Portal de Periódicos da CAPES

Update on Small Bowel Imaging

2007; Elsevier BV; Volume: 132; Issue: 5 Linguagem: Inglês

10.1053/j.gastro.2007.03.084

1528-0012

Jonathan A. Leighton, Michael B. Wallace,

Gastrointestinal disorders and treatments

The small bowel (SB) has historically been difficult to evaluate because of its length, tortuosity, and limitations of available technology. As a result, diseases of the SB have been difficult to diagnose, resulting in multiple tests and poor clinical outcomes. Until recently, the best way to evaluate the SB was using some combination of push enteroscopy (PE), barium SB follow through (SBFT), and/or a computed tomography (CT) scan. However, these tests have inherent limitations in their ability to adequately evaluate the entire SB, particularly the mucosa. Improvements in technology have led to significant advances in SB imaging. New endoscopic advancements in SB imaging include capsule endoscopy (CE) and double balloon enteroscopy (DBE). CE allows for a complete view of the SB and a more detailed view of the mucosa. DBE provides not only a closer look at the mucosa, but also therapeutic capabilities. Radiologic advancements with CT enterography (CTE) provide information regarding mucosal and transmural inflammation and wall thickness, as well as information regarding extraintestinal findings. These new technologies have allowed us to advance the science of SB diseases.Capsule EndoscopyCapsule endoscopy has revolutionized our ability to more completely assess the integrity of the SB mucosa (Figure 1). The PillCam SB (Given Imaging, Yoqneam, Israel) is 26 mm long and 11 mm wide, captures 2 images per second, and has a battery life of approximately 8 hours. This allows for complete SB transit in the majority of cases. The images are transmitted to a data recorder via digital radio frequency communication. This information is downloaded to a computer workstation where it is read. Olympus (Olympus Co, Center Valley, PA) is also introducing a capsule endoscope in the near future called EndoCapsule. The size is similar to the PillCam SB and it has structural enhancement capabilities that allow for extremely clear images. Both devices provide excellent images and have similar yields.Capsule endoscopy was first approved for obscure gastrointestinal bleeding (OGIB). Two large trials both showed that the highest yield for CE was in the setting of overt bleeding when no source was found after standard upper endoscopy and colonoscopy.1Pennazio M. Santucci R. Rondonotti E. Abbiati C. Beccari G. Rossini F.P. De Franchis R. Outcome of patients with obscure gastrointestinal bleeding after capsule endoscopy: report of 100 consecutive cases.Gastroenterology. 2004; 126: 643-653Abstract Full Text Full Text PDF PubMed Scopus (855) Google Scholar, 2Carey E.J. Leighton J.A. Heigh R.I. Shiff A.D. Sharma V.K. Post J.K. Fleischer D.E. A single-center experience of 260 consecutive patients undergoing capsule endoscopy for obscure gastrointestinal bleeding.Am J Gastroenterol. 2007; 102: 89-95Crossref PubMed Scopus (269) Google Scholar More important, both studies showed an improvement in clinical outcomes after CE as measured by subsequent procedures, hospitalizations, and transfusion requirements. CE appears to have an overall yield (identification of a potential source of bleeding) ranging from 45% to 66% in OGIB and may be comparable to intraoperative endoscopy. A meta-analysis of prospective comparative studies of CE in OGIB found a significantly higher yield for CE compared with PE and SB radiography and a 30% incremental yield for clinically significant findings.3Triester S.L. Leighton J.A. Leontiadis G.I. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with obscure gastrointestinal bleeding.Am J Gastroenterol. 2005; 100: 2407-2418Crossref PubMed Scopus (556) Google Scholar CE proved to be particularly helpful in identifying lesions beyond the reach of PE.Capsule endoscopy is also approved for the evaluation of SB Crohn’s disease (CD). The ability of SBFT to detect the early subtle lesions of CD can be challenging. A recent meta-analysis of prospective comparative studies in nonstricturing CD showed the yield of CE is superior to SBFT, PE, and CTE.4Triester S.L. Leighton J.A. Leontiadis G.I. Gurudu S.R. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with non-stricturing small bowel Crohn’s disease.Am J Gastroenterol. 