1. CROHN DESEASE New Imaging
BEN ROMDHANE MH
Hopital AVICENNE BOBIGNY

2. role cross-sectional imaging expanded
CT and MRI allow rapid acquisition of high-resolution images of the intestines.
Protocoles necessary to acquire images
of diagnostic quality
Sensitivity (CT and MR I ) of over 95% for the detection of CD

3. Chronic granulomatous GI tract inflammation
peak between 15 and 25 years of age
tendency toward remission and relapse
affect any part of the GI tract
often multiple discontinuous sites
Small intestine 80% of cases,
terminal ileum most commonly
Colon affected with (50% of cases) or without (15%–20%) involvement of the small intestine

4. Earliest change in the submucosa with lymphoid hyperplasia and lymphedema
Early stage: subtle elevations and aphthoid ulcers.
Transmurally extension to serosa (transmural stage) and
Extension to mesentery and adjacent organs (extramural stage).
Aphthoid ulcers develop into linear ulcers and fissures to produce an ulceronodular or “cobblestone” appearance.

5. bowel wall thickened by fibrosis and / or inflammatory infiltrates
common complications of advanced disease:
Bowel obstruction, strictures, abscesses or phlegmon, fistulas, and sinus tracts
not common, toxic megacolon and neoplasms (lymphoma and carcinoma)

6. Endoscopy and barium studies limited in demonstrating the transmural or extramural
extent or extraintestinal complications
Cross-sectional imaging may not detect subtle mucosal lesions
but reveals pathologic changes of the intestinal mucosa
help compensate for the limitations of conventional imaging

7. CT currently the cross-sectional imaging modality of choice at most institutions
MRI has also proved highly effective
CT and MRI allow rapid acquisition of high-resolution images of the intestines during a breath-hold examination.
CT and MRI provide useful information in the diagnosis and in treatment planning

8. limited spatial resolution of CT and MRI compared with enteroclysis studies results in lower rates of depiction of early disease manifestations
Detection and characterization of intestinal lesions require appropriate preparation and scanning techniques.
GI tract should be empty and clean, with the lumen distended

9. review preparations, contrast agents, and scanning techniques
illustrate the characteristic imaging appearances of CD
Review findings that indicate the presence of inflammatory lesion activity
discuss advantages, limitations and role of cross-sectional imaging

10. Fast for 6 H prior examination (decreases the alimentary residue
Collapsed bowel loops may mimic a segment with wall thickening, an abscess, or enlarged lymph nodes
Administration of large amount of intraluminal contrast distends bowel loops for better visualisation of anatomie and morphologic changes
IV contrast demonstrate the presence of lesions and help assess their inflammatory activity

11. Advantages of cross-sectional imaging
demonstrate :
transmural extent of inflammation,
skip lesions beyond severe luminal stenoses,
intraperitoneal or extraintestinal complications
provide three-dimensional information
and, vascular information with use of contrast material

12. Entéroscanner
Ingestion soluté hyperosmolaire/ Sonde entéroclyse sous scopie dans D3
Antispasmodique IV
Scanner sans et après injection IV produit de contraste

14. The contrast agent should allow imaging with
- homogeneous luminal enhancement
-high contrast between lumen and bowel wall
-minimal mucosal absorption
- absence of artifact formation
- no significant adverse effects

15. To minimize bowel movement or contraction and motion artifact from intestinal peristalsis:
- Antiperistaltic agents prior to scanning
- short scanning time
Intravenous contrast medium indicated for :
- better visualization of the bowel wall
extraintestinal structures, and lesions
- precise evaluation of the degree of
inflammatory activity

16. Computed Tomography
Various types of intraluminal contrast media are used to provide positive or negative contrast between the bowel lumen and surrounding structures
Positive contrast agent with high attenuation at CT aids in differentiating bowel loops from enlarged lymph nodes or an extramural fluid collection such as an abscess.
The presence of small bowel obstruction or fistulas is also well appreciated.

17. with the use of positive intraluminal contrast material, mural enhancement after iv injection may obscure subtle Crohn lesions.
The use of negative intraluminal contrast agents with low attenuation facilitates depiction of the wall of normal and diseased bowel segments, particularly after iv contrast material administration

19. technique for intraluminal contrast material administration is common to both CT and MRI
Between 1,500 and 2,000 mL of contrast material administered orally 45–90 minutes prior to the examination
To provide adequate and uniform distention of the bowel loops, patients are asked to steadily ingest the contrast material over a 20–60-minutes period

20. The contrast material may be administered through a nasojejunal catheter at a rate of 100–250 mL/min with the help of a roller pump
CT or MR imaging performed with this technique is called CT or MR enteroclysis
Use of a nasojejunal catheter allows better luminal distention but causes patient discomfort
If necessary, 300– 1,000 mL of contrast agent can be administered transrectal

21. CT scans with the patient in the prone position is recommended to disperse the small bowel loops
With multi–detector row CT scanners, thinner collimation (0.5–2.5 mm) is possible. Sections with a 5–7-mm thickness or thinner sections, overlapping reconstructed images, or multiplanar reformatted images
IV administration of iodinated contrast essential, 100–150 ml at a rate of 2.5–4ml /sec with a delay time of 40–70 sec

22. MR Imaging
Various kinds of intraluminal contrast agents positive, negative, or biphasic
Positive agents produce high intraluminal signal
Negative agents produce little or no intraluminal signal
Biphasic contrast agents may produce either high or low signal depending on the pulse sequence used, usually demonstrating low signal intensity on T1 and high signal on T2
Negative or biphasic agents more suitable

