Positron emission tomography with 18F-fluorothymidine for monitoring therapeutic effect after chemoradiation therapy

本研究的目的是评估差异的发生率，并在接受FDG-PET和FLT-PET的患者中获得更准确的诊断。13名患者在完成新辅助化疗或放化疗后接受了FDG-PET和FLT-PET扫描。在38个病灶中，32个为真阳性病灶。有10处病变（26%）的结果不一致。对于这些病变，FDG-PET显示4个真阳性和2个真阴性，FLT-PET显示2个真阳性和2个真阴性。总体而言，FDG-PET基于病变的敏感性、特异性、阳性预测值、阴性预测值和准确性分别为50%、33%、80%、11%和47%，而FLT-PET分别为38%、67%、86%、17%和42%。此外，13名患者进行了FDG-PET和FLT-PET扫描，以进行分化、分期或再分期。在29个病灶中，26个为真阳性病灶。有9处病变（31%）的结果不一致。对于这些病变，FDG-PET显示5个真阳性，FLT-PET显示2个真阳性和2个真阴性。总体而言，FDG-PET的敏感性、特异性、阳性预测值、阴性预测值和准确性分别为62%、33%、89%、9%和59%，而FLT-PET的敏感性、特异性、阳性预测值、阴性预测值和准确性分别为50%、100%、100%、19%和50%。基于这些初步数据，我们得出结论：（i）FDG-PET倾向于产生更多的假阳性结果，而FLT-PET假阴性结果，（ii）诊断差异发生在四分之一到三分之一的病变中，每项研究的准确性为一半，（iii）FLT-PET的阳性预测值相当高。FLT-PET可能有助于检测非FDG-avid转移性病变。

The aim of this study was to assess the prevalence of discrepancy and which yielded more accurate diagnoses in patients who underwent both FDG-PET and FLT-PET. Thirteen patients underwent both FDG-PET and FLT-PET scans after they have completed neoadjuvant chemotherapy or chemo-radiation therapy. Of 38 lesions, 32 were true positive lesions. There were 10 lesions (26%) with discrepant findings. For these lesions, FDG-PET yielded 4 true-positives and 2 true-negatives, and FLT-PET showed 2 true-positives and 2 true-negatives. Overall, the lesion-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FDG-PET were 50%, 33%, 80%, 11% and 47%, respectively, while those of FLT-PET were 38%, 67%, 86%, 17% and 42%, respectively. In addition, 13 patients had FDG-PET and FLT-PET scans for the purpose of differentiation, staging or restaging. Of 29 lesions, 26 were true positive lesions. There were 9 lesions (31%) with discrepant findings. For these lesions, FDG-PET yielded 5 true-positives and FLT-PET showed 2 true-positives and 2 true-negatives. Overall, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FDG-PET were 62%, 33%, 89%, 9%, and 59%, respectively, while those of FLT-PET were 50%, 100%, 100%, 19%, and 50%, respectively. Based on these preliminary data, we concluded (i) FDG-PET tended to yield more false positive findings, while FLT-PET false negative findings, (ii) the diagnostic discrepancy occurred in one-fourth to one-third of the lesions, with the half accuracy of each study, and (iii) the positive predictive value of FLT-PET was reasonably high. FLT-PET could be helpful for detecting non-FDG-avid metastatic lesions.