Search

The visibility of the colon in positron emission tomography (PET) scans of patients without gastrointestinal disease indicating the presence of 18F Fluorodeoxyglucose (18FDG) is well recognised, but unquantified and unexplained. In this paper a qualitative scoring system was applied to PET scans from 30 randomly selected patients without gastrointestinal disease to detect the presence of 18FDG in 4 different sections of the colon and then both the total pixel value and the pixel value per unit length of each section of the colon were determined to quantify the amount of 18FDG from a randomly selected subset of 10 of these patients. Analysis of the qualitative scores using a non-parametric ANOVA showed that all sections of the colon contained 18FDG but there were differences in the amount of 18FDG present between sections (p<0.05). Wilcoxon matched-pair signed-rank tests between pairs of segments showed statistically significant differences between all pairs (p<0.05) with the exception of the caecum and ascending colon and the descending colon. The same non-parametric statistical analysis of the quantitative measures showed no difference in the total amount of 18FDG between sections (p>0.05), but a difference in the amount/unit length between sections (p<0.01) with only the caecum and ascending colon and the descending colon having a statistically significant difference (p<0.05). These results are consistent since the eye is drawn to focal localisation of the 18FDG when qualitatively scoring the scans. The presence of 18FDG in the colon is counterintuitive since it must be passing from the blood to the lumen through the colonic wall. There is no active mechanism to achieve this and therefore we hypothesise that the transport is a passive process driven by the concentration gradient of 18FDG across the colonic wall. This hypothesis is consistent with the results obtained from the qualitative and quantitative measures analysed. [ABSTRACT FROM AUTHOR]

In this paper, we propose a fast three-material modeling for electronic cleansing (EC) in computed tomographic colonography. Using a triple arch projection, our three-material modeling provides a very quick estimate of the three-material fractions to remove ridge-shaped artifacts at the T-junctions where air, soft-tissue (ST), and tagged residues (TRs) meet simultaneously. In our approach, colonic components including air, TR, the layer between air and TR, the layer between ST and TR (LST/TR), and the T-junction are first segmented. Subsequently, the material fraction of ST for each voxel in LST/TR and the T-junction is determined. Two-material fractions of the voxels in LST/TR are derived based on a two-material transition model. On the other hand, three-material fractions of the voxels in the T-junction are estimated based on our fast three-material modeling with triple arch projection. Finally, the CT density value of each voxel is updated based on our fold-preserving reconstruction model. Experimental results using ten clinical datasets demonstrate that the proposed three-material modeling successfully removed the T-junction artifacts and clearly reconstructed the whole colon surface while preserving the submerged folds well. Furthermore, compared with the previous three-material transition model, the proposed three-material modeling resulted in about a five-fold increase in speed with the better preservation of submerged folds and the similar level of cleansing quality in T-junction regions. [ABSTRACT FROM PUBLISHER]

Background and Aims: To prospectively evaluate the role of contrast-enhanced computed tomography (CE-CT) in the detection of colonic diverticular bleeding (CDB). Patients and Methods: Consecutive patients who presented with hematochezia and were clinically suspected of CDB were prospectively enrolled. Those who could undergo both CE-CT and total colonoscopy, and who were finally diagnosed as CDB, were included in the analysis. Results: Fifty-two cases were finally included in the analysis. The detection rate of CDB by CT was 15.4 % (8/52). Univariate analysis showed that the interval from the latest episode of hematochezia to the performance of CT and the presence of a past history of CDB were contributing factors for detection. The interval was 1.6 ± 4.6 h (mean ± SD) in patients detected by CT, and 3.4 ± 3.2 h in those without detection. The detection rate of CDB by total colonoscopy was 38.5 % (20/52). The overall detection rate was 46.2 % (24/52), which was superior to what CT or colonoscopy alone achieved. Conclusions: CE-CT may play a complementary role to colonoscopy in patients with suspected CDB, but is not recommended for all cases due to its low detection rate. Patients who can be examined within 2 h of last hematochezia would be candidates for urgent CT. [ABSTRACT FROM AUTHOR]

Human colon has complex structures mostly because of the haustral folds. The folds are thin flat protrusions on the colon wall, which complicate the shape analysis for computer-aided detection (CAD) of colonic polyps. Fold segmentation may help reduce the structural complexity, and the folds can serve as an anatomic reference for computed tomographic colonography (CTC). Therefore, in this study, based on a model of the haustral fold boundaries, we developed a level-set approach to automatically segment the fold surfaces. To evaluate the developed fold segmentation algorithm, we first established the ground truth of haustral fold boundaries by experts’ drawing on 15 patient CTC datasets without severe under/over colon distention from two medical centers. The segmentation algorithm successfully detected 92.7% of the folds in the ground truth. In addition to the sensitivity measure, we further developed a merit of segmented-area ratio (SAR), i.e., the ratio between the area of the intersection and union of the expert-drawn folds and the area of the automatically segmented folds, to measure the segmentation accuracy. The segmentation algorithm reached an average value of SAR = 86.2%, showing a good match with the ground truth on the fold surfaces. We believe the automatically segmented fold surfaces have the potential to benefit many postprocedures in CTC, such as CAD, taenia coli extraction, supine-prone registration, etc. [ABSTRACT FROM PUBLISHER]

Abstract: In three-dimensional (3D) CT colonography (CTC), a wider viewing angle provides a larger field of view. The purpose of this study was to investigate the polyp detection rate and time efficiency of unidirectional 240°-angle 3D CTC compared with bidirectional 120°-angle CTC. CTC data sets of 40 patients were reviewed by two readers using the two methods. The unidirectional 240°-angle CTC showed a performance in polyp detection similar to the bidirectional 120°-angle CTC with improved time efficiency. [Copyright &y& Elsevier]

Abstract: Purpose: To evaluate the feasibility and sensitivity of the 3D-reading of fecal-tagging CT colonography (CTC) with a novel structure-analysis electronic cleansing (SAEC) in detecting colorectal flat lesions in comparison with a cleansed 3D reading with Viatronix V3D Colon system (V3D) and primary uncleansed 2D reading (2D). Materials and methods: Forty CTC cases with flat lesions were retrospectively observed. The Subjects from a multicenter clinical trial underwent cathartic bowel preparation with orally administrated barium-based fecal-tagging. Sixty-nine flat lesions were confirmed using colonoscopy and histopathology as a reference standard. The results from SAEC reading were compared with those of prospective V3D and 2D readings. Results: Overall detection sensitivity with SAEC was 52% (36/69), which was statistically higher than that of 32% (22/69) and 29% (20/69) with V3D and 2D readings, respectively (p <0.05). The sensitivities in detecting not-on-fold flat lesions were 63% (24/38), 45% (17/38), and 42% (16/38) with SAEC, V3D, and 2D readings, respectively; whereas those of on-fold flat lesions were 39% (12/31), 16% (5/31), and 13% (4/31), respectively. None of the eight flat lesions (2-9mm) at cecum was detected by any of the three reading methods. Excluding the flat lesions at cecum, the sensitivity with SAEC for detecting flat lesion ≥4mm increased to 84% (31/37). Conclusions: The fecal-tagging CTC with structure-analysis electronic cleansing could yield a high sensitivity for detecting flat lesions ≥4mm. The not-on-fold flat lesions were detected with higher sensitivity than on-fold flat lesions. [Copyright &y& Elsevier]

