EUS compared with CT, magnetic resonance imaging, and angiography and the influence of biliary stenting on staging accuracy of ampullary neoplasms

Background: Computerized tomography (CT), magnetic resonance imaging (MRI), and transabdominal ultrasound frequently fail to detect ampullary lesions. Endoscopic ultrasound (EUS) is a sensitive modality for detecting and stag ing ampullary tumors. Accurate staging may be affected by biliary stenting, which is frequently performed in these patients with obstructive jaundice. The present study assessed the accuracy of ampullary tumor staging with mu ltiple imaging modalities in patients with and those without endobiliary st ents. Methods: Fifty consecutive patients with ampullary neoplasms from two endos onography centers were preoperatively staged by EUS plus CT (37 patients), MRI (13 patients), or angiography (10 patients) over a 3 1/2 year period. T wenty-five of the 50 patients had a transpapillary endobiliary stent presen t at the time of endosonographic examination. Accuracy of EUS, CT, MRI, and angiography was assessed with the TNM classification system and compared w ith surgical-pathologic staging. The influence of an endobiliary stent pres ent at the time of EUS on staging accuracy of EUS was also evaluated. Results: EUS was more accurate than CT and MRI in the overall assessment of the T stage of ampullary neoplasms (EUS 78%, CT 24%, MRI 46%). No signific ant difference in N stage accuracy was noted between the three imaging moda lities (EUS 68%, CT 59%, MRI 77%). EUS T stage accuracy was reduced from 84 % to 72% in the presence of a transpapillary endobiliary stent. This was mo st prominent in the understaging of T2/T3 carcinomas. Conclusions: EUS is superior to CT and MRI in assessing T stage but not N s tage of ampullary lesions. The presence of an endobiliary stent at EUS may result in underestimating the need for a Whipple resection because of tumor understaging.