Background Virtual colonoscopy has been evaluated for use as a colorectal cancer screening tool, and in prior studies, it has been estimated that the evaluation of extra-colonic findings adds $28-$34 per patient studied. Methods As an ancillary study to a prospective cohort study comparing virtual colonoscopy to conventional colonoscopy for colorectal cancer detection, the investigators retrospectively determined the number and estimated costs of all clinic visits, imaging and laboratory studies, and medical procedures that were generated as a direct result of extra-colonic findings at virtual colonoscopy. Results We enrolled 143 subjects who underwent CTC followed by conventional colonoscopy. Data were available for 136 subjects, and 134 (98%) had at least one extra-colonic finding on CT. Evaluation of extra-colonic findings was performed in 32 subjects (24%). These subjects underwent 73 imaging studies, 30 laboratory studies, 44 clinic visits, 6 medical procedures, and 44 new or return outpatient visits over a mean of 38 months following the CTC. The most common findings causing further evaluation were lung nodules and indeterminate kidney lesions. No extra-colonic malignancies were found in this study. A total of $33,690 was spent in evaluating extra-colonic findings, which is $248 per patient enrolled. Conclusions The cost of the evaluation of extra-colonic findings following virtual colonoscopy may be much higher in actual practice than is suggested by prior studies. This will impact the cost-effectiveness of using virtual colonoscopy for asymptomatic colorectal cancer screening and underscores the importance of standardizing the reporting of extra-colonic findings to encourage appropriate follow-up.

