 MD city in evaluation of ampullary and peri-ampullary tumours with histopathological correlation. Introduction to ampoule of water is an important landmark where the CPD and MPD converged in the major duodenal papilla. Peri-ampullary lesions arise within two centimetres of ampoule and duodenum and include lesions from pancreatic head, lower CBD, peri-ampullary duodenum and from within ampoule itself. There are several imaging modalities available which includes endoscopic ultrasound, ERCP, MRI and CT. CT has evolved as a predominant single modality for diagnosis and pre-operative staging of ampullary and peri-ampullary tumours. The aims of this study was to evaluate ampullary and peri-ampullary tumours by MD city and correlate the findings with histopathology. The objectives were to determine the efficacy of MD city imaging in evaluation of ampullary and peri-ampullary tumours and to correlate with histopathological studies to differentiate between benign and malignant tumours. Materials and methods, source of data, patients with clinical suspicion of any ampullary and peri-ampullary tumours refer to the department of radiodarnosis for CT evaluation. Method of collection of data for comparative analytical study was conducted on 44 patients. Image analysis for all the cases suspected of peri-ampullary tumours, the location and the extinction of tumours that adjacent to organ involvement, rectal status, pescular invasion, distant and lymph nodal metastasis and post-contrast enhancement of the tumours were documented. Any lesion that arises within 2 cm of the ampullar in the duodenum was analysed. The origin of such lesions could be from the pancreas, the common bile duct, the duodenum or from the ampullar itself. The status of the intrapartic biliria radicals, the common bile duct and the pancreatic duct was analysed. The lesion in the peri-ampullary region usually lead to upstream dilatation of these ducts depending upon the location of the lesion. It is called as double duct sign. However, significant dilatation was not observed in benign conditions. Signs of malignant structure include relatively abrupt narrowing of the biliary and of pancreatic duct with irregular margins in the distal narrow segment, gradual tapering of the distal parts of the ducts with smooth counters and without total obstruction was characterised as benign structure. Dilatation of the ducts down to the level of ampullar was considered to be an inconclusive finding as this can be caused by malignant as well as benign conditions. Adjacent organ involvement was determined by indistinct or ill-defined fat planes with the tumours and mainly consisted in infiltration of colon, stomach or mycentric. Vessel infiltration describes infiltration of superior mycentric vessels, portal vein and spenomocentric confluence. This was determined by ill-defined fat planes with the tumour and gazed vessel with tumour on both sides producing concentric or eccentric narrowing or occlusion of the vessel or thrombosis of the affected vessels. Distant metastasis to liver and peritoneum was evaluated. Liver metastasis were defined as more than one centimetre focal solid appearing lesions. If multiple sub-centimetric lesions without typical benign appearance were also classified as metastasis, acytas or contrast enhancing peritoneal nodules were considered as evidence of peritoneal tumour spread. Annancing lymph nodes with the short axis of more than one centimetre outside the peripancreatic draining chains were also considered as signs of metastatic disease. The HU value of pancreatic head carcinoma was slightly lower than the normal pancreatic parankaima. The arterial and venous phases show a slight early enhancement but lower than the normal pancreatic parankaima. The internal erotic area was not significantly enhanced and the boundary was unclear. In distal collangio carcinoma the thickening of the walls showed isodensity. Obvious delayed enhancement was noted in such lesions. The enhancement degree in ampillary carcinoma was higher than in pancreatic cancer and lower than in cohen welder cancer. Benign lesions did not show enhancement however they were not significant. Results and conclusion. MDCT plays a vital role in the characterization of ampillary or periampillary tumours. In our study of 44 cases, 33 patients had malignant and 11 had benign lesions in which collangio carcinoma was the most common. Out of 32 subjects with malignant lesions in HPE, 93.8% were picked up by the CT scan and 6.2% were falls negative. Out of 12 subjects with benign lesions in HPE, 25% were malignant and 75% were benign in CT. So we conclude that there is significant association between CT scan, CT scan diagnosis and HPE diagnosis in ampillary and periampillary tumours. CT diagnosis distribution of subjects. The commonest diagnosis on CT was collangio carcinoma followed by ampillary carcinoma and pancreatic head malignancy. 75% of the cases were found to be malignant. HPE diagnosis distribution of subjects. Majority of the patients who underwent biopsy were found to have adenocarcinoma. This was followed by chronic pancreatitis and non-special dodenitis on histopathological analysis. Majority were found to be malignant. This is axial CT scan showing case of group pancreatitis with calcification smootred within it. This is axial CT scan showing pancreatic head carcinoma. The carcinoma is enhancing less compared to normal pancreas. This is case of pancreatic head carcinoma, portal phase showing dilated main pancreatic duct. This is abdominal CT scan showing dilated common pancreatic duct and MPD caused by the endoluminal duodenal mass. This is contrast enhanced CT scan of the suspicion lesion at the distal end of CBD which turned out to be collangio carcinoma. This is contrast enhanced axial CT and coronal reformated image showing small polyporeal lesion representing carcinoma in the ampillary duct. This is contrast enhanced axial and coronal reconstructed CT images showing soft tissue density filling defect in distal common bile duct representing invasive grade 3 adenocarcinoma. These are my references. Thank you.