***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: OBJECTIVE This study was conducted to determine the criteria for unresectability of major peripancreatic vessels in patients with pancreatic carcinoma as revealed by optimally enhanced , pancreatic-phase thin-section helical CT . SUBJECTS AND METHODS Twenty-five patients with pancreatic adenocarcinoma who underwent local dissection during curative or palliative surgery also underwent preoperative pancreatic-phase thin-section helical CT  ( 40- to 70-sec delay , 2.5- to 3-mm collimation ) . Tumor involvement of the portal and superior mesenteric veins and the celiac , hepatic , and superior mesenteric arteries was prospect ively grade d on a 0 - 4 scale based on circumferential contiguity of tumor to vessel . Subsequent surgical results were then correlated with the CT grade s. RESULTS At surgery , definitive evaluation was possible for 80 vessels . Forty-eight of 48 vessels grade d 0 and three of three vessels grade d 1 were resectable . Four of seven vessels grade d 2 , seven of eight vessels grade d 3 , and 14 of 14 vessels grade d 4 were unresectable . A threshold of between grade s 2 and 3 , which corresponded to tumor involvement of one-half circumference of the vessel , yielded the lowest number of false-negatives and an acceptable number of false-positives for unresectability . Such a threshold would have yielded a sensitivity of 84 % , a specificity of 98 % , a positive predictive value of 95 % , and a negative predictive value of 93 % for unresectability of the vessels studied . CONCLUSION A grading system for tumor involvement of the major vessels in patients with pancreatic adenocarcinoma can be based on the degree of circumferential contiguity of tumor to vessel . Involvement of vessel to tumor that exceeds one-half circumference of the vessel is highly specific for unresectable tumor BACKGROUND Complex , highly variable , anatomic relationships in the portal hilum complicate the surgical management at hilar cholangiocarcinoma . Preoperative three-dimensional ( 3D ) imaging to stage the tumor and define anatomy may help in planning for curative resection . METHODS Between 2003 and 2006 , 20 consecutive patients with hilar cholangiocarcinoma underwent preoperative multidetector row computed tomography ( MDCT ) cholangiography ;  3D images of the portal vein , hepatic artery , and bile ducts were created and viewed simultaneously . Longitudinal tumor extension was evaluated by direct cholangiography and 3D cholangiography , and contiguous spread by 2D computed tomography ( CT ) .  Of 20 patients , 15 underwent surgical resection . Liver resection was planned based on 3D imaging that allowed visualization of the relationship between the tumor and the umbilical portion of the left portal vein , or the bifurcation of the anterior and posterior branch of the right portal vein . Preoperative and operative findings were compared . RESULTS All patients tolerated  3D CT without serious complication . The accuracy rates of longitudinal tumor extension , using the Bismuth-Corlette classification system , were 85 % ( 11/13 ) and 87 % ( 13/15 ) with direct cholangiography and 3D cholangiography , respectively . The sensitivity , specificity , and accuracy rates were 100 % , 80 % , and 87 % for portal invasion and 75 % , 91 % , and 87 % for hepatic arterial invasion . The number of bile duct orifices in the cut end of the hilar plate was estimated correctly in 13 of 15 patients . There were no operative deaths . Potentially curative resection was achieved in 14 of 15 patients . CONCLUSIONS 3D images provide accurate information about the relationship between hilar cholangiocarcinoma and adjacent vessels . This technique is a powerful new tool for improving the proportion of potentially curative resection The pre-operative radiological assessment of proximal bile duct tumours is clinical ly important as resection may be limited by tumour extension along the bile ducts , into hepatic parenchyma or the adjacent vascular structures . Demonstration of the extent of biliary and vascular involvement can direct additional investigations and definitive treatment . 22 patients with hilar cholangiocarcinoma were studied pre-operatively by conventional ultrasound ( US ) and duplex sonography ( DS ) . The extent of tumour infiltration and vascular involvement was compared with arteriography and operative findings . Bile duct dilatation and the level of obstruction was documented by US in 22 ( 100 % ) , and the tumour was shown by US in 19 ( 86 % ) . In these 19 patients , the extent of extraductal extension compared with operative findings was correct in 13 , underestimated in two , and in four infiltration was massed . Vascular patency or involvement was correctly determined by DS in 19 ( 86 % ) , and by arteriography in 18 ( 82 % ) . In two of the three incorrect DS interpretations , lobar atrophy and contralateral hypertrophy distorted the hilar anatomy . US with DS is valuable in the pre-operative staging of proximal bile duct tumours in predicting ductal and vascular involvement BACKGROUND / AIMS To evaluate prospect ively the preoperative use of 16-multidetector computed tomography ( MDCT ) with cholangiography and angiography in determining the resectability of hilar cholangiocarcinoma . METHODOLOGY From January 2002 to January 2008 , 75 consecutive patients with hilar cholangiocarcinoma underwent preoperative MDCT with cholangiography and angiography .  3D images of the portal vein , hepatic artery , and bile ducts were created and viewed simultaneously . The accuracy of MDCT with cholangiography and angiography was determined by comparison with intraoperative and pathologic findings . RESULTS All patients tolerated the CT imaging well and without serious complication . The sensitivity , specificity , and accuracy rates were 92.9 % , 100 % , and 96 % for portal vein invasion and 83.3 % , 100 % , and 93.3 % for hepatic arterial invasion . The accuracy rate of longitudinal tumor extension , using the modified Bismuth-Corlette classification , was 96 % . The sensitivity , specificity , and accuracy of prediction of resectability were 95.7 % , 82.1 % , and 90.7 % , respectively . CONCLUSIONS Preoperative MDCT with cholangiography and angiography gave a good assessment of the degree of biliary and vascular involvement of hilar cholangiocarcinoma . It also accurately predicted resectability BACKGROUND The purpose of the current study was to evaluate the accuracy of (18)F-FDG PET/CT in staging hilar cholangiocarcinoma . MATERIAL S AND METHODS From June 2004 to December 2007 , patients evaluated for surgical treatment of hilar cholangiocarcinoma were entered into a prospect i ve data base . Dual modality (18)F-FDG PET/CT was performed before surgery . The report was review ed with comparison to the operative and pathological results in each case for tumour-node-metastasis staging . RESULTS Seventeen patients ( 6 women , 11 men ) of a median age of 62 years were included in the study . Radical tumour resection was performed on seven patients . Ten patients underwent surgical exploration . The sensitivity of PET/CT  in detecting primary tumour was found to be 58.8 % ( 25 % in T2 tumour , 70 % in T3 tumour , 66.7 % in T4 tumour ) . The sensitivity/specificity of PET/CT in detecting lymph node metastasis and distant metastasis were 41.7%/80 % and 55.6%/87.5 % , respectively . Positive (18)F-FDG uptake in the bile duct was found to be associated with surgical non-resectability ( P = 0.05 ) . CONCLUSION Dual-modality PET/CT imaging was found to have a high specificity in detection of lymph node and distant metastasis in hilar cholangiocarcinoma , with a limited value in correct judgement of surgical resectability for tumours in stadium UICC I-III 
    Output:
    
Data primarily concern CT , which has an acceptable accuracy for assessment of ductal extent , portal vein and hepatic artery involvement , but low sensitivity for nodal status