ASSESSMENT OF MYOCARDIAL VIABILITY BY THALLIUM SCINTIGRAPHY

存活的缺血心肌与不可逆心肌的区别 运动心肌-Tl-201(Tl)显像术造成的心肌疤痕常见 不精确，与在缺血中发展的许多TL灌注缺陷一样多 运动中的心肌在随后的3-4小时内不会恢复正常。 重新分发(RD)图像。我们最近展示了1 MCI的 应激反应后即刻静息时TL再注射(RI) 在其他区域识别缺血但存活的心肌 在明显不可逆转的基础上被解释为伤疤 RD影像上的缺陷。RI Rep后对TL的摄取是可行的 心肌已通过改善的区域灌注和壁厚得到验证 保留局部冠状动脉血运重建后的运动 正电子发射断层扫描(PET)上的代谢活性，以及 门控磁共振保留局部收缩期室壁增厚 学习。此外，RI后的24小时延迟成像不提供 94%的患者对心肌存活的更多见解 在RD处存在不可逆的TL缺陷。以确定TL RI是否也更多 在检测存活心肌方面，我们比REST-RD成像更敏感 20例冠心病患者的运动-RD-TL成像研究 然后是1 MCI TL RI，并将图像与REST-RD TL图像进行比较 1-2周后相同的患者。两者之间的和谐与不和谐 将REST-RD显像和TLRI显像与代谢标记物进行比较 宠物。结果表明，REST-RD和TLRI成像提供了 关于大多数患者心肌存活性的一致信息 地区，但REST-RD低估了有 与TL RI和PET相比，TL活性严重降低。

The distinction between viable but ischemic myocardium and irreversibly scarred myocardium by exercise thallium-201 (Tl) scintigraphy is often imprecise, as many Tl perfusion defects that develop in ischemic myocardium during exercise do not normalize on subsequent 3-4 hr. redistribution (RD) images. We have recently demonstrated that 1 mCi of Tl reinjection (RI) at rest immediately after stress-RD imaging identifies ischemic but viable myocardium in regions that would otherwise have been interpreted as scar on the basis of apparently irreversible defects on RD imaging. That the uptake of Tl after RI rep[resents viable myocardium has been verified by improved regional perfusion and wall motion after coronary artery revascularization, preserved regional metabolic activity on positron emission tomography (PET), and by preserved regional systolic wall thickening by gated magnetic resonance studies. Furthermore, 24 hour delayed imaging following RI provides no additional insights regarding myocardial viability in 94% of patients with irreversible Tl defects at RD. To determine if Tl RI is also more sensitive than rest-RD imaging for detecting viable myocardium, we studied 20 pts with coronary artery disease by exercise-RD Tl imaging followed by 1 mCi Tl RI and compared the images to rest-RD Tl images in the same patients 1-2 weeks later. Concordance and discordance between rest-RD imaging and Tl RI imaging were compared to metabolic marker by PET. The results indicate that rest-RD and Tl RI imaging provide concordant information regarding myocardial viability in the majority of regions, but rest-RD underestimates viable myocardium in regions with severely reduced Tl activity when compared to Tl RI and PET.