Diagnostic accuracy of CT colonography and optical colonoscopy evaluated using surgically resected specimens

Preoperative CT Colonography in Partially Obstructed Colon Cancer, and its Benefit in Surgical Management

Background and aims

Stenotic colorectal carcinoma impending obstruction (SCRCIO) is a frequently encountered situation complicating 10% to 19% of colorectal cancers. This group of patients cannot undergo complete colonoscopic assessment. The aim of this study is to examine the accuracy of computed tomographic colonography (CTC) as preoperative assessment of the colon of patients with SCRCIO and to measure the effect on the surgical decision.

Materials and methods

This was a prospective study, from September 2009 through December 2012, on a cohort of symptomatic adult patients with SCRCIO. Patients underwent CTC evaluation after failed conventional colonoscopy (CC), followed by a follow-up endoscopic examination 3–6 months after surgical treatment.

Results

Twenty-nine patients with an average age of 55 were included in this study; the majority of stenotic masses were located in the sigmoid colon. Preoperative CTC matched the colonoscopy location of the stenotic masses (17 patients). CTC sensitivity per stenotic lesion detection was 100% and 92.5% for the location. Sensitivity was 100% for synchronous lesions, and CTC changed surgical plan in 17% of the patients.

Conclusion

CTC presented high sensitivity, specificity and accuracy for the identification of colonic lesions of any size. Preoperative CTC may possibly become the diagnostic procedure of choice for SCRCIO patients. It enables surgeons to evaluate the entire colon, minimizing the possibility of surgical re-intervention if there is a finding of synchronous neoplastic lesions at postoperative follow-up endoscopy.

Evolving role of computed tomographic colonography in colon cancer screening and diagnosis

Computed tomographic colonography (CTC) is a relatively new imaging modality for the examination of patients for colorectal polyps and cancer. It has been validated in its accuracy for the detection of colon cancer and larger polyps (more than likely premalignant). CTC, however, is not widely accepted as a primary screening modality in the United States at present by many third-party payers, including Medicare, and its exact role in screening is evolving. Moreover, there has been opposition to incorporating CTC as an accepted screening instrument, especially by gastroenterologists. Heretofore, optical colonoscopy has been the mainstay in this screening. We discuss these issues and the continuing controversies concerning CTC.

Computed tomography findings of bowel wall thickening: its significance and relationship to endoscopic abnormalities

INTRODUCTION

The aim of this study was to conduct retrospective analysis of abdominopelvic computed tomography (CT) reports, identifying those patients in whom bowel wall thickening (BWT) was observed, and to correlate these reports with subsequent endoscopic evaluation.

METHODS

Formal reports for all patients undergoing abdominopelvic CT between February 2007 and September 2009 were reviewed. Where patients were identified as having colorectal 'wall thickening', results of subsequent endoscopic evaluations were documented. Only those patients with a report of BWT who had follow-up endoscopy (colonoscopy, sigmoidoscopy) were included in the analysis.

RESULTS

A total of 165 patients were included. Abnormalities on endoscopy at the exact site of the BWT on CT were found in 95 patients (57.58%); in 36 cases (21.82%) this was a malignant lesion. BWT of the transverse colon was significantly more likely to correspond to an endoscopic finding of cancer than other sites (p=0.034). Rectal bleeding was reported significantly more often in patients with BWT and neoplastic disease on endoscopy compared with those with normal endoscopy (p=0.04). Excluding patients with inflammatory/diverticular lesions, 59.02% of Caucasians had a neoplastic lesion at the site of reported BWT, significantly higher than the other ethnic groups (p=0.008). There were 38 patients (23.03%) who did not present with bowel symptoms and, of these, 6 were diagnosed subsequently with colorectal cancer.

CONCLUSIONS

This study supports endoscopic evaluation to investigate patients with CT evidence of BWT, especially in cases involving the transverse colon, in Caucasian patients or in association with symptoms of rectal bleeding.

Colonoscopy for colonic wall thickening at computed tomography: a worthwhile pursuit?

BACKGROUND

In the absence of official guidance for the management of colonic wall thickening identified by computed tomography (CT), a common clinical dilemma surrounds the volume of colonoscopies subsequently performed.

METHODS

To identify whether colonic wall thickening identified at CT consistently warrants colonoscopy, consecutive colonoscopies performed at Leeds Teaching Hospitals Trust in 2008 and recorded as "possible colonic lesion on cross-sectional abdominal CT" in an endoscopic database were retrospectively analyzed. Clinical, radiologic, colonoscopic, and histologic data were obtained from medical records.

RESULTS

Of 4,702 colonoscopies, 94 (2%) had a full data set meeting the inclusion criteria. The primary diagnoses were normal condition (n = 11, 11.7%), adenocarcinoma (n = 25, 26.6%), adenoma (n = 23, 24.5%), diverticular disease (n = 12, 12.8%), nonspecific colitis (n = 6, 6.4%), Crohn's disease (n = 4, 4.3%), and hyperplastic polyp (n = 3, 3.2%). Computed tomography and colonoscopy were concordant for specific pathology in 79.8% of the cases (n = 75). Compared with diagnosis after histology, colonoscopy alone correctly identified specific pathology in 18.1% of the cases (n = 17), and CT alone was correct in 4.3% of the cases (n = 4)), whereas both were incorrect in 3.2% of the cases (n = 3). Computed tomography had a sensitivity of 72.3% (95% confidence interval [95% CI], 61.9-80.8%), a specificity of 96.5% (95% CI, 94.9-97.6%), a positive predictive value of 72.3%, and a negative predictive value of 96.5%. In 63.8% of the cases (n = 60), CT identified pathology necessitating further intervention at the time of colonoscopy or afterward, and in 28.7% of the cases (n = 27), CT identified pathology requiring no additional intervention. In the remaining 7.4% of the cases (n = 7), CT detected no new pathology.

CONCLUSION

Computed tomography is highly predictive of colonic pathology compared with final outcome after colonoscopy and biopsy. For patients without a pre-existing diagnosis, colonic wall thickening demonstrated at CT warrants further investigation with colonoscopy.