Laser-induced interstitial thermotherapy of liver tumors using real-time MR-monitoring sequence: fundamental and clinical examinations

作为一项基础实验，激光照射动物体内和离体肝脏，在不同的激光应用参数下使用不同的参数。使用的设备是Dornier Medilas Fibertom 5100 (Dornier Medizintechnik, Germany)，产生波长为1064nm的Nd:YAG激光器。在宏观和显微镜下评估热消融病变的大小。我们评估了激光输出(W)与病变大小之间的关系，照射时间与病变大小之间的关系，以及体外和体内肝脏病变大小的差异。由此可见，在25W（最大输出）输出时，热烧蚀病灶的尺寸最大，且随激光照射时间的增加而增大。在相同参数下，体内肝脏的病变大小比体外肝脏小约1/9。因此，在实际临床应用中，为了有效治疗肝脏肿瘤，应将激光输出功率设置得尽可能高。采用开放磁场的0.2T MAGNETOM OPEN VIVA (Siemens, Germany)，对2D-FLASH和True FISP等多个MR序列进行评估，用于动物肝脏LITT的在线监测。激光通过激光尖端照射，输出功率分别为25W和10W。在整个过程中，大约每30秒获得一次连续MR图像。对比所有MR图像的信号变化和动物肝脏的实际热变化，2D-FLASH在实时监测LITT方面优于True FISP。为了临床应用，将激光光纤用专用的涂抹器置入肝脏肿瘤。未获厚生劳动省批准临床使用。因此，对患者转移性肝肿瘤的实际例子的强制执行尚未完成，将是一个未来的课题。然而，我们正在通过动物实验来检查LITT操作的安全性。LITT有望成为转移性肝肿瘤的一种有用的治疗选择，特别是考虑到MR. Less对热消融变化的实时监测

As a fundamental experiment, laser irradiation was applied to both in-vivo and in-vitro animal livers, using various parameters under various parameters of laser application. The equipment used is Dornier Medilas Fibertom 5100 (Dornier Medizintechnik, Germany) which generates Nd:YAG laser with a wavelength of 1064nm. Size of thermoablative lesions were evaluated both macroscopically and microscopically. We evaluated a relationship between laser output (W) and lesion size, a relationship between irradiation time and lesion size, and a difference of lesion size between in-vitro and in-vivo liver.Consequently, it became clear that size of thermoablative lesion was the maximum at the output of 25W (maximum output) and increased in proportion to laser irradiation time. Moreover, lesion size of in-vivo liver turned out to be smaller than that of in-vitro liver by about 1/9 under same parameters. Therefore, in actual clinical application, in order to treat liver tumors effectively, a laser ou … More tput should be set as high as possible.Using 0.2T MAGNETOM OPEN VIVA (Siemens, Germany) of the open magnetic field, several MR sequences, including 2D-FLASH and True FISP, were evaluated for online monitoring of LITT of animal liver. Laser irradiation were applied through laser tip in 25W and 10W output. Serial MR images were obtained approximately every 30 second during procedure. Comparing signal changes of all MR images and actual thermal changes of animal liver, 2D-FLASH was superior to True FISP for real-time monitoring of LITT.For clinical application of LITT, laser fiber was placed into liver tumors using special applicator. Applicator is not approved for clinical use by Ministry of Health, Labor and Welfare. Therefore, enforcement to the patient to the actual example of metastatic liver tumors was not completed and will be a future subject. However, the safety of LITT procedure was being checked through our animal experiment. LITT is expected to be a useful therapeutic option for metastatic liver tumors, especially in view of the real-time monitor of the thermoablative change by MR. Less