PubMed Health⌕ Search

Biomedical subjects

Philippe Lefere

Publications and source records attributed to Philippe Lefere.

8 recordsLinked to original sources
PubMed2007

European Society of Gastrointestinal and Abdominal Radiology (ESGAR): consensus statement on CT colonography.

Rapid clinical dissemination of CT colonography (CTC) is occurring in parallel with continued research into technique optimisation and diagnostic performance. A need exists therefore for current guidance as to basic prerequisites for effective clinical implementation. A questionnaire detailing CTC technique, analysis, training and clinical implementation was developed by the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) CTC committee and circulated to all faculty members of previous ESGAR "hands-on" CTC training courses. Responses were collated and a consensus statement produced. Of 27 invited to participate, 24 responded. Reasonable consensus was reached on bowel preparation, colonic distension, patient positioning, use of IV contrast and optimal scan parameters. Both primary 2D and primary 3D analysis were advocated equally, with some evidence that more experienced readers prefer primary 2D. Training was universally recommended, although there was no consensus regarding minimum requirements. CTC was thought superior to barium enema, although recommended for screening only in the presence of validated local experience. There was consensus that polyps 4 mm or less could be ignored assuming agreement from local gastroenterological colleagues. There is increasing consensus amongst European experts as to the current best practice in CTC.

Advisory Committees↗
PubMed2006

Comparison of routine and unprepped CT colonography augmented by low fiber diet and stool tagging: a pilot study.

BACKGROUND: We performed a pilot study examining the feasibility of a new unprepped CT colonography (CTC) strategy: low fiber diet and tagging (unprepped) vs. low fiber diet, tagging and a magnesium citrate cleansing preparation (prepped). Prior reports of tagging were limited in that the residual stool was neither measured and stratified by size nor did prior reports subjectively evaluate the ease of interpretation by a reader experienced in interpreting CTC examinations. METHODS: Prospective randomized to unprepped n = 14 and prepped n = 14. Colonic segments were subjectively evaluated for residual stool that would potentially interfere with interpretation. Scores were given in the following categories: percentage of residual stool that was touching or nearly touching mucosa, the largest piece of retained stool, effectiveness of tagging, height of residual fluid, degree of distention, ease of interpretation, and reading time. RESULTS: Ease of the CT read (scale where 4 = optimal read) averaged 1.3 for the unprepped group and 2.3 for the prepped group. The mean read time averaged 17.5 min for unprepped and 17.9 min for prepped. The degree of distention (scale where 4 = well distended) averaged 3.7 for unprepped and 3.6 for prepped. Supine and prone images combined, the unprepped group had 160 segments with stool; prepped group had 58 segments. The amount of stool covering the mucosa in all segments averaged 1.6 (33%-66% coverage) in the unprepped group and 0.35 (<33% mucosal coverage) in the prepped group. The mean size of the largest piece of stool was 33.67 mm for unprepped and 4.01 mm for prepped. Percentage of tagged stool was not significantly different between the groups (range of 94-98%). The height of residual fluid averaged 8.37 mm for unprepped and 13.4 mm for prepped. Three polyps in three patients were found during optical colonoscopy (OC) in the unprepped group (5, 6, and 10 mm), none of which were prospectively detected at CTC. Three polyps in three patients were detected during OC in the prepped group (5, 10, and 15 mm), two of which were prospectively detected at CTC. Two false-positive lesions were observed at CTC in one patient in the prepped group. CONCLUSION: There was more stool in the unprepped group and while this factor did not slow down the reading time, it made the examination subjectively harder to interpret and likely caused the three polyps in this group to be missed. We conclude that a truly unprepped strategy that leaves significant residual stool, even if well tagged, is not desirable.

Adult↗
PubMed2006

Polyp measurement and size categorisation by CT colonography: effect of observer experience in a multi-centre setting.

The extent measurement error on CT colonography influences polyp categorisation according to established management guidelines is studied using twenty-eight observers of varying experience to classify polyps seen at CT colonography as either 'medium' (maximal diameter 6-9 mm) or 'large' (maximal diameter 10 mm or larger). Comparison was then made with the reference diameter obtained in each patient via colonoscopy. The Bland-Altman method was used to assess agreement between observer measurements and colonoscopy, and differences in measurement and categorisation was assessed using Kruskal-Wallis and Chi-squared test statistics respectively. Observer measurements on average underestimated the diameter of polyps when compared to the reference value, by approximately 2-3 mm, irrespective of observer experience. Ninety-five percent limits of agreement were relatively wide for all observer groups, and had sufficient span to encompass different size categories for polyps. There were 167 polyp observations and 135 (81%) were correctly categorised. Of the 32 observations that were miscategorised, 5 (16%) were overestimations and 27 (84%) were underestimations (i.e. large polyps misclassified as medium). Caution should be exercised for polyps whose colonographic diameter is below but close to the 1-cm boundary threshold in order to avoid potential miscategorisation of advanced adenomas.

