1. Inflammatory Bowel Disease
MR Enterography
Inflammatory Bowel Disease

2. Why? What the clinician wants to know
Presence, localization, and extent of disease
Complications – strictures, abscesses, fistulas
Disease activity – active vs fibrotic

3. How to do it? Patient prep Oral contrast
Bowel prep day before – low residue diet, fluids, laxative
Overnight fasting or NPO 4-6 hrs prior to study
Oral contrast
Water results in inadequate distention, long transit time
Biphasic oral contrast agents
Different signal intensities on different sequences (low T1, bright T2)
VoLumen - a low-conc barium (0.1% weight/volume) that contains sorbitol (CHOP, Emory 2007)
Mannitol, sorbitol and polyethylene glycol have been used to slow down intestinal reabsorption of water
Can cause N/V, diarrhea, cramping

4. How to do it? Prone positioning Glucagon IM or IV Timing –
to stop peristalsis
½ dose before study starts, ½ dose prior to contrast
Timing –
Typical adult L over min
Child 1 L one hour prior to exam
Filling of TI occurs in kids at minutes, adults 1 hour
Rectal contrast – water enema for better distention of colon, TI
not generally used unless incomplete colonoscopy
MR Entercolysis – improved bowel distention (esp jejunum)
Invasive, time consuming

5. Egleston Protocol No patient prep
Oral contrast – Kool-aide with gastroview
Powerade/gatorade cannot be used due to susceptibility artifact
Timing
2 doses – first dose wait one hour, then drink ½ scan 30 minutes later
Ex : 24/12
Volume and timing same as CT guidelines
No glucagon
Supine position
Magnevist

6. Sequences T2w HASTE (haste, spair) TrueFISP (trufi, space)
Post contrast
Axial and coronal planes
Coronal plane good for terminal ileum, appy; good overview
Sagittal thru pelvis

7. HASTE haste – non FS spair - FS Fast
High contrast between bowel lumen and wall
Best sequence for determining bowel wall thickness
Fluid collections
Submucosal edema (spair)
Sensitive to intraluminal flow voids
Poor evaluation of mesentery

8. TrueFISP trufi space - pelvis Fast Relatively motion insensitive
High contrast between small bowel lumen and bowel walls
Homogeneous endoluminal opacification
Good mesenteric anatomy (LAN, comb sign, vessels)
Susceptibility artifacts from intraluminal air
Chemical shift artifacts – black boundary
Occurs in pixels with fat & water
Improved with FS

9. Post contrast VIBE & FLASH
Venous, delayed for bowel (enteric phase at 75 sec post gad)
VIBE 3D more motion sensitive
FLASH 2D, thicker slices, but relatively motion insensitive (Shiran insurance plan)
Combination of FS and low SI intraluminal contrast increase the ability to detect wall enhancement
Active vs fibrotic disease
Bowel wall enhancement in active disease and fibrotic disease
Stratification can indicate active disease
Enhancing mesenteric adenopathy – sign of active disease
Complications – fistulas, abscess best seen post gad

10. Pelvis – T1 axial FS, high res
Post gad T1 images are better for the pelvis than the gradient echo (VIBE and FLASH)
Gas/stool in rectum degrade images thru the pelvis due to susceptibility artifact on the gradient echo images
Motion is not usually a big issue in pelvis

11. MR Features IBD Transmural bowel wall thickening, thickened folds
Cobblestone
Submucosal Edema – use spair images; indicates active dz
Mesenteric changes
Fat wrapping/creeping fat
Lymphadenopathy
Vascular hyperemia – comb sign
Complications
Strictures
Fistulas
Abscess
***Early disease with mucosal ulceration and nodularity is not well seen on MR***

12. Fold thickening & ulceration
Deep ulcerations – focal linear areas of high SI through thickened bowel wall
Normal bowel wall and folds are low SI on both the true FISP and HASTE images

13. Deep ulcerations

14. Bowel wall thickening > 3 mm abnormal
Most patients in crohn’s 5-10 mm
Marked wall thickening terminal ileum

15. Bowel wall thickening
Coronal true-FISP (A) and axial HASTE (B) images shows polypoid thickening of the cecal wall (arrows). Compare this with the normal wall thickness of the descending colon (arrowhead).