2006; 101: 954-964Crossref PubMed Scopus (476) Google Scholar Future applications may include the documentation of mucosal healing, assessing for postsurgical recurrence of CD, and in reclassifying indeterminate colitis into CD.In addition to OGIB and CD, CE appears to be useful for the diagnosis of SB tumors. At this time, CE and PE should be considered complimentary modalities in the diagnosis of SB neoplasms. There are several small trials suggesting that CE may also be of value in the evaluation of patients with celiac disease because of its ability to accurately identify changes such as villous atrophy, scalloping, or stacked folds, or a mosaic appearance of the mucosa. Although the data are limited, these studies emphasize the need for physicians who perform CE to be aware of the endoscopic mucosal changes associated with celiac disease.As with any new technology, there are definite issues of concern with CE that must be addressed. Patients with significant swallowing disorders may need to have the capsule placed endoscopically. Although there are data to suggest that CE is safe in patients with cardiac pacemakers, it is still a contraindication to the procedure. Capsule retention in the SB is the most concerning potential complication. Risk factors for SB retention include NSAID use, abdominal radiation, and CD. In OGIB, it occurs in <2% of cases, but in patients with known CD, it may be as high as 13%. It is important to note that capsule retention often identifies a significant lesion responsible for the patient’s symptoms and in fact, surgical removal is therapeutic. The Agile Patency capsule, a dissolvable “dummy” capsule recently approved by the Food and Drug Administration, can identify those at risk for capsule retention.Double Balloon EnteroscopyDBE is a new technique that allows for more extensive evaluation of the SB, including the ability to carefully inspect the mucosa (Figure 2). It is performed using a 2-meter endoscope through a 145-cm overtube, both with a latex balloon attached to the distal end. In coordination with serial inflation and deflation of the balloons, a reduction of the SB with telescoping over the endoscope allows for advancement deep into the SB. DBE can be performed via the oral or rectal route. A complete SB evaluation is usually not possible using 1 route alone and most often requires combined oral and rectal approaches. The advantage of DBE over CE and CTE is that it also allows for therapeutic intervention. Therapeutic options with DBE include electrocautery, argon plasma coagulation, polypectomy, endoscopic mucosal resection, balloon dilation, and stent placement. DBE is more labor intensive, but compliments CE because of its therapeutic capabilities. Sedation methods for DBE range from general anesthesia to conscious sedation. It is quite safe with similar risks and complications associated with traditional endoscopy.Figure 2Double balloon enteroscopy. The drawings above show the technique of “push and pull enteroscopy” using the double-balloon enteroscope with overtube to facilitate examination of the SB.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Several studies have shown that DBE has a yield similar to CE for the evaluation of suspected SB disease.5May A. Nachbar L. Pohl J. Ell C. Endoscopic interventions in the small bowel using double balloon enteroscopy: feasibility and limitations.Am J Gastroenterol. 2007; 102: 527-535Crossref PubMed Scopus (221) Google Scholar, 6Mehdizadeh S. Ross A. Gerson L. Leighton J. Chen A. Schembre D. Chen G. Semrad C. Kamal A. Harrison E.M. Binmoeller K. Waxman I. Kozarek R. Lo S.K. What is the learning curve associated with double-balloon enteroscopy? Technical details and early experience in 6 U.S. tertiary care centers.Gastrointest Endosc. 2006; 64: 740-750Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar Based on limited data, it appears that both devices can explore the SB with a high success rate and complement each other. DBE may be superior to radiologic studies for detecting aphthae, erosions, and small ulcers in the ileum. SB strictures also can be effectively evaluated and dilated with DBE.CT EnterographyTechnological improvements in multidetector row CT, such as increased speed and resolution, have made this imaging modality an ideal method for noninvasively evaluating the SB. CT imaging of the gastrointestinal tract has the advantage of evaluating not only the SB, but also extraluminal disease as well. CTE is a new method of evaluating the SB and is different from routine abdominopelvic CT (Figure 3).7Paulsen S.R. Huprich J.E. Fletcher J.G. Booya F. Young B.M. Fidler J.L. Johnson C.D. Barlow J.M. Earnest Ft CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases.Radiographics. 