COLORECTAL CARCINOMA is the leading cause of cancer-related death in the nonsmoking United States population, with about 60,000 annual fatalities.1 Yet it is the most preventable cancer if the cancer precursor, polyps, can be detected and removed at an early stage. The current gold standard for colorectal cancer screening is optical colonoscopy because of its high accuracy compared to other screening methods such as fecal occult blood test, double-contrast barium enema, and sigmoidoscopy. Increased optical colonoscopy compliance for subjects over 50 would substantially decrease the cancer mortality; however, fewer than 40% of the average risk adults reported having received a optical colonoscopy in the past 5 years.1 Optical colonoscopy compliance is low due to its discomfort, perforation risk, high cost, and high negative statistic. Computed tomographic colonography (CTC), or virtual colonoscopy, has been considered a promising replacement for optical colonoscopy as a regular screening method since its introduction in 19942 and has been an active research field for both clinical researchers and technology developers. On the clinical side, many medical centers perform a CTC procedure, and some of them are doing large population clinical experiments on CTC. A multi-center clinical trial3 of CTC over a large asymptomatic population (1233 subjects) published encouraging results, which show the viability of virtual colonoscopy as a screening tool. Regarding radiologist interpretation, CTC acceptance has been hindered by two issues, detection accuracy, which is generally unacceptable for clinical practice, and interobserver variances. 4, 6, 7With observers at diverse levels of expertise and using different reading methods, multiple centers reported radiologists’ CTC results with sensitivities between 20% and 90% for 6-mm and larger polyps.5 Aside from interpretation variation, detection performance is affected by different raw image quality due to patient preparation, scanner parameters, and dose consideration. On the technology side, in addition to CT scanner improvement from single to multi-row detectors, researchers have made efforts to use computer techniques to solve the above clinical problems. Volume rendering and visualization that are available on commercial systems directly affect radiologists’ results.8 Computer-aided polyp detection (CAPD) or computerized polyp detection (CPD) may improve the platform to address the above issues in clinical research. Yoshida and Nappi reported a fully automatic CPD system tested on 43 patients with 12 polyps and yielded 1 to 2 false positive results (FPs)/case.9 Nappi and yoshida have extended the algorithm by introducing another geometric feature, modified gradient concentration, and applied the system to more patients but with no substantial improvement.10 Gokturk et al reported their statistical ROSS method used in false positive reduction,(11,12) which produced a 40-50% increment of specificity without sensitivity loss, an encouraging result but still far from radiologist accuracy, especially for the very low specificity. The main difficulties and challenges of CAPD in CTC are summarized by Summers.13 Given the CTC raw data, segmentation is the first step in our CPD scheme. There are two major segmentation approaches, surface methods and volume methods. In surface methods, a mesh surface that represents the colon lumen needs to be segmented from the volume data.14-16 In volume methods, the lumen surface voxels and/or their neighboring voxels are segmented using gradient operators(9, 10, 17) and volume subtraction.9 There is no convincing proof for the advantage of either method. For the subsequent polyp detection, there are also two sources for feature calculation. They are: Local volumetric information calculated from the intensity values of a small volumetric neighborhood. Local shape information calculated from the mesh surface structure. The local volumetric information approach uses the intensities of voxels in a neighborhood and the extracted features computed from them so that a CPD algorithm can classify the neighborhood. For example, Yoshida and Nappi.9 defined the local shape index (SI), curvedness (CV), and directional gradient concentration (DCG) as three geometric features in their classifier. Statistical values based on voxel intensities may provide useful features. When local shape information from the mesh surface is used, curvature-based shape features can be calculated from a group of connected vertices or from the polyp candidates. Also the size, roundness, etc., can be obtained easily from the surface data. Furthermore, the surface method intrinsically reduces the noise effect in curvature calculation. Making the decision to use one or both of the sources to calculate the geometric features is the beginning of feature selection and reduction. Selection is accomplished by observation, expert opinion, taking all possible measurements, and/or any other methods that transform knowledge of the system into metrics. Feature reduction is the subsequent and optional procedure to find the most useful and most independent set of features, from the originals, that also produces the optimum classification. In many practical situations, feature reduction is accomplished by observation or evaluating the system performance with a framing database. The goal of classifier selection is to find the best classifier for partitioning the feature space. Bayes classifiers18 are well-studied and widely used in many medical applications. A hyperplane, corresponding to a linear discriminant function (LDF), and a second-order surface, corresponding to a quadratic discriminant function (QDF), are the most frequently used Bayes classifiers because of their simplicity and effectiveness. Support vector machines (SVM) transform the given feature space to higher dimensions so that the sample vectors are linearly separable in the transformed space.11 In the above classifiers, we often assume(1) normal distributions for both the true positive and false positive, or non-polyp categories, and (2) sufficient training samples for parameter estimation. However, these assumptions are not quite practical in polyp detection. The first reason is that the false positive category is the dominant class, which may bias the calculation of the average covariance matrices. The second reason is that the normal distribution assumption for the false positive category is questionable because the category embraces anything other than polyps and the occurrences of the feature vectors of false positives in the feature space are generally unpredictable. Therefore, we propose an MLDF method, which corresponds to several empirical hyperplanes that frame a hypercubic region in a given feature space, and a MAP method, which requires parametric training only for the polyp category. We have developed a fully automatic CPD system, which begins with raw DICOM data and ends with a list of detected polyps by employing a typical CAPD/CPD scheme: segmentation, polyp candidate generation, and false positive reduction. In our system, both supine and prone scans are combined to increase the colon coverage in computerized segmentation14 and in turn to improve the detection sensitivity. Colon deformation between the two positions makes the surface registration practically unsolvable. Fortunately, the clinical significance of patient-based accuracy of CTC renders registration unnecessary; if a polyp showed in either or both scans, the patient would be forwarded to optical colonoscopy. In this specific situation, we redefine the accuracy terms for the CPD when using both scans. A true positive occurs when an optical colonoscopy polyp finding is CPD detected in either or both scans; a false positive occurs when a CPD finding in any scan cannot be matched to any of the optical colonoscopy polyp findings. Our results demonstrate that using both scans improves the detection sensitivity. The segmentation algorithm is presented in the accompanying article.14 In this article, we focus on the subsequent polyp detection. The details of our detection algorithm as well as a brief introduction of segmentation are presented below in Methodology, while the section titled Data describes the scanner parameters and the procedure for data acquisition. A description of the detection results follows; and we close with the Discussion and Conclusions.

