Sunday, December 29, 2013

Pictures of the Gut

Capsule Endoscopy and IBD

Wireless capsule endoscopy, first introduced in 2000, provided a new method for imaging of the small bowel.  A patient with suspected IBD (generally Crohn’s disease), could swallow a “pill” after an overnight fast.  The pill contained a camera, a wireless transmission circuit, and a power source that lasted up to 8 hours.  The patient was required to wear a belt that would receive the signals from the pill, and then transmit them to a computer for image review.(1)  Since its inception, wireless capsule endoscopy (WCE) has undergone extensive testing and improvements in both protocol and technology.  How does it compare to other imaging techniques, is it contraindicated for anyone, and when should it be used?

First, WCE is now an accepted diagnostic tool – most insurance companies will pay for its use in the diagnosis of suspected Crohn’s disease, small bowel cancer, or suspected bleeding lesions in the small bowel.  It is widely available from practitioners, and is a relatively painless procedure.  The newer technology available provides high resolution imagery and up to 24 hours of battery life.  After swallowing the pill, the patient waits until it progresses through their system and then the pill itself is excreted and flushed.

The primary benefit of WCE is the imaging of the small intestine, specifically the middle portions.  A colonoscopy allows for the viewing of part of the terminal ileum (the end of the small intestine), and an upper endoscopy will allow for the viewing of the stomach and the beginning of the duodenum, but standard scopes don’t image the majority of the small intestine.  There are more invasive procedures, including single-and-double balloon endoscopy (balloons are used to allow the scope to travel up or down, depending on the insertion point, through the majority of the small intestine) and intraoperative enteroscopy (where a small incision in the bowel is made and a scope is inserted by a surgeon), but these are generally reserved as secondary options.  Traditionally, the primary imaging option has been an upper GI series with a small bowel follow-through, where the patient swallows radioactive barium (yummy!) and has their small bowel imaged as the barium coats it on its way through the intestines.  How does WCE compare to the traditional first line approach?

In a 2009 meta-analysis, the various studies comparing WCE to traditional imaging were reviewed.  The initial comparisons looked at suspected Crohn’s disease patients.  Compared to computed tomography enterography  (CT scans-based small bowel imagery using contrast), WCE won out with 68 vs. 21% yields.  Similarly, colonoscopy (including ileoscopy) found a higher yield for WCE (47 vs. 25% ).  Similar results were found in existing Crohn’s patients with computed tomography. (2)

What about magnetic resonance imaging and WCE?  The results are mostly comparable – the sensitivity and specificity of both approaches was very similar overall, though the number of studies performed (and the number of individuals in each study) were limited.(3,4,5)  One item of disagreement comes up, though, in a meta-analysis looking at CT v. MRI based approaches – that analysis found CT to be mostly equivalent to MRI (with the downside of additional radiation), which is inconsistent with MRI performing better and WCE.  More WCE work needs to be done on larger patient populations to confirm the results.(6)
For a second-line approach, WCE was again favorable when compared to single insertion double balloon endoscopy (inserted from the mouth or the anus), but not as good when measured against double balloon endoscopy.(7)  The risks and impact of double balloon endoscopy are higher, however, than other approaches and it is primarily a secondary option.

If WCE is comparable to existing small bowel studies, why isn't it used more often?  First, WCE is a newer technique, and not all facilities will have the ability to offer it as a diagnostic tool.  Second, there is the possibility of retention of the capsule, requiring medical or surgical intervention.  In suspected Crohn’s disease patients, a meta-analysis found a 2.6% retention rate, likely due to structuring.(8)  For existing Crohn’s disease patients, another study found 13% capsule retention due to structuring.  This risk can be reduced by giving a patency pill (a similar sized pill that dissolves over time) prior to the capsule endoscopy.(9)  Most retentions can be resolved without surgery, and there has even been an argument that retention itself is a valuable diagnostic tool.(10)  Third, reviewing the 50,000+ images from WCE can be time consuming, generally up to an hour and a half for the gastroenterologist.  Software is getting more advanced to assist with this task.  Fourth, the gastroenterologist cannot control pill transit time – some sections of the small bowel may have fewer images due to rapid movement.  This makes pinpointing the exact location of problem areas difficult.  Finally, any findings requiring surgical intervention (e.g. a biopsy or polyp removal) require a secondary procedure be performed.

For those with ulcerative colitis of Crohn’s colitis, WCE is not likely to be as helpful.  The preparation regimen (generally the worst part of the procedure) is similar for both.(11)  The value in colonoscopy, however, for UC and Crohn’s colitis patients is the biopsy and potential immediate removal of polyps and other colonic lesions.  While WCE may be helpful for general cancer screening, it is not at present a good substitute for routine colonoscopies.