2006; 26 (discussion 657–662): 641-657Crossref PubMed Scopus (341) Google Scholar Unlike routine CT, which uses high-density oral contrast, IV contrast, and thicker sections, CTE uses thin sections and large volumes of a neutral oral contrast such as water, methylcellulose, or low-density barium along with intravenous contrast. This allows for better visualization of the SB wall thickness and enhancement characteristics, which can correlate with inflammation and/or hypervascular lesions.Figure 3CT enterography. (A) A normal SB image. (B) A patient with SB CD as manifested by increased wall thickness and mural enhancement.View Large Image Figure ViewerDownload Hi-res image Download (PPT)CTE is particularly useful for evaluating CD.8Hara A.K. Leighton J.A. Heigh R.I. Sharma V.K. Silva A.C. De Petris G. Hentz J.G. Fleischer D.E. Crohn disease of the small bowel: preliminary comparison among CT enterography, capsule endoscopy, small-bowel follow-through, and ileoscopy.Radiology. 2006; 238: 128-134Crossref PubMed Scopus (252) Google Scholar This is because CTE not only visualizes the entire thickness of the SB wall and detects strictures and fistulas, but it allows superior evaluation of deep ileal loops that are difficult to palpate with traditional SBFT. CTE findings of active bowel inflammation include mural hyperenhancement, increased mural thickness,9Booya F. Fletcher J.G. Huprich J.E. Barlow J.M. Johnson C.D. Fidler J.L. Solem C.A. Sandborn W.J. Loftus Jr., E.V. Harmsen W.S. Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.Radiology. 2006; 241: 787-795Crossref PubMed Scopus (157) Google Scholar mural stratification, soft tissue stranding, and engorged vasa recta. CTE and CE appear to have equal sensitivity for CD, but CTE may have higher specificity. Studies also suggest that CTE may provide a noninvasive method for monitoring CD activity, because bowel wall enhancement on CTE correlates with endoscopic and histologic severity.10Colombel J.F. Solem C.A. Sandborn W.J. Booya F. Loftus Jr, E.V. Harmsen W.S. Zinsmeister A.R. Bodily K.D. Fletcher J.G. Quantitative measurement and visual assessment of ileal Crohn’s disease activity by computed tomography enterography: correlation with endoscopic severity and C reactive protein.Gut. 2006; 55: 1561-1567Crossref PubMed Scopus (203) Google Scholar Although CTE is very safe, if it is to be used as a noninvasive method to monitor CD activity, the risk of ionizing radiation must be considered. It is also critical that adequate SB distention is achieved to minimize false-positive examinations.In addition to CD, CTE is also useful in the detection and evaluation of SB tumors. Tumors may appear as masses, focal wall thickening, or increased mural enhancement. Certain lesions may enhance more than others, such as carcinoid and gastrointestinal stromal tumors. It may also detect SB changes seen in celiac disease. CTE may also play a role in the evaluation of OGIB and the detection of AVMs but more studies are needed.ConclusionsThe ability to evaluate the integrity of the SB has been greatly enhanced by CE, DBE, and CTE. There is evidence that these new technologies also improve clinical outcomes. It is important to clarify the most efficient and cost-effective ways to utilize these procedures. Based on limited data, CE appears to be a reasonable screening tool for suspected SB pathology, especially when there is no evidence of SB obstruction. When obstruction or mass lesions are suspected, CTE is a reasonable alternative and may even compliment CE. Once a lesion has been identified or if there is a high suspicion that a SB lesion is present despite negative tests, then DBE should be strongly considered. The small bowel (SB) has historically been difficult to evaluate because of its length, tortuosity, and limitations of available technology. As a result, diseases of the SB have been difficult to diagnose, resulting in multiple tests and poor clinical outcomes. Until recently, the best way to evaluate the SB was using some combination of push enteroscopy (PE), barium SB follow through (SBFT), and/or a computed tomography (CT) scan. However, these tests have inherent limitations in their ability to adequately evaluate the entire SB, particularly the mucosa. Improvements in technology have led to significant advances in SB imaging. New endoscopic advancements