探讨利用MR钆造影剂清除差异进行脑肿瘤亚靶区勾画的可行性

目的:研究MR钆造影剂清除差异指导脑肿瘤亚靶区勾画的可行性。方法:获取26例脑肿瘤患者T 2加权图像及造影剂注射5、60 min后的T 1加权增强图像，处理两次T 1加权增强图像得到含有造影剂清除差异及有无肿瘤活性信息的延迟造影剂外渗的图像。根据T 2加权图像有无液化坏死...

Evaluation of the feasibility of Gd-based contrast clearance difference to delineate subvolume target in radiotherapy for primary and metastatic brain tumors

Objective To evaluate the feasibility of delineating subvolume target in radiotherapy for brain tumors using Gd-based contrast clearance difference. Methods Twenty-six patients with malignant brain tumors were scanned with MRI. The first and second acquisitions of standard T₂-weighted images (T₂WI) and T₁-weighted images (T1WI) were performed at 5min and 60min after injection of contrast agent. Delayed contrast extravasation (DCEM) MRI computed by Brainlab comprised regions of contrast agent clearance representing active tumors and regions of contrast accumulation representing non-tumor tissues. Based on T₂WI images,14 patients with liquefaction necrosis were divided into group A, and 12 patients without liquefaction necrosis into group B, respectively. Then, gross target volume (GTV) was delineated on T1WI images. Based on the GTV, active tumor (GTV_tumor) and non-tumor regions (GTV_non-tumor) were delineated on T₁WI-DCEM fusion images, while liquefaction necrosis (GTV_liquefaction) and non-liquefaction (GTV_{non-liquefaction}) were delineated on T₁-T2WI fusion images. Finally, the differences between different subvolumes were compared by paired t-test. Results In group A, the GTV_{non-liquefaction} and GTV_liquefaction were (13.65±18.15) cm³ and (6.30±7.57) cm³. The GTV_tumor was (10.40±13.52) cm³ and the GTV_non-tumor was (9.55±14.57) cm³. The GTV_{non-liquefaction} was significantly increased by 16.3% on average compared with the GTV_tumor (P<0.05). The GTV_non-tumor was significantly increased by 16.3% on average compared with the GTV_liquefaction (P<0.05). In group B, The GTV_non-tumor was significantly reduced by 68.8% on average compared with the GTV_tumor (P<0.05). Conclusions Compared with T₂WI, DCEM has advantages in identifying the liquefaction area and can clearly differentiate the subvolume of active tumors from non-liquefaction necrosis. DCEM provides evidence for guiding the delineation of subvolume in primary and metastatic brain tumors.