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PubMed2006

Availability, indications, and technical performance of computed tomographic colonography: a national survey.

PURPOSE: To determine the availability, indications, and technique of computed tomographic colonography (CTC) in Sweden and to investigate opinions on its future role in colon imaging. MATERIAL AND METHODS: In May 2004, a questionnaire on CTC was mailed to all Departments of Radiology in Sweden, and one year later a telephone interview was conducted with the departments that intended to start a CTC service. RESULTS: Ninety-nine departments (83%) answered the questionnaire, indicating that 23/ 99 (23.2%) offered a CTC service. Reasons for non-implementation of CTC were lack of CTC training in 34/73 (46.6%) and non-availability of multi-detector row CT scanners in 33/73 (45.2%), while 26% were awaiting further scientific documentation on CTC. Incomplete colonoscopy was the main indication for CTC in 21/23 (91.3%) departments performing CTC. Dual positioning, room air insufflation, and thin-slice collimation were used in all the responding departments. The number of CTC studies performed varied from 1-5 (26.1%) to more than 200 (17.4%). Intravenous contrast material was routinely administered by 9/23 (39.1%) departments. Out of 30 (39.5%) departments that in 2004 intended to start CTC, 9 (30%) had done so by June 2005. A total of 32/99 (32.3%) departments had therefore started CTC by June 2005. Half of the departments that replied believed that CTC would absolutely or probably replace barium enema in the future. CONCLUSION: The survey shows relatively limited diffusion of CTC practice in Sweden, with approximately one-third of radiology departments offering a CTC service, mostly on a small scale. A wider dissemination of CTC requires further scientific documentation of its capability, intensified educational efforts, and additional funding.

Colonic Diseases↗
PubMedDate not supplied

[Computed tomographic colonography: applications, advantages and disadvantages].

INTRODUCTION: Complete preoperative study of the colon is required in the management of colorectal cancer, due to the frequent association of primary colonic neoplasms with colonic adenomas (28%) and/or synchronous carcinomas (5%) of the colon. We present a series of patients who underwent computed tomographic colonography, the indications for this procedure, and the results. PATIENTS AND METHODS: We performed a descriptive prospective study. Between May 2003 and August 2004, 50 computed tomographic colonographies were performed in 50 patients with suspected stenosing colorectal cancer and incomplete conventional colonoscopy. RESULTS: Fifty computed tomographic colonographies were performed. The findings were as follows: three were normal (6%), and in the remainder, one was a false positive for a suspected neoplastic pelvic mass (3.125%) and two were false positives (11.7%) for colonic polyps. Fifty percent of the findings (n = 32) were related to peritoneal metastases and colonic neoplasms. There were 12 technical complications [lack of cleaning of the colon (5), lack of distension (2), little air insufflation (5)]. Patient complications included vegetative manifestations in one (vomiting) and rectal bleeding in another. The overall complication rate was 27.4% (23.4% corresponded to technical complications and the remaining 4% were patient-related). There was no mortality related to the procedure. CONCLUSION: Because computed tomographic colonography is safe, effective and well tolerated by the patient, it should be considered as a technical alternative in the study of stenosing neoplasms of the proximal colon with incomplete colonoscopy. In addition, it allows other associated findings, both intra- and extracolonic, to be obtained and improves the diagnostic and therapeutic management of the patient.

Adenocarcinoma↗
PubMed2002

Optimisation of colon cleansing prior to computed tomographic colonography.

Colon preparation technique is a major determinant factor for patient compliance and polyp detection in computed tomographic colonography (CTC). The purpose of this study is to compare three different colon cleansing techniques in terms of patient discomfort, sensitivity and specificity. The following colon cleansing methods were compared in 20 patients each: 1. standard colonoscopy cleansing (ScCl) the day of the examination, based on polyethylene glycol (PEG), 2. a slightly reduced cleansing (RcCI) the day prior to the examination, based on a combination of diet, bisacodyl and a reduced intake of PEG, and 3. a cleansing with dietary fecal tagging (FT) the day prior to the examination, based on a combination of diet, bisacodyl, magnesium citrate and a dedicated barium suspension. ScCl resulted in a clean colon, but produces fluid levels hampering a complete CTC and possibly resulting in false negative diagnosis. RcCl reduced the problem of fluid levels, but was faced with the problem of fecal residues, resulting in false positive diagnosis. FT offered the possibility to obtain a dry colon, with labelled fecal residues, thus reducing false positive findings. Optimisation of the diet and replacement of PEG by magnesium citrate in FT reduced the preparation related discomfort and improved the final opinion. FT is the preferred colon cleansing technique because, compared to ScCl, fluid levels are reduced, and compared to RcCl, differentiation between faecal residues and polyps is improved. Moreover, FT reduces preparation related discomfort, compared to both RcCl and ScCl.

