| Objective:The aim of this study was to evaluate the diagnostic value of positron emission tomography with computed tomography(PET-CT) using18F-fluor-odeoxyglucose (FDG) in detecting retroperitoneal lymph node metastasis in patients with common gynecological malignancies, using histopathologic fndings as reference standard.Methods:This was a prospective study involving30consecutive patients with newly diagnosed gynecological malignant tumors (age range29-81years, mean age51.1years) at our institution between November2010and December2011. All of them underwent PET-CT examination for detecting whether lymph nodes metastasis before surgery. All patients received radical hysterectomy, including pelvic lymphadenectomy with or without para-aortic nodes sampling after PET-CT examination. According to different positions, pelvic lymph nodes and para-aortic lymph nodes were divided into seven regions, and the imaging findings were compared with pathological results. We calculated the sensitivity, specificity, positive predictive value(PPV),negative predictive value(NPV) and accuracy of PET-CT for retroperitoneal lymph node metastasis in common malignant gynecological tumors on regional node-based and patient-based respectively. The Student’s t-test was applied for comparison of the SUVmax of primary tumors with or without lymph node metastases. A level of p value<0.05was regarded as statistically significant.Results:(1) All thirty patients were confirmed gynecological malignancies pathologically and all of them without peri-operative complications. Cervical cancer in14cases (squamous cell carcinoma9, adenocarcinoma4, adenosquamous carcinoma1), endometrial carcinoma in12cases (endometrial adenocarcinoma8, serous papillary adenocarcinoma2, mucinous adenocarcinoma1, clear cell carcinoma1),3cases of serous ovarian cancers and1case of serous fallopian tube caicinoma.(2) According to the pathological results,12patients had lymph node metastasis,7of whom were correctly identified by F-FDG PET-CT. PET-CT accurately diagnosed all18patients without lymph node metastasis. The overall patient-based sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) and accuracy of PET-CT for detecting nodal metastases were58.3%(7/12),100%(18/18),100%(7/7),78.3%(18/23) and83.3%(25/30), respectively.(3)30pathologically positive nodes regions were found in199dissected nodes regions,16of which were accurately identified on the PET-CT imagings. PET-CT examination diagnosed2false-positive regional lymph nodes and14false-negative regional lymph nodes. Thus, the overall regional node-based sensitivity, specificity, positive predictive value(PPV), negative predictive value(NPV) and accuracy were53.3%(16/30),98.8%(167/169),88.9%(16/18),92.3%(167/181) and92.0%(183/199). The sensitivity, specificity, PPV, NPV and accuracy on the basis of analysis of pelvic lymph nodes regions alone were53.9%,99.4%,99.3%,92.7%and92.8%, respectively; the same figures on the basis of analysis of paraaortic lymph nodes regions alone were50.0%,93.3%,66.7%,87.5%and84.2%, respectively.(4) Although the difference has no statistically significant in our series, primary tumor with lymph node metastasis tended to have a larger SUVmax than that without lymph node metastasis.Conclusions:Integrated18F-FDG PET-CT may not have enough sensitivity to predict all metastatic lymph nodes preoperatively in patients with gynecological malignancies. Combined PET-CT demonstrates high positive value in identifying retroperitoneal lymph nodes, suggests that regional lymphadenectomy may be necessary for radical surgery. The high negative value may help in selecting patients who could refrain from retroperitoneal lymphadenectomy in staging operation. |
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