in SB imaging include capsule endoscopy (CE) and double balloon enteroscopy (DBE). CE allows for a complete view of the SB and a more detailed view of the mucosa. DBE provides not only a closer look at the mucosa, but also therapeutic capabilities. Radiologic advancements with CT enterography (CTE) provide information regarding mucosal and transmural inflammation and wall thickness, as well as information regarding extraintestinal findings. These new technologies have allowed us to advance the science of SB diseases. Capsule EndoscopyCapsule endoscopy has revolutionized our ability to more completely assess the integrity of the SB mucosa (Figure 1). The PillCam SB (Given Imaging, Yoqneam, Israel) is 26 mm long and 11 mm wide, captures 2 images per second, and has a battery life of approximately 8 hours. This allows for complete SB transit in the majority of cases. The images are transmitted to a data recorder via digital radio frequency communication. This information is downloaded to a computer workstation where it is read. Olympus (Olympus Co, Center Valley, PA) is also introducing a capsule endoscope in the near future called EndoCapsule. The size is similar to the PillCam SB and it has structural enhancement capabilities that allow for extremely clear images. Both devices provide excellent images and have similar yields.Capsule endoscopy was first approved for obscure gastrointestinal bleeding (OGIB). Two large trials both showed that the highest yield for CE was in the setting of overt bleeding when no source was found after standard upper endoscopy and colonoscopy.1Pennazio M. Santucci R. Rondonotti E. Abbiati C. Beccari G. Rossini F.P. De Franchis R. Outcome of patients with obscure gastrointestinal bleeding after capsule endoscopy: report of 100 consecutive cases.Gastroenterology. 2004; 126: 643-653Abstract Full Text Full Text PDF PubMed Scopus (855) Google Scholar, 2Carey E.J. Leighton J.A. Heigh R.I. Shiff A.D. Sharma V.K. Post J.K. Fleischer D.E. A single-center experience of 260 consecutive patients undergoing capsule endoscopy for obscure gastrointestinal bleeding.Am J Gastroenterol. 2007; 102: 89-95Crossref PubMed Scopus (269) Google Scholar More important, both studies showed an improvement in clinical outcomes after CE as measured by subsequent procedures, hospitalizations, and transfusion requirements. CE appears to have an overall yield (identification of a potential source of bleeding) ranging from 45% to 66% in OGIB and may be comparable to intraoperative endoscopy. A meta-analysis of prospective comparative studies of CE in OGIB found a significantly higher yield for CE compared with PE and SB radiography and a 30% incremental yield for clinically significant findings.3Triester S.L. Leighton J.A. Leontiadis G.I. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with obscure gastrointestinal bleeding.Am J Gastroenterol. 2005; 100: 2407-2418Crossref PubMed Scopus (556) Google Scholar CE proved to be particularly helpful in identifying lesions beyond the reach of PE.Capsule endoscopy is also approved for the evaluation of SB Crohn’s disease (CD). The ability of SBFT to detect the early subtle lesions of CD can be challenging. A recent meta-analysis of prospective comparative studies in nonstricturing CD showed the yield of CE is superior to SBFT, PE, and CTE.4Triester S.L. Leighton J.A. Leontiadis G.I. Gurudu S.R. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with non-stricturing small bowel Crohn’s disease.Am J Gastroenterol. 2006; 101: 954-964Crossref PubMed Scopus (476) Google Scholar Future applications may include the documentation of mucosal healing, assessing for postsurgical recurrence of CD, and in reclassifying indeterminate colitis into CD.In addition to OGIB and CD, CE appears to be useful for the diagnosis of SB tumors. At this time, CE and PE should be considered complimentary modalities in the diagnosis of SB neoplasms. There are several small trials suggesting that CE may also be of value in the evaluation of patients with celiac disease because of its ability to accurately identify changes such as villous atrophy, scalloping, or stacked folds, or a mosaic appearance of the mucosa. Although the data are limited, these studies emphasize the need for physicians who perform CE to be aware of the endoscopic mucosal changes associated with celiac disease.As with any new technology, there are definite issues of concern with CE that must be addressed. Patients with significant swallowing disorders may need