title: Role of CT Colonography in Colonic Lesions and Its Correlation with Conventional Colonoscopic Findings.
abstract: BACKGROUND
  Preoperative evaluation in patients with colorectal carcinoma is essential for a correct therapeutic plan. Conventional colonoscopy has certain limitations including its inability to detect synchronous lesions in case of distal obstructive mass and inaccurate tumour localization. CT colonography combines cross sectional imaging with virtual colonoscopic images and offers a comprehensive preoperative evaluation in patients with colorectal carcinoma including detection of synchronous lesions with accurate segmental localization and loco regional staging.
  
  
  OBJECTIVE
  The objective was to determine the role of CT colonography in various colonic lesions and to correlate the findings with conventional colonoscopy and histopathological findings.
  
  
  METHODS
  This prospective study included 50 patients with clinical symptoms suspicious of colonic pathology.
  
  
  METHODS
  All the patients underwent both CT colonography and conventional colonoscopy on the same day. CT colonography was performed in supine and prone position. Considering histopathological and/or surgical findings as gold standard, sensitivity and specificity of both the modalities were calculated.
  
  
  RESULTS
  Conventional colonoscopy missed two synchronous lesions proximal to occlusive mass and one lesion proximal to the anastomotic site; all were detected with CT colonography. One carpet lesion in rectum and one case of mild ulcerative colitis were missed by CT colonography. Sensitivity and specificity for detection of colorectal cancer were 97.56% and 100%, resp. with PPV and NPV of 100% and 93.75%, for CT colonography and 92.68% and 100%, respectively with PPV and NPV of 100% and 83.3% for conventional colonoscopy. Sensitivity for correct detection of acute and chronic ulcerative colitis of CT colonography was 66.6 % and 100 %, resp.
  
  
  CONCLUSIONS
  CT colonography has higher sensitivity than conventional colonoscopy for detection of colorectal carcinoma, including its ability to detect abnormalities proximal to obstructing lesion, accurate segmental localization of lesions and staging. However, some limitations of CT colonography were difficulty in detection of flat lesions and lack of information about hyperemia and superficial mucosal erosion, where conventional colonoscopy scored over CT colonography.
authors.affiliation: Assistant Professor, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Kunwarpal
authors.initials: K
authors.lastname: Singh
authors.affiliation: Post Graduate, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Aparna Kaur
authors.initials: AK
authors.lastname: Narula
authors.affiliation: Professor and Head, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Chuni Lal
authors.initials: CL
authors.lastname: Thukral
authors.affiliation: Professor, Department of Surgery, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Neeti Rajan
authors.initials: NR
authors.lastname: Singh
authors.affiliation: Assistant Professor, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Amandeep
authors.initials: A
authors.lastname: Singh
authors.affiliation: Senior Resident, Department of Radiodiagnosis, Sri Guru Ram Das Institute of Medical Sciences and Research , Vallah, Amritsar, India .
authors.forename: Harmeet
authors.initials: H
authors.lastname: Kaur
keywords: Colorectal Carcinoma; Ulcerative colitis; Virtual colonoscopy