Intended learning outcomeIntended learning outcome

The student should learn at the end of this The student should learn at the end of this lecture principles of Gastrointestinal lecture principles of Gastrointestinal Radiology.Radiology.

GASTROINTESTINAL RADIOLOGYGASTROINTESTINAL RADIOLOGY

1. Liver Lesions – Haemangioma and HCC1. Liver Lesions – Haemangioma and HCC

2. CT Colonography2. CT Colonography

3. Small bowel - CT, MRI or fluoroscopy?3. Small bowel - CT, MRI or fluoroscopy?

4. Rectal tumor – MRI staging4. Rectal tumor – MRI staging

5. Anal fistula – MRI imaging5. Anal fistula – MRI imaging

Topics to be covered

Liver – Haemangioma (US)Liver – Haemangioma (US)

Atypical

Liver Haemangioma CT Liver Haemangioma CT A) Pre-contrastA) Pre-contrast

B) Arterial phaseB) Arterial phase

C) Portal venous phaseC) Portal venous phase

D) Delayed phaseD) Delayed phase

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

Haemangioma SummaryHaemangioma Summary Common- often incidentalCommon- often incidental US – Echogenic -no halo. No colour flow.US – Echogenic -no halo. No colour flow. Aytpical – hypo-echoic in fatty liverAytpical – hypo-echoic in fatty liver

- mixed echotexture- mixed echotexture CT – C- low densityCT – C- low density

C+ peripheral vessels (uneven)C+ peripheral vessels (uneven) C+ PV /delay progressive fill-inC+ PV /delay progressive fill-in

Small haemangioma fill in immediately and Small haemangioma fill in immediately and cannot be distinguished from metastates.cannot be distinguished from metastates.

MRI features similar to CT post GadoliniumMRI features similar to CT post Gadolinium

CT -HCC CT -HCC pre contrastpre contrast

Arterial enhancement Arterial enhancement (central and early)(central and early)

Washout on portal venousWashout on portal venousindicates fast flow indicates fast flow

HCC SummaryHCC Summary

US - usually heterogeneous Usually HepB +ve with US - usually heterogeneous Usually HepB +ve with raised alpha FPraised alpha FP

CT – C- low densityCT – C- low density C+A – central early contrast (high flow rate)C+A – central early contrast (high flow rate) C+PV – washout cf with liverC+PV – washout cf with liver

– – may have a capsulemay have a capsule

MR – intracellular fat on T1 out of phaseMR – intracellular fat on T1 out of phase - similar perfusion characteristics to CT- similar perfusion characteristics to CT

MRI IMAGES of LIVERMRI IMAGES of LIVER

Look at CSF first to tell if T1 or T2Look at CSF first to tell if T1 or T2 T1-in/out. T1-in/out. T1 are grey. Fluid is dark. Black outlineT1 are grey. Fluid is dark. Black outline

T2-incl HASTE.T2-incl HASTE. More definition. Fluid is bright.More definition. Fluid is bright.

Gadolinium – always with T1Gadolinium – always with T1

Fatty liver with sparingFatty liver with sparing

Same pt - out of phase T1 MRISame pt - out of phase T1 MRI

Same patient - CT non-contrastSame patient - CT non-contrast

CT COLONOGRAPHYCT COLONOGRAPHY

DissectionStrip, anus to caecum

Endoluminal(for fun only)

800/40 windowAxial to loops

OrientationOverview

Advantages / disadvantagesAdvantages / disadvantages Sensitivity and specificity is of the order of 90 % Sensitivity and specificity is of the order of 90 %

for 10 mm polyps.for 10 mm polyps. Easy, quick and well tolerated.Easy, quick and well tolerated. Beats barium enema hands down.Beats barium enema hands down. Safer than optical colonoscopy Safer than optical colonoscopy Approx. half the price of optical colonoscopyApprox. half the price of optical colonoscopy No intervention possible as in optical CyNo intervention possible as in optical Cy At present for “Ba enema” indications, but is likely At present for “Ba enema” indications, but is likely

to be used for screening in future.to be used for screening in future. Radiology manpower training required.Radiology manpower training required. Radiation dose equivalent to Ba Enema Radiation dose equivalent to Ba Enema

Incidence of Colonic Perforation at CT Colonography: Review of Existing Data and Implications for Screening Asymptomatic Adult Source: International Working Group on Virtual Colonoscopy

Total VC studies considered 21,923

Symptomatic Perforation Rates for VC* 0.005%

Total Perforation Rates for VC 0.009%

Perforation Rates for Conventional Colonoscopy 0.1-0.2%

Pickhardt 2007

Longer tube and patient can apply air Longer tube and patient can apply air themselvesthemselves