16. Mesenteric changes TrueFISP Small mesenteric lymph nodes Comb sign
Small lymph nodes seen in active and chronic disease
Enhancement LN suggest active disease

17. Mesenteric changes
T1 and true FISP – comb sign and creeping fat

18. Mesenteric changes

19. Active vs. Chronic post contrast images
Fibrosis – low level, mild to moderate inhomogeneous enhancement
Active disease – homogeneous intense enhancement or stratified enhancement

20. Ileal and appendix dz
haste
Post gad
haste
Post gad

21. Active vs Chronic Submucosal Edema
D. Martin RSNA 2007
TI post gad very sensitive for detection of IBD but spair better for determining active vs chronic
Submucosal edema classic finding in active inflammation
Use spair images (haste fs) to detect submucosal edema
Study found many false positives for post gad
T2 images better correlated with active vs inactive disease

22. Active vs Chronic haste Post gad venous -enhancing abnl loop post gad
-no edema on spair
-thus FIBROTIC disease
Spair/haste FS

23. Enhancement
Stratified enhancement (c,d) indicative of active disease.

24. Stratified Enhancement – active disease

25. Complications - strictures
Coronal images good for looking for strictures
> 3 cm bowel distention upstream indicates functional obstruction

26. Complications “Star sign” – internal fistula
Post gad
Star sign of internal fistula
Patient had entero-entero fistula
HASTE

27. Complications – perianal dz
HASTE
Fistula post gad
FS post gad

28. Complications – perianal fistula
spair
Post gad

29. Complications – perianal fistula on T2 images

30. Complications – perianal abscess

31. Complications – phelgmon/abscess
Post-gad
trueFISP
Medial wall of terminal ileum is partially indistinct and bulging medially suggesting phlegmon/early abscess.

32. Pitfalls Incomplete luminal distention
Can mimic bowel wall thickening
Black border artifact on trueFISP can over estimate wall thickness
use HASTE for wall thickness
Intraluminal flow artifact on HASTE can simulate cobblestone
Check TrueFISP
Fistula can be missed since not dynamic

33. Pitfalls
True FISP MR image shows extensive susceptibility artifacts generated by trapped endoluminal air
Susceptibility artifact
Signal dropout
Bright spots
Spatial distortion

34. Pitfalls – artifacts HASTE TruFISP Arrowheads – black boundary
Arrow – susceptibility artifact from trapped air
*curved arrow on both – TI thickening

35. Summary
Haste, trufi and post contrast images to identify abnormal bowel
Coronal images good for terminal ileum, overall picture
Evaluate for strictures
Look for associated mesenteric changes
Active vs fibrotic
Haste vs spair ?submucosal edema
Stratification of edema post contrast
Use space, T1 post gad high res images to look for perianal disease
Post contrast images for fistula, abscess

36. References
Prassopoulos P, Papanikolaou N, Grammatikakis J, Rousomoustakaki M, Maris T, Gourtsoyiannis N. MR enteroclysis imaging of Crohn disease. RadioGraphics 2001;21(Spec Issue):S161–S172
Essary B, Kim J, Anupindi S, et al. Pelvic MRI in children with Crohn disease and suspected perianal involvement. Pediatr Radiol. 2007;37:201–208
Darge K, Anupindi S, Jaramillo D. MR Imaging of the Bowel: Pediatric Applications. MRI Clinics N America.2008;16(3):
Toma P, Granata C, Magnano G, Barabino A. CT and MRI of paediatric Crohn disease. Pediatr Radiol. 2007;37:
Greenhalgh R, Punwani S, Austin C; Halligan S, Taylor S. The MRI manifestations of small bowel Crohn’s disease revealed. Presented at RSNA
Udayasankar U, Lauenstein T, Martin D. Role of SPAIR T2 fat suppressed MR imaging in active inflammatory bowel disease. Presented at RSNA 2007.
Herrmann K, Michaely H, Seiderer J, et al. The “star-sign” in magnetic resonance enteroclysis: a characteristic finding of internal fistulae in Crohn's disease. Scand J Gastroenterol. 2006;41:239–241

37. Good resource http://lakeside2007.rsna.org/#
Electronic posters and papers through RSNA website
Lakeside Learning Center
Radiographics password

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