Moran G R, Thornhill R E, Sykes J, Prato F S
Department of Nuclear Medicine and Magnetic Resonance, Lawson Health Research Institute, St Joseph's Health Care, London, Canada.
Magn Reson Med. 2002 Nov;48(5):791-800. doi: 10.1002/mrm.10289.
Results of simulations are shown which illustrate how the concentration-time curves of an extravascular extracellular (EVEC) contrast agent, such as Gd-DTPA, vary in myocardial tissue. The simulations show that the variable permeability of dead myocytes within a recent myocardial infarction will significantly alter delayed enhancement patterns following a bolus injection, invariably reducing the sensitivity of this technique for the detection of permanently damaged tissue. It is further predicted that if the bolus injection is followed by a suitably selected constant infusion, the infarct size and infarct volume of distribution may be more accurately determined, even though the degree of enhancement of an infarcted region (with normal flow) above normal tissue is slightly higher for the bolus technique within the first 30 min following the injection. The degree of enhancement of an infarcted region (with normal flow) above normal tissue was comparable between the two techniques at the point in the constant infusion at which the volume of contrast injected was the same as in the bolus case, i.e., at approximately 30 min after the bolus injection. The constant infusion approach became superior thereafter as overall tissue concentrations became greater in both normal and infarcted tissue, and these concentrations remained more stable with the constant infusion approach. Preliminary experimental results in a canine model of infarction/reperfusion illustrated a delayed wash-in of contrast agent in infarcted tissue, which may be explained by a physiological model in which dead myocytes in infarcted myocardium have non-infinite permeability.
模拟结果表明，其说明了血管外细胞外（EVEC）造影剂（如钆喷酸葡胺）在心肌组织中的浓度-时间曲线是如何变化的。模拟结果显示，近期心肌梗死区域内死亡心肌细胞的可变渗透性将显著改变团注后延迟强化模式，必然会降低该技术检测永久性受损组织的敏感性。进一步预测，如果在团注后进行适当选择的持续输注，则梗死面积和梗死分布容积可能会更准确地确定，尽管在注射后的前30分钟内，团注技术使梗死区域（血流正常）相对于正常组织的强化程度略高。在持续输注过程中，当注入的造影剂体积与团注时相同时，即在团注后约30分钟时，两种技术下梗死区域（血流正常）相对于正常组织的强化程度相当。此后，持续输注方法变得更具优势，因为正常组织和梗死组织中的总体组织浓度都更高，并且持续输注方法下这些浓度保持更稳定。梗死/再灌注犬模型的初步实验结果表明梗死组织中造影剂的延迟注入，这可以用一个生理模型来解释，即梗死心肌中的死亡心肌细胞具有非无限渗透性。
