Li Yuezhi, Li Mingzhao, Xu Tao
Department of Engineering, Shenzhen University, Shenzhen, P.R. China.
J Fluoresc. 2007 Nov;17(6):643-8. doi: 10.1007/s10895-006-0072-1. Epub 2006 Jun 23.
The difference in time-resolved fluorescence spectrum between the cortical sarcoma and the adjacent normal tissue was studied in both experimental and theoretical ways. The Clinical data were obtained in vivo using a time-resolved fluorescence spectrometer employing a single fiber-optic probe for excitation and detection. Tissue was modeled as s-180 sarcoma tumor surrounded with normal muscle and was mediated by the Palladium-porphyrin photosensitizer (Pd-TCPP). The emitted fluorescence was considered as arising from the tumor tissue or the normal muscle, due to the presence of the photosensitizer. A computational code which could simulating time-resolved fluorescence emission was presented and applied to comparing fluorescence decay of photosensitizer in different stages of tumor growth. In this code the different stages of the tumor was modeled through changing the time tau, the delay of the fluorescence photon emission and z (max), the thickness of the tumor. It was found in the in vivo experiment that the fluorescence from tumor tissue decayed more quickly than from the adjacent normal muscle. For the ten rats in the first experiment day, the mean decay constant of tumor T (s) and normal tissue T (n) were 554 and 526 mus, respectively. And T (s) increased with the tumor growth, from 554 mus in the first day to 634 mus in the eighth day while T (s) kept steady. It was believed that the more adequate oxygen supplied by the normal tissue can more effectively quench the fluorescence and in the normal tissue the photosensitizer lifetime is smaller. As a result the simulated time-resolved fluorescence spectrum of normal tissue showed more quickly decay. And the thickness of the tumor can also delay the fluorescence decay. Both the experimental and simulated results indicated that the germination of the tumor would increase the decay constant of the time-resolved fluorescence spectrum. So decay constant of the tumor tissue spectrum should be larger than that of adjacent normal tissue for the reason of hypoxia and overgrowth. This fact could be of use in the tumor diagnoses.
采用实验和理论相结合的方法，研究了皮质肉瘤与其相邻正常组织之间时间分辨荧光光谱的差异。临床数据是在活体状态下，使用配备单光纤探头进行激发和检测的时间分辨荧光光谱仪获取的。将组织建模为被正常肌肉包围的S-180肉瘤肿瘤，并由钯卟啉光敏剂（Pd-TCPP）介导。由于光敏剂的存在，所发射的荧光被认为来自肿瘤组织或正常肌肉。提出了一个能够模拟时间分辨荧光发射的计算代码，并将其用于比较肿瘤生长不同阶段光敏剂的荧光衰减情况。在该代码中，通过改变时间τ（荧光光子发射的延迟时间）和z（max）（肿瘤的厚度）来模拟肿瘤的不同阶段。在活体实验中发现，肿瘤组织发出的荧光比相邻正常肌肉发出的荧光衰减得更快。在实验的第一天，对于十只大鼠，肿瘤T（s）和正常组织T（n）的平均衰减常数分别为554和526微秒。并且T（s）随着肿瘤生长而增加，从第一天的554微秒增加到第八天的634微秒，而T（n）保持稳定。据信，正常组织提供的更充足的氧气能够更有效地淬灭荧光，并且在正常组织中光敏剂的寿命更短。结果，正常组织的模拟时间分辨荧光光谱显示衰减更快。并且肿瘤的厚度也会延迟荧光衰减。实验和模拟结果均表明，肿瘤的萌发会增加时间分辨荧光光谱的衰减常数。因此，由于缺氧和过度生长，肿瘤组织光谱的衰减常数应大于相邻正常组织的衰减常数。这一事实可用于肿瘤诊断。