OBJECTIVE:Although evidence exists linking smoking to precancerous colorectal adenomatous polyps, few studies have examined the association between cigarette smoking and recurrence of colorectal polyps. This association was investigated prospectively with data from the Polyp Prevention Trial.METHODS:Cigarette smoking data were collected through baseline interviews. The study was completed by 1872 men and women with presence of adenomas at baseline colonoscopy. Multiple logistic regression analysis was used to examine the association between cigarette smoking and polyp recurrence (adenomatous and hyperplastic) up to four years from baseline.RESULTS:Adenoma recurrence was not related to cigarette smoking. Current smokers had increased odds of hyperplastic polyps at follow-up compared to never smokers (OR 2.88, 95% CI 2.06-4.01). Current smoking was associated with subsequent distal (OR 3.44, 95% CI 2.38-4.95) and rectal (OR 3.53, 95% CI 2.15-5.78) hyperplastic polyps, but not subsequent proximal hyperplastic polyps. Cigarette smoking was associated with subsequent multiple and small size (4 mm) hyperplastic polyps. Significant linear trends were observed between development of subsequent hyperplastic polyps and all smoking variables.CONCLUSIONS:Although no association with recurrent adenomas was observed, cigarette smoking was significantly associated with hyperplastic polyp development, except for those in the proximal colon. This prospective study confirms that cigarette smoking has a significant effect on the development of hyperplastic colorectal polyps.

Infected pancreatic necrosis is the leading cause of death in patients with severe acute pancreatitis. Early prophylactic antibiotic treatment is effective in preventing conversion of sterile necrosis to pancreatic infection, but its effect on mortality remains unproven. Fungal infections may predict a worse outcome, but no evidence supports the use of antifungal prophylaxis. Because infection of pancreatic necrosis by enteric bacteria can develop despite prophylaxis, a high index of suspicion should allow early detection followed by aggressive management.

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.

