GASTROINTESTINAL RADIOLOGY Dr Mohamed El Safwany, MD.

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

GASTROINTESTINAL RADIOLOGY  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 Topics to be covered

Liver – Haemangioma (US) Atypical

Liver Haemangioma CT A) Pre-contrast

B) Arterial phase

C) Portal venous phase

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

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

CT -HCC pre contrast

Arterial enhancement (central and early)

Washout on portal venous indicates fast flow

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+A – central early contrast (high flow rate) C+PV – washout cf with liver C+PV – washout cf with liver – may have a capsule – may have a capsule  MR – intracellular fat on T1 out of phase - similar perfusion characteristics to CT - similar perfusion characteristics to CT

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

Fatty liver with sparing

Same pt - out of phase T1 MRI

Same patient - CT non-contrast

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

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

Longer tube and patient can apply air themselves

Lateral topogram

workstation layout

Incomplete air column -Excess fluid SupineProne Can rotate image volume to view as a Ba enema in 3D

Diverticular disease

4 mm Polyp

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

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

The dirty caecum

Complex Folds at flexures

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

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

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

Terminal ileum

Skip lesions - Proximal

Follow-through time-consuming flocculation Strictures may be hidden Is superseded by other tests

Enteroclysis- same patient

Intra-luminal mass

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

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

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

MRI ENTEROCLYSIS TRUFI

Normal- HASTE sequence

Terminal ileum

Cutaneous fistula Post Gadolinium T1 fat sat

Caecum / TI

Crohns disease

Normal FAT SATURATION

Sag, axial and coronal

Normal anal canal - sagittal Subcutaneous External sphincter Puborectalis Internal sphincter

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

Normal anal canal - coronal Internal Sphincter Puborectalis External Sphincter

Post Gad fat saturation T1 Drain in situ ANTERIOR POSTERIOR

UC - mucinous tumour

Anal canal tumour

Text Book  David Sutton’s Radiology  Clark’s Radiographic positioning and techniques

Assignment  Two students will be selected for assignment.

Question  Describe role of adequate preparation in CT colonoscopy?

 Thank You