to have the capsule placed endoscopically. Although there are data to suggest that CE is safe in patients with cardiac pacemakers, it is still a contraindication to the procedure. Capsule retention in the SB is the most concerning potential complication. Risk factors for SB retention include NSAID use, abdominal radiation, and CD. In OGIB, it occurs in <2% of cases, but in patients with known CD, it may be as high as 13%. It is important to note that capsule retention often identifies a significant lesion responsible for the patient’s symptoms and in fact, surgical removal is therapeutic. The Agile Patency capsule, a dissolvable “dummy” capsule recently approved by the Food and Drug Administration, can identify those at risk for capsule retention. Capsule endoscopy has revolutionized our ability to more completely assess the integrity of the SB mucosa (Figure 1). The PillCam SB (Given Imaging, Yoqneam, Israel) is 26 mm long and 11 mm wide, captures 2 images per second, and has a battery life of approximately 8 hours. This allows for complete SB transit in the majority of cases. The images are transmitted to a data recorder via digital radio frequency communication. This information is downloaded to a computer workstation where it is read. Olympus (Olympus Co, Center Valley, PA) is also introducing a capsule endoscope in the near future called EndoCapsule. The size is similar to the PillCam SB and it has structural enhancement capabilities that allow for extremely clear images. Both devices provide excellent images and have similar yields. Capsule endoscopy was first approved for obscure gastrointestinal bleeding (OGIB). Two large trials both showed that the highest yield for CE was in the setting of overt bleeding when no source was found after standard upper endoscopy and colonoscopy.1Pennazio M. Santucci R. Rondonotti E. Abbiati C. Beccari G. Rossini F.P. De Franchis R. Outcome of patients with obscure gastrointestinal bleeding after capsule endoscopy: report of 100 consecutive cases.Gastroenterology. 2004; 126: 643-653Abstract Full Text Full Text PDF PubMed Scopus (855) Google Scholar, 2Carey E.J. Leighton J.A. Heigh R.I. Shiff A.D. Sharma V.K. Post J.K. Fleischer D.E. A single-center experience of 260 consecutive patients undergoing capsule endoscopy for obscure gastrointestinal bleeding.Am J Gastroenterol. 2007; 102: 89-95Crossref PubMed Scopus (269) Google Scholar More important, both studies showed an improvement in clinical outcomes after CE as measured by subsequent procedures, hospitalizations, and transfusion requirements. CE appears to have an overall yield (identification of a potential source of bleeding) ranging from 45% to 66% in OGIB and may be comparable to intraoperative endoscopy. A meta-analysis of prospective comparative studies of CE in OGIB found a significantly higher yield for CE compared with PE and SB radiography and a 30% incremental yield for clinically significant findings.3Triester S.L. Leighton J.A. Leontiadis G.I. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with obscure gastrointestinal bleeding.Am J Gastroenterol. 2005; 100: 2407-2418Crossref PubMed Scopus (556) Google Scholar CE proved to be particularly helpful in identifying lesions beyond the reach of PE. Capsule endoscopy is also approved for the evaluation of SB Crohn’s disease (CD). The ability of SBFT to detect the early subtle lesions of CD can be challenging. A recent meta-analysis of prospective comparative studies in nonstricturing CD showed the yield of CE is superior to SBFT, PE, and CTE.4Triester S.L. Leighton J.A. Leontiadis G.I. Gurudu S.R. Fleischer D.E. Hara A.K. Heigh R.I. Shiff A.D. Sharma V.K. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with non-stricturing small bowel Crohn’s disease.Am J Gastroenterol. 2006; 101: 954-964Crossref PubMed Scopus (476) Google Scholar Future applications may include the documentation of mucosal healing, assessing for postsurgical recurrence of CD, and in reclassifying indeterminate colitis into CD. In addition to OGIB and CD, CE appears to be useful for the diagnosis of SB tumors. At this time, CE and PE should be considered complimentary modalities in the diagnosis of SB neoplasms. There are several small trials suggesting that CE may also be of value in the evaluation of patients with celiac disease because of its ability to accurately identify changes such as villous atrophy, scalloping, or stacked folds, or a mosaic appearance of the mucosa. Although the data are limited, these studies