Abstract: Objective: To assess the performance of radiographers in CT colonography (CTC) after a tele-training programme, supervised by 2 experienced radiologists. Materials and methods: Five radiographers underwent training in CTC using a tele-training programme mainly based on the interpretation of 75 training cases performed in the novice department. To evaluate the educational performance, each radiographer was tested on 20 test cases with 27 lesions >6mm (12: 6–9mm; 15: >10mm). Sensitivity, specificity and PPV for polyps ≥6mm and ≥10mm were calculated with point estimates and 95% confidence interval (95% CI). The results were compared by comparing 95% CI with a 5% significance level. Results: In the training cases overall per-polyp sensitivity was 57% (95% CI 46.1–67.9) and 69.1% (95% CI 50.6–87.5) for lesions ≥6mm and ≥10mm, respectively. Overall per patient sensitivity, specificity and PPV were 86.4% (95% CI 76.7–96.1), 85.4% (95% CI 77–93.9) and 78.3% (95% CI 64.9–91.7), respectively. In the test cases overall per-polyp sensitivity was 80.7% (95% CI 69.5–92) and 94.7% (95% CI 85.6–100×) for lesions ≥6mm and ≥10mm, respectively. Overal per patient sensitivity, specificity and PPV were 92.9% (95% CI 83.1–100×), 64% (95% CI 13.1–100×) and 87.8% (95% CI 71.7–100×), respectively. There was a statistically significant improvement in per-polyp sensitivity for lesions ≥6mm in the test cases. No statistically significant differences were found in per patient sensitivity, specificity and PPV, but there was an improvement. Conclusion: This training programme based on tele-training obtained good performance of radiographers in detecting tumoral lesions in CTC. [Copyright &y& Elsevier]

Objective: The objective of this study was to determine the rate of salvage resections in patients with stage II and III colorectal cancer following intensive surveillance in a comprehensive cancer center. Methods: Patients with stage II and III colorectal cancer with a minimum follow-up of 3 years were included. Carcinoembryonic antigen was obtained every 3 months for 2 years and then every 6 months for years 3-5. CT scans of the chest, abdomen and pelvis were performed every 6 months for 2 years and then yearly for years 3-5. Colonoscopy was performed at year 1 and then every 3 years. Results: One hundred and seventy-seven patients were followed for a median of 60 months; 44 patients were diagnosed with recurrent disease. CT was the first sign of recurrence in 68% of patients. Carcinoembryonic antigen test was normal in 20 patients (45%) at the time of disease recurrence. Twenty-five patients (57%) with recurrent disease underwent curative-intent resection, 12 of whom are still cancer free at a median follow-up of 81 months. Conclusions: In this retrospective study, intensive radiographic screening was associated with a high salvage resection rate, which led to favorable clinical outcomes. Randomized clinical trials are urgently needed to define the optimal duration and schedule of radiographic screening in stage II and III colorectal cancer. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

To explore the regional anatomy of the fasciae and spaces around the right-side colon from laparoscopic perspective, we observed the location, extension, and boundaries of the spaces around the right-side colon in seven cadavers and in 49 patients undergoing laparoscopic right hemicolectomy for cancer, and reviewed computed tomography images from patients and healthy individuals. Between the ascending mesocolon and prerenal fascia (PRF), there was a right retrocolic space (RRCS), which extended in all directions. The anterior, posterior, medial, lateral, cranial, and caudal boundaries of the RRCS were the ascending mesocolon, PRF, superior mesenteric vein, right paracolic sulcus, inferior margin of the duodenum, and inferior margin of the mesentery radix, respectively. Between the transverse mesocolon and the pancreas and duodenum, there was a transverse retrocolic space, which was enclosed cranially by the radix of the transverse mesocolon. In CT images, healthy PRF was noted as slender line of middle density, continuing to the transverse fascia. The retrocolic spaces was unidentifiable, unless they were filled with retroperitoneal lesions. The RRCS and transverse retrocolic space are natural surgical planes for laparoscopic right hemicolectomy for cancer. The boundaries of these fusion fascial spaces are the best access, and the PRF is the best guide. [ABSTRACT FROM AUTHOR]

OBJECTIVE: Reports on the accuracy of computed tomographic colonography (CTC) mainly involve series from expert institutions. The aims of this study were to assess CTC accuracy in a nationwide population and to relate it to radiologist performance in their initial training. DESIGN: Nationwide multicentre trial. SETTING: Twenty-eight radiologists, working in 26 mostly academic clinical units, were involved in the study after having attended a formal specialised 2-day training session on CTC. They worked through a training set of 52 cases with automatic feedback after an attempt at each case. PATIENTS: The study enrolled 845 patients with average and high risk of colorectal cancer, 737 of whom had both complete CTC and videocolonoscopy data, which constituted the dataset. INTERVENTIONS: Patients underwent same-day CTC followed by videocolonoscopy with segmental unblinding of CTC results. MAIN OUTCOME MEASURES: Sensitivity, specificity and positive and negative predictive values for detection of polyps ≥6 mm in per-patient and per-lesion analyses of CTC without computer-aided detection. RESULTS: Sensitivity, specificity and positive and negative predictive values for patients with polyps ≥6 mm were 69% (95% CI 61% to 77%), 91% (95% CI 89% to 94%), 67% (95% CI 59% to 74%) and 92% (95% CI 90% to 94%), respectively. Univariate analysis showed that the detection rate for polyps ≥6 mm was linked to neither radiologist case volume nor number of polyps, but was related to sensitivity achieved in the training set. Pooled sensitivity was 72% (95% CI 63% to 80%) versus 51% (95% CI 40% to 60%) for radiologists achieving above and below median sensitivity in the training set (61%), respectively. Multivariate analysis showed that sensitivity for polyps ≥6 mm in the training set was the only remaining significant predictive factor for subsequent performance. CONCLUSIONS: Radiologist sensitivity CTC for detection of polyps ≥6 mm in training was the sole independent predictor for subsequent sensitivity in detection of such polyps. [ABSTRACT FROM AUTHOR]

