Bestetti A, Scalzi P B, Alessi A, Di Leo C, Tagliabue L, Del Sole A, Lomuscio A, Vergani D, Marano L, Lombardi F, Tarolo G
Cattedra di Medicina Nucleare, Università degli Studi, Milano.
Ital Heart J Suppl. 2000 Jun;1(6):790-6.
Gated-SPECT using 99mTc-labeled flow tracers provides the simultaneous assessment of global and regional myocardial perfusion and function. The aim of this study was to identify patients with stress-induced postischemic stunning, among those with reversible stress perfusion defects, and patients with artifactual defects among those with fixed defects, in order to assess the value of the functional data provided by gated acquisition of perfusion imaging in the characterization of ischemia.
We studied 221 consecutive patients who underwent conventional diagnostic dual day stress/rest gated-SPECT following injection of 925 MBq of 99mTc-tetrofosmin using a dual head SPECT camera, 115 of whom (52%) showed reversible perfusion defects, and 66 (30%) fixed defects. Perfusion was analyzed on ungated images using 20 segments scored on a 5-point scale (0 = normal, 4 = no uptake), while wall thickening was assessed visually on stress/rest end-systolic images using a 4-point score (0 = normal, 3 = absence of wall thickening). Left ventricular ejection fraction and volumes were calculated using an automatic algorithm (quantitative gated-SPECT). Fifty-two out of 221 (23.5%) patients underwent coronary angiography.
In 40/115 (35%) patients with reversible perfusion defects, post-stress left ventricular ejection fraction was > 5% lower than that at rest (Group A: stunned), whereas in the remaining 75 patients, post-stress left ventricular ejection fraction was either +/- 5% or greater than that at rest (Group B: non-stunned). Peak exercise angina and ischemic electrocardiographic response to exercise were present in 79 and 58% respectively of Group A patients and in 33 and 39% of Group B patients. The number of patients with multivessel disease was significantly higher in Group A compared to Group B (58 vs 41%, p < 0.05). The total stress and rest perfusion scores were significantly higher in Group A than in Group B (p < 0.01); even the total stress wall thickening score was significantly higher in Group A (p < 0.001). As for global parameters, post-stress end-systolic volume was significantly higher in the stunned group (p < 0.05). In 40 out of 66 (60.5%) patients without reversible ischemia fixed defects were judged to be ischemic (Group C), while in 26/66 (39.5%) they were attributed to attenuation artifacts (Group D). Eighty percent of Group C patients had a previous myocardial infarction against none of Group D. Stress/rest perfusion and wall thickening scores were significantly higher in Group C than in Group D.
Gated-SPECT myocardial perfusion evaluation allowed us to identify a subgroup of post-stress stunned coronary artery diseased patients. The post-stress left ventricular ejection fraction reduction in this population seems to be due to the increase in end-systolic volume. The stunned patients showed more severe perfusion defects and wall thickening abnormalities.
使用99mTc标记的血流示踪剂的门控单光子发射计算机断层扫描（Gated-SPECT）可同时评估整体和局部心肌灌注及功能。本研究的目的是在可逆性负荷灌注缺损患者中识别出应激诱导的缺血后心肌顿抑患者，在固定缺损患者中识别出伪影缺损患者，以评估门控采集灌注成像所提供的功能数据在缺血特征描述中的价值。
我们研究了221例连续接受常规诊断性双日负荷/静息门控SPECT检查的患者，这些患者在注射925MBq的99mTc-替曲膦后使用双头SPECT相机进行检查，其中115例（52%）显示可逆性灌注缺损，66例（30%）显示固定缺损。使用20节段5分制（0 = 正常，4 = 无摄取）在非门控图像上分析灌注，而在负荷/静息收缩末期图像上使用4分制（0 = 正常，3 = 无室壁增厚）目测评估室壁增厚情况。使用自动算法（定量门控SPECT）计算左心室射血分数和容积。221例患者中有52例（23.5%）接受了冠状动脉造影。
在115例可逆性灌注缺损患者中的40例（35%）中，负荷后左心室射血分数比静息时降低>5%（A组：心肌顿抑），而在其余75例患者中，负荷后左心室射血分数与静息时相比变化±5%或更高（B组：非心肌顿抑）。A组患者中分别有79%和58%出现运动高峰心绞痛和运动时缺血性心电图反应，B组患者中分别为33%和39%。与B组相比，A组多支血管病变患者数量显著更高（58%对41%，p < 0.05）。A组的总负荷和静息灌注评分显著高于B组（p < 0.01）；甚至A组的总负荷室壁增厚评分也显著更高（p < 0.001）。至于整体参数，心肌顿抑组负荷后收缩末期容积显著更高（p < 0.05）。在66例无可逆性缺血的固定缺损患者中的40例（60.5%）被判定为缺血（C组），而在26/66例（39.5%）中归因于衰减伪影（D组）。C组80%的患者既往有心肌梗死，而D组无一例。C组的负荷/静息灌注和室壁增厚评分显著高于D组。
门控SPECT心肌灌注评估使我们能够识别出负荷后心肌顿抑的冠状动脉疾病患者亚组。该人群中负荷后左心室射血分数降低似乎是由于收缩末期容积增加。心肌顿抑患者表现出更严重的灌注缺损和室壁增厚异常。
