| Objective:To investigate the diagnostic accuracy of 18F-FDG PET/MR for preoperative TNMstaging of rectal cancer and the relationship between 18F-FDG PET/MR SUVmax and clinicopathological features of colorectal cancer.Subjects and methods:1.A prospective clinical trial was conducted to study 42 cases of rectal cancer,including 24 males and 18 females,with an average age of 62.18± 11.45 years.Inclusion criteria:1.Patients with rectal adenocarcinoma which is pathologically confirmed by colonoscopy biopsy;2.Total Mesorectal Excision will be proposed for the patient and pathological examination after operation is essential;3.Patients without contraindications of MRI and metal implants in the body;4.Patients know the research protocol and sign informed consent.Exclusion criteria:1.The patient is unable to tolerate general anesthesia,such as the combination of severe heart,lung,liver and other major organ dysfunction or serious metabolic diseases;2.Rectal cancer with intestinal obstruction,perforation,or massive hemorrhage;3.Pregnant and lactation patients;4.Patients with severe coagulation dysfunction;5.Extensive metastases in the pelvic cavity;6.patients with claustrophobic intolerance to magnetic resonance examination.TNM staging is according to the eighth edition of "AJCC cancer staging manual" for patients with rectal cancer.Using the postoperative pathological examination as the gold standard to analyze the accuracy,sensitivity and specificity of the TNM staging by 18F-FDG PET/MR,and Kappa test is performed to test the consistency of the results.2.A prospective clinical trial was conducted to study 58 patients with colorectal cancer,including 34 cases of male,24 cases of female;the average age is 60.14±9.27 years;The inclusion criteria were extended to the patients with colorectal cancer on the basis of the first part of the study.The exclusion criteria were adjusted for those who were unable to accept colorectal cancer surgery and colorectal cancer with intestinal obstruction,perforation or massive bleeding.The size of primary tumor is measured by preoperative 18F-FDG PET/MR sagittal and coronal T2WI fat suppression sequence measurement.Regarding the longest diameter as the length of primary tumor.To analyze the relationship between the size of the lesion,sex,age,the degree of differentiation of the tumor,the lymph node and the distant metastasis,and the SUVmax of the primary foci.Results:1.The accuracy rate of 18F-FDG PET/MR was 83.3%(Kappa=0.74,p=0.000),the accuracy rate of T1-T4 was 95.2%(40/42),83.3%(35/42),88%(37/42),100%(42/42);the sensitivity was 75%(3/4),85.7%(18/21),75%(9/12),100%(5/5);specificity was 97.3%(37/38),81%(17/21),93.3%(28/30),100%(37/37);PET on N staging accuracy rate was 81%(34/42)(Kappa=0.586 p=0.000),the sensitivity was 82.1%,specificity 78.6%(23/28)(11/14);M staging accuracy rate was 100%2.The SUVmax in primary colorectal cancer is not related to gender(P=0.193)and age(P=0.714).It is positively correlated with the length and diameter of primary tumor(r=0.433,p=0.001),and negatively correlated with the differentiation degree of tumor tissue.There was no significant difference in the size of primary lesions in different metastatic status(P=0.717),while SUVmax had significant difference(P=0.000),Logistic regression analysis showed that SUvmax was the only factor affecting the transfer,and the risk of metastasis increased by 1.935 times per unit(P=0.001).Conclusions:1.18F-FDG PET/MR is more accurate in the diagnosis of preoperative TNM staging for rectal cancer,especially for the diagnosis of lymph node and distant metastasis,which is superior to the existing methods of examination.2.SUVmax of primary tumor was associated with metastasis of colorectal cancer,and the risk of metastasis increased by 1.935 times per 1 unit of SUVmax(P=0.001).SUVmax of primary tumor can be used as a predictor of lymphatic and distant metastasis of colorectal cancer. |
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