Single-contrast vs double-contrast barium enema in the detection of colonic polyps

Radiographic and colonoscopic correlation in 139 patients with 234 colonic polyps compared the sensitivity of single- and double-contrast barium enema. Single-contrast barium enema detected 68 (80%) of polyps, with 72% of polyps under 1 cm and 94% of those 1 cm or over detected. Double-contrast barium enema detected 135 (91%) of 149 polyps, with 88% of polyps under 1 cm and 96% of larger polyps detected. Thus, the double-contrast barium enema was more effective than the single-contrast examination only for detection of polyps under 1 cm. The single-contrast barium enema was more likely performed on patients in poor physical condition and in those over 70 years old. The results suggest that for elderly patients, who may have difficulty in cooperating for a double-contrast enema, a properly performed single-contrast examination is an acceptable option.     

Colonic cleansing for radiographic detection of neoplasia: efficacy of the magnesium citrate-castor oil-cleansing enema regimen

To optimize detection of colonic polyps, we instituted a cleansing regimen of dietary restriction, hydration, magnesium citrate, castor oil, and a cleansing enema. We then conducted a review of serially performed barium enemas to determine the percentage of patients with clean colons in a mixed population of 500 inpatients and outpatients in whom this regimen had been used. The same regimen also was used before single- and double-contrast barium enemas were performed in 139 patients with 234 polyps, and radiologic-endoscopic correlation was used to determine the percentage of polypoid neoplasms detected. The review indicated that a clean colon had been achieved in 97% of the 500 cases. In an additional 1.4% of patients, fecal residue was limited to small amounts in the cecum or ascending colon. In only two cases (0.4%) did fecal material prevent an examination that was suitable for detection of large polypoid or circumferential lesions. The single- and double-contrast barium enemas detected 80% and 91%, respectively, of polypoid lesions of all sizes. Single-contrast examinations detected 94% of polyps 10 mm or larger and 72% of polyps 5-9 mm. Double-contrast studies detected 96% of polyps 10 mm or larger and 88% of those 5-9 mm. The results of this study indicate that with this regimen, fecal residue does not significantly interfere with the detection of colonic polyps via barium enema examination.     

Positive predictive value and posttest probability of diagnosis of colonic polyp on single- and double-contrast barium enema

The positive predictive value for a radiographic diagnosis of colonic polyp, the prevalence of polypoid disease, and posttest probability relative to patient age were studied. The positive predictive value for colonic polyp on single- and double-contrast barium enema was determined for 191 polyps found radiographically in 136 patients who also underwent colonoscopy for confirmation. Of 72 polyps seen in 54 patients on single-contrast examination, 59 were confirmed endoscopically; 110 of 119 polyps seen in 82 patients on double-contrast examination were confirmed similarly, giving positive predictive values of 82% and 92%, respectively. Positive predictive values per patient, disregarding the number of polyps present, were 87% (47/54) and 90% (74/82) for the single- and double-contrast examinations, respectively. False-positive errors were due to stool, air bubbles, haustration, and misinterpretation of an appendiceal stump. By using specificities derived from our prevalence of polypoid disease and previously reported sensitivities, we drew posttest probability curves showing that predictive values depend both on the chance of disease before the test is done and on the efficacy of the test used.     

Sensitivity of double-contrast barium study for left-colon polyps

A blinded, prospective study was conducted to determine the sensitivity of double-contrast barium enema examination (DCBE) in detecting left-colon polyps. Metal clips were endoscopically placed on normal mucosa either adjacent to polyps (in 65 study subjects with 92 polyps) or not adjacent to polyps (in 50 control subjects). DCBE had a high sensitivity for detection of polyps greater than or equal to 1 cm and 6-9 mm in size (100% and 83% detection, respectively) but was insensitive in detecting polyps in the 4 to 5-mm and 2 to 3-mm size ranges (56% and 22% detection, respectively). The factors contributing most commonly to false-negative interpretations were the presence of air bubbles, overlap of bowel loops, and luminal fecal debris. No error in radiographic technique was evident to account for false-negative interpretations in 14 (41%) of 34 polyps that were not detected by DCBE.     