Lateral topogramLateral topogram

workstation layoutworkstation layout

Incomplete air column -Excess fluid Incomplete air column -Excess fluid

SupineSupine ProneProne

Can rotate image volume to view as a Ba enema in 3D

Diverticular diseaseDiverticular disease

4 mm Polyp4 mm Polyp

Ileo-caecal valveIleo-caecal valve

Residualtagging

Arrow pointsTo caecum

Caecal pole

Dirty Caecum- Dirty Caecum- not fully open on supine or prone viewsnot fully open on supine or prone views

54 yr54 yrRecomm Recomm opticaloptical colonoscopycolonoscopy

The dirty caecumThe dirty caecum

Complex Folds at flexuresComplex Folds at flexures

RadiationRadiation Barium enema 6 – 8 mSvBarium enema 6 – 8 mSv CTC estimate of 7.6 mSv with low mAs. CTC estimate of 7.6 mSv with low mAs.

Increased noise, but high resolution Increased noise, but high resolution improves definition of small polypsimproves definition of small polyps

Thin slice, limit tube currentThin slice, limit tube current Background radiation is 2.4 MSv/yearBackground radiation is 2.4 MSv/year

Small Bowel ImagingSmall Bowel Imaging

< 35 yrs – MRI for radiation reasons< 35 yrs – MRI for radiation reasons However if pre-surgical workup–fluoroscopyHowever if pre-surgical workup–fluoroscopy CT Enteroclysis – only difference from CT is CT Enteroclysis – only difference from CT is

negative contrast in bowel. No advantage to negative contrast in bowel. No advantage to do if recent normal CT.do if recent normal CT.

MR Small bowel – breath-hold sequences, MR Small bowel – breath-hold sequences, dynamic change between sequences. Good dynamic change between sequences. Good soft tissue differentiation. +/- Gadoliniumsoft tissue differentiation. +/- Gadolinium

Normal Fluoroscopic EnteroclysisNormal Fluoroscopic Enteroclysis

Jejunal intubationLow density bariumPumped in to distendIntubation 10 minStudy 20 min

Terminal ileumTerminal ileum

Skip lesions - Proximal Skip lesions - Proximal

Follow-throughFollow-throughtime-consumingtime-consumingflocculationflocculationStrictures may Strictures may be hiddenbe hiddenIs superseded Is superseded by other testsby other tests

Enteroclysis- same patientEnteroclysis- same patient

Intra-luminal massIntra-luminal mass

CT EnteroclysisCT Enteroclysis

Tumor shows up against negative contrast in bowel. Positive contrast could hide it

Histo- GIST

CT ENTEROCLYSISCT 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 BowelMRI Small Bowel Good for Crohns patients with multiple studies Good for Crohns patients with multiple studies

and large radiation dose over time.and large radiation dose over time. Coronal TRUFICoronal TRUFI Coronal TRUFI fat saturationCoronal TRUFI fat saturation Coronal HASTECoronal HASTE Axial HASTEAxial HASTE Coronal T1Coronal T1

MRI MRI ENTEROCLYSISENTEROCLYSIS

TRUFITRUFI

Normal- HASTE sequenceNormal- HASTE sequence

Terminal ileumTerminal ileum

Cutaneous fistulaCutaneous fistula

Post Gadolinium T1 fat sat

Caecum / TICaecum / TI

Crohns diseaseCrohns disease

NormalNormal

FAT SATURATION

Sag, axial and coronalSag, axial and coronal

Normal anal canal - sagittalNormal anal canal - sagittal

Subcutaneous External sphincter

Puborectalis

Internal sphincter

Normal anal canal - axial at PRNormal anal canal - axial at PR

mucosa

Internalsphincter

Fat in inter-sphincteric space

Pubo-rectalis= upper externalsphincter

Normal anal canal - coronalNormal anal canal - coronal

Internal Sphincter

Puborectalis

ExternalSphincter

Post Gad fat saturation T1Post Gad fat saturation T1Drain in situDrain in situ

ANTERIOR

POSTERIOR

UC - mucinous tumourUC - mucinous tumour

UC - mucinous tumourUC - mucinous tumour

Anal canal tumourAnal canal tumour

Text BookText Book

David Sutton’s RadiologyDavid Sutton’s Radiology Clark’s Radiographic positioning and Clark’s Radiographic positioning and

techniquestechniques

AssignmentAssignment

Two students will be selected for Two students will be selected for assignment.assignment.

QuestionQuestion

Describe role of adequate preparation in Describe role of adequate preparation in CT colonoscopy?CT colonoscopy?

Thank YouThank You