Gastrointestinal Flashcards
Sialolithiasis – INITIAL/REFERRING Patient Pathway
Likely route via GP, or possibly dentist
What imaging modalities are used for Sialolithiasis?
Positives and limitations
Plain X-rays will show radiopaque calculi
sialography:
fluoro with contrast
exact size and location
calculi will show as a filling defect
contraindication with infection
US:
visualise stone and gland
hyperechoic lesion (stone) + shadow
Can visualise radiolucent stone
acute obstructive cases, appearance of enlarged glands and dilated ducts
CT:
visualise stones within ducts and glands
Acute presentation may identify gland enlargement and inflammation
potential artifact from filling
MRI:
Excellent demonstration of the gland and the ductal architectural, especially when there is intra-glandular duct dilatation
INITIAL/REFERRING Patient Pathway for oral carcinoma?
Referral often via dentist, but could also be via GP
What imaging modalities are used for oral carcinoma?
MRI:
depiction