FDG PET对非小细胞肺癌合并肺不张三维适形放疗时靶区确定的临床意义

Targetting in atelectatic lung by positron emission tomography in non-small cell lung cancer patients treated with three-dimensional conformal radiation therapy

目的 探讨^18F-脱氧葡萄糖（FDG）PET对合并肺不张的非小细胞肺癌（NSCLC）行三维适形放疗时病变靶区确定的临床意义。方法 对14例经病理组织学证实为NSCLC且其影像学检查伴有不同程度肺不张者，先后行胸部增强明扫描及胸部或全身FDGP盯肿瘤显像。根据扫描及显像结果勾画原发病灶范围，分别称为CT-GTV和PET-GTV，并由CMS治疗计划系统给出GTV体积的具体数值加以比较。结果 全部患者的CT-GTV与PET-GTV均有不同程度差别，其中1例患者PET-GTV较CT-GTV增加16．9％（22cm^3），CT-GTV为130cm3，PET-G11V为152cm^3；13例患者PET-GTV较CT-GTV平均减少20．4％（27．2cm^3），CT-GTV平均为133cm^3（90-180cm^3），PET-GTV平均为106cm^3（60—153cm^3）（P=0．000）。GTV的减少主要原因是PET显像除外了因肿瘤原因造成的肺不张，从而引起靶区范围的缩小，进而避免对周围正常组织（主要是正常或不张的肺组织、脊髓及心血管）的不必要照射，最大限度地保护了正常组织。结论 FDG PET在确定肺不张与局部病变相互关系方面具有一定临床价值，并由此提高了靶区定位的精确性。

Objective To investigate the potential benefit of incorporating fluorodeoxyglucose positron emission tomography（FDG PET） to delineate the gross tumor volunre（GTV） in patients with non-small cell lung cancer（NSCLC） complicated with atelectasis who are to be treated with three-dimensional conformal radiation therapy （3DCRT）. Methods Fourteen patients histopathologically proven as having NSCLC with image diagnosed as complicated with various degrees were studied in this study. All patients were scanned with bith thoracic CT and thoracic or whole body PET. The GTV was delineated basing on both CT image and PET image（ CT-GTV, PETGTV） and the volume of each GTV（designated CT-GTV and PET-GTV） was compared by 3DCRT plan. Results Each paired CT-GTV and PET-GTV was different from each other. All patients＇ GTV was reduced to an average of 27 cm^3（20.4%） with median CT-PET of 133 cm3（90-180 cm^3） and median PET-GTV of 106 cm3, with a increase of 16.9% ,22 cm^3）. The reduction of PET-GTV was due to PET could so differ cancer-induced atelectasis from gross tumor that it reduced the tarbet volume and spared more surrounding normal tissues. Conclusions The incorporation of FDG PET data with gross tumor delineation is able to improve the accuracy of 3DCRT for nonsmall cell lung cancer patients complicated with atelectasis.