GASTROINTESTINAL RADIOLOGY

1. GASTROINTESTINAL RADIOLOGY Topics to be covered • 1. Liver Lesions – Haemangioma and HCC • 2. CT Colonography • 3. Small bowel - CT, MRI or fluoroscopy? • 4. Rectal tumor – MRI staging • 5. Anal fistula – MRI imaging

2. Liver – Haemangioma (US) Atypical

3. Liver Haemangioma CT A) Pre-contrast

4. B) Arterial phase

5. C) Portal venous phase

6. D) Delayed phase CT – we will not do delayed phase unless haemangioma suspected. Please specify “? haemangioma” on request form.

7. Haemangioma Summary • Common- often incidental • US – Echogenic -no halo. No colour flow. Aytpical – hypo-echoic in fatty liver - mixed echotexture • CT – C- low density C+ peripheral vessels (uneven) C+ PV /delay progressive fill-in Small haemangioma fill in immediately and cannot be distinguished from metastates. • MRI features similar to CT post Gadolinium

8. CT -HCC pre contrast

9. Arterial enhancement (central and early)

10. Washout on portal venousindicates fast flow

11. HCC Summary • US - usually heterogeneous Usually HepB +ve with raised alpha FP • CT – C- low density C+A – central early contrast (high flow rate) C+PV – washout cf with liver – may have a capsule • MR – intracellular fat on T1 out of phase - similar perfusion characteristics to CT

12. MRI IMAGES of LIVER • Look at CSF first to tell if T1 or T2 • T1-in/out. • T1 are grey. Fluid is dark. Black outline • T2-incl HASTE. • More definition. Fluid is bright. • Gadolinium – always with T1

13. Fatty liver with sparing

14. Same pt - out of phase T1 MRI

15. Same patient - CT non-contrast

16. CT COLONOGRAPHY Dissection Strip, anus to caecum Endoluminal (for fun only) Orientation Overview 800/40 window Axial to loops

17. Advantages / disadvantages • Sensitivity and specificity is of the order of 90 % for 10 mm polyps. • Easy, quick and well tolerated. • Beats barium enema hands down. • Safer than optical colonoscopy • Approx. half the price of optical colonoscopy • No intervention possible as in optical Cy • At present for “Ba enema” indications, but is likely to be used for screening in future. • Radiology manpower training required. • Radiation dose equivalent to Ba Enema

19. CTC vs Optical Colonoscopy Consider “Is intervention likely to be needed?” – (cf MRCP vs ERCP) • CTC for average risk and Fam Hx pts. • > 50 yrs (radiation) • Contraindicated if inflammatory bowel or on steroids (risk of perforation as inflation is done “blind” as opposed to Ba enema). • Optical Colonoscopy – if biopsy or polypectomy prob needed • All polyposis syndromes • High risk • Inflammatory Bowel Disease

20. Overview of CT colonography? • Process Currently Future • CLEANSE -Tagging -Subtraction • DISTEND -Air -CO2 • COMPUTE -Workstation -new programs • VIEW -Time - CAD • REPORT -Issues

21. Prep and tagging Slide courtesy Dr Helen Moore

22. Longer tube and patient can apply air themselves Slide courtesy Dr Helen Moore

23. Lateral topogram

24. Philips workstation layout

25. Incomplete air column -Excess fluid Supine Prone Can rotate image volume to view as a Ba enema in 3D

26. Diverticular disease

27. 4 mm Polyp

28. Ileo-caecal valve Caecal pole Arrow points To caecum Residual tagging

29. Dirty Caecum- not fully open on supine or prone views 54 yr Recomm optical colonoscopy

30. The dirty caecum

31. Complex Folds at flexures

32. Radiation • Barium enema 6 – 8 mSv • CTC estimate of 7.6 mSv with low mAs. Increased noise, but high resolution improves definition of small polyps • Thin slice, limit tube current • Background radiation is 2.4 MSv/year The worldwide average background dose for a human being is about 2.4 millisievert (mSv) per year.[1] This exposure is mostly from cosmic radiation and natural isotopes in the Earth. This is far greater than human-caused background radiation exposure, which in the year 2000 amounted to an average of about 0.01 mSv per year from historical nuclear weapons testing, nuclear power accidents and nuclear industry operation combined,[2] and is greater than the average exposure from medical tests, which ranges from 0.04 to 1 mSv per year. Source Wikipedia.

33. Small Bowel Imaging • < 35 yrs – MRI for radiation reasons • However if pre-surgical workup–fluoroscopy • CT Enteroclysis – only difference from CT is negative contrast in bowel. No advantage to do if recent normal CT. • MR Small bowel – breath-hold sequences, dynamic change between sequences. Good soft tissue differentiation. +/- Gadolinium

34. Normal Fluoroscopic Enteroclysis Jejunal intubation Low density barium Pumped in to distend Intubation 10 min Study 20 min

35. Terminal ileum

36. Skip lesions - Proximal

37. Follow-throughtime-consumingflocculationStrictures may be hiddenIs superseded by other tests

38. Enteroclysis- same patient

39. Intra-luminal mass

40. CT Enteroclysis Histo- GIST Tumor shows up against negative contrast in bowel. Positive contrast could hide it

41. CT ENTEROCLYSIS Volumen oral contrast for 45 min pre scan IV Maxolon IV contrast on table CT to include anal canal and with sagittal.

42. CT ENTEROCLYSIS Jejunum often thick-walled Can evaluate bowel wall due to negative contrast in lumen and IV contrast in wall. Evaluates stomach well also Plus standard CT Reserved for older patients due to radiation dose

43. MRI Small Bowel • Oral Volumen 30 – 45 min prior (or Ioscan) • +/- IM Buscopan for peristaltic movement • Good for Crohns patients with multiple studies and large radiation dose over time. • Coronal TRUFI • Coronal TRUFI fat saturation • Coronal HASTE • Axial HASTE • Coronal T1

44. MRI ENTEROCLYSISTRUFI

45. Normal- HASTE sequence

46. Terminal ileum

47. Cutaneous fistula Post Gadolinium T1 fat sat

48. Caecum / TI

49. Crohns disease

50. Normal FAT SATURATION