Comparison of radiologists' confidence in excluding significant colorectal neoplasia with multidetector-row CT colonography compared with double contrast barium enema

The aim of this study was to compare the confidence of experienced radiologists in excluding colonic neoplasia with CT colonography (CTC) compared with barium enema. 78 patients (median age 70 years, range 61-87 years, 44 women) underwent same day CTC and barium enema. Two radiologists experienced in reporting barium enema assessed whether the examination had excluded a polyp 6 mm or greater as "yes", "probably" or "no" for each of 6 colonic segments. Two different radiologists experienced in CTC independently performed the same assessment on the CT datasets. Responses were compared using a paired exact test. Formal barium enema and CT reports were compared with any endoscopic examination performed within 1 year. Studies reporting polyps 6 mm+ in patients not subsequently undergoing endoscopy were reviewed by two independent observers. Radiologists stated they had confidently excluded a significant lesion in 314 (71%) and 382 (86%) of 444 segments with barium enema and CTC, respectively (p<0.001). Confidence was significantly higher with CTC in the in the descending and ascending colon (p = 0.02 and p<0.001, respectively), and caecum (p<0.001). 22 patients underwent some form of endoscopy. Of five patients with proven colorectal neoplasia (including two with cancer), CTC and barium enema correctly identified five and three, respectively. In 56 patients not undergoing endoscopy, CTC reported 17 polyps 6 mm+, of which 16 were retrospectively classified as definite or probable. 11 could not be identified on the barium enema, even in retrospect. Confidence in excluding polyps 6 mm or larger is significantly greater with CT colonography particularly in the proximal colon.     

Importance of the dimensions and histologic nature of polyps of the colon in a comparison between double contrast enema and colonoscopy

In 244 patients the results obtained by double contrast barium enema and endoscopy in the detection of small colonic polyps were compared. The results were evaluated by subdividing the polyps according to size. In order to define the endoscopic false positives percentage, controversial cases were re-examined with a second double contrast barium enema. The authors put forward a few considerations on the suitability of diagnosing small colonic polyps on the basis of their histologic nature.     

Barium filling for glucagon-resistant spasm on double-contrast barium enema examinations

Severe glucagon-resistant spasm on double-contrast barium enema (DCE) examinations may occasionally lead to a nondiagnostic examination or erroneously suggest colonic disease. In such cases, this glucagon-resistant spasm may be overcome by refilling the colon with single-contrast barium immediately after completion of the DCE examination.     

Accuracy of double-contrast barium enema in diagnosing colorectal polyps and cancer

CRC is a common malignancy, and reduced mortality can be achieved through detection and treatment of early cancers and by removal of colonic adenomas. Although current screening recommendations, especially in the average-risk individual, typically promote the use of FOBT and FS, a substantial minority of colonic cancers and many colonic adenomas are not detected by these methods. Modalities that examine the entire colon, such as the barium enema and colonoscopy, can detect most clinically important colorectal neoplasms; however, their additional costs and potential risks have limited their use as initial screening examinations. But recent changes in governmental policies regarding reimbursement for CRC screening and increasing emphasis on total colon examinations have altered these recommendations.

This review on the accuracy of the DCBE has emphasized the detection of colonic polyps and cancers and has updated the changing role of this examination in screening patients at variable risk for CRC. The efficacy of the barium enema depends on many factors that radiologists must understand and control to perform accurate examinations. Current recommendations for CRC screening and approved reimbursement of the barium enema for that purpose provide a new impetus to radiologists to maintain and improve their skills in performing and interpreting this radiologic examination. The barium enema may have a future in the new millennium.     

Spiral CT pneumocolon: applications, status and limitations

CT pneumocolon is a promising new technique in the diagnosis and management of colon pathology. CT pneumocolon can detect (sensitivity >95%) and stage (accuracy 79%) colorectal cancer and is very accurate in the differentiation of malignant from benign colonic pathologies. It has excellent detection rates for polyps >10 mm in diameter. Several studies using 3D virtual colonoscopy have already proven its high sensitivity and specificity in polyp detection making this technique robust as a screening tool. The combined results for virtual colonoscopy, from all centres, show a sensitivity of >85% in the detection of polyps 10 mm or greater in size, 70-80% for 5-9 mm polyps and an overall specificity of 90%. CT pneumocolon is a safe, non-invasive and cost-effective method for detecting colonic carcinomas and adenomas and correctly identifying which patients need further colonoscopy. The technique is quick, well tolerated and non-operator dependent. It can also image the proximal colon when distal stenoses prevent endoscopic and barium examination. CT pneumocolon is able to identify the features and complications of inflammatory bowel disease. Further research is warranted to fully assess its impact in terms of a screening tool, acceptability, availability and cost benefit.     