We thank Dr. Tursi for his comments. We agree that conventional colonoscopy (CC) remains the “gold standard” for colorectal cancer screening, especially in very high-risk individuals. In fact, most virtual colonoscopy (VC) trials have excluded recognized high-risk conditions preventing results to be extrapolated to this population. The accuracy of polyp detection in the study by Johnson et al.1Johnson C.D. Harmsen W.S. Wilson L.A. MacCarty R.L. Welch T.J. Ilstrup D.M. Ahlquist D.A. Prospective blinded evaluation of computed tomographic colonography for screen detection of colorectal polyps.Gastroenterology. 2003; 125: 311-319Abstract Full Text Full Text PDF PubMed Scopus (310) Google Scholar was significantly lower than ours and other reported studies2Yee J. Akerkar G.A. Hung R.K. Steinauer-Gebauer A.M. Wall S.D. McQuaid K.R. Colorectal neoplasia performance characteristics of CT colonography for detection in 300 patients.Radiology. 2001; 219: 685-692Crossref PubMed Scopus (450) Google Scholar, 3Fenlon H.M. Nunes D.P. Schroy III, P.C. Barish M.A. Clarke P.D. Ferrucci J.T. A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps.N Engl J Med. 1999; 341 ([erratum in N Engl J Med 2000;342:524]): 1496-1503Crossref PubMed Scopus (666) Google Scholar, 4Fletcher J.G. Johnson C.D. Welch T.J. MacCarty R.L. Ahlquist D.A. Reed J.E. Harmsen W.S. Wilson L.A. Optimization of CT colonography technique prospective trial in 180 patients.Radiology. 2000; 216: 704-711Crossref PubMed Scopus (303) Google Scholar, 5Pineau B.C. Paskett E.D. Chen G.J. Espeland M.A. Phillips K. Han J.P. Mikulaninec C. Vining D.J. Virtual colonoscopy using oral contrast compared with colonoscopy for the detection of patients with colorectal polyps.Gastroenterology. 2003; 125: 304-310Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar but similar to the disappointing results from a multicenter trial in which our center performed well.6Cotton P.B. Durkalski V.L. Palesch Y.Y. Mauldin P.D. Pineau B.C. Vining D.J. et al.Virtual colonoscopy final results from a multicenter study (abstr).Gastrointest Endosc. 2003; : 57Google Scholar We agree that an important hurdle facing VC today is the discrepant results between, as well as within, centers. The reader’s experience has been singled out as a logical culprit.7Rex D.K. Is virtual colonoscopy ready for widespread application?.Gastroenterology. 2003; 125: 608-610Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar However, the variability of results seen in the study by Johnson et al. suggests that either a minimum of 150 VC cases is insufficient for competency, or other variables are equal or more important offenders. We believe that the technique for bowel preparation is critical to the diagnostic success of VC; we used oral sodium phosphate catharsis, oral contrast to opacify residual colonic fluid, and electronically controlled CO2 insufflation for improved bowel preparation.8Vining D.J. Pineau B.C. Improved bowel preparation for virtual colonoscopy examinations (abstr).Gastroenterology. 1999; 116: A524Google Scholar We are currently critically evaluating the value of oral contrast on the accuracy of lesion detection. Recent data suggest that the variability in hardware and software platforms is less likely to be the cause of discrepant results.9Johnson C.D. Toledano A.Y. Herman B.A. Dachman A.H. McFarland E.G. Barish M.A. Brink J.A. Ernst R.D. Fletcher J.G. Halvorsen Jr, R.A. Hara A.K. Hopper K.D. Koehler R.E. Lu D.S. Macari M. MacCarty R.L. Miller F.H. Morrin M. Paulson E.K. Yee J. Zalis M. Computerized tomographic colonography performance evaluation in a retrospective multicenter setting.Gastroenterology. 2003; 125: 688-695Abstract Full Text Full Text PDF PubMed Scopus (91) Google Scholar Hopefully, computer-aided lesion detection will help improve diagnostic accuracy and decrease interobserver variability. Although advanced pathology can be found in small polyps, reports suggest a prevalence of malignancy in diminutive polyps of approximately 0.25%, a figure that is likely to be even lower in purely average-risk individuals.5Pineau B.C. Paskett E.D. Chen G.J. Espeland M.A. Phillips K. Han J.P. Mikulaninec C. Vining D.J. Virtual colonoscopy using oral contrast compared with colonoscopy for the detection of patients with colorectal polyps.Gastroenterology. 2003; 125: 304-310Abstract Full Text Full Text PDF PubMed Scopus (165) Google Scholar The question of what truly constitutes a clinically significant polyp in an average-risk individual is an extremely important public health issue that deserves close scrutiny. We agree that missing small polyps may lead to the erroneous conclusion that an individual is polyp-free. However, this problem is not unique to VC as conventional colonoscopy by experts can miss up to 24% of all adenomas (including 6% of those >1 cm).10Rex D.K. Cutler C.S. Lemmel G.T. Rahmani E.Y. Clark D.W. Helper D.J. Lehman G.A. Mark D.G. Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.Gastroenterology. 1997; 112: 24-28Abstract Full Text PDF PubMed Scopus (1365) Google Scholar Also, in clinical practice, CC can miss up to 5% of colorectal cancers.11Rex D.K. Rahmani E.Y. Haseman J.H. Lemmel G.T. Kaster S. Buckley J.S. Relative sensitivity of colonoscopy and barium enema for detection of colorectal cancer in clinical practice.Gastroenterology. 1997; 112: 17-23Abstract Full Text PDF PubMed Scopus (510) Google Scholar Considering our imperfect “gold standard,” should average risk individuals with a negative screening conventional colonoscopy wait 10 years for a repeat examination as our guidelines recommend?12Levin B. Brooks D. Smith R.A. Stone A. Emerging technologies in screening for colorectal cancer CT colonography, immunochemical fecal occult blood tests, and stool screening using molecular markers.CA Cancer J Clin. 2003; 53: 44-55Crossref PubMed Scopus (174) Google Scholar If not, how will this impact the costs associated with colorectal cancer screening? Before VC can be embraced as an acceptable alternative to screening CC, these and several other issues will need to be resolved. At this juncture, we agree that VC should remain in expert centers.