emphasize the need for physicians who perform CE to be aware of the endoscopic mucosal changes associated with celiac disease. As with any new technology, there are definite issues of concern with CE that must be addressed. Patients with significant swallowing disorders may need to have the capsule placed endoscopically. Although there are data to suggest that CE is safe in patients with cardiac pacemakers, it is still a contraindication to the procedure. Capsule retention in the SB is the most concerning potential complication. Risk factors for SB retention include NSAID use, abdominal radiation, and CD. In OGIB, it occurs in <2% of cases, but in patients with known CD, it may be as high as 13%. It is important to note that capsule retention often identifies a significant lesion responsible for the patient’s symptoms and in fact, surgical removal is therapeutic. The Agile Patency capsule, a dissolvable “dummy” capsule recently approved by the Food and Drug Administration, can identify those at risk for capsule retention. Double Balloon EnteroscopyDBE is a new technique that allows for more extensive evaluation of the SB, including the ability to carefully inspect the mucosa (Figure 2). It is performed using a 2-meter endoscope through a 145-cm overtube, both with a latex balloon attached to the distal end. In coordination with serial inflation and deflation of the balloons, a reduction of the SB with telescoping over the endoscope allows for advancement deep into the SB. DBE can be performed via the oral or rectal route. A complete SB evaluation is usually not possible using 1 route alone and most often requires combined oral and rectal approaches. The advantage of DBE over CE and CTE is that it also allows for therapeutic intervention. Therapeutic options with DBE include electrocautery, argon plasma coagulation, polypectomy, endoscopic mucosal resection, balloon dilation, and stent placement. DBE is more labor intensive, but compliments CE because of its therapeutic capabilities. Sedation methods for DBE range from general anesthesia to conscious sedation. It is quite safe with similar risks and complications associated with traditional endoscopy.Several studies have shown that DBE has a yield similar to CE for the evaluation of suspected SB disease.5May A. Nachbar L. Pohl J. Ell C. Endoscopic interventions in the small bowel using double balloon enteroscopy: feasibility and limitations.Am J Gastroenterol. 2007; 102: 527-535Crossref PubMed Scopus (221) Google Scholar, 6Mehdizadeh S. Ross A. Gerson L. Leighton J. Chen A. Schembre D. Chen G. Semrad C. Kamal A. Harrison E.M. Binmoeller K. Waxman I. Kozarek R. Lo S.K. What is the learning curve associated with double-balloon enteroscopy? Technical details and early experience in 6 U.S. tertiary care centers.Gastrointest Endosc. 2006; 64: 740-750Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar Based on limited data, it appears that both devices can explore the SB with a high success rate and complement each other. DBE may be superior to radiologic studies for detecting aphthae, erosions, and small ulcers in the ileum. SB strictures also can be effectively evaluated and dilated with DBE. DBE is a new technique that allows for more extensive evaluation of the SB, including the ability to carefully inspect the mucosa (Figure 2). It is performed using a 2-meter endoscope through a 145-cm overtube, both with a latex balloon attached to the distal end. In coordination with serial inflation and deflation of the balloons, a reduction of the SB with telescoping over the endoscope allows for advancement deep into the SB. DBE can be performed via the oral or rectal route. A complete SB evaluation is usually not possible using 1 route alone and most often requires combined oral and rectal approaches. The advantage of DBE over CE and CTE is that it also allows for therapeutic intervention. Therapeutic options with DBE include electrocautery, argon plasma coagulation, polypectomy, endoscopic mucosal resection, balloon dilation, and stent placement. DBE is more labor intensive, but compliments CE because of its therapeutic capabilities. Sedation methods for DBE range from general anesthesia to conscious sedation. It is quite safe with similar risks and complications associated with traditional endoscopy. Several studies have shown that DBE has a yield similar to CE for the evaluation of suspected SB disease.5May A. Nachbar L. Pohl J. Ell C. Endoscopic interventions in the small bowel using double balloon enteroscopy: feasibility and limitations.Am J Gastroenterol. 