A retrospective 5-year study on the accuracy of the barium enema examination performed by radiographers

Barium enema examinations have been undertaken by radiographers at the Frenchay Hospital for more than 10 years. We have performed a retrospective study to assess the accuracy of this radiographer service by reviewing those patients who have been examined by both Barium enema and colonoscopy/flexible sigmoidoscopy to determine agreement, and reasons for disagreement. This paper does not attempt to compare the two techniques. In the 5 years between 1992 and 1996, 595 patients had both barium enema and colonoscopy or flexible sigmoidoscopy. In 488 (82%) of these patients the barium enema examination was performed by a radiographer. Comparisons with endoscopy indicate that 96% of polyps >1 cm, and 97% of carcinomas were detected radiologically. We conclude that radiographer performed barium enemas with double reporting produces a very high standard of examination with detection rates for significant lesions comparable with published data.     

Colorectal cancer: screening double-contrast barium enema examination in average-risk adults older than 50 years

PURPOSE: To retrospectively determine the diagnostic yield of double-contrast barium enema examinations performed for colorectal cancer screening of neoplasms 1 cm or larger or advanced neoplastic lesions of any size in average-risk adults older than 50 years. MATERIALS AND METHODS: The Institutional Review Board at the affiliated Veterans Affairs Medical Center approved this HIPAA-compliant study protocol and did not require informed consent from patients. Computerized databases revealed 276 double-contrast barium enema examinations performed for colorectal cancer screening in average-risk adults older than 50 years. Radiographic and pathologic reports were reviewed to determine the number of patients who had polypoid lesions 1 cm or larger, polyps smaller than 1 cm, or advanced neoplastic lesions of any size. Forty-five (16.3%) of the 276 patients underwent follow-up sigmoidoscopy or colonoscopy. Medical, endoscopic, and pathologic records were reviewed and compared with radiographic findings. RESULTS: The results of double-contrast barium enema examination revealed 74 (26.8%) of 276 patients with 104 polypoid lesions in the colon, including 32 patients (11.6%) with 41 polypoid lesions 1 cm or larger, 15 patients (5.4%) with 19 polyps 6-9 mm, and 27 patients (9.8%) with 44 polyps 5 mm or smaller. Endoscopy was performed in 24 (75%) of 32 patients, the results of which confirmed 23 (72%) of 32 radiographically diagnosed lesions 1 cm or larger in 16 (67%) of 24 patients. In two of these individuals, the polyps were hyperplastic. The remaining 14 patients had a total of 21 neoplastic lesions 1 cm or larger, including 11 tubular adenomas, seven tubulovillous adenomas, one villous adenoma with marked dysplasia, and two cancers. The diagnostic yield of screening double-contrast barium enema examination was 5.1% (14 of 276 patients) for neoplastic lesions 1 cm or larger and 6.2% (17 of 276 patients) for advanced neoplastic lesions of any size. CONCLUSION: Double-contrast barium enema examinations performed in average-risk adults older than 50 years have a diagnostic yield of 5.1% for neoplastic lesions 1 cm or larger and 6.2% for advanced neoplastic lesions, regardless of size.     

Performance of barium examinations after acute myocardial infarction: report of a survey

A survey of members of the Society of Gastrointestinal Radiologists was conducted to ascertain the standards of practice and timing for elective barium studies of the gastrointestinal tract in patients recovering from acute myocardial infarction. Sixty-two percent of respondents do not have cardiac monitoring apparatus readily available in the fluoroscopy suite. When readily available, such equipment is rarely (42%) or never (58%) used during routine barium examinations. Twenty-four percent of respondents take special precautions when performing examinations on these patients by reducing patient movement, the length of the examination, and the number of radiographs exposed, and by employing cardiac monitoring. Seventy-two (89%) of 81 respondents noted at least one adverse cardiovascular reaction. This was most often chest pain, but there were 10 deaths from cardiac causes. Two-thirds of respondents delay elective barium examinations of any kind for at least 4 weeks after acute myocardial infarction. The remaining one-third perform these studies earlier than 4 weeks. The latter typically limit their studies to the upper gastrointestinal tract (82%), 42% of which are single-contrast; the rest are equally divided between double-contrast and biphasic studies. This minority of radiologists is twice as likely to perform a single-contrast barium enema than a double-contrast barium enema during this period. No such preference for single-contrast (47%) over double-contrast (53%) barium enema is revealed by the majority who delay their elective barium enemas 4 or more weeks. The data indicate a strong preference to defer elective barium examinations a minimum of 4 weeks after acute myocardial infarction. A sizable minority (one-third) of radiologists, however, feel comfortable performing a single-contrast upper gastrointestinal examination at an earlier time.     