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s Submitted for the 68th Annual Scientific Meeting of the American College of Gastroenterology October 10-15, 2003, Baltimore, Maryland: PANCREATIC/BILIARY: PDF Only

1Department of Medicine, Winston-Salem, North Carolina, USA 2Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA

The purpose of this study was to determine the sensitivity and specificity of CT colonography (CTC) to detect colorectal polyps and cancer compared with conventional colonoscopy. In this investigation, 300 patients (97% male; mean age 62.6 yr) at a university-affiliated Veterans Affair hospital were recruited to undergo CTC 2–3 h before a clinically indicated conventional colonoscopy. Colonic lavage was achieved with 10 oz of magnesium citrate and 4 L of a polyethylene glycol electrolyte lavage solution; colonic distention was performed using hand-bulb insufflation of air. Volumetric data were acquired under 60 s using a single-slice spiral CT scan of the abdomen and pelvis in the supine position, and repeated in the prone position. Lesion size at CTC was determined by measuring the largest diameter with computed calipers; polyp size at conventional colonoscopy was estimated in reference to open biopsy forceps.

Case: A 51 year old male with a history of coronary artery disease, hypertension, dyslipidemia and gallstones presented with fever, chills, and acute right upper quadrant pain radiating to the right chest and shoulder associated with elevated liver enzymes. His medications included losartan, atorvastatin, rabeprazole and multivitamins. His mother and two maternal uncles died from pancreatic cancer. Attempted ERCP at the referring institution showed an abnormal ampulla of Vater; cannulation was unsuccessful. Upon transfer, his temperature was 100.6° F and mild jaundice was evident. Physical examination was otherwise unremarkable. The hemoglobin was 12.4 g/dl, bilirubin 4.1 mg/dl, alkaline phosphatase 250 IU/L, AST 77 IU/L and ALT 246 IU/L. Repeat ERCP revealed tissue proliferation at the ampulla. Deep cannulation of the common bile duct (CBD) was successful following a needle-knife sphincterotomy revealing a dilated CBD to 8-mm; the pancreatic duct was normal. Numerous ampullary biopsies following sphincterotomy showed atypical lymphoid cells with a follicular pattern on microscopic examination. Molecular cytogenetics identified bcl-2 and immunohistochemistry was CD 20 positive. These findings supported a follicular center cell type, grade 1 lymphoma of the ampulla of Vater. A subsequent CT scan showed duodenal thickening at the ampulla but was otherwise normal. A bone marrow examination was normal. The patient is currently undergoing chemotherapy.

Blunt neck trauma can cause isolated esophageal injuries that may be difficult to recognize. A high index of suspicion is necessary for optimal identification and management of this condition. We report a case of blunt esophageal trauma resulting from a motor vehicle accident that was initially unrecognized until the patient developed a tight stricture of the cervical esophagus. This was successfully dilated endoscopically. Aerodigestive trauma resulting from neck injuries is reviewed with emphasis on the pathophysiology of esophageal trauma.

Purpose: To determine the prevalence of extracolonic findings at virtual colonoscopy using CT scanning of the abdomen and pelvis for data acquisition.

