| Objetive: To study the value of multiphasic contrast-enhanced 3.0T MRI in the preoperative assessment of resectability in pancreatic cancer,to provide a accurate and safe method for pancreatic cancer patients,and a useful reference for clinic to select appropriate treatment options.Methods: Thirty-eight patients with pancreatic cancer,proved by operation and pathology were performed with multiphasic contrast-enhanced imaging on 3.0T MR,which were collected from April 2013 to March 2015 in The First Hospital of Anhui Medical University.MRI plain scan included axial T1 WI and T2 WI of Fat suppression and MRCP.The dynamic enhanced MRI was performed with the bolus injection of contrast medium for Gadopentetate dimeglumine(0.1mol/Kg,injection speed of 3.0ml/s)through vein on the back of hands.Acquisition image of arterial phase,venous phase and equilibrium phase,which started scan at the twentieth second,the fiftieth second and the one-hundred-eightieth second after contrast medium injection with LAVA sequence.MRI signs as follows indicate that the pancreatic cancer can not be resected:(1)The important vessels near pancreas are invaded,including celiac axis(CA),hepatic artery(HA),superior mesenteric artery(SMA)and portal vein(PV).(2)Two or more organs were invaded,or single organ except spleen was invaded with contact surface larger than 5cm.(3)Liver or distant organs metastasis.(4)Peritoneum,mesenterium and omenta were involved in.The resectable pancreatic cancer should be locating in pancreatic velamen without direct infiltration,and no structure around pancreas is involved in,no lymphaden metastasis and regional lymph node tumidity and no other organ metastasis.The criterion of invasion to vessel around pancreas basing on imaging : Grade 0 : The vessel surrounded by fatty and normal pancreas tissue.Grade1:Less than 1/2 caliber of vessel surrounded by tumor.Grade 2: More than 1/2 caliber of vessel surrounded by tumor.Grade 3: The vessel is imbeded and blocked up,and can not be exhibited or with filling defect in it and bypass circuit formation.It is agreed that grade 0 and l indicate no invasion of vessel and grade 2 and 3 indicate vessel invasion.The standard of predicating the vessel invasion by pancreatic cancer during operation was that these great vessels were found being invaded,imbeded and/or blocked up by tumor through operative exposure or touching,and can not be seperated from tumor.If the adherence between vessel and tumor could be separated,the vessel wasn’t belonged to the invasion.The standard of resectable tumor was that the tumor could be resected completely with pathologic negative cutting edge.If the tumor was resected with positve cutting edge,it was judged unresectable.Kappa test was selected to analyze the accuracy of the possibility evaluation of operative excision.Results:Of 38 pancreatic cancer,32 lesions located in the head,4 tumors in the body and 2 lesions in tail of pancreas.17(44.7%)of them were successful resection,16 lesions(42.1%)with the palliative operation,5 lesions(13.2%)with only the biopsy.MRI predicted 19 tumors resectable and 17 lesions of them were successful resection,the accuracy of the positive predictive value for resectability was 89.5%.Two cases were thought being with resectable tumor by mistake because MRI failed to show the invaded mesenterium,peritoneum and liver capsule metastasis.Nineteen lesions were predicted to be unresectable by MRI and which were verified by surgery,the positive predictive value for unresectability was 100%.MRI signs indicate that the pancreatic cancer can not be resected which the primary causes of unresectability contained peripancreatic main vessels involvement,including celiac axis,hepatic artery,superior mesenteric artery and portal vein.where the vessel is embedded,rigidity wall,less than half caliber of vessel surrounded and blocked up;and bypass circuit formation liver metastasis,lymphadenopathy and peritoneal metastasis.5 lesions with liver metastasis verified by surgical exploration,in which MRI predicted 4 lesions;MRI predicted only1 lesion for ascites formation,while 4 lesions peritoneal metastasis were discovered of intraoperative.Among 16 lesions with the palliative operation,10 cases with vessel near pancreas were invaded,MRI showed eight cases,two cases for initiation part of hepatic artery was failed to show.Eight cases with organs near pancreas invaded,in which MRI correctly showed 7 cases,one was failed to show with invaded gastrocolic omentum.Of 5 lesions with only the biopsy,the vessel of superior mesenteric artery or vein and PV were embedded and blocked completely in all of cases,and node metastasis were touched in the surface of liver in two cases.More than 1/2 caliber of vessel surrounded by tumor and liver metastasis were predicted to be unresectable by MRI and which were verified by surgery.The consistency of results between operation and MRl was satisfied(k=0.83).Conclusions:3.0T MRI multiphasic contrast-enhanced scan has higher sensitivity,specificity and accuracy of the preoperative evaluation on the excision possibility of pancreatic cancer. |
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