Chi-Square Distribution↗
PubMed2006

CT colonography interpretation times: effect of reader experience, fatigue, and scan findings in a multi-centre setting.

Our purpose was to assess the effect of reader experience, fatigue, and scan findings on interpretation time for CT colonography. Nine radiologists (experienced in CT colonography); nine radiologists and ten technicians (both groups trained using 50 validated examinations) read 40 cases (50% abnormal) under controlled conditions. Individual interpretation times for each case were recorded, and differences between groups determined. Multi-level linear regression was used to investigate effect of scan category (normal or abnormal) and observer fatigue on interpretation times. Experienced radiologists (mean time 10.9 min, SD 5.2) reported significantly faster than less experienced radiologists and technicians; odds ratios of reporting times 1.4 (CI 1.1, 1.8) and 1.6 (1.3, 2.0), respectively (P<or=0.001). Experienced and less-experienced radiologists took longer to report abnormal cases; ratio 1.2 (CI 1.1,1.4, P<0.001) and 1.2 (1.0, 1.3, P=0.03), respectively. All groups took 70% as long to report the final five cases as they did with an initial five; ratio 0.7 (CI 0.6 to 0.8), P<0.001. For technicians only, accuracy increased with longer reporting times (P=0.04). Experienced radiologists report faster than do less-experienced observers and proportionally spend less time interpreting normal cases. Technicians who report more slowly are more accurate. All groups reported faster as the study period progressed.

Clinical Competence↗
PubMed2006

Virtual colonoscopy--an overview.

Virtual colonoscopy is emerging as a technique for the detection of tumor lesions in the colon. Being a patient-friendly examination, virtual colonoscopy could play an important role in colorectal cancer screening. This article reviews the current state of the art of virtual colonoscopy with future developments and issues to be resolved.

Colonic Neoplasms↗
PubMed2005

CT colonography after fecal tagging with a reduced cathartic cleansing and a reduced volume of barium.

OBJECTIVE: The objective of our study was to assess the efficacy of fecal tagging with a small volume of barium in combination with a reduced cathartic cleansing before CT colonography. MATERIALS AND METHODS: The study consists of a review of 200 patients examined in a clinical setting. Conventional colonoscopy and CT colonography or follow-up were used as the gold standard. All patients prepared for CT colonography the day before the examination with a dedicated low-residue diet. Fecal tagging was performed with 50 mL of barium. The residual feces and fluid were evaluated on a segmental basis. The residual feces was divided in two categories (< 6 mm and > or = 6 mm). The amount of fluid was assessed on the axial slices. The efficacy of tagging was evaluated visually. RESULTS: For the study, 1,200 segments were evaluated. Residual feces was present in 413 segments (34.41%), with feces less than 6 mm in 210 segments (17.5%) and feces 6 mm or greater in 203 segments (16.92%). There was residual fluid in 527 segments (43.91%). Nontagged feces 6 mm or greater was present in 49 segments (4.08%) and nontagged fluid in 178 segments (14.83%). All nontagged feces 6 mm or greater was easy to assess. All fluid redistributed with dual positioning. A total of 65 lesions 6 mm or greater were correctly diagnosed on primary CT colonography. In two patients, two lesions adjacent to each other were misinterpreted as being only one. Another 8-mm lesion was missed. CONCLUSION: In the present study, CT colonography after fecal tagging with 50 mL of barium combined with a reduced cathartic cleansing was feasible.

Aged↗
PubMed2003

Diverticular disease in CT colonography.

The aim of this study was to evaluate findings on CT colonography (CTC) in patients with diverticular disease. In a retrospective analysis of 160 consecutive patients, who underwent CTC and conventional colonoscopy (CC), patients with diverticular disease were retrieved. The CTC images were compared with CC and, if possible, with pathology. Findings on both 2D and 3D images are illustrated with emphasis on diagnostic problems and the possible solutions to overcome these problems. Several aspects of diverticulosis were detected: prediverticulosis (3%); global (55.6%); and focal wall thickening (4%) caused by thickened haustral folds, fibrosis, inflammation and adenocarcinoma; diverticula (52%); pseudopolypoid lesions caused by diverticular fecaliths (39%); inverted diverticula (1.2%); and mucosal prolapse (0.6%). Solutions to overcome pitfalls are described as abdominal windowing, content of the pseudopolypoid lesion, comparison of 2D and 3D images, prone-supine imaging and the aspect of the pericolic fat. In this series there were equivocal findings in case of mucosal prolapse (0.6%) and focal wall thickening (4%). Diverticulosis is a challenge for CTC to avoid false-positive diagnosis of polypoid and tumoral disease. Knowledge of possible false causes of polypoid disease and comparison of 2D and 3D images are necessary to avoid false-positive diagnosis. In case of equivocal findings additional conventional colonoscopy should be advised whenever a clinically significant lesion (> or = 1 cm) is suspected.

Adult↗