Bisacodyl↗
PubMed2003

Feature-guided analysis for reduction of false positives in CAD of polyps for computed tomographic colonography.

We evaluated the effect of our novel technique of feature-guided analysis of polyps on the reduction of false-positive (FP) findings generated by our computer-aided diagnosis (CAD) scheme for the detection of polyps from computed tomography colonographic data sets. The detection performance obtained by use of feature-guided analysis in the segmentation and feature analysis of polyp candidates was compared with that obtained by use of our previously employed fuzzy clustering technique. We also evaluated the effect of a feature called modified gradient concentration (MGC) on the detection performance. A total of 144 data sets, representing prone and supine views of 72 patients that included 14 patients with 21 colorectal polyps 5-25 mm in diameter, were used in the evaluation. At a 100% by-patient (95% by-polyp) detection sensitivity, the FP rate of our CAD scheme with feature-guided analysis based on round-robin evaluation was 1.3 (1.5) FP detections per patient. This corresponds to a 70-75% reduction in the number of FPs obtained by use of fuzzy clustering at the same sensitivity levels. Application of the MGC feature instead of our previously used gradient concentration feature did not improve the detection result. The results indicate that feature-guided analysis is useful for achieving high sensitivity and a low FP rate in our CAD scheme.

Algorithms↗
PubMed2004

Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia.

CONTEXT: Conventional colonoscopy is the best available method for detection of colorectal cancer; however, it is invasive and not without risk. Computed tomographic colonography (CTC), also known as virtual colonoscopy, has been reported to be reasonably accurate in the diagnosis of colorectal neoplasia in studies performed at expert centers. OBJECTIVE: To assess the accuracy of CTC in a large number of participants across multiple centers. DESIGN, SETTING, AND PARTICIPANTS: A nonrandomized, evaluator-blinded, noninferiority study design of 615 participants aged 50 years or older who were referred for routine, clinically indicated colonoscopy in 9 major hospital centers between April 17, 2000, and October 3, 2001. The CTC was performed by using multislice scanners immediately before standard colonoscopy; findings at colonoscopy were reported before and after segmental unblinding to the CTC results. MAIN OUTCOME MEASURES: The sensitivity and specificity of CTC and conventional colonoscopy in detecting participants with lesions sized at least 6 mm. Secondary outcomes included detection of all lesions, detection of advanced lesions, possible technical confounders, participant preferences, and evidence for increasing accuracy with experience. RESULTS: A total of 827 lesions were detected in 308 of 600 participants who underwent both procedures; 104 participants had lesions sized at least 6 mm. The sensitivity of CTC for detecting participants with 1 or more lesions sized at least 6 mm was 39.0% (95% confidence interval [CI], 29.6%-48.4%) and for lesions sized at least 10 mm, it was 55.0% (95% CI, 39.9%-70.0%). These results were significantly lower than those for conventional colonoscopy, with sensitivities of 99.0% (95% CI, 97.1%->99.9%) and 100%, respectively. A total of 496 participants were without any lesion sized at least 6 mm. The specificity of CTC and conventional colonoscopy for detecting participants without any lesion sized at least 6 mm was 90.5% (95% CI, 87.9%-93.1%) and 100%, respectively, and without lesions sized at least 10 mm, 96.0% (95% CI, 94.3%-97.6%) and 100%, respectively. Computed tomographic colonography missed 2 of 8 cancers. The accuracy of CTC varied considerably between centers and did not improve as the study progressed. Participants expressed no clear preference for either technique. CONCLUSIONS: Computed tomographic colonography by these methods is not yet ready for widespread clinical application. Techniques and training need to be improved.

Colonography, Computed Tomographic↗
PubMed2003

Colonoscopy and multidetector-array computed-tomographic colonography: detection rates and feasibility.

