Hendel R C
Department of Medicine, Northwestern University Medical School, Chicago, Illinois.
J Nucl Med. 1994 Apr;35(4 Suppl):23S-31S.
The identification of viable myocardium is an important consideration for patient selection prior to interventional procedures, especially in patients with severe left ventricular dysfunction. Myocardial perfusion imaging may reflect viability, because tracer uptake requires adequate perfusion, cellular integrity and metabolic function. The underestimation of myocardial viability noted with traditional stress and redistribution thallium imaging has lead to the development of alternative protocols to detect viable myocardium, such as late (24-hr) imaging and the thallium reinjection method. Rest-redistribution thallium imaging may be a useful procedure for predicting recovery of ventricular function following revascularization. Quantitative analysis of thallium activity provides important information, because mild or moderate defects are usually metabolically active as determined by PET. Administration of adjunct medications, such as ribose or nitroglycerin, can increase the detection of reversible perfusion abnormalities. Technetium-99m perfusion agents offer great promise for perfusion imaging, but their role in the detection of myocardial viability is not well defined. Underestimation of myocardial viability has been described with 99mTc-sestamibi scintigraphy; however, use of quantitative perfusion image analysis or the addition of functional data provided by gated tomography or first-pass imaging may enhance the assessment of viability. Although the optimal method for the detection of myocardial viability with single-photon agents is not apparent, current methods have substantially improved discrimination between nonviable and viable myocardium. In certain instances, however, metabolic imaging with single-photon fatty acid analogs or positron-emitting radionuclides may be necessary.
在进行介入手术前，识别存活心肌是患者选择的重要考量因素，尤其是对于左心室功能严重受损的患者。心肌灌注成像可反映心肌存活情况，因为示踪剂摄取需要足够的灌注、细胞完整性和代谢功能。传统的负荷及再分布铊显像对心肌存活的低估促使了检测存活心肌的替代方案的发展，如延迟（24小时）显像和铊再注射法。静息-再分布铊显像可能是预测血运重建后心室功能恢复的有用方法。铊活性的定量分析提供了重要信息，因为正电子发射断层扫描（PET）显示轻度或中度缺损通常具有代谢活性。使用辅助药物，如核糖或硝酸甘油，可增加可逆性灌注异常的检出率。锝-99m灌注剂在灌注成像方面前景广阔，但其在检测心肌存活中的作用尚未明确界定。99mTc- sestamibi心肌显像存在对心肌存活低估的情况；然而，使用定量灌注图像分析或添加门控断层扫描或首次通过成像提供的功能数据可能会增强对存活情况的评估。尽管目前尚不清楚使用单光子显像剂检测心肌存活的最佳方法，但现有方法已显著提高了对无存活心肌和存活心肌的鉴别能力。然而，在某些情况下，可能需要使用单光子脂肪酸类似物或正电子发射放射性核素进行代谢显像。