2007; 102: 527-535Crossref PubMed Scopus (221) Google Scholar, 6Mehdizadeh S. Ross A. Gerson L. Leighton J. Chen A. Schembre D. Chen G. Semrad C. Kamal A. Harrison E.M. Binmoeller K. Waxman I. Kozarek R. Lo S.K. What is the learning curve associated with double-balloon enteroscopy? Technical details and early experience in 6 U.S. tertiary care centers.Gastrointest Endosc. 2006; 64: 740-750Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar Based on limited data, it appears that both devices can explore the SB with a high success rate and complement each other. DBE may be superior to radiologic studies for detecting aphthae, erosions, and small ulcers in the ileum. SB strictures also can be effectively evaluated and dilated with DBE. CT EnterographyTechnological improvements in multidetector row CT, such as increased speed and resolution, have made this imaging modality an ideal method for noninvasively evaluating the SB. CT imaging of the gastrointestinal tract has the advantage of evaluating not only the SB, but also extraluminal disease as well. CTE is a new method of evaluating the SB and is different from routine abdominopelvic CT (Figure 3).7Paulsen S.R. Huprich J.E. Fletcher J.G. Booya F. Young B.M. Fidler J.L. Johnson C.D. Barlow J.M. Earnest Ft CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases.Radiographics. 2006; 26 (discussion 657–662): 641-657Crossref PubMed Scopus (341) Google Scholar Unlike routine CT, which uses high-density oral contrast, IV contrast, and thicker sections, CTE uses thin sections and large volumes of a neutral oral contrast such as water, methylcellulose, or low-density barium along with intravenous contrast. This allows for better visualization of the SB wall thickness and enhancement characteristics, which can correlate with inflammation and/or hypervascular lesions.CTE is particularly useful for evaluating CD.8Hara A.K. Leighton J.A. Heigh R.I. Sharma V.K. Silva A.C. De Petris G. Hentz J.G. Fleischer D.E. Crohn disease of the small bowel: preliminary comparison among CT enterography, capsule endoscopy, small-bowel follow-through, and ileoscopy.Radiology. 2006; 238: 128-134Crossref PubMed Scopus (252) Google Scholar This is because CTE not only visualizes the entire thickness of the SB wall and detects strictures and fistulas, but it allows superior evaluation of deep ileal loops that are difficult to palpate with traditional SBFT. CTE findings of active bowel inflammation include mural hyperenhancement, increased mural thickness,9Booya F. Fletcher J.G. Huprich J.E. Barlow J.M. Johnson C.D. Fidler J.L. Solem C.A. Sandborn W.J. Loftus Jr., E.V. Harmsen W.S. Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.Radiology. 2006; 241: 787-795Crossref PubMed Scopus (157) Google Scholar mural stratification, soft tissue stranding, and engorged vasa recta. CTE and CE appear to have equal sensitivity for CD, but CTE may have higher specificity. Studies also suggest that CTE may provide a noninvasive method for monitoring CD activity, because bowel wall enhancement on CTE correlates with endoscopic and histologic severity.10Colombel J.F. Solem C.A. Sandborn W.J. Booya F. Loftus Jr, E.V. Harmsen W.S. Zinsmeister A.R. Bodily K.D. Fletcher J.G. Quantitative measurement and visual assessment of ileal Crohn’s disease activity by computed tomography enterography: correlation with endoscopic severity and C reactive protein.Gut. 2006; 55: 1561-1567Crossref PubMed Scopus (203) Google Scholar Although CTE is very safe, if it is to be used as a noninvasive method to monitor CD activity, the risk of ionizing radiation must be considered. It is also critical that adequate SB distention is achieved to minimize false-positive examinations.In addition to CD, CTE is also useful in the detection and evaluation of SB tumors. Tumors may appear as masses, focal wall thickening, or increased mural enhancement. Certain lesions may enhance more than others, such as carcinoid and gastrointestinal stromal tumors. It may also detect SB changes seen in celiac disease. CTE may also play a role in the evaluation of OGIB and the detection of AVMs but more studies are needed. Technological improvements in multidetector row CT, such as increased speed and resolution, have made this imaging modality an ideal method for noninvasively evaluating the SB. CT imaging of the gastrointestinal tract has the advantage of evaluating not only the SB, but also extraluminal disease as well. CTE is a new method of evaluating the SB and is different from routine abdominopelvic CT (Figure 3).7Paulsen S.R. Huprich J.E. Fletcher J.G. Booya F. Young B.M. Fidler J.L. Johnson C.D. Barlow J.M. Earnest Ft CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases.Radiographics. 