硝酸甘油介入^(99)Tc^m-tetrofosminSPECT与^(18)F-FDG PET显像评估心肌活力比较

Evaluation of myocardial viability with ^(99)Tc^m-tetrofosmin after nitrate administration:comparison with FDG PET imaging

目的比较硝酸甘油介入^(99)Tc^m-tetrofosmin SPECT 心肌血流灌注显像与^(18)F-FDG PET 心肌代谢显像评估心肌活力的价值。方法既往有心肌梗死史伴左心功能不全经冠状动脉造影确诊为冠心病的患者36例,行二日法静息和硝酸甘油介入^(99)Tc^m-tetrofosmin SPECT 显像,并在1周内再行^(18)F-FDG PET 心肌代谢显像及静息超声心动图检查。将左心室分成13个节段,分析超声心动图室壁运动,并分析相同节段^(99)Tc^m-tetrofosmin 与^(18)F-FDG 的相对摄取比值,以^(99)Tc^m-tetrofosmin 摄取比值55%,^(18)F-FDG 摄取比值50%为判断心肌活力有无的阈值。以 k 统计比较3种方法的一致性。结果超声心动图示131个节段呈无运动或反向运动。^(99)Tc^m-tetrofosmin 静息显像示其中78个节段(60%)心肌有活力,53个节段(40%)无活力。该53个节段中14个(26%)在硝酸甘油介入后可见再填充,余39个节段无改变。在^(18)F-FDG PET 显像中,硝酸甘油介入显像再填充节段的心肌放射性摄取明显增高。再填充节段与无填充节段比较,心肌 FDG 摄取分别为(76±15)%和(58±17)%,差异有统计学意义(P<0.01)。硝酸甘油介入显像中,92个心肌节段(70%)有活力,39个无活力。tetrofosmin静息显像评估心肌活力与 FDG PET 显像比较,k 值为0.35,而硝酸甘油介入^(99)Tc^m-tetrofosmin SPECT与^(18)F-FDG PET 显像结果比较,k 值为0.53。结论硝酸甘油介入^(99)Tc^m-tetrofosmin SPECT 显像可提高对心肌活力的检测能力,与^(18)F-FDG PET 心肌代谢显像有很好的一致性。

Objective The purpose of this study was to assess the relationship between tetrofosmin uptake after nitrate administration and the metabolic activity assessed by ^18F-FDG PET in patients with ischemic left ventricular （LV） dysfunction. Methods A baseline ^99 Tc^m-tetrofosmin SPECT at rest and a repeated study after sublingual administration of 10 mg isosorbide dinitrate within two days were undertaken in 36 patients with chronic myocardial infarction and LV dysfunction. All patients underwent metabolic PET imaging with ,^18F-FDG in the following week. ^99Tc^m-tetrofosmin uptake and metabolic activity in 13 segments of myocardium were measured in every patient. A 55% peak activity on tetrofosmin and 50% peak activity on FDG were used as the differential threshold in evaluating myocardial viability, and the uptakes compared with regional LV function assessed by echocardiography. Results Fifty-three （40%） of the 131 akinetic or dyskinetic segments had reduced tracer uptake. Of those segments, 14 （26%） segments showed increased tetrofosmin uptake after nitrate intervention （ 〉 10% vs baseline ）, 39 （74%） segments remained no change. The sensitivity and specificity of baseline tetrofosmin SPECT for detecting preserved metabolic activity were 69% and 86% , respectively. After nitrate administration, the sensitivity increased to 81% （P 〈 0. 05 ）. Concordance between tetrofosmin SPECT and FDG PET in differentiating viable and necrotic myocardium was 94/131 （72%） of akinetic or dyskinetic segments at baseline （ k = 0. 35 ） and 108/131 （ 82% ） after nitrate administration （k = 0. 53 ）. Conclusion ^99 Tc^m-tetrofosmin SPECT after nitrate administration may improve the identification of ischemic but still viable myocardium in patients with chronic ischemic LV dysfunction.