正电子发射断层延迟显像在腹部和盆腔的应用

为明确正电子发射断层(PET)延迟显像对常规显像发现的腹部或盆腔可疑病灶的进一步诊断价值,对70例患者在注射18F-脱氧葡萄糖后约3h进行延迟显像,期间通过饮水、进食、排尿或排便等改变胃肠道及泌尿系统的生理状态。通过病理诊断或临床随访,33例诊为恶性肿瘤,37例为生理性摄取或良性病变。以延迟显像中病灶的标准摄取值降低或升高超过10%诊断良性或恶性,则灵敏度、特异性、准确性、阳性预测值和阴性预测值分别为51%(17/33)、62%(23/37)、57%(40/70)、81%(17/21)和85%(23/27)。故PET延迟显像对腹部和盆腔病变具有一定的鉴别诊断价值。但须注意子宫、卵巢生理性摄取可导致假阳性,而胃癌在进食撑开胃部后摄取可能会减低。

The role of delayed imaging of positron emission tomography on differentiation of abdominal and pelvic lesions

The value of delayed imaging of positron emission tomography(PET) was assessed by analyzing 70 patients with suspicious abdominal or pelvic lesions on routine whole-body studies.The delayed imaging was performed nearly 3 hours after injection of 18F-fluorodeoxyglucose(FDG),and before that,the patients were suggested to drink water,take food,urinate,and even defecate to change the physiological status of gastrointestinal system and urinary system.Thirty-three cases were finally proved as malignancies,including cervical or ovarian cancers(13),gastric cancer(10),colorectal carcinoma(4),and others(6) by pathology and/or clinical follow-up;thirty-seven were diagnosed as physiological or benign uptake,including physiological uterine or ovarian uptake(18),regional bowel uptake(8),regional urine retention(7),and others(4).In delayed imaging,the standardized uptake value(SUV) of the lesions increased more than 10% in 21 cases,and the positive predictive value for malignancy was 81%(17/21).The 4 pseudo-positive cases came from the physiological uptakes of uterus or ovaries,which were related to menstrual cycle and could be excluded by correlating with other imaging modalities,such as ultrasonography.The SUV decreased more than 10% in 27 cases,and the negative predictive value was 85%(23/27).Although 3 cases of gastric cancer also had decreased uptake for more than 10%,the lesions were actually much more prominent compared to the distended normal gastric wall after taking food.In conclusion,delayed imaging of FDG PET benefited the differentiation of intense-uptake lesions at abdomen or pelvis.