It is with interest that we read the article by Akerkar et al.1Akerkar GA Yee J Hung R McQuaid K. Patient experience and preferences toward colon cancer screening: a comparison of virtual colonoscopy and conventional colonoscopy.Gastrointest Endosc. 2001; 54: 310-315Abstract Full Text Full Text PDF PubMed Scopus (119) Google Scholar on patient tolerance and preference between conventional colonoscopy (CC) and virtual colonoscopy (VC). This is an important issue because VC attempts to create its place in the colorectal cancer screening armamentarium. In our experience, the technique used to achieve colonic insufflation during VC is of extreme importance. As reported by many other groups,2Hara AK Johnson DC Reed JE Ahlquist DA Nelson H MacCarty RL et al.Detection of colorectal polyps with CT colography: initial assessment of sensitivity and specificity.Radiology. 1997; 205: 59-65PubMed Google Scholar, 3Fenlon HM Nunes DP Schroy III, PC Barish MA Clarke PD Ferrucci JT. A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps.N Engl J Med. 1999; 341: 1496-1503Crossref PubMed Scopus (666) Google Scholar, 4Fletcher JG Johnson CD Welch TJ MacCarty RL Ahiquist DA Reed JE et al.Optimization of CT colonography technique: prospective trial in 180 patients.Radiology. 2000; 216: 704-711Crossref PubMed Scopus (303) Google Scholar the authors attained colonic insufflation with a hand-bulb technique to “maximum patient tolerance.” To paraphrase, colonic distention continues until the patient can no longer tolerate this rapid and crude method of distention, that is, not to maximal patient “tolerance” but rather to a degree of “intolerance.” Any screening test that is designed to reach a level of patient intolerance starts at a major disadvantage. In contrast, we achieve colonic distention by gradual insufflation of the colon with an electronic carbon dioxide insufflator, the same kind used for laparoscopic surgery.5Vining DJ Pineau BC. Improved bowel preparation for virtual colonoscopy examinations.Gastroenterology. 1999; 116 ([abstract]): 524AGoogle Scholar Contrary to results published herein, our initial assessment of patient preference during virtual colonoscopy with this technique showed a preference for virtual colonoscopy.6Pineau BC Sevick MA Mikulaninec C Vining DJ. Evaluation of patient preference: virtual colonoscopy versus endoscopic.Gastroenterology. 1999; 116 ([abstract]): 486Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar In the current study, the authors assessed patient tolerance with a 7-point Likert scale immediately after VC (before CC), yet ignored these results in the analysis. These data are extremely valuable as they show that the two procedures are comparable with regards to pain (VC: 1.98 [SD 1.38] vs. CC: 1.57 [1.14), discomfort (VC: 1.86 [1.34] vs. CC: 1.45 [0.91]), and lack of respect (VC: 1.86 [0.87] vs. CC: 1.18 [0.61]). The difference in pretest perception between VC and CC is an extremely important factor that could partly explain the results of Akerkar et al.1Akerkar GA Yee J Hung R McQuaid K. Patient experience and preferences toward colon cancer screening: a comparison of virtual colonoscopy and conventional colonoscopy.Gastrointest Endosc. 2001; 54: 310-315Abstract Full Text Full Text PDF PubMed Scopus (119) Google Scholar In our experience, preprocedure questionnaires have shown that patients perceive VC more favorably than CC, an unsurprising finding considering the less invasive nature of VC.6Pineau BC Sevick MA Mikulaninec C Vining DJ. Evaluation of patient preference: virtual colonoscopy versus endoscopic.Gastroenterology. 1999; 116 ([abstract]): 486Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Patients may have tolerated CC better than anticipated leading them to subsequently rate CC better and revising their score for VC to a less favorable one. A measurement of pretest anxiety and perception for VC and CC would have been helpful in this regard. Another possible explanation is that different individuals administered these questionnaires. The post-VC questionnaire was obtained by a radiology technologist whereas a registered nurse (presumably an endoscopy nurse) administered the post-CC questionnaires. Responder bias may have occurred resulting in lower (better) scores for VC during initial assessment and higher subsequent scores. This shortcoming may have been prevented by patient-administered questionnaires or by having the same study coordinator administer both questionnaires. Midazolam only affects anterograde but not retrograde memory,7Twersky RS Hartung J Berger BJ McClain J Beaton C. Midazolam enhances anterograde but not retrograde amnesia in pediatric patients.Anesthesiology. 1993; 78: 51-55Crossref PubMed Scopus (94) Google Scholar hence patients are more likely to recall the VC than CC. Unfortunately, the authors do not report the dosage of the agents used for conscious sedation. In addition, although the time interval between completion of CC and the administration of the questionnaires (tolerance and time trade-off techniques) was not specified, these were completed before discharge from the endoscopy unit. Considering that midazolam has a half-life of 1.3 to 2.2 hours,8Brown CR Sarnquist FH Canup CA Pedley TA. Clinical, electroencephalographic, and pharmacokinetic studies of a water-soluble benzodiazepine, midazolam maleate.Anesthesiology. 1979; 50: 467-470Crossref PubMed Scopus (93) Google Scholar the information captured by these questionnaires was most likely obtained at a time when patients were chemically impaired. The mail-in response may have given a better assessment of tolerability, preference, and time trade-off techniques; however, contrary to the authors statement that this is an “acceptable return rate,” a 28% response rate is clearly inadequate and prevents any conclusions to be drawn from these data. Finally, as the authors stated in the discussion, this predominantly (>97%) male population from a Veterans Affairs Hospital is not representative of the general population. Hence caution should be exercised before widespread misconception develops regarding tolerability and patient acceptance of a potentially extremely valuable tool for colorectal cancer screening. Dr. Vining is the founder, Chief Executive Officer, and major stockholder in PointDx, Inc., a radiological software company. He is also a consultant to EZEM, Inc. Dr. Pineau is a minor stockholder in PointDx, Inc.

