CT colonography for synchronous colorectal lesions in patients with colorectal cancer: initial experience.
ABSTRACT To assess accuracy of CT colonography (CTC) in identifying synchronous lesions in patients with colorectal carcinoma.
This study included 174 consecutive patients undergoing CTC as part of staging or primary investigation where a colorectal cancer was diagnosed between 2004 and 2007. Prone unenhanced and portal phase enhanced supine series with air or CO(2) distension were acquired using 4- or 16-slice CT (Toshiba) and read by 2D +/- 3D formats. Synchronous lesions were classified according to American College of Radiology's (ACR) polyp classification. Segmental gold standard was flexible sigmoidoscopy/colonoscopy within 1 year and/or histology of colonic resection supplemented by follow-up. Nine patients without gold standard were excluded. Sensitivity, specificity and accuracy were calculated on a per polyp, per patient and per segment basis and discrepancies analysed.
Direct comparable data were available for 764/990 colonic segments from 165 patients. Of 41 (C2-C4) synchronous lesions on "gold standard", 33 were correctly identified on virtual colonoscopy (VC), overall per polyp sensitivity was 80.5%, with detection rates of 20/24 C3 (83.3%) and 3/3 C4 (100%) with per patient and per segment specificity of 95.4% and 99.2%, respectively.
CTC is an accurate technique to assess for significant synchronous lesions in patients with colorectal cancer and is applicable for total pre-operative colonic visualisation.
- [show abstract] [hide abstract]
ABSTRACT: To assess whether computed tomography colonography (CTC) is a viable alternative to colonoscopy or double contrast barium enema in the follow-up of patients after diverticulitis. Fifty patients underwent CTC followed immediately by colonoscopy. Results were blinded to the examiners. Findings of diverticular disease and patient acceptance were evaluated. Bowel preparation and distension were good in the majority of CTC and colonoscopy examinations. Diverticular disease was found in 96% of patients at CTC and in 90% at colonoscopy. The rate of agreement between CTC and colonoscopy for diverticular findings in the sigmoid colon was good (kappa=0.64). No complications were seen. Patients found colonoscopy more uncomfortable (p<0.03), more painful (p<0.001), and more difficult (p<0.01) than CTC. Of the patients favouring one examination, 74% preferred CTC. CTC appears to have a better diagnostic potential for imaging of diverticular disease-specific findings, when compared with colonoscopy. Also, CTC was less uncomfortable and was preferred by a majority of patients. CTC seems to be a reasonable alternative in follow-up of patients with symptomatic diverticular disease.Clinical Radiology 08/2007; 62(7):645-50. · 1.82 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: To evaluate our experience in the 1st year of computed tomographic (CT) colonography screening since the initiation of local third-party payer coverage. This HIPAA-compliant study was approved by the institutional review board, and informed consent was waived. Over a 1-year period that ended on April 27, 2005, 1110 consecutive adults (585 women, 525 men; mean age, 58.1 years) underwent primary CT colonography screening. More than 99% were covered by managed care agreements. CT colonographic interpretation was performed with primary three-dimensional polyp detection, and the final results were issued within 2 hours. Patients with large (> or =10-mm) polyps were referred for same-day optical colonoscopy, and patients with medium-sized (6-9-mm) lesions had the option of immediate optical colonoscopy or short-term CT colonography surveillance. Large colorectal polyps were identified at CT colonography in 43 (3.9%) of 1110 patients. Medium-sized lesions were identified in 77 (6.9%) patients, 31 (40%) of whom chose optical colonoscopy and 46 (60%) of whom chose CT colonography surveillance. Concordant lesions were identified in 65 of 71 patients who underwent subsequent optical colonoscopy (positive predictive value, 91.5%). Sixty-one (86%) of 71 optical colonoscopic procedures were performed on the same day as CT colonography, thereby avoiding the need for repeat bowel preparation. The actual endoscopic referral rate for positive findings at CT colonography was 6.4% (71 of 1110 patients). The demand for CT colonography screening from primary care physicians and their patients increased throughout the study period. As a primary colorectal screening tool, CT colonography covered by third-party payers has an acceptably low endoscopic referral rate and a high concordance of positive findings at optical colonoscopy.Radiology 12/2006; 241(2):417-25. · 6.34 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: The purpose of our study was to develop a method to subtract barium-labeled stool from the colon using a phantom and to evaluate the performance of the technique in a pilot human population. A phantom containing 6-mm flat polyps and three types of simulated stool (homogeneous, moderately heterogeneous, and severely heterogeneous) mixed with barium was created, scanned, and tested using three stool subtraction algorithms but no cathartic. Thirty patients with suspected colorectal polyps were studied using stool tagging to determine which was the most effective stool subtraction algorithm. Colonoscopy was the reference standard. Examinations were evaluated blindly using the unsubtracted and 6 weeks later both the unsubtracted and subtracted data sets. A threshold of 200 H and expansion and convolution techniques were the most effective tools for subtracting stool and minimizing artifacts. When applied to the human population, sensitivities using the unsubtracted data sets were 90% (18/20) and 68% (26/38) for polyps > or = 1 cm and > or = 5 mm, respectively. Specificities were 100% (4/4) and 75% (3/4) for polyps > or = 1 cm and > or = 5 mm. For the stool-subtracted data sets, sensitivities were 90% (18/20) and 71% (27/38) for polyps > or = 1 cm and > or = 5 mm. Per patient sensitivities were 88% (15/17) and 77% (20/26) for > or = 1 cm and > or = 5 mm polyps. Specificities were 100% (4/4) for large polyps and 25% (1/4) for smaller polyps. Image processing tools combining thresholding, expansion, and convolution were the most useful for stool subtraction. Laxative-free colon examinations using barium for stool labeling can be performed at CT colonography with or without stool subtraction with high accuracy. Further study is warranted.American Journal of Roentgenology 01/2007; 188(1):W29-36. · 2.90 Impact Factor