磁共振成像在肺癌放疗肿瘤区确认中的价值

Value of Magnetic Resonance Imaging in Tumor Region of Radiation Therapy Identification

目的:探讨在肿瘤界限不明的肺癌放疗中应用磁共振常规扫描联合扩散加权成像对确定照射范围的作用。方法:选取伴有阻塞性肺炎(6例)或肺不张(24例)的肺癌患者30例。放疗前分别采用1.5 T和3.0 T磁共振成像系统各检查患者15例,DWI在1.5 T和3.0 T扫描中扩散加权系数(b值)分别选择为600 s/mm2和1 000 s/mm2。根据MRI影像判断勾画放疗的肿瘤区(GTV)。结果:3.0 T磁共振成像对比度及信噪比高,判断病变良恶性的价值更大,但超高场强易产生空间几何扭曲伪影。而1.5 T磁共振成像系统中的几何变形相对少,但判断病变良恶性的价值不如3.0 T。MRI可协助明确判断GTV范围的占63.3%。结论:对肺癌患者放疗难以判断GTV界限时,磁共振平扫联合DWI有助于进一步明确靶区的勾画范围,采用1.5 T的磁共振成像系统效果更佳。

Objective To probe into the function of identification in the range of radiation therapy on unknown limits radiotherapy in lung cancer of the application of magnetic resonance imaging（MRI） combined with diffusion-weighted imaging（DWI）.Methods Pathological diagnosis was associated with obstructive pneumonia（6 cases） or atelectasis（24 cases） of 30 patients with lung cancer.Before radiotherapy with 1.5T and 3.0T magnetic resonance imaging system to check 15 patients in two groups each,diffusion-sensitive factor（B value） 1.5T as 600/mm2,3.0T as 1000/mm2.According to MRI image conclusion to outline the gross tumor volume（GTV） of radiotherapy target.Results Due to its high contrast ratio and signal to noise ratio,3.0T was more valuable to diagnose the lesions which were benign or malignant,but the high field strength magnetic field inhomogeneity was easy to produce geometric distortion artifacts.The geometric distortion of 1.5T MRI system was relatively milder,less deformable,but to judge the value of benign and malignant lesions were relatively smaller.MRI could help determine the scope of the GTV clearly accounted for 63.3%.Conclusion When the lung cancer radiotherapy GTV boundary is hard to determine,MRI combined DWI image of the outline will help further clarify the target range.1.5T magnetic resonance imaging system can get better effect.