Electronic cleansing (EC) is a method that segments fecal material tagged by an X-ray-opaque oral contrast agent in computed tomographic colonography (CTC) images, and effectively removes the material for digitally cleansing the colon. In this study, we developed a novel EC method, called mosaic decomposition (MD), for reduction of the artifacts due to incomplete cleansing of inhomogeneously tagged fecal material in CTC images, especially in noncathartic CTC images. In our approach, the entire colonic region, including the residual fecal regions, was first decomposed into a set of local homogeneous regions, called tiles, after application of a 3-D watershed transform to the CTC images. Each tile was then subjected to a single-class support vector machine (SVM) classifier for soft-tissue discrimination. The feature set of the soft-tissue SVM classifier was selected by a genetic algorithm (GA). A scalar index, called a soft-tissue likelihood, is formulated for differentiation of the soft-tissue tiles from those of other materials. Then, EC based on MD, called MD-cleansing, is performed by first initializing of the level-set front with the classified tagged regions; the front is then evolved by use of a speed function that was designed, based on the soft-tissue index, to reserve the submerged soft-tissue structures while suppressing the residual fecal regions. The performance of the MD-cleansing method was evaluated by use of a phantom and of clinical cases. In the phantom evaluation, our MD-cleansing was trained with the supine (prone) scan and tested on the prone (supine) scan, respectively. In both cases, the sensitivity and specificity of classification were 100%. The average cleansing ratio was 90.6%, and the soft-tissue preservation ratio was 97.6%. In the clinical evaluation, 10 noncathartic CTC cases (20 scans) were collected, and the ground truth of a total of 2095 tiles was established by manual assignment of a material class to each tile. Five cases were randomly selected for training GA/SVM, and the remaining five cases were used for testing. The overall sensitivity and specificity of the proposed classification scheme were 97.1% and 85.3%, respectively, and the accuracy was 94.6%. The area under the ROC curve (Az) was 0.96. Our results indicated that the use of MD-cleansing substantially improved the effectiveness of our EC method in the reduction of incomplete cleansing artifacts. [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to assess the accuracy of water enema computed tomography (WECT) for the diagnosis of colon cancer. Methods: A total of 191 patients referred for clinically suspected colon cancer were prospectively evaluated by WECT in a multicenter trial. Examination was contrast enhanced helical CT after colon filling through a rectal tube. For all the cases, final diagnosis was obtained by colonoscopy and/or surgery. CT data were interpreted both locally and at a centralized site by a specialized and general radiologist. Results: Seventy-one patients were diagnosed with colon cancer. Overall, WECT sensitivity and specificity were 98.6 and 95.0%, respectively. Positive and negative predictive values were 92.1 and 99.1%, respectively. In a subgroup of 33 patients with unclean bowel, the sensitivity and specificity of WECT were 95.0 and 92.3%, respectively. The correlation between local radiologists and the specialized radiologist was excellent (Kappa = 0.87) as was the correlation between the general radiologist and the specialist (Kappa = 0.92). Conclusion: This prospective analysis demonstrates that WECT is an effective, safe, and simple imaging technique for the diagnosis of colon cancer and can be proposed when a strong clinical suspicion of colon cancer is present, especially in frail patients. [ABSTRACT FROM AUTHOR]

Colorectal cancer is second only to lung cancer as the leading cause of death among North Americans of both sexes. Although screening rates for colorectal cancer in the United States have increased over the past decade, these rates (in the range of 45%-60%) are still lower than the screening rates for breast cancer (approximately 80%). Optical colonoscopy has been recognized as the preferred method for colorectal cancer screening in the United States, but computed tomography colonography has recently been gaining favor. This article compares the 2 methods with respect to both advantages and disadvantages. Mt Sinai J Med 77:214–224, 2010. © 2010 Mount Sinai School of Medicine [ABSTRACT FROM AUTHOR]

Backround: Sigmoid colon cancer metachronous metastases commonly occur in the liver and lungs with sporadic reports also to the spleen, stomach, thyroid gland, abdominal wall and upper urinary tract. This is a rare case of metachronous metastases invading the mesorectum and the abdominal wall. Case presentation: A 72-year-old female underwent sigmoidectomy for stage I (T2N0 M0) sigmoid colon cancer in May 2008. In June 2009, an abdominal computed tomography scan revealed a tumor 2 cm in size at the lower anterior mesorectum and a second mass 2 cm in size at the anterior abdominal wall midline. Total colonoscopy showed no mucosal lesion. The serum carcinoembryonic antigen level was normal. A biopsy of the mesorectum tumor showed similar histologic characteristics with the primary tumor. Since no other site of recurrence was identified, an abdominoperineal resection was attempted. During the operation and after the removal of the incision recurrence, sinus bradycardia and signs of myocardial ischemia were noticed. A loop transverse colostomy was immediately perfomed and the operation was terminated. Postoperative cardiologic examination revealed an acute myocardium infract. Chemo-radiation of the mesorectum tumor and re-evaluation for surgical excision was decided. Conclusion: Metachronous metastasis of the mesorectum from sigmoid colon cancer is extremely rare. Although patterns of lymphatic spread from rectal cancer to sigmoid colon have recently been demonstrated, there is no evidence of metachronous mesorectum invasion from sigmoid colon cancer. This could be the issue for future trials. [ABSTRACT FROM AUTHOR]

Abstract: Microcomputed tomography colonography (mCTC) is a new method for detecting colonic tumors in living animals and estimating their volume, which allows investigators to determine the spontaneous fate of individually annotated tumors as well as their response to chemotherapeutics. This imaging platform was developed using the Min mouse, but is applicable to any murine model of human colorectal cancer. MicroCT is capable of 20micron resolution, however, 100microns is sufficient for this application. Scan quality is primarily dependent on animal preparation with the most critical parameters being proper anesthesia, bowel cleansing, and sufficient insufflation. The detection of colonic tumors is possible by both 2D and 3D rendering of image data. Tumor volume is estimated using a semi-automated five-step process which is based on three algorithms within the Amira software package. The estimates are precise, accurate and reproducible enabling changes in volume as small as 16% to be readily observed. Confirmation of mCTC observations by gross examination and histology is sometimes useful in this otherwise non-invasive protocol. Finally, mCTC is compared to other newly developed small animal imaging platforms including microMRI and microoptical colonoscopy. A major advantage of these platforms is that investigators can be perform longitudinal studies, which often have much greater statistical power than traditional cross-sectional studies; consequently, fewer animals are required for testing. [Copyright &y& Elsevier]