Given all of the above data, where does the evidence show WCE can be best utilized?  First, it is best utilized for suspected or known small bowel disease and a colonoscopy is superior for known lower-GI disease.   Second, it is currently a toss-up whether or not an MRI-based small bowel study or WCE review is the best option for suspected Crohn’s disease.*  Because of this, the cost, availability, and experience of your gastroenterologist are likely to be the deciding factor.  If WCE is used, a patency pill check should be performed first. 

For existing Crohn’s patients, WCE can also be used as a first line monitoring tool.  If a patency pill test is successful, it is again a toss-up between WCE and MRI-based approaches. 

WCE technologies are improving, and pill size decreasing, every year.  As the size of the pill decreases and the image quality and software review capabilities improve, WCE is likely to be used more frequently as a first line diagnostic tool.

Bottom Line

·         Wireless Capsule Endoscopy is an accurate, effective first line tool for diagnosing suspected small bowel Crohn’s disease with comparable or better results than traditional imaging.
·         For individuals with suspected structuring, a patency pill should be given first to check for potential pill retention.
·         Wireless Capsule Endoscopy is not currently as useful for Crohn’s colitis or UC patients.

*CT approaches, while having equivalent diagnostic value, expose patients to additional radiation.  They are more readily available, however, and less expensive in most cases.  These are all factors to consider with your physician.
1.       Iddan, Gavriel, Gavriel Meron, Arkady Glukhovsky, and Paul Swain. "Wireless capsule endoscopy." Nature 405 (2000): 417.
2.       Dionisio, Paula M., Suryakanth R. Gurudu, Jonathan A. Leighton, Grigoris I. Leontiadis, David E. Fleischer, Amy K. Hara, Russell I. Heigh, Arthur D. Shiff, and Virender K. Sharma. "Capsule endoscopy has a significantly higher diagnostic yield in patients with suspected and established small-bowel Crohn's disease: a meta-analysis." The American journal of gastroenterology (2009).
3.       Horsthuis, Karin, Shandra Bipat, Pieter CF Stokkers, and Jaap Stoker. "Magnetic resonance imaging for evaluation of disease activity in Crohn’s disease: a systematic review." European radiology 19, no. 6 (2009): 1450-1460.
4.       Jensen, Michael Dam, Torben Nathan, Søren Rafael Rafaelsen, and Jens Kjeldsen. "Diagnostic accuracy of capsule endoscopy for small bowel Crohn's disease is superior to that of MR enterography or CT enterography." Clinical Gastroenterology and Hepatology 9, no. 2 (2011): 124-129.
5.       Kovanlikaya, Arzu, Elizabeth Watson, Jessica Hayward, Debra Beneck, Robbyn Sockolow, Aliza Solomon, Paul Christos, and Paula W. Brill. "Magnetic resonance enterography and wireless capsule endoscopy in the evaluation of patients with inflammatory bowel disease." Clinical imaging 37, no. 1 (2013): 77-82.
6.       Panes, Julian, Rosa Bouzas, M. Chaparro, V. GarcíaSánchez, J. P. Gisbert, Blanca Martínez de Guereñu, Juan Luis Mendoza et al. "Systematic review: the use of ultrasonography, computed tomography and magnetic resonance imaging for the diagnosis, assessment of activity and abdominal complications of Crohn’s disease." Alimentary pharmacology & therapeutics 34, no. 2 (2011): 125-145.
7.       Chen, Xiang, Zhi-Hua Ran, and Jin-Lu Tong. "A meta-analysis of the yield of capsule endoscopy compared to double-balloon enteroscopy in patients with small bowel diseases." World Journal of Gastroenterology 13, no. 32 (2007): 4372.
8.       Liao, Zhuan, Rui Gao, Can Xu, and Zhao-Shen Li. "Indications and detection, completion, and retention rates of small-bowel capsule endoscopy: a systematic review." Gastrointestinal endoscopy 71, no. 2 (2010): 280-286.
9.       Cheifetz, Adam S., Asher A. Kornbluth, Peter Legnani, Ira Schmelkin, Alphonso Brown, Simon Lichtiger, and Blair S. Lewis. "The risk of retention of the capsule endoscope in patients with known or suspected Crohn's disease."The American journal of gastroenterology 101, no. 10 (2006): 2218-2222.
10.   Maunoury, Vincent, Gwenola VernierMassouille, and JeanFrederic Colombel. "Value in capsule retention in Crohn's disease." Inflammatory Bowel Diseases17, no. 8 (2011): E84-E85.

11.   Drew, K., S. Hardcastle, A. J. Lobo, D. S. Sanders, R. Sidhu, and M. McAlindon. "PTU-222 A comparison of patient tolerance of bowel preparation regimens used for conventional colonoscopy, small bowel and colon capsule endoscopy." Gut 61, no. Suppl 2 (2012): A276-A276.

No comments:

Post a Comment