overestimate perfusion defects. Hence, attenuation correction should be considered when combining FDG PET and sestamibi SPECT for diagnosing myocardial viability to avoid overestimation of mismatch patterns in those regions.
正电子发射断层扫描（PET）使用13N-氨和18FDG进行心肌存活检测已得到广泛应用。由于PET设备的可用性有限，最近的研究将锝99m甲氧基异丁基异腈单光子发射计算机断层扫描（SPECT）与18FDG PET或18FDG SPECT相结合。这种方法能够同时评估局部心肌血流和代谢，并显著提高存活检测能力。为验证99mTc-甲氧基异丁基异腈SPECT是否可替代13N-氨PET，我们在因冠状动脉疾病导致严重左心室功能障碍的患者中比较了这两种检查方法。
纳入31例经血管造影证实患有冠状动脉疾病的患者（平均年龄57±8岁；平均射血分数27%±8%）。以随机顺序进行氨-PET和甲氧基异丁基异腈-SPECT扫描。在左心室的20节段模型中，两名盲法观察者采用五点量表对总共610个节段进行评分。在20例患者的子集中，对400个节段进行了两次评分，以评估两种技术的观察者间差异。节段评分差异用于比较成像方式。通过将两种血流示踪剂与FDG PET相结合来评估对存活检测的影响。
PET和SPECT研究的节段比较在74%的节段中得出相似（差异≤1）结果，分别反映外侧、心尖、前壁、间隔和下壁心肌区域的一致性值为86%、82%、71%、66%和63%。间隔和下壁的差异主要是由于甲氧基异丁基异腈SPECT对灌注缺损的高估，导致这些区域不匹配模式的比例更高。PET和SPECT研究的总体观察者间差异分别为7.5%和5.8%。
对于严重左心室功能障碍的患者，13N-氨PET和99mTc-甲氧基异丁基异腈SPECT心肌灌注成像结果相似，但间隔和下壁区域除外。在这些区域，SPECT倾向于高估灌注缺损。因此，在将FDG PET和甲氧基异丁基异腈SPECT联合用于诊断心肌存活时应考虑衰减校正，以避免高估这些区域的不匹配模式。