Aim: To evaluate whether computer-aided detection (CAD) as a second reader using perspective filet view [three-dimensional (3D) filet] improves the performance of inexperienced readers at computed tomography colonography (CTC) compared with unassisted 3D filet and unassisted two-dimensional (2D) CTC. Material and methods: Fifty symptomatic patients underwent CTC and same-day colonoscopy with segmental unblinding. Two inexperienced readers read the CTC studies on 3D filet and 2D several weeks apart. Four months later, readers re-read the cases only evaluating CAD marks using 3D filet. Suspicious CAD marks not previously described on 3D filet were recorded. Jackknife free-response receiver operating characteristic (JAFROC-1) analysis was used to compare the observers'' performances in detecting lesions with 3D filet, 2D and 3D filet with CAD. Results: One hundred and three lesions ≥3mm were detected at colonoscopy with segmental unblinding. CAD alone had a sensitivity of 73% (75/103) at a mean false-positive rate per patient of 12.8 in supine and 11.4 in prone. For inexperienced readers sensitivities with 3D filet with CAD were 58% (60/103) and 48% (50/103) with an improvement of 14–16 percentage points (p <0.05) compared with 2D and of 10–11 percentage points (p <0.05) compared with 3D filet. For inexperienced readers, the false-positive rate was 25–41% and 71–200% higher with 3D filet with CAD compared with 3D filet and 2D, respectively. JAFROC-1 analysis showed no significant differences in per-lesion overall performance among reading modes (p =0.8). Conclusion: CAD applied as a second reader using 3D filet increased both sensitivity and the number of false positives by inexperienced readers compared with 3D filet and 2D, thus not improving overall performance, i.e., the ability to distinguish between lesions and non-lesions. [Copyright &y& Elsevier]

The article discusses a study which investigated the sensitivity and specificity of computed tomographic (CT) colonography in detecting advanced neoplasia 6 millimeters or larger in individuals in Italy at increased risk of developing colorectal cancer (CRC). The study is considered a multicenter, cross-sectional one, which involves persons at increased risk of CRC due to either family history of advanced neoplasia or personal history of colorectal adenomas. It was found that CT colonography resulted in a negative predictable value of 96.3 percent overall compared to colonoscopy.

Previous studies of patient experience with bowel screening tests, in particular CT colonography (CTC), have superimposed global rating scales and not explored individual experience in detail. To redress this, we performed qualitative interviews in order to characterize patient expectations and experiences in depth. Following ethical permission, 16 patients undergoing CTC, 18 undergoing colonoscopy and 15 undergoing barium enema agreed to a semi-structured interview by a health psychologist. Interviews were recorded, responses transcribed and themes extracted with the aim of assimilating individual experiences to facilitate subsequent development and interpretation of quantitative surveys of overall satisfaction with each diagnostic test. Transcript analysis identified three principal themes: physical sensations, social interactions and information provision. Physical sensations differed for each test but were surprisingly well tolerated overall. Social interactions with staff were perceived as very important in colouring the whole experience, particularly in controlling the feelings of embarrassment, which was critical for all procedures. Information provision was also an important determinant of experience. Verbal feedback was most common during colonoscopy and invariably reassuring. However, patients undergoing CTC received little visual or verbal feedback and were often confused regarding the test outcome. Barium enema had no specific advantage over other tests. Qualitative interviews provided important perspectives on patient experience. Our data demonstrated that models describing the quality of medical encounters are applicable to single diagnostic episodes. Staff interactions and information provision were particularly important. We found advantages specific to both CTC and colonoscopy but none for barium enema. CTC could benefit greatly from improved information provision following examination. [ABSTRACT FROM AUTHOR]

In an earlier paper (1) a new pump device for medical applications was described. This enabled a continuous flow of saline, barium contrast agent and gases. We now report further study of this device: The use of gases was experimentally studied to give a basis for use in CT-colonography. We also report experiences from injection of barium contrast agent via a naso-duodenal tube for radiological investigation of the small intestine in patients with gastrointestinal suffering. The radiation exposure to the x-ray staff was reduced. The investigation procedure was standardised and shortened. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The potential effect of CT colonography (CTC) on endoscopic colonoscopy (EC) has been the topic of much speculation. The aim of this study was to evaluate the impact of a CTC screening program on colonoscopy in clinical practice. METHODS: At our institution a third-party reimbursed CTC colorectal cancer (CRC) screening program was established in 2004. The number of CTC monthly exams performed, monthly EC total and screening exams performed, EC with polypectomy performed, and the number of referrals for EC screening exams requested were prospectively examined in the first 33 months after introduction of a CTC CRC screening program. RESULTS: The mean number of overall (378.5 vs 413.1) and screening (150.7 vs 162.9) colonoscopy exams performed per month did not change significantly after screening CTC was introduced. The mean number of monthly CTC exams performed rose significantly throughout the first year of the study from 39 initially to a peak of 147.6 cases per month but decreased slightly to 114.3 monthly exams at the end of 2006. A mean 10.0 patients per month were sent for EC after a positive CTC exam. The mean number of monthly colonoscopies with polypectomy remained constant after the introduction of CTC (197.0 vs 180.2). Monthly referrals for screening EC exams initially decreased but were unchanged 3 yr after institution of a CTC screening program (255.0 vs 253.5). CONCLUSIONS: (a) In our tertiary care center the initiation of a screening CTC program did not result in a decrease in the number of total colonoscopy exams, screening colonoscopy exams performed, nor requests for screening colonoscopy. (b) Only a small number of CTC exams were referred for EC with polypectomy, therefore a CTC screening program may not increase the overall number of therapeutic colonoscopies performed. [ABSTRACT FROM AUTHOR]

The purpose was to evaluate low-dose CT colonography without cathartic cleansing in terms of image quality, polyp visualization and patient acceptance. Sixty-one patients scheduled for colonoscopy started a low-fiber diet, lactulose and amidotrizoic-acid for fecal tagging 2 days prior to the CT scan (standard dose, 5.8-8.2 mSv). The original raw data of 51 patients were modified and reconstructed at simulated 2.3 and 0.7 mSv levels. Two observers evaluated the standard dose scan regarding image quality and polyps. A third evaluated the presence of polyps at all three mSv levels in a blinded prospective way. All observers were blinded to the reference standard: colonoscopy. At three times patients were given questionnaires relating to their experiences and preference. Image quality was sufficient in all patients, but significantly lower in the cecum, sigmoid and rectum. The two observers correctly identified respectively 10/15 (67%) and 9/15 (60%) polyps > or =10 mm, with 5 and 8 false-positive lesions (standard dose scan). Dose reduction down to 0.7 mSv was not associated with significant changes in diagnostic value (polyps > or =10 mm). Eighty percent of patients preferred CT colonography and 13% preferred colonoscopy (P<0.001). CT colonography without cleansing is preferred to colonoscopy and shows sufficient image quality and moderate sensitivity, without impaired diagnostic value at dose-levels as low as 0.7 mSv. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the usefulness of computed tomography (CT) enteroclysis in patients with obscure gastrointestinal (GI) bleeding. Materials and methods: In a prospective study, CT enteroclysis was performed in 21 patients (median age 50 years; range 13–71 years) with obscure GI bleeding in which the source of the bleeding could not be detected despite the patient having undergone both upper GI endoscopic and colonoscopic examinations. The entire abdomen and pelvis was examined in the arterial and venous phases using multisection CT after distending the small intestine with 2l of 0.5% methylcellulose as a neutral enteral contrast medium and the administration of 150ml intravenous contrast medium. Results: Adequate distension of the small intestine was achieved in 20 of the 21 (95.2%) patients. Potential causes of GI bleeding were identified in 10 of the 21 (47.6%) patients using CT enteroclysis. The cause of the bleeding could be detected nine of 14 (64.3%) patients with overt, obscure GI bleeding. However, for patients with occult, obscure GI bleeding, the cause of the bleeding was identified in only one of the seven (14.3%) patients. The lesions identified by CT enteroclysis included small bowel tumours (n =2), small bowel intussusceptions (n =2), intestinal tuberculosis (n =2), and vascular lesions (n =3). All vascular lesions were seen equally well in both the arterial and venous phases. Conclusions: The success rate in detection of the cause of bleeding using CT enteroclysis was 47.6% in patients with obscure GI bleeding. The diagnostic yield was higher in patients with overt, obscure GI bleeding than in those with occult obscure GI bleeding. [Copyright &y& Elsevier]