Esophageal cancer is a common cause of dysphagia and upper endoscopy is the accepted standard for making the diagnosis; however, the accuracy of endoscopy is not known. The purpose of this study is to determine the sensitivity of upper endoscopy in making the diagnosis of esophageal cancer in clinical practice. All patients with a new diagnosis of esophageal cancer from 1997 to 2001 in the Tumor Registry of Wake Forest University Baptist Medical Center were identified. The medical records were reviewed to identify all patients who had undergone a previous endoscopy within two years that failed to diagnose esophageal cancer. The reason for failure was recorded. One hundred ten new cases of esophageal carcinoma were identified, and ten patients had had a previous false-negative endoscopy within two years for a sensitivity of 90.9% in clinical practice. The reasons for the failure of endoscopy were (1) lesion not seen in seven patients, (2) lesion seen and biopsied with benign histology in two patients, and (3) lesion seen but felt to be benign and not biopsied in one patient. Given the uncertain natural history of esophageal cancer, the data were also analyzed using a one-year window; this resulted in a sensitivity of 94.5%. The sensitivity of upper endoscopy in the diagnosis of esophageal cancer in general clinical practice is 90.9% using a two-year window and 94.5% using a one-year window. Understanding the reasons for the failure of endoscopy may allow us to improve the practice of endoscopy.

Esophageal bezoar, although uncommon, is now recognized as a distinct clinical entity. It has been reported with casein-containing nutritional supplements with or without the use of sucralfate, mostly in patients confined to the intensive care unit (ICU). It is thought to be caused by the coagulation of casein at a low pH. Coagulation of this substance is inhibited and liquefied by pancreatic enzymes in vitro. This is a case of a complete esophageal obstruction that, after unsuccessful endoscopic management, was successfully treated by intra-esophageal instillation of pancreatic enzymes at an alkaline pH. This report includes experimental data regarding the in vitro solubility of mixtures of casein containing nutritional supplements with sucralfate and pancreatic enzyme extract at various pH values. To our knowledge, this is the first report of successful treatment of an esophageal bezoar using pancreatic enzyme extract.