Gayed Isis, Vu Thuan, Iyer Revathy, Johnson Marcella, Macapinlac Homer, Swanston Nancy, Podoloff Donald
Department of Nuclear Medicine, M.D. Anderson Cancer Center, University of Texas, Houston, Texas 77030, USA.
J Nucl Med. 2004 Jan;45(1):17-21.
Gastrointestinal stromal tumors (GISTs) are gaining the interest of researchers because of impressive metabolic response to the targeted molecular therapeutic drug imatinib mesylate. Initial reports suggest an impressive role for (18)F-FDG PET in follow-up of therapy for these tumors. However, the role of (18)F-FDG PET versus that of CT has not been established. Therefore, we compared the roles of (18)F-FDG PET and CT in staging and evaluation of early response to imatinib mesylate therapy in recurrent or metastatic GIST.
The study included 54 patients who underwent (18)F-FDG PET and CT scans within 3 wk before initiation of imatinib mesylate therapy. Forty-nine of these patients underwent repeat scans 2 mo after therapy. The numbers of sites or organs containing lesions on (18)F-FDG PET and CT scans were compared. Corresponding lesions on (18)F-FDG PET and CT scans or those confirmed to be malignant in appearance by other imaging modalities or on follow-up were considered true positives. Lesions seen on (18)F-FDG PET or CT scans but not seen or confirmed to be of benign appearance with other imaging modalities or on follow-up were considered false positives. Measurements of the maximum standard uptake value (SUV) on (18)F-FDG PET scans and tumor size on CT scans were used for quantitative evaluation of early tumor response to therapy.
A total of 122 and 114 sites and/or organs were involved on pretherapy (18)F-FDG PET and CT scans, respectively. The sensitivity and positive predictive values (PPVs) for CT were 93% and 100%; whereas these values for (18)F-FDG PET were 86% and 98%. However, the differences between these values for CT and (18)F-FDG PET were not statistically significant (P = 0.27 for sensitivity and 0.25 for PPV). This suggests comparable performance of (18)F-FDG PET and CT in staging GISTs. Repeat scans at 2 mo after therapy showed agreement between (18)F-FDG PET and CT scans in 71.4% of patients (57.1% having a good response to therapy and 14.3% lacking a response). Discrepant results between (18)F-FDG PET and CT were recorded for 28.6% of the patients. (18)F-FDG PET predicted response to therapy earlier than did CT in 22.5% of patients during a longer follow-up interval (4-16 mo), whereas CT predicted lack of response to therapy earlier than (18)F-FDG PET in 4.1%. One patient did not undergo long-term follow-up. These findings suggest that (18)F-FDG PET is superior to CT in predicting early response to therapy in recurrent or metastatic GIST patients.
The performances of (18)F-FDG PET and CT are comparable in staging GISTs before initiation of imatinib mesylate therapy. However, (18)F-FDG PET is superior to CT in predicting early response to therapy. Thus, (18)F-FDG PET is a better guide for imatinib mesylate therapy.
胃肠道间质瘤（GISTs）因对靶向分子治疗药物甲磺酸伊马替尼有显著的代谢反应而引起研究人员的关注。初步报告表明，（18）F-FDG PET在这些肿瘤的治疗随访中发挥着重要作用。然而，（18）F-FDG PET与CT的作用尚未明确。因此，我们比较了（18）F-FDG PET和CT在复发性或转移性GIST中甲磺酸伊马替尼治疗的分期及早期反应评估中的作用。
本研究纳入了54例在开始甲磺酸伊马替尼治疗前3周内接受（18）F-FDG PET和CT扫描的患者。其中49例患者在治疗2个月后接受了重复扫描。比较（18）F-FDG PET和CT扫描中含有病变的部位或器官数量。（18）F-FDG PET和CT扫描上相应的病变，或经其他影像学检查或随访证实外观为恶性的病变被视为真阳性。在（18）F-FDG PET或CT扫描上看到但经其他影像学检查或随访未看到或未证实为良性外观的病变被视为假阳性。（18）F-FDG PET扫描上的最大标准摄取值（SUV）测量值和CT扫描上的肿瘤大小用于定量评估肿瘤对治疗的早期反应。
治疗前（18）F-FDG PET和CT扫描分别累及122个和114个部位和/或器官。CT的敏感性和阳性预测值（PPV）分别为93%和100%；而（18）F-FDG PET的这些值分别为86%和98%。然而，CT和（18）F-FDG PET这些值之间的差异无统计学意义（敏感性P = 0.27，PPV P = 0.25）。这表明（18）F-FDG PET和CT在GIST分期中的表现相当。治疗2个月后的重复扫描显示，71.4%的患者（18）F-FDG PET和CT扫描结果一致（57.1%对治疗反应良好，14.3%无反应）。28.6%的患者（18）F-FDG PET和CT结果存在差异。在更长的随访期（4 - 16个月）内，22.5%的患者中（18）F-FDG PET比CT更早预测治疗反应，而4.1%的患者中CT比（18）F-FDG PET更早预测无治疗反应。1例患者未进行长期随访。这些发现表明，在预测复发性或转移性GIST患者的早期治疗反应方面，（18）F-FDG PET优于CT。
在开始甲磺酸伊马替尼治疗前，（18）F-FDG PET和CT在GIST分期中的表现相当。然而，（18）F-FDG PET在预测早期治疗反应方面优于CT。因此，（18）F-FDG PET是甲磺酸伊马替尼治疗更好的指导。
