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首页> 外文期刊>Photodiagnosis and Photodynamic Therapy >Monitoring photodynamic oxygen consumption by endogenous oxygen contrast MRI
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Monitoring photodynamic oxygen consumption by endogenous oxygen contrast MRI

机译：通过内源性氧气对比MRI监测光动力耗氧量

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摘要

Photodynamic oxygen consumption was measured by changes in spin-lattice relaxation time (T-1)in aqueous solution in a clinical GE scanner at 1.5 T. Similar measurements were attempted in excised laryngeal and thyroid tissues that were infused with Rose Bengal. First, T-1 was measured as a function of dissolved oxygen in argon and in oxygen pre-saturated water samples that were opened to the atmosphere in a series of steps allowing air to diffuse into or out of solution; for both argon and oxygen saturated water solutions, stepwise air re-equilibration resulted in a return to air-saturated water T-1. Secondly, T-1 was measured as a function of time under type II photooxidative conditions in aqueous solution. Under type II photooxidative conditions, a 492 +/- 53 ms increase in T-1 was measured following 300 s of visible light illumination of aqueous solutions containing the photosensitizer Rose Bengal (2.5 x 10(-6)M) and the singlet oxygen trap methionine (0.0012 M). The 492 +/- 53 ms increase in T, corresponded to consumption of all the measurable dissolved oxygen ((-) 0.1 mg O-2 in 15.0 mL of H2O) during photooxidation of methionine in air saturated water. This rapid oxygen consumption, indicated by an increase inT(1), is due to irreversible trapping of photogenerated singlet oxygen by methionine. Thirdly, an increase in T-1 was observed in Rose Bengal infused normal laryngeal tissue, and in normal and cancerous thyroid tissue samples following 20 min of exposure to visible light. An increase in T-1 was not observed after 40 min of illumination which suggests that the increases in T-1 observed after 20 min were not due to water uptake, but rather to photoconsumption of interstitial dissolved oxygen.
机译：通过在临床GE扫描仪中于1.5 T下水溶液中自旋晶格弛豫时间（T-1）的变化来测量光动力耗氧量。在注入玫瑰红的切除的喉和甲状腺组织中尝试了类似的测量。首先，测量T-1作为氩气和氧气预饱和水中样品中溶解氧的函数，这些样品通过一系列步骤向大气开放，使空气扩散到溶液中或从溶液中扩散出来；对于氩气和氧气饱和的水溶液，逐步进行的空气重新平衡导致返回到空气饱和的水T-1。其次，在II型光氧化条件下在水溶液中测量T-1随时间的变化。在II型光氧化条件下，在含有光敏剂Rose Bengal（2.5 x 10（-6）M）和单线态氧陷阱的水溶液的可见光照射300 s后，测得T-1增加492 +/- 53毫秒蛋氨酸（0.0012 M）。 T的增加492 +/- 53 ms，对应于在空气饱和水中的蛋氨酸光氧化过程中所有可测量的溶解氧（在15.0 mL H2O中的（-）0.1 mg O-2（-））的消耗。 T（1）的增加表明这种快速的氧气消耗是由于蛋氨酸不可逆地捕获光生单重态氧。第三，在暴露于可见光20分钟后，在玫瑰孟加拉注入的正常喉组织以及正常和癌性甲状腺组织样本中观察到T-1升高。光照40分钟后未观察到T-1的增加，这表明20分钟后观察到的T-1的增加不是由于吸水，而是由于间隙溶解氧的光消耗。

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