BACKGROUND AND STUDY AIMS: Computed-tomographic (CT) colonography has been introduced as a minimally invasive colon examination for the detection of colorectal neoplasms. The aim of this study was to compare the performance characteristics of multidetector-array CT colonography (MDCTC) and conventional colonoscopy in a prospective, blinded design. PATIENTS AND METHODS: Sixty-six symptomatic patients, 75 patients undergoing polyp and cancer surveillance, and seven patients undergoing preoperative colonoscopy due to colorectal cancer (CRC) were examined with MDCTC and subsequent colonoscopy. The gold standard was colonoscopy. If MDCTC was positive and the first-pass colonoscopy was negative, a second-pass colonoscopy served as the gold standard. RESULTS: Complete colonoscopy was achieved in 91% of the patients, while technically satisfying MDCTC was obtained in 76% of the patients (P < 0.01), insufficient air distension in the sigmoid colon being the main problem. MDCTC and colonoscopy both detected all 11 carcinomas. Overall detection rates for polypoid lesions 6 mm or larger in size were 81% (95% CI, 70% to 90%) for MDCTC and 87% (95% CI, 77% to 94%) for colonoscopy (P = 0.52), with a significant difference with regard to the detection of polyps 6-9 mm in size in favor of colonoscopy (P = 0.008). The specificity of MDCTC at a 6-mm level was 97% (95% CI, 92% to 99%). CONCLUSIONS: MDCTC and colonoscopy show equal overall sensitivity for the detection of polypoid lesions 6 mm or larger in size, but more patients are inadequately examined when MDCTC is used.

Adult↗
PubMed2005

Computed tomographic colonography: prevalence, nature, and clinical significance of extracolonic findings in a community screening program.

OBJECTIVE: Colorectal neoplasia screening by computed tomographic colonography (CTC) may lead to the detection of incidental extracolonic findings. We report the prevalence and clinical significance of extracolonic pathology found within a community-based CTC screening program and the cost of clinical follow-up and further investigation of these findings. METHODS: A total of 432 asymptomatic subjects at an average risk of colorectal neoplasia, aged 50-69, had screening by CTC using a low radiation dose protocol. Axial images were prospectively examined for extracolonic lesions and those considered clinically relevant were followed up. All clinic visits and further investigations were tallied to calculate the incremental cost to the screening CTC. RESULTS: A total of 146 extracolonic lesions were detected in 118 (27.3%) subjects. Thirty-two (7.4%) subjects had clinically relevant extracolonic abnormalities and nine (2.1%) subjects may derive a clinical benefit from the detection of these lesions. A single CTC costed $171.12, and following up extracolonic findings resulted in an additional $24.37 (14.2%) per CTC. Limiting reporting to the aorta and kidneys would have reduced the number of subjects requiring follow-up to 14 (3.2%), and decreased the cost increment to 4.7% without detriment to clinical outcome. CONCLUSIONS: Extracolonic findings of screening CTC are common, but infrequent of clinical importance. The additional burden of following up these findings was modest and could have been further reduced if clear clinical and radiological criteria and pathways for their further investigation were defined.

Age Distribution↗
PubMedDate not supplied

Analysis of air contrast barium enema, computed tomographic colonography, and colonoscopy: prospective comparison.

BACKGROUND: The usefulness of currently available colon imaging tests, including air contrast barium enema (ACBE), computed tomographic colonography (CTC), and colonoscopy, to detect colon polyps and cancers is uncertain. We aimed to assess the sensitivity of these three imaging tests. METHODS: Patients with faecal occult blood, haematochezia, iron-deficiency anaemia, or a family history of colon cancer underwent three separate colon-imaging studies--ACBE, followed 7-14 days later by CTC and colonoscopy on the same day. The primary outcome was detection of colonic polyps and cancers. Outcomes were assessed by building an aggregate view of the colon, taking into account results of all three tests. FINDINGS: 614 patients completed all three imaging tests. When analysed on a per-patient basis, for lesions 10 mm or larger in size (n=63), the sensitivity of ACBE was 48% (95% CI 35-61), CTC 59% (46-71, p=0.1083 for CTC vs ACBE), and colonoscopy 98% (91-100, p<0.0001 for colonoscopy vs CTC). For lesions 6-9 mm in size (n=116), sensitivity was 35% for ACBE (27-45), 51% for CTC (41-60, p=0.0080 for CTC vs ACBE), and 99% for colonoscopy (95-100, p<0.0001 for colonoscopy vs CTC). For lesions of 10 mm or larger in size, the specificity was greater for colonoscopy (0.996) than for either ACBE (0.90) or CTC (0.96) and declined for ACBE and CTC when smaller lesions were considered. INTERPRETATION: Colonoscopy was more sensitive than other tests, as currently undertaken, for detection of colonic polyps and cancers. These data have important implications for diagnostic use of colon imaging tests.