Purpose: To estimate the cost-effectiveness of detecting colorectal polyps with computed tomographic colonography (CTC) and subsequent polypectomy with primary colonoscopy (CC), using CC as the alternative strategy. Material and Methods: A marginal analysis was performed regarding 103 patients who had had CTC prior to same-day CC at two hospitals, H-I (n = 53) and H-II (n = 50). The patients were randomly chosen from surveillance and symptomatic study populations (148 at H-I and 231 at H-II). Populations, organizations, and procedures were compared. Cost data on time consumption, medication, and minor equipment were collected prospectively, while data on salaries and major equipment were collected retrospectively. The effect was the (previously published) sensitivities of CTC and CC for detection of colorectal polyps > or = 6 mm (H-I, n = 148) or > or = 5 mm (H-II, n = 231). Results: Thirteen patients at each center had at least one colorectal polyp > or = 6 mm or > or = 5 mm. CTC was the cost-effective alternative at H-I (euro187 vs. euro211), while CC was the cost-effective alternative at H-II (euro239 vs. euro192). The cost-effectiveness (costs per finding) mainly depended on the sensitivity of CTC and CC, but the depreciation of equipment and the staff's use of time were highly influential as well. Conclusion: Detection of colorectal polyps > or = 6 mm or > or = 5 mm with CTC, followed by polypectomy by CC, can be performed cost-effectively at some institutions with the appropriate hardware and organization. [ABSTRACT FROM AUTHOR]

The article discusses studies that determine the significance of virtual colonoscopy in cancer screening. This study is based on a multicenter study signifying that virtual colonoscopy has compared well with traditional colonoscopy in the detection of polyps, while 2 other studies did not. In December 2003, Dr. Perry Pickhardt and colleagues found out that computed tomography colonography (CTC) compared well with colonoscopy in detecting polyps in asymptotic adults. In April 2004, Dr. Peter Cotton and colleagues found that CTC was not ready for main stream clinical use until a significant amount of enhancement took place in the use of this technology. In January 2005, Dr. Don Rockey and colleagues also found that CTC is less sensitive for detecting polyps when compared with colonoscopy. INSETS: What patients can expect during a virtual co!onoscopy;Remove that polyp? With virtual colonoscopy, it's not automatic.

Background: the main colonic imaging modalities, including barium enema, colonoscopy and computed tomography colonography, require bowel preparation. Performing these imaging procedures in the elderly can difficult due to immobility, incontinence and poor tolerance of bowel cleansing. Minimal preparation CT (MPCT) colon was introduced in the early 1990s in the UK. Much of the published literature on MPCT colon is limited by small patient numbers and short duration of follow-up. Objective: the aim of this study is to review our experience with the MPCT technique involving a large consecutive cohort of patients with long follow-up. Methods: all studies of MPCT performed in a 1-year period between July 2000 and July 2001 at our institution were reviewed retrospectively. MPCT reports were cross-referenced with the cancer registry to allow for an average period of 30 months follow-up. A definite diagnosis of cancer was only given following the appearance on the cancer registry. Those patients who had negative MPCT colon were assumed to be true negatives if no corresponding name was identified on the cancer registry. In the event of data mismatch, patient notes were reviewed to ascertain a diagnosis. Results: 391 MPCT examinations were performed during the period of the study (209 males, median age 82: age range 56-91 years). Thirty-four patients who had MPCT colon during the study period appeared on the cancer registry. A further three patients with disseminated colorectal malignancy identified on MPCT colon died without histological confirmation (tumour prevalence = 9.5%). Thirty-two of the registry confirmed 34 cases were detected on MPCT colon, giving a sensitivity of 0.94 (95% confidence interval 0.86-1.00). Including the three cases without histological confirmation gives a slightly higher sensitivity of 0.95. There were seven patients with definitely abnormal MPCT colons, who did not appear on the registry, resulting in specificity for definite abnormality of 0.98 (confidence interval 0.97-1.0). However, three of these seven are those who died of disseminated colorectal malignancy as above, raising the specificity to 0.99. Fourteen cases (3.5%) of extra-colonic malignancies were observed in this study. Conclusion: even with the longer follow-up of this large cohort of patients the sensitivity and specificity in our study for the diagnosis of colorectal cancer with MPCT remains comparable with that of other studies and this technique competes well with other common colonic imaging modalities. [ABSTRACT FROM AUTHOR]

Aim: Computed tomographic colonography (CTC) represents a valuable advance in imaging technology for patients with colonic symptoms who are unfit for or fail to complete investigation with conventional techniques of colonoscopy or barium enema. The aim of this study was to examine whether CTC was sufficient to exclude colorectal cancer in such a population. As our patients were unfit for or unable to complete conventional investigations, we used 1 year clinical follow-up to exclude colonic malignancy. Materials and Methods: CTC examination was performed using multi-slice CT in patients fitting pre-determined criteria. All patients who had completed 12 months of follow-up after CTC were included. Data were extracted from patient records and lack of presentation within the 12 months following a negative CTC was assumed to equate to lack of colorectal cancer at initial investigation. Results: One hundred and twelve patients underwent CTC with a median age of 78 years (range 39-95) and median follow-up of 18 months (range 12-26). CTC detected 7 colorectal cancers, with 3 false positives and 1 false negative, giving a sensitivity of 87.5% and specificity of 97.1% for the detection of colorectal cancer. Conclusions: CTC is a good imaging tool for the exclusion of colorectal cancer in a population unfit for or unable to complete colonoscopy or barium enema, with reasonable sensitivity and specificity for detection of colorectal cancer. However, the optimum investigative strategy for fitter symptomatic individuals is still debated and should be clarified by the results of ongoing randomised controlled trials. [ABSTRACT FROM AUTHOR]