2006; 26 (discussion 657–662): 641-657Crossref PubMed Scopus (341) Google Scholar Unlike routine CT, which uses high-density oral contrast, IV contrast, and thicker sections, CTE uses thin sections and large volumes of a neutral oral contrast such as water, methylcellulose, or low-density barium along with intravenous contrast. This allows for better visualization of the SB wall thickness and enhancement characteristics, which can correlate with inflammation and/or hypervascular lesions. CTE is particularly useful for evaluating CD.8Hara A.K. Leighton J.A. Heigh R.I. Sharma V.K. Silva A.C. De Petris G. Hentz J.G. Fleischer D.E. Crohn disease of the small bowel: preliminary comparison among CT enterography, capsule endoscopy, small-bowel follow-through, and ileoscopy.Radiology. 2006; 238: 128-134Crossref PubMed Scopus (252) Google Scholar This is because CTE not only visualizes the entire thickness of the SB wall and detects strictures and fistulas, but it allows superior evaluation of deep ileal loops that are difficult to palpate with traditional SBFT. CTE findings of active bowel inflammation include mural hyperenhancement, increased mural thickness,9Booya F. Fletcher J.G. Huprich J.E. Barlow J.M. Johnson C.D. Fidler J.L. Solem C.A. Sandborn W.J. Loftus Jr., E.V. Harmsen W.S. Active Crohn disease: CT findings and interobserver agreement for enteric phase CT enterography.Radiology. 2006; 241: 787-795Crossref PubMed Scopus (157) Google Scholar mural stratification, soft tissue stranding, and engorged vasa recta. CTE and CE appear to have equal sensitivity for CD, but CTE may have higher specificity. Studies also suggest that CTE may provide a noninvasive method for monitoring CD activity, because bowel wall enhancement on CTE correlates with endoscopic and histologic severity.10Colombel J.F. Solem C.A. Sandborn W.J. Booya F. Loftus Jr, E.V. Harmsen W.S. Zinsmeister A.R. Bodily K.D. Fletcher J.G. Quantitative measurement and visual assessment of ileal Crohn’s disease activity by computed tomography enterography: correlation with endoscopic severity and C reactive protein.Gut. 2006; 55: 1561-1567Crossref PubMed Scopus (203) Google Scholar Although CTE is very safe, if it is to be used as a noninvasive method to monitor CD activity, the risk of ionizing radiation must be considered. It is also critical that adequate SB distention is achieved to minimize false-positive examinations. In addition to CD, CTE is also useful in the detection and evaluation of SB tumors. Tumors may appear as masses, focal wall thickening, or increased mural enhancement. Certain lesions may enhance more than others, such as carcinoid and gastrointestinal stromal tumors. It may also detect SB changes seen in celiac disease. CTE may also play a role in the evaluation of OGIB and the detection of AVMs but more studies are needed. ConclusionsThe ability to evaluate the integrity of the SB has been greatly enhanced by CE, DBE, and CTE. There is evidence that these new technologies also improve clinical outcomes. It is important to clarify the most efficient and cost-effective ways to utilize these procedures. Based on limited data, CE appears to be a reasonable screening tool for suspected SB pathology, especially when there is no evidence of SB obstruction. When obstruction or mass lesions are suspected, CTE is a reasonable alternative and may even compliment CE. Once a lesion has been identified or if there is a high suspicion that a SB lesion is present despite negative tests, then DBE should be strongly considered. The ability to evaluate the integrity of the SB has been greatly enhanced by CE, DBE, and CTE. There is evidence that these new technologies also improve clinical outcomes. It is important to clarify the most efficient and cost-effective ways to utilize these procedures. Based on limited data, CE appears to be a reasonable screening tool for suspected SB pathology, especially when there is no evidence of SB obstruction. When obstruction or mass lesions are suspected, CTE is a reasonable alternative and may even compliment CE. Once a lesion has been identified or if there is a high suspicion that a SB lesion is present despite negative tests, then DBE should be strongly considered.