Barium Sulfate↗
PubMed2002

The future of colorectal imaging: computed tomographic colonography.

The development of colorectal cancer screening alternatives that are attractive to patients and effective for screening is critical for reducing this too-common and deadly disease. CTC is an exciting technique that is the only imaging alternative developed since the barium enema for colon screening. In the past few years, many obstacles to clinical implementation of CTC have been eliminated. For example, there is no longer any post-processing time, which was previously as long as 8 to 10 hours, and the interpretation time has been drastically reduced from 4 hours to 15 to 20 minutes. The majority of studies have demonstrated excellent results for detection of lesions > or = 1 cm, with few false positives. This examination will continue to improve with the development of automated (computer) detection programs and automated 3D rendering algorithms. In addition, cathartic bowel preparation, one of the biggest obstacles to patient compliance with colorectal cancer screening, may be eliminated if successful fecal tagging can be developed. The most important issue that remains is its performance in a screening population, and studies are currently underway to answer that important question.

Clinical Trials as Topic↗
PubMed2006

Improvement of visualization in computed tomographic colonography after mechanic air insufflation.

OBJECTIVE: Our aim was to develop an insufflation system for CT colonography enabling even and quick air inflation as well as pressure control and optional emergency decompression. PATIENTS AND METHODS: A modified air insufflation system for CT colonography, consisting of an electric air pump, manometer, safety valve, and a balloon tip is presented. Thirty one patients underwent CT colonography from August to December, 2004. RESULTS: Optimal distension was achieved in 30 patients; the distension was incomplete (partial) only in one case. The insufflation was performed within 60 seconds in 28 of the cases, in 2 patients--within 180 seconds and in one patient--after 180 seconds. CONCLUSIONS: The presented insufflation system allows optimization of CT colonography technique, reduces the risk of adverse events during examination and improves the precision of the method.

Air↗
PubMed2004

Computed tomographic colonography without cathartic preparation for the detection of colorectal polyps.

BACKGROUND AND AIMS: We prospectively compared the performance of low-dose multidetector computed tomographic colonography (CTC) without cathartic preparation with that of colonoscopy for the detection of colorectal polyps. METHODS: A total of 203 patients underwent low-dose CTC without cathartic preparation followed by colonoscopy. Before CTC, fecal tagging was achieved by adding diatrizoate meglumine and diatrizoate sodium to regular meals. No subtraction of tagged feces was performed. Colonoscopy was performed 3-7 days after CTC. Three readers interpreted the CTC examinations separately and independently using a primary 2-dimensional approach using multiplanar reconstructions and 3-dimensional images for further characterization. Colonoscopy with segmental unblinding was used as reference standard. The sensitivity of CTC was calculated both on a per-polyp and a per-patient basis. For the latter, specificity, positive predictive values, and negative predictive values were also calculated. RESULTS: CTC had an average sensitivity of 95.5% (95% confidence interval [CI], 92.1%-99%) for the identification of colorectal polyps > or =8 mm. With regard to per-patient analysis, CTC yielded an average sensitivity of 89.9% (95% CI, 86%-93.7%), an average specificity of 92.2% (95% CI, 89.5%-94.9%), an average positive predictive value of 88% (95% CI, 83.3%-91.5%), and an average negative predictive value of 93.5% (95% CI, 90.9%-96%). Interobserver agreement was high on a per-polyp basis (kappa statistic range, .61-.74) and high to excellent on a per-patient basis (kappa statistic range, .79-.91). CONCLUSIONS: Low-dose multidetector CTC without cathartic preparation compares favorably with colonoscopy for the detection of colorectal polyps.