Aim: To externally validate a computer-assisted detection (CAD) system for computed tomography (CT) colonography, using data from a single centre uninvolved with the software development. Materials and Methods: Twenty-five multi-detector CT colonography examinations of patients with validated polyps accumulated at a single centre were examined by two readers who used endoscopic and histopathological data to identify polyp coordinates. A CAD system that had been developed using data from elsewhere, and had not previously encountered the present data, was then applied to the data at sphericity filter settings of 0.75 and 0.50 and identified potential polyps. True-positive, false-negative, and false-positive counts were determined by comparison with the known polyp coordinates. Results: Twenty-five patients had 57 polyps, median size 6mm (range 1-15mm). Per-patient sensitivity for the CAD system was 96% (24 of 25). The CAD system detected 44 (77%) polyps at sphericity setting 0.75 and 49 (86%) polyps at sphericity 0.50: the additional five polyps detected all measured 5mm or less. Sphericity of 0.75 resulted in a median of 10 (one to 34) easily dismissed false-positive prompts per patient and a median of 4 (zero to 15) that needed three-dimensional rendering before dismissal. This rose to 32 (16 to 99) and 11 (three to 35), respectively, at sphericity 0.5. Conclusions: A per-patient sensitivity of 96% was found for the CAD system (in patients with a median polyp diameter of 6mm) using external validation, a more stringent test than either internal cross-validation or temporal validation. Decreasing sphericity increases sensitivity for small polyps at the expense of decreased specificity. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: This report proposes an alternative method for the automatic detection of colonic polyps that is robust enough to be directly applicable on low-dose computed tomographic data. Materials and Methods: The polyp modeling process takes into account both the gray-level appearance of polyps (intensity profiles) and their geometry (extended Gaussian images). Spherical harmonic decompositions are used for comparison purposes, allowing fast estimation of the similarity between a candidate and a set of previously computed models. Starting from the original raw data (acquired at 55 mA), five patient data sets (prone and supine scans) are reconstructed at different dose levels (to 5 mA) by using different kernel filters, slice overlaps, and increments. Additionally, the efficacy of applying an edge-preserving smoothing filter before detection is assessed. Results: Although image quality decreases when decreasing acquisition milliamperes, all polyps greater than 6 mm are detected successfully, even at 15 mA. Although not important at high doses, smoothing improves detection results for ultra-low-dose (tube current<15 mA) data. Conclusion: The advantage of low-dose scans is a significant decrease in effective dose from 4.93 to 1.61 mSv while retaining high detection values, particularly important when thinking of population screening. [ABSTRACT FROM AUTHOR]

Aim: To compare wet and dry preparation methods for computed tomography colonography (CTC) in terms of preparation quality, interpretation time, and diagnostic performance for polyp detection in a population with a high residue diet. Materials and Methods: Eighty-six patients were divided into two groups. Group 1 (n=24) received a wet preparation of 4l polyethylene glycol (PEG) solution, and group 2 (n=62) received a dry preparation of phosphor-soda. Abnormal findings, including polyps, and the time required to interpret the CTC images in both groups were documented by a radiologist. CTC findings were compared to those of colonoscopy as a reference standard. Two radiologists evaluated the quality of CTC with regard to residual fluid, faeces, and colonic distension using a four-point scale in consensus. Statistical differences for residual fluid, faeces, distensibility on CTC, and interpretation time between the two groups were analysed. The diagnostic performance of CTC in both groups was also compared. Results: One-hundred and ninety polyps in 70 patients were identified using colonoscopy. Regarding the quality of images produced the wet preparation was significantly better than the dry preparation (p<0.05). The average interpretation time was significantly shorter for the wet group (11.7 min) than the dry group (16.4 min) (p<0.05). For per-patient analysis, the positive predictive value (PPV) was significantly better for the wet (100%) than the dry group (79.6%; p=0.025). Sensitivities and PPV for >or=10 mm polyps were comparable between two groups (p>0.05). Conclusion: In a population with a high-residue diet, CTC with wet preparation can be interpreted in a time-efficient manner and is comparable with CTC with dry preparation. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Computed tomographic colonography (CTC) offers great promise in the management of patients with disorders of the colon. Few complications have been reported with its use thus far. We describe herein a case of colonic perforation during CTC in a patient with active stenosing ileocolonic Crohn's disease. To our knowledge, this is the first reported case of CTC-related perforation in the setting of Crohn's disease, and the third reported perforation overall. Perforation likely occurred in this case due to barotrauma in the setting of colonic strictures and an inflamed, weakened colonic wall. Physician awareness of the increased risk of perforation with CTC in the setting of inflammatory and/or obstructive disease of the colon will allow for improved clinical decision-making in the care of these patients. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate patient acceptance of computed tomography (CT) colonography compared with conventional colonoscopy by means of a self‐assessed questionnaire. Material and Methods: Four‐hundred‐and‐one patients with valid address information from our patient collective were preselected. Patient acceptance was evaluated retrospectively using a self‐assessed questionnaire. The patients underwent CT colonography in our institution using 4× or 16× multi‐detector row (MDR) CT. Two‐hundred‐and‐forty‐six patients returned a completed questionnaire, 157 of these indicating that they had undergone both virtual and conventional colonoscopy. Results: One‐hundred‐and‐twenty (76.4%) of the 157 patients would undergo another CT colonography if necessary, while only 14 patients would not. One‐hundred‐and‐sixteen (73.9%) patients favored the actual examination procedure of CT colonography ( P <0.0001), while only 6.4% preferred the conventional method. Preparation prior to CT colonography was experienced as more convenient than preparation prior to conventional colonoscopy (52.2% versus 14%). Conclusion: CT colonography was preferred in terms of both preparation and the actual procedure itself. [ABSTRACT FROM AUTHOR]

This review focuses on the detection of extracolonic findings at CT colonography (CTC). Since its introduction, it has been regarded as a promising alternative to conventional colonoscopy for the detection of colorectal polyps and cancers. Unlike conventional colonoscopy and barium enema, CTC allows evaluation not only of the colon but also visualization of the lung bases, the abdomen, and the pelvis. CTC is performed with thin sections (1-5 mm) and small intervals (0.5-2 mm), enabling superb image reconstruction. The ability to evaluate the extracolonic structures can present a clinical dilemma. On the one hand, CTC may incidentally demonstrate asymptomatic malignant diseases or other clinically important conditions, thus possibly reducing morbidity or mortality. On the other hand, CTC may reveal numerous findings of no clinical relevance; this could result in costly additional diagnostic examinations with an increase in morbidity and overall negative impact on patients' health. In this article, extracolonic findings at CTC will be reviewed and the potential benefits and disadvantages will be presented. [ABSTRACT FROM AUTHOR]

