^(18)F-FDGhPET/CT显像在肿瘤诊断中的应用

Applications of ^(18)F-FDG imaging with a dual head coincidence SPECT/CT in the detection of tumors

采用双探头单光子发射型计算机断层(Singlephotonemissioncomputedtomography,SPECT)显像仪(Hawkeye,1英寸NaI晶体)对109例确诊或疑有恶性肿瘤者进行了18F-脱氧葡萄糖(18F-Fluoro-2-deoxyglucose,18F-FDG)符合线路显像,每位患者在空腹状态下静脉注射18F-FDG222—296MBq,安静休息约40—60min后开始采集图像数据。经CT自动生成的衰减校正图校正,用迭代法预先分组最大期望值法(Orderedsubsetsexpectationmaximization,OSEM)进行图像重建,获得横断面、矢状面和冠状面图像,以及三维(3D)、CT和同机FDG图像融合。显示109例患者中最后确诊为恶性肿瘤者89例,进行18F-FDG检查后,发现显像阳性者87例,灵敏度为94.38%(84/89),其中假阳性3例,阳性预测值96.6%(84/87);显像阴性者22例,其中假阴性4例,特异性为90%(18/20),阴性预测值81.8%(18/22)。18F-FDG符合线路显像(hybridpositronemissioncomputedtomography,hPET)显像结果与CT或B超检查结果相一致的有26例(24%)、不一致的有73例(66.97%),其中18F-FDG检查结果中其病变范围较CT或B超病灶数增多的有52例(71.23%),而病灶数减少的仅有5例(6.85%)。表明18F-FDG-hPET显像对肿瘤的诊断具较良好的灵敏度与特异性。采用FDG显像与CT同机融合技术能进一步改进病灶的定位,从而有助于肿瘤良恶性的鉴别;肿瘤患者的分期与再分期;残留肿瘤组织和复发的检测;手术、化疗或放疗方案的制定和随访;以及预后的估测。随着临床经验的积累和技术的改进,18F-FDG符合线路显像必将更广泛得到应用。但是由于受SPECT分辨率的限制,以及种种炎性病变所致假阳性等,在实际的应用中,必须结合临床资料和其他影像资料加以考虑,才能作出正确诊断。

The objective of the work is to assess the clinical value of ^18F-FDG images with a dual head coincidence SPECT （ DHC SPECT ） in the diagnosis of tumors and compare the diagnostic accuracy obtained with a DHC SPECT with those obtained with CT and ultrasound （US）. Total 109 patents with known or suspected malignancies underwent ISF-FDG images 40-50min after injection of 222-296 MBq ^18F-FDG The images were reconstructed using iterative algorithms after attenuation correction with a CT map. 89 of 109 patients were proven to have malignancies. There were 87 patients with positive images including 3 cases of false positive, the sensitivity was 94.38% （84/89） with positive predict value of 96.55% （84/87）. The specificity was 90% （ 18/20 ） with negative predict value of 81.81% （18/22）. There were 26 patients with ^18F-FDG coincidence images matched with CT or US, and 73 cases mismatched with CT or US. 52 patients had more lesions on ^18F-FDG imaging than on CT or US, only 5 patients less than on CT or US. The ^18F-FDG coincidence imaging is therefore a valuable tool for diagnosis of tumors with higher sensitivity and specificity. Combined FDG image with CT will facilitate the precise localization of tumors. It is useful for differentiating malignancy from benign tumor; for tumor staging and restaging; for detecting recurrence or residual tumor; for monitoring the response to treatment including surgery, chemotherapy or radiotherapy; and for predicting the prognosis. With accumulation of clinical experience and improvement of technology, ^18F-FDG coincidence imaging will be popularized. But due to the limitation of SPECT＇s resolution and the false positive from various inflammation, a correct diagnosis must be based on the combination of SPECT imaging with clinical and other imaging data.