Adult↗
PubMedDate not supplied

Colorectal polyp detection with virtual colonoscopy (computed tomographic colonography); the reliability of the method.

BACKGROUND/AIMS: The aim of this study was to compare the reliability of virtual colonoscopy with conventional colonoscopy in detection of colorectal polyps. METHODOLOGY: Between November 1997 and February 2000, 23 patients (14 males, 9 females) aged 43-86 years (mean: 63) with colorectal polyps who underwent colonoscopy in our endoscopy unit, were referred for virtual colonoscopy. The colon was distended with an enema tube for rectal insufflation and subsequently was scanned by helical CT (Toshiba X-vision) using the following parameters: KV 120, mAs 200, table feed 5 mm/sec, slice thickness 5 mm and reconstruction intervals 2.5 mm. Using SPARC Station 20, virtual colonoscopy was generated. RESULTS: A total of 30 polyps (19 with diameter 8-15 mm and 11 larger than 15 mm) were detected with conventional colonoscopy. Virtual colonoscopy visualized 27 polyps (17 with diameter 8-15 mm and 10 with diameter > 15 mm). CONCLUSIONS: Virtual colonoscopy is a non-invasive, well-tolerated, safe technique and can be useful for detection of colorectal polyps. Weaknesses of the method are the inability to detect small lesions and to perform biopsies.

Adult↗
PubMed2002

Contrast-enhanced computed tomographic colonography in the follow-up of colorectal cancer patients: a feasibility study.

The aim of our study was to assess whether contrast-enhanced CT colonography is a feasible alternative to both conventional colonoscopy and liver ultrasonography in the follow-up program of colorectal cancer patients. Thirty-five patients, surgically treated for colorectal cancer, underwent a follow-up program that included physical examination, carcinoembryonic antigen serum assay, conventional colonoscopy, liver ultrasonography, and chest X-ray. For these patients, we added a yearly contrast-enhanced CT colonography. All CT examinations were performed with a high-resolution protocol using a multidetector spiral CT scanner (Siemens, Erlangen, Germany) prior to and after the administration of 130 ml of i.v. contrast material. Images were directly analyzed on a dedicated workstation by two radiologists to determine colonic evaluation, visualization of colonic anastomosis, presence of polyps, and extra-colonic findings. Colonic evaluation was judged as optimal in 91.7% of all colonic segments. All mechanical surgical anastomoses were visualized with CT colonography. There was no evidence of anastomotic recurrence. Seven polyps were detected in five different patients with CT colonography, with two false-positive and no false-negative examinations. Three liver metastases and two basal pulmonary nodules were also identified. Contrast-enhanced CT colonography is a feasible alternative to both conventional colonoscopy and liver ultrasonography in the follow-up of patients operated on for colorectal cancer.

Adenocarcinoma↗
PubMed2003

Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps.

BACKGROUND & AIMS: This study used a low lesion prevalence population reflective of the screening setting to estimate the sensitivity and specificity of computerized tomographic (CT) colonography for detection of colorectal polyps. METHODS: This prospective, blinded study comprised 703 asymptomatic persons at higher-than-average risk for colorectal cancer who underwent CT colonography followed by same-day colonoscopy. Two of 3 experienced readers interpreted each CT colonography examination. RESULTS: Overall lesion prevalence for adenomas >/=1 cm in diameter was 5%. Seventy percent of all lesions were proximal to the descending colon. With colonoscopy serving as the gold standard, CT colonography detected 34%, 32%, 73%, and 63% of the 59 polyps >/=1 cm for readers 1, 2, 3, and double-reading, respectively; and 35%, 29%, 57%, and 54% of the 94 polyps 5-9 mm for readers 1, 2, 3, and double-reading, respectively. Specificity for CT colonography ranged from 95% to 98% and 86% to 95% for >1 cm and 5-9-mm polyps, respectively. Interobserver variability was high for CT colonography with kappa statistic values ranging from -0.67 to 0.89. CONCLUSIONS: In a low prevalence setting, polyp detection rates at CT colonography are well below those at colonoscopy. These rates are less than previous reports based largely on high lesion prevalence cohorts. High interobserver variability warrants further investigation but may be due to the low prevalence of polyps in this cohort and the high impact on total sensitivity of each missed polyp. Specificity, based on large numbers, is high and exhibits excellent agreement among observers.

Aged↗