We retrospectively reviewed the computed tomographic colonographic datasets of 22 patients. Mean attenuation values of benign polyps before and after contrast administration were 30 +/- 15 HU and 90 +/- 18 HU, respectively. Mean attenuation values of colorectal cancer before and after contrast administration were 43 +/- 15 HU and 124 +/- 18 HU, respectively. The mean attenuation value of solid fecal residuals was 43 +/- 15 HU. The difference in attenuation value between precontrast and postcontrast studies of polyps was statistically significant (mean 60 HU, p < 0.01); the same was true for colorectal cancer (mean 81 HU, p < 0.01). The difference between postcontrast density of polyps and cancer with respect to density of solid fecal residuals was statistically significant (p < 0.01). The use of contrast medium could be of help in computed tomographic colonography for discriminating polypoid benign lesions and colorectal cancer from fecal residuals. [ABSTRACT FROM AUTHOR]

To compare the clinical importance of extracolonic findings at intravenous (IV) contrast-enhanced CT colonography versus those at non-enhanced CT colonography. IV contrast medium-enhanced (n=72) and non-enhanced (n=30) multidetector CT colonography was performed in 102 symptomatic patients followed by conventional colonoscopy on the same day. The impact of extracolonic findings on further work up and treatment was assessed by a review of patient records. Extracolonic findings were divided into two groups: either leading to further work up respectively having an impact on therapy or not. A total of 303 extracolonic findings were detected. Of those, 71% (215/303) were found on IV contrast-enhanced CT, and 29% (88/303) were found on non-enhanced CT colonography. The extracolonic findings in 25% (26/102) of all patients led to further work up or had an impact on therapy. Twenty-two of these patients underwent CT colonography with IV contrast enhancement, and four without. The percentage of extracolonic findings leading to further work up or having an impact on therapy was higher for IV contrast-enhanced (31%; 22/72) than for non-enhanced (13%; 4/30) CT scans (P=0.12). IV contrast-enhanced CT colonography produced more extracolonic findings than non-enhanced CT colonography. A substantially greater proportion of findings on IV contrast-enhanced CT colonography led to further work up and treatment than did non-enhanced CT colonography. [ABSTRACT FROM AUTHOR]

Objective To investigate the techniques and clinical applications of multislice helical computed tomography (CT) colonography in colonic lesions. Methods Fitly-nine patients with malignant lesions of colon underwent volume scanning using multislice helical CT. Four types of reconstruction including CT virtual colonoscopy (CTVC), shaded surface display (SSD), Raysum, and multiple planar reconstruction (MPR) were used for image post-processing. The results were compared with those of colonoscopy and pathology. Results Multislice helical CT colonography detected 54 colorectal carcinomas, 4 adenomas with focal carcinoma, 1 non-Hodgkin's lymphoma (NHL). The lesions' number, size, location, morphology, stricture of intestinal cavity, infiltration, and metastasis were shown satisfactorily by multislice helical CT colonography. Whole colon could be shown in all patients. CT colonography displayed 4 synchronous colonic tumors, 1 ascending colon carcinoma combined with left renal carcinoma among 54 patients with colonic carcinomas. The accuracy of location of CT colonography was 100%. There were 9 cases that CT showed the tumor location was different from the finding of conventional colonoscopy, while all of the CT location were proven exact by operation. CT colonography also displayed the infiltration of serous layer and fatty tissue in 45 cases; 21 cases matched the pathological results in all the 24 cases of suspicious lymph node metastasis, the sensitivity was 87.5%, the specificity was 90.6%; 9 cases hepatic metastasis, 2 ovarian metastasis, and 1 double adrenal gland metastasis. Conclusions Multislice helical CT colonography is effective in preoperative diagnosis, location, stage, and making treatment plan of colorectal carcinoma. It can display the portion not seen during colonoscopy and may have an adjunctive role. [ABSTRACT FROM AUTHOR]

Focuses on the various aspects of virtual colonoscopy or computed tomographic (CT) colonography (CTC). Features and advantages of CTC over other diagnostic imaging methods; Steps in CTC patient preparation; Data acquisition methods and interpretation for the procedure; Patients who should undergo CTC; Factors that characterize a significant lesion.

Abstract: Cystic pneumatosis of the colon is a rare condition characterized by the presence of multiple gas-filled cysts within the colonic wall. We report a case of idiopathic cystic pneumatosis of the colon and stress the role of imaging in the diagnosis, evaluation and clinical management of this rare disease. We present endoscopic, endosonographic and CT findings including results of virtual colonoscopy. [Copyright &y& Elsevier]

Rationale and Objective: To present an algorithm to automatically locate seeds for colon segmentation in computed tomography colonography (CTC). Materials and Methods: The algorithm automatically locates two points (seeds) inside the colon lumen. Because of their high distention and fixed anatomic position, we focus on the cecum and rectum for automatic seed placement. We use two-dimensional morphological operators that find pockets of colonic air of sufficient size. For the rectum, we search within an inferiorly and centrally located CT slice. For the cecum, we search in a group of CT slices in the middle of the scanned volume on the patient's right side. We applied our automated algorithm to segment the colon in 292 consecutive cases of CTC (146 prone, 146 supine). Results: After automated seed placement, 83.2% (243 of 292) of the colons were segmented completely and 9.6% (28 of 292) were segmented partially. The unsegmented colon parts were present in datasets where the colon was collapsed in more than one place or because seeds could not be placed in regions filled with fluid. In the remaining 7.2% (21 of 292) of cases, the automatic segmentation leaked outside the colon because of a limitation of the contrast-enhanced fluid detection algorithm. Conclusion: Fully automatic seed placement for colonic segmentation is feasible in the majority of cases without seeding of undesired extracolonic air. [ABSTRACT FROM AUTHOR]

An automatic method to segment colonic polyps in computed tomography (CT) colonography is presented in this paper. The method is based on a combination of knowledge-guided intensity adjustment, fuzzy c-mean clustering, and deformable models. The computer segmentations were compared with manual segmentations to validate the accuracy of our method. An average 76.3% volume overlap percentage among 105 polyp detections was reported in the validation, which was very good considering the small polyp size. Several experiments were performed to investigate the intraoperator and interoperator repeatability of manual colonic polyp segmentation. The investigation demonstrated that the computer-human repeatability was as good as the interoperator repeatability. The polyp segmentation was also applied in computer-aided detection (CAD) to reduce the number of false positive (FP) detections and provide volumetric features for polyp classification. Our segmentation method was able to eliminate 30% of FP detections. The volumetric features computed from the segmentation can further reduce FP detections by 50% at 80% sensitivity. [ABSTRACT FROM AUTHOR]

We describe a method to perform postacquisitioil processing of computed tomography colonography (virtual colonoscopy) datasets that results in electronic removal of opacified, ingested bowel contents while reconstructing natural appearing boundaries of colon lumen and thereby permitting three-dimensional visual analyses of the resulting colon models. [ABSTRACT FROM AUTHOR]

Discusses the tomographic protocols and scanning techniques in virtual colonoscopy. Consideration for the patient morbidity in virtual colonoscopy compared with conventional procedures; Use of a twenty-four hour colon cleansing preparation using magnesium citrate, stool tagging, and barium sulfate suspension; Use of computers in diagnosis.

