A Comparative Study On The Diagnostic Value Of 18F-FDG PET-CT And WB-DWI In TNM Staging Of Colorectal Cancer Patients

Objectives: In this paper, we explore the application value of 18F-FDG PET-CT and WB-DWI in TNM staging of colorectal cancer by the standard of clinical and pathological staging, and make a comparative study, aiming to provide a basis for choosing a better imaging methods in clinic.Materials and Methods: 60 patients, all of which were definitely diagnosed by colonoscopy, with colorectal cancer in our hospital from January 2012 to October 2014 were studied. Each group 30 cases respectively diagnosed by 18F-FDG PET-CT and WB-DWI.The primary tumor of all patients without distant metastasis were confirmed by surgical pathology, those patients with distant metastasis without operation were confirmed by MR and clinical follow-up in 3-6 months. Lymph node metastases were confirmed by lymph node dissection and pathology; distant metastasized lesions were confirmed by biopsy, CT and MR, and clinical follow-up in 3-6 months. Distant metastasis lesion biopsy without operation were cofirmed by biopsy Bultrasound, CT, MR and whole body bone SPECT imaging, and the clinical follow-up in 3-6 months.18F-FDG PET-CT scan used a GE Discovery STE PET-CT machine, WB-DWI scan used Siemens Skyra 3.0T MRI. The test results of PET-CT and WB-DWI were separately checked by two physicians with more than 3 years’ working experience of PET-CT and WB-DWI. TNM classification used the method of TNM staging modified in 2003, which was developed jointly by the Union for International Cancer Control(UICC) and the American Joint Committee on Cancer(AJCC). Statistical methods: The software of SPSS13.0 was used in the data analyzing and processing. The diagnostic accuracy of T staging of colorectal cancer by the two methods, the sensitivity, specificity, false positive rate and false negative rate of M stage and N stage were calculated. c 2was employed for the comparison between two calculating methods. The variation were in statistical sense when P<0.05.The consistency of the two methods with clinical pathologic stages was analysized by Kappa test separately.Results: 1. The overall diagnostic accuracy(in 30 cases) of PET-CT for colorectal cancer T staging was 63.3%, K=0.421, reached the moderate consistency with the results of the pathological stage. The overall diagnostic accuracy(in 30 cases) of WB-DWI for colorectal cancer T staging was 66.7%. K=0.466, reached the moderate consistency with the results of the pathological stage. The difference was in no statistical sense after compared with two methods for P>0.05.2. The diagnostic sensitivity(in 30 cases) of PET-CT for colorectal cancer N staging was 77.8%, specificity 75.0%, accuracy 76.7%. K=0.650, of good consistency with the results of clinical pathology. The diagnostic sensitivity(in 30 cases) of WB-DWI for colorectal cancer N staging was 68.4%, specificity 81.8%, accuracy 73.3%. K=0.650, of good consistency with the results of clinical pathology. The difference was in no statistical sense after compared with two methods for P>0.05.3. The diagnostic sensitivity(in 30 cases) of PET-CT for colorectal cancer M staging was 100%, specificity 100%, accuracy 100%. K=1.000, consistent with the results of pathological stage. The diagnostic sensitivity(in 30 cases) of WB-DWI for colorectal cancer M staging was 100%, specificity 96.0%, accuracy 96.7%. K=0.889, of superb consistency with the results of pathological stage. The difference was in no statistical sense after compared with two methods for P>0.05.Conclusion: 1. There is no statistically significant difference between the two methods of PET-CT and WB-DWI in N staging of colorectal cancer. However, the WB-DWI displays a stronger capacity of the intestinal wall than PET-CT for combining T2 WI image.2. There is no statistically significant differe nce between the two methods of PET-CT and WB-DWI in N staging of colorectal cancer. It is difficult for WB-DWI in accurately orientating the small focus, because of the lack anatomic information res ulted by the restraint of background signal. Nevertheless, PET-CT can provide the location, the size and metabolism signal of lymph nodes with the better images.3. There is no significant statistically difference in M staging of colorectal cancer between PET-CT and WB-DWI, both with high sensitivity and specificity and accuracy rate. In some organs, taking lung metastases as an example, the display capacity of PET-CT is higher than WB-DWI, and the image quality is better than WB-DWI.