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Intended learning outcome

Intended learning outcome. The student should learn at the end of this lecture principles of G astrointestinal Radiology. GASTROINTESTINAL RADIOLOGY. Topics to be covered. 1. Liver Lesions – Haemangioma and HCC 2. CT Colonography 3. Small bowel - CT, MRI or fluoroscopy?

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Intended learning outcome

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  1. Intended learning outcome The student should learn at the end of this lecture principles of Gastrointestinal Radiology.

  2. 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

  3. Liver – Haemangioma (US) Atypical

  4. Liver Haemangioma CT A) Pre-contrast

  5. B) Arterial phase

  6. C) Portal venous phase

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

  8. 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

  9. CT -HCC pre contrast

  10. Arterial enhancement (central and early)

  11. Washout on portal venousindicates fast flow

  12. 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

  13. 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

  14. Fatty liver with sparing

  15. Same pt - out of phase T1 MRI

  16. Same patient - CT non-contrast

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

  18. 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. Longer tube and patient can apply air themselves

  20. Lateral topogram

  21. workstation layout

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

  23. Diverticular disease

  24. 4 mm Polyp

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

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

  27. The dirty caecum

  28. Complex Folds at flexures

  29. 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

  30. 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

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

  32. Terminal ileum

  33. Skip lesions - Proximal

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 Follow-throughtime-consumingflocculationStrictures may be hiddenIs superseded by other tests

  35. Enteroclysis- same patient

  36. Intra-luminal mass

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

  38. 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

  39. MRI Small Bowel • 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

  40. MRI ENTEROCLYSISTRUFI

  41. Normal- HASTE sequence

  42. Terminal ileum

  43. Cutaneous fistula Post Gadolinium T1 fat sat

  44. Caecum / TI

  45. Crohns disease

  46. Normal FAT SATURATION

  47. Sag, axial and coronal

  48. Normal anal canal - sagittal Puborectalis Internal sphincter Subcutaneous External sphincter

  49. Normal anal canal - axial at PR mucosa Internal sphincter Fat in inter- sphincteric space Pubo-rectalis = upper external sphincter

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