In this paper, a method is presented for detection of colonic polyps using both morphological and texture features of the colon wall from the abdominal computed tomography (CT) images. This method consists of two steps. In the first step, suspicious patches of the colon wall are quickly identified by utilizing special local and global geometrical information of the segmented inner-wall mucosa layer. In the second step, a special mapping strategy is employed to identify the growing region of each suspected polyp. Then its internal CT density textures are extracted and quantitatively analyzed based on an assumed ellipsoid polyp model. Finally, both the extracted texture and morphological information are applied to eliminate the false-positives from the identified suspicious patches. With all the extracted geometrical, morphological and texture features, this presented computer-aided detection (CAD) method has demonstrated a significant improvement in detection of the colonic polyps over the previously reported geometry-based CAD methods for CT-based virtual colonoscopy. [Copyright &y& Elsevier]

The term virtual endoscopy refers to using either spiral computed tomography (CT colonography) or magnetic resonance scanning (MR colonography) combined with computer technology to produce high-resolution two- and three-dimensional imaging of the large bowel. Current CT techniques require meticulous bowel preparation and gas insufflation prior to the examination. The advantages of CT colonography over conventional colonography include safety, its ability to demonstrate the entire large bowel in almost all patients, even following incomplete endoscopy, to accurately localize lesions, and to examine the entire colon in patients with obstructing tumors. Additionally, CT colonography allows simultaneous preoperative tumor staging. Screening for colorectal polyps is a controversially discussed indication for CT colonography. Sensitivity and specificity range widely and decrease with decreasing polyp size. However, better results can be achieved using multidetector technology. Most frequently, the examination is well tolerated and assessed by patients to be more acceptable than conventional colonoscopy. There are no reported complications from CT colonography. The procedure requires a scan time of about 25 to 30 seconds with new multidetector CT scanners, and sedation is not used. Currently, CT colonography is less cost-effective than conventional endoscopy. Another disadvantage is the relatively high irradiation exposure associated with CT colonography. Therefore, at the moment, this technique does not appear ready to be included in general screening strategies. However, ongoing and future improvements may prove its value in colorectal examination strategies. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the discomfort associated with CT colonography compared with colonoscopy and bowel purgation cleansing, and to evaluate patient preference between CT colonography and colonoscopy. In a total of 124 patients, scheduled for multidetector virtual CT colonography and diagnostic colonoscopy, patient acceptance and future preference were assessed during the different steps of the procedure (colon preparation, CT examination, and conventional colonoscopy). Patients who described contradictory findings between the degree of discomfort and their preference regarding follow-up examinations were retrospectively reinterviewed regarding the reason for this discrepancy. Colonoscopy was graded slightly more uncomfortable than virtual CT colonography, but the preparation was clearly the most uncomfortable part of the procedure. Concerning their preference regarding follow-up examinations, 71% of the patients preferred virtual CT colonography, 24% preferred colonoscopy, and 5% had no preference. Twenty-eight percent of the patients preferred virtual CT colonography despite that they thought it was equally or even more uncomfortable than colonoscopy. This was mainly due to the faster procedure (17 patients), the lower physical challenge (14 patients), and the lack of sedation (12 patients) of virtual CT colonography. Factors other than the discomfort related to the examinations play an important role in the patient's preference for virtual CT colonography, namely the faster procedure, the lower physical challenge, and the lack of sedation. Since the preparation plays a major decisive factor in the patient acceptance of virtual CT colonography, more attention should be given to fecal tagging. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the impact of the learning curve on the diagnostic performances of CT colonography. Two blinded teams, each having a radiologist and gastroenterologist, prospectively examined 50 patients using helical CT scan followed by colonoscopy. Intermediate data evaluation was performed after 24 data sets (group 1) and compared with data from 26 subsequent patients (group 2). Parameters evaluated included sensitivity, specificity, false-positive and false-negative findings, time of data acquisition and interpretation. Using colonoscopy as the gold standard, sensitivity for CT colonography was for lesions >5 mm 63% for both teams for group 1 patients; for group 2 patients sensitivity was 45% for team 1 and 64% for team 2. Specificity per patients was for patient group 1 42% for team 1 and 58% for team 2; for patient group 2 it was 79% for both teams ( p=0.04 for team 1; p=0.2 for team 2). Comparing group 1 with group 2, the number of false-positive findings decreased significantly ( p=0.02). Furthermore, the mean time of data evaluation decreased from 45 to 17 min ( p=0.002) and the mean time of data acquisition from 19 to 17 min. With increasing experience, specificity and the time required for data interpretation improved and false positives decreased. There was no significant change of sensitivity, false-negative findings and time of data acquisition. A minimum experience of the readers is required for data interpretation of CT colonography. [ABSTRACT FROM AUTHOR]

Introduction: Computed tomography colonography, or virtual colonoscopy, is a good alternative to optical colonoscopy. However, suboptimal patient preparation or colon distension may reduce the diagnostic accuracy of this imaging technique.Case Presentation: We report the case of an 83-year-old Caucasian woman who presented with a five-month history of pneumaturia and fecaluria and an acute episode of macrohematuria, leading to a high clinical suspicion of a colovesical fistula. The fistula was confirmed by standard contrast-enhanced computed tomography. Optical colonoscopy was performed to exclude the presence of an underlying colonic neoplasm. Since optical colonoscopy was incomplete, computed tomography colonography was performed, but also failed due to inadequate colon distension. The insufflated air directly accumulated within the bladder via the large fistula.Conclusions: Clinicians should consider colovesical fistula as a potential reason for computed tomography colonography failure. [ABSTRACT FROM AUTHOR]

Primary adenocarcinomas of the retrorectal (presacral) space are uncommon and usually arise from cystic lesions developing from remnants of the embryological postanal gut (tail gut cysts) containing mucous-secreting epithelium. A singular case of a patient who presented with a retrorectal mass is described. A 70-year-old previously healthy man had a four-month history of perianal pain during defecation. Preoperative colonoscopy showed external compression of the lower rectum with normal mucosa; pelvic computed tomography demonstrated a 5.5×4.5 cm2 retrorectal oval mass, originating from the posterior lower rectal wall, containing cystic components and some small calcifications. The tumor, after complete resection via transanal approach, was shown to be a very rare case of primary adenocarcinoma of the presacral space. The patient had an uneventful postoperative course and he is free from disease 4 years after surgery. Clinicopathological features and surgical treatment of this unusual tumor are discussed. [ABSTRACT FROM AUTHOR]

The article discusses research being done on colorectal cancer. It references a study by D. Regge et al, published in the 2009 issue of the "Journal of American Medical Association." A total of 973 subjects at risk for colon cancer on the basis of family history were considered. Computed tomography colonoscopy (CTC) and optical colonoscopy (OTC) were used to detect advanced neoplasia among the patients.