Kahn T, Bettag M, Ulrich F, Schwarzmaier H J, Schober R, Fürst G, Mödder U
Institute of Diagnostic Radiology, Heinrich Heine University, Düsseldorf, Germany.
J Comput Assist Tomogr. 1994 Jul-Aug;18(4):519-32. doi: 10.1097/00004728-199407000-00002.
Laser-induced interstitial thermotherapy (LITT) using a neodymium:yttrium aluminum garnet (Nd: YAG) laser is a new therapeutic approach in the treatment of brain tumors. The purpose of our study was to determine the value of MRI in monitoring LITT.
Eight patients with intracerebral tumors were treated with LITT. The light guide was inserted via an applicator sheath that was implanted stereotaxically with CT guidance. The laser irradiation was performed within the MR unit and monitored by repetitive measurements of a T1-weighted 2D-FLASH sequence.
During therapy in all patients, typical changes of signal intensity were seen. A gradually increasing central zone of high signal intensity was surrounded by an increasing peripheral area of reduced signal intensity. The diameter of an enhancing rim at the outer border of the peripheral area after Gd-DTPA was considered as the total lesion size. The lesion size as determined on 2D-FLASH scans during LITT accounted for 88-100% (mean 93.5%) of total lesion size on T1-weighted images after Gd-DTPA acquired immediately after therapy. On T2-weighted images the signal intensities of the two zones were vice versa. Follow-up studies showed a decrease of total lesion size (15-87%).
Our results demonstrate that MRI is feasible and effective in monitoring LITT. However, the role of LITT in the therapeutic workup of brain tumors still has to be defined in future clinical studies.
使用钕钇铝石榴石（Nd:YAG）激光的激光间质热疗（LITT）是治疗脑肿瘤的一种新的治疗方法。我们研究的目的是确定MRI在监测LITT中的价值。
8例脑肿瘤患者接受了LITT治疗。光导通过在CT引导下立体定向植入的穿刺鞘插入。激光照射在MR设备内进行，并通过重复测量T1加权二维快速低角度激发（2D-FLASH）序列进行监测。
在所有患者的治疗过程中，均观察到典型的信号强度变化。中央逐渐增加的高信号强度区被周围逐渐增加的低信号强度区包围。钆喷酸葡胺（Gd-DTPA）增强后，外周区域外边界增强环的直径被视为总病变大小。LITT期间二维快速低角度激发扫描确定的病变大小占治疗后立即采集的T1加权图像上钆喷酸葡胺增强后总病变大小（T1WI-Gd）的88%-100%（平均93.5%）。在T2加权图像上，两个区域的信号强度则相反。随访研究显示总病变大小减小（15%-87%）。
我们的结果表明，MRI在监测LITT方面是可行且有效的。然而，LITT在脑肿瘤治疗评估中的作用仍有待未来的临床研究来确定。