Causes of errors in polyp detection at air-contrast barium enema examination

PURPOSE: To retrospectively determine the cause of errors in air-contrast barium enema (ACBE) examination for detection of polyps 6 mm or larger. MATERIALS AND METHODS: The study had institutional review board approval. Informed consent was waived for this HIPAA-compliant study. ABCE findings in 41 subjects with 56 missed polyps were evaluated by two radiologists to determine if the cause of errors was perceptual or technical. A comparison was made between total number of polyps in the proximal and distal colon and those missed at each location (Fisher exact test). The 288 ACBE examinations were assessed on a scale of 0-4 (0, excellent; 4, very poor) for six colonic segments (paired t test). RESULTS: Of 17 polyps 1 cm or larger not detected in 15 subjects, 11 (65%) were missed because of technical errors and six (35%) because of perceptual errors. Eight (72%) technical and four (67%) perceptual errors occurred proximal to the splenic flexure. One 3.5-cm cecal carcinoma was not diagnosed prospectively (perceptual error). Of 39 6-9-mm polyps not detected in 26 subjects, 35 (90%) were missed because of technical errors and four (10%) because of perceptual errors. Eighty percent of technical and 75% of perceptual errors were in the proximal colon. When the proportion of polyps in the proximal and distal colon was compared, 22 (63%) of 35 polyps in the distal colon and 15 (26%) of 58 in the proximal colon were detected (P = .0009). There were no detectable differences in the quality of studies in subjects whose polyps were detected and subjects whose polyps were missed (P > .05). CONCLUSION: Technical errors were more common than perceptual errors. The majority of missed polyps were in the proximal colon. Detection rates of polypoid lesions might increase if the quality of ACBE examination can be improved, especially in the proximal colon.     

Dark-lumen MR colonography with fecal tagging: a comparison of water enema and air methods of colonic distension for detecting colonic neoplasms

The purpose was to evaluate MR colonography (MRC) with barium fecal tagging in detecting colorectal pathology and to determine how air-based and water-based colonic distension influences MRC. We studied 83 patients with high risk of colonic neoplasms. All received oral barium sulfate for colonic preparation before unenhanced and enhanced T1-weighted gradient-echo MRC using either water (n=54) or air (n=29) for colonic distension. Fecal tagging, distension, and artifacts were recorded. All patients underwent conventional colonoscopy within 2 weeks of MRC; the techniques were compared for detection of malignant neoplasms and polyps >or=1 cm, 6-9 mm, and or=1 cm, but more air-distended MRC were excluded for poor quality. MRC with fecal tagging is useful for detecting lesions >or=1 cm. Air distension was inferior to water distension in most aspects. Water-based colonic distension should be used for barium-tagging MRC.     

Large colonic neoplasms missed by endoscopy

Endoscopy is commonly accepted as the gold standard in the evaluation of neoplastic colonic disease. The procedure is used to confirm or exclude lesions detected on barium enemas, with the assumption that the endoscopist was successful in reaching the appropriate segment of the colon. We collected 18 cases, all with proved colonic neoplasm 2-8 cm in diameter that were detected by barium enema but overlooked on initial endoscopy. All of the lesions were relatively flat with little intraluminal protuberance. Histologic examination showed malignant foci in six of 11 tumors that were resected. In two of the other seven patients, unresected lesions progressed to advanced carcinomas. This experience suggests that a repeat barium enema is indicated when endoscopy fails to detect a colonic tumor suspected on barium enema examination.     