23. An antiperistaltic agent injected to minimize potential artifact of bowel movement or contraction
Prone position recommended for separating bowel loops and decreasing the scanning volume. This position is also safe for patients should they vomit

24. To increase the signal-to-noise ratio, use of abdominal phased array radiofrequency coils
Coronal images obtained with a 4–7-mm section thickness, a 128– matrix, and a field of view of 350 mm or more
Thicker sections to monitor the infusion process ( 70–180 mm)
Acquisition of axial, sagittal, or multiplanar images may be necessary for precise evaluation

25. Protocol should include both T1- and T2- to detect and characterize each lesion
T1-weighted imaging with iv contrast essential for assessing inflammatory lesion activity.
True fast imaging with a steady precession (FISP),
half-Fourier acquired single shot fast spin-echo,
T2-weighted turbo spin-echo,
combination of these sequences recommended

26. Gadolinium enhanced fat-suppressed spoiled gradient-echo T1 2D ou 3D
excellent visualization of the enhancing bowel wall ( contrasts with the low signal mesenteric fat and negativ intraluminal contrast material)
Morphologic features and degree of enhancement both aid in assessing CD activity
Images covering the bowel loops in their entirety can be obtained within 30 sec
Scanning is performed after a bolus iv injection of 0.1–0.2 mmol/kg of gadopentetate dimeglumine with a delay time of 40–80 sec

27. CT and MR Imaging Findings in CD
In proved or suspected CD images analyzed specifically for : - altered bowel segment(wall thickness, attenuation , degree of enhancement, length of involvement) - stenosis and prestenotic dilatation - skip lesions, fistulas, abscess, fibrofatty proliferation, increased vascularity of the vasa recta (comb sign), mesenteric adenopathy, and other extra-intestinal disease involvement

28. Normal thickness of the wall of the small intestine1–2 mm and colon 3 mm when lumen is distended
Any portion of the bowel wall that exceeds 4–5 mm is considered abnormal
Bowel wall thickening, usually ranging from 1–2 cm, is the most consistent feature of CD

29. Paroi

31. number of lesions and extent of Involvement
involved segment homogeneous or stratified appearance (alternating layers of higher or lower attenuation or signal intensity) CT / MRI

33. Mural stratification (“target” or “double halo” appearance) often seen in active lesions after iv contrast
inflamed bowel wall demonstrates marked enhancement after iv contrast
intensity of enhancement correlates with degree of inflammatory lesion activity

36. Activité

37. normal small intestine lumen less
than 2.5 cm
Luminal narrowing and associated prestenotic dilatation easily recognized
Deformity of bowel loops such as pseudo-diverticulum formation caused by asymmetric involvement by longitudinal ulcers and ulcer scars is well demonstrated on both axial and coronal images.

40. early-stage lesions such as enlarged lymph follicles, slight distortion of the bowel folds, and tiny aphtae are not consistently visible at either CT or MRI due to inadequate spatial resolution

41. Fibrofatty proliferation of the mesentery is commonly seen adjacent to involved bowel segment in CD
CT and MRI demonstrate fibrofatty proliferation,
which has slightly increased CT attenuation and
slightly decreased MRI signal intensity compared with normal fat separating the bowel loops.

42. Signes extrapariétaux: graisse et vaisseaux
Lessignes extra pariétaux touchent la graisse mésentérique bordant les anses malades et les organes adjacents.Graisse subit des phénomène inflammatoire, les vaisseaux dans les régions inflammatoires sont engorgés: signe du peigne. Si l’inflammation de la graisse est ancienne, elle s’hypertrophie et se fibrose, c’est la sclérolipomatise qui élargit l’esapce inter anse et fige les nase digestive.

43. Abscess and phlegmon well demonstrated at CT and fat-saturated T2-MRI
can occur in small bowel mesentery abdominal wall psoas muscle or around the anus
Fistulas and sinus tracts are also depicted
MRI sensitivity for depicting sinus tracts is 50%–75% /conventional enteroclysis

46. Mesenteric lymphadenopathy ranging from 3 to 8 mm in size depicted at CT and MRI
When lymph nodes larger than 10 mm, lymphoma and carcinoma must be excluded.

48. Inflammatory activity
well appreciated at CT and MR imaging
Findings include :
thickened bowel wall
with marked contrast enhancement,
mural stratification,
pericolic or perienteric hypervascularity
(comb sign)
hyperintensity T 2 of the bowel wall
lymph node enlargement,
extramural complications: phlegmon abscess

50. CT sensitivity 94%–100% specificity 95%
Sensitivity increases to 98% in the diagnosis of transmural or extramural
only 70% for early-stage disease.
multiplanar images with axial images significantly improves observer confidence
Sensitivity of MRI 96%–100%
sensitivity on a per lesion 85 % and 100% when superficial lesions excluded

51. MRI role similar to that of CT with
High soft-tissue contrast
absence of ionizing radiation exposure
more time consuming,
less readily available,
more expensive
Advantages of CT over MR imaging
greater availability, shorter examination
times, flexibility in choosing imaging
thickness and planes after acquisition
higher spatial resolution.

52. Conclusion
Appropriate treatment planning in CD requires correct assessment of the severity, extent, and inflammatory activity of lesions and of the presence of extraintestinal complications
CT and MRI with intraluminal and intravenous contrast material provide excellent visualization of most intestinal lesions and demonstrate mural and extramural extent, and complications
Disease activity well appreciated( CT and MRI)
Aid in selecting appropriate treatment options