| Part One The Diagnostic Value and Diagnostic Criteria of18F-FDG PET/CT Imaging in Preoperative Staging ofLymph Nodes of Rectal CancerObjective：To evaluate the diagnostic value of18F-FDG PET/CT and diagnostic criteria of18F-FDG PET/CT imaging in preoperative staging of lymph nodes of rectal cancer.Methods：Imaging results from patients underwent18F-FDG PET/CT imaging andcolonoscopy and colonoscopy pathology tips for rectal cancer were reviewed in ourstudy,dating from feb.2013to feb.2014,and all of the patients underwent3.0T MRIconventional sequence and DWI sequence. All of the examination were finished in aweek before the radical surgery and no radiotherapy or chemotherapy in the treatmentof all patients before the radical surgery,postoperative pathology confirmed thediagnosis of rectal cancer.We measured the SUVmax values、the long-axis diametersand the short-axis diameters of lymph nodes on PET/CT images,and final diagnosiswas made by postoperative histopathology if the lymph nodes were metastatic ornon-metastatic. Receiver operating characteristic (ROC) curve was used to assess thediagnostic efficiency of the SUVmax values、the long-axis diameters and theshort-axis diameters of lymph nodes for differentiating metastatic lymph nodes fromnon-metastatic lymph nodes and the optimal diagnostic critical values weredetermined. Use Z test to compare the areas under ROC curve and use χ2test tocompare the sensitivities and specificities.P＜0.05showed that there were significantdifferences between them.Results：32patients with rectal cancer were included in our study,including26males and6famales,and20patients were verified with metastatic lymph nodes by histopatho-logy,12patients were verified with non-metastatic lymph nodes.505lymph nodeswere resected and84lymph nodes were metastatic,421lymph nodes werenon-metastatic.109lymph nodes were found on18F-FDG PET/CT images and66lymph nodes were metastatic,43lymph nodes were non-metastatic. The area under theROC curve of the SUVmax values、the long-axis diameters and the short-axisdiameters of lymph nodes were0.803,0.786and0.815,respectively. Z test showed thatthere were no significant differences between them （P=0.567,P=0.6837, P=0.223）. The best SUVmax value,long-axis diameter,short-axis diameter for preoperativestaging of lymph nodes of rectal cancer was1.65,7.6mm and5.65mm,respectively.The corresponding sensitivities of the best SUVmax value, long-axis diameter andlong-axis diameter were68.2%,71.2%and74.2%,the specificities were86%,74.4%and79.1%and the accuracies were75.2%,72.5%and76.1%, respectively and therewere no significant differences between them.If we considered the lymph node asmetastatic, with either the SUVmax value≥1.65or the short-axis diameter≥5.65mm,the sensitivity would reach80.3%and the accuracy would reach78.9%,thespecificities decreased slightly than the SUVmax value or the short-axis diameteralone but there were no significant differences between them.Conclusions：18F-FDG PET/CT imaging in preoperative staging of lymph nodes of rectalcancer had some superior clinical value.With the diagnostic criteria of either theSUVmax value≥1.65or the short-axis diameter≥5.65mm,the sensitivity and theaccuracy of preoperative staging of lymph nodes of rectal cancer would be higher by18F-FDG PET/CT and the specificities decreased slightly than the SUVmax value orthe short-axis diameter alone. Part Two The Diagnostic Value of Combining18F-FDGPET/CT with3.0T MRI-DWI Imaging in PreoperativeStaging of Lymph Nodes of Rectal CancerObjective：To evaluate the diagnostic value of combining18F-FDG PET/CT with3.0T MRI-DWIimaging in preoperative staging of lymph nodes of rectal cancer.Methods：Imaging results from patients underwent18F-FDG PET/CT imaging andcolonoscopy and colonoscopy pathology tips for rectal cancer were reviewed in ourstudy,dating from feb.2013to feb.2014,and all of the patients underwent3.0T MRIconventional sequence and DWI sequence. All of the examination were finished in aweek before the radical surgery and no radiotherapy or chemotherapy in the treatmentof all patients before the radical surgery,postoperative pathology confirmed thediagnosis of rectal cancer.We predicted nodal staging of rectal cancer on PET/CT andMRI-DWI, and final diagnosis was made by postoperative histopathology. N stagingstandard referenced the newest USA United Cancer Council (AJCC)/International Union againstcancer (UICC)TNM staging for colorectal cancer.Use Kappa consistency test to examine therelationship between diagnosis methods and pathological result and use χ2test to examine thedifferences between each data. P＜0.05showed that there were significant differencesbetween them.Results：32patients with rectal cancer were included in our study,including26males and6famales,and20patients were verified with metastatic lymph nodes by histopatho-logy,12patients were verified with non-metastatic lymph nodes. The sensitivities ofPET/CT、MRI-DWI and the combination of PET/CT with MRI-DWI for lymph nodesstaging of rectal cancer were85%,75%,90%, the specificities were58.3%,66.7%and66.7%, the accuracies were75%,71.9%and81.3%, and the Kappa values were0.448,0.41,0.586. χ2tests showed that there were no statistically differences betweenPET/CT、MRI-DWI and the combination of PET/CT with MRI-DWI for preoperativestaging of lymph nodes of rectal cancer.Conclusions：The combination of18F-FDG PET/CT with3.0T MRI-DWI for preoperativestaging of lymph nodes of rectal cancer was superior to PET/CT or3.0T MRI-DWI alone, a higher sensitivity,a higher accuracy and a higher N staging accuracy wouldbe revealed and the specificitie was the same with3.0T MRI-DWI.To make sure thediagnosis value of combination18F-FDG PET/CT with3.0T MRI-DWI forpreoperative staging of lymph nodes of rectal cancer needed to collect more patientsand study further. |
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