Barium enema and endoscopy for the detection of colorectal neoplasia: sensitivity, specificity, complications and its determinants

AIM: To analyse sensitivity, specificity and complication rate of endoscopy, and barium enema for the detection of colorectal neoplasia. MATERIALS AND METHODS: A MEDLINE search was performed (1980-2000) directed at the endoscopic and radiologic literature on barium enema. Articles were selected based on the type of study, availability of sensitivity and specificity values in sizeable patient groups, and reports on complications. Sixty articles were included in the analysis. RESULTS: Endoscopy proved to have superior sensitivity for polyps in patients at high-risk for colorectal neoplasia. The role of endoscopy and radiology in average-risk screening populations is not known. Sensitivity and specificity rates ranged widely, probably due to bias. For the detection of small polyps endoscopy has superior performance, whereas sensitivity is similar for endoscopy and barium enema for the detection of larger (>1 cm) polyps and tumours. Overall, endoscopy is associated with a higher complication rate. CONCLUSION: Endoscopy is the preferred detection method in high-risk patients. The role of endoscopy and radiology in a screening setting requires evaluation. This review provides the test characteristics of endoscopy and radiology which are relevant for a cost-effectiveness analysis. Double-contrast barium enema may play an important role for screening purposes, owing to its good sensitivity for detecting larger (>1 cm) polyps and its lack of major complications. de Zwart, I. M.et al. (2001). Clinical Radiology56, 401-409.     

The value of a barium enema in the investigation of patients with rectal carcinoma

A review of 545 patients with clinically diagnosed rectal carcinoma was conducted to determine the diagnostic usefulness of pre-operative barium enema and the frequency with which it was employed. Only 118 patients underwent pre-operative barium enema (21.7%). This successfully outlined the whole colon in 107 (90%). Synchronous carcinomas were detected in 9.3% of patients who underwent complete barium enema, compared to 4.3% of those who underwent laparotomy alone (P less than 0.05). Polyps were found in 23.4% of patients who had a barium enema but in only 14.7% of those who did not (P less than 0.05). Twenty-nine per cent of synchronous carcinomas and 11% of polyps were proximal to the descending colon and would have been beyond the reach of a flexible sigmoidoscope. Barium enema remains a useful investigation in patients with rectal carcinoma. It will outline the whole colon in most cases and will result in the detection of more synchronous carcinomas and polyps than if the surgeon relies on operative palpation alone.     

Usefulness of CT colonography in the preoperative evaluation of patients with distal occlusive colorectal carcinoma

PURPOSE: To evaluate the role of preoperative virtual colonoscopy to study the proximal colon in patients with distal occlusive carcinomas, diagnosed by conventional colonoscopy. MATERIAL AND METHODS: We examined 19 patients aged 46 to 83 years (13 men and 6 women) with distal occlusive colorectal carcinomas diagnosed by conventional colonoscopy, who were preoperatively studied with virtual colonoscopy. Patients with acute bowel obstruction were excluded. Results were compared with the findings of preoperative conventional colonoscopy and barium enema examination, intraoperative colon palpation, histopathologic outcome, postoperative conventional colonoscopy and barium enema examination. RESULTS: Virtual colonoscopy identified all 19 distal occlusive colon carcinomas and 22 synchronous lesions, 2 cancers (prevalence 10,6%) and 20 polyps (prevalence 68,4%). Both synchronous cancers were confirmed intraoperatively by direct palpation. Postoperative conventional colonoscopy, which was performed in 18 patients, confirmed the presence of 15 polyps in 12 patients. Three subcentimeter polyps were removed during conventional colonoscopy and were missed at virtual colonoscopy. Two polyps shown by virtual colonoscopy were not found at conventional colonoscopy. Postoperative barium enema was performed in three patients and confirmed three polyps identified at virtual colonoscopy. Preoperative barium enema was performed in five patients and failed to adequately demonstrate the proximal colon. Virtual colonoscopy showed a sensitivity of 87% and a specificity of 75%. CONCLUSIONS: Virtual CT colonoscopy can be considered an important diagnostic technique to evaluate preoperatively the proximal colon in patients with distal occlusive carcinomas,as it gives better results than barium enema or conventional colonoscopy, as well as being well tolerated and less invasive.     

Computed tomographic colonography (CTC) performance: one-year clinical follow-up

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.