Imaging of the Small BowelCarmen Meier, MDMarch 24, 2012

Small Bowel FactsConsists of: duodenum, jejunum, ileum20 to 30 feet longRoleDigestion of proteins, carbohydrates, lipidsAbsorption of nutrients

Why image the small bowel?Structural problemsStrictures (medications, Crohns disease)Inflammation (Crohns, infection, ischemia)Masses or polypsForeign bodies (capsules)BleedingVascular ectasia (AVMs)Masses/tumorsPolypsMeckel's diverticulumDieulafoy's lesionUlcerations

Radiology ImagingSmall Bowel Follow ThroughEnteroclysisCTTagged RBC scanAngiography

SBFTPo radio-opaque contrast followed by serial x-raysPosition changes, abdominal pressure often neededUnable to see small lesions or mucosal lesions (AVMs)

SBFTUseful for fistulas (Crohns disease)

EnteroclysisInjection of contrast followed by methylcellulose through nasoduodenal tube. Contrast coats the intestine and the methylcellulose distends the lumen to help with visualization.

EnteroclysisCon: nasoduodenal tube, uncomfortable, time-intensive

CT EnterographyHigh volume (1200ml) negative oral contrast over 1 hour (no tube)improves small bowel distension c/w regular CTGive IV contrast to evaluate bowel wall

CrohnsDiseaseCrohnsdisease

Tagged RBC scanSmall amount of blood drawn and labeled with radioactive material (Technetium)Blood then re-injected and circulates: picked up by gamma scan

Tagged RBC scanPro: may pick up slower bleedCon:Only approximate location givenDoes not pick up intermittently bleeding lesionsNo option for intervention

AngiographySelective cannulation and contrast injection of blood vessels by interventional radiologist under fluoroscopy to pick up brisk/active bleeding

AngiographyPro: Intervention possible (occlusion of bleeding vessel with coils, etc)Con:Fast, active bleeds onlyNeed at least approximate locationInvasiveHigh IV contrast load -> renal issuesNot available everywhere

Endoscopic Imaging of Small BowelVideo Caspule EndoscopyPush EnteroscopySingle Balloon EnteroscopyDouble Balloon Enteroscopy

Capsule EndoscopySmall capsule capable of taking sequential still images that are transmitted to receiver is swallowed by patient.Capsule disposable.Images downloaded from receiver and analyzed by MD.

Capsule EndoscopyPro: NoninvasiveCon:No control over imagesUnable to interveneStill requires prepTakes some timeNot all patients suitable candidates

Standard EnteroscopyPro:Able to interveneBiopsy, polypectomy, cautery, foreign body retrivalCon:InvasiveNot suitable for all patients

Push EnteroscopySimply pushing a (pediatric) colonoscope (180cm) or dedicated enteroscope (200cm) into the small bowel as far as possibleLimitations:Uncomfortable (anesthesia)Small bowel is non-fixed, and therefore difficult to simply advance scopeLooping in stomach

Single Balloon EnteroscopyPush-and-pull mechanismNeeded: Balloon Control Unit and single-use splinting tubeMost procedures take about 1 hourLimitations:Still uncomfortable for patient (anesthesia)Post-surgical anatomyContraindicated with varices

Single Balloon Enteroscopy

Double Balloon EnteroscopyOne balloon on endoscope, one on overtubeVisualization of more distal small bowelLimitations:Fujinon systemMore difficult to learn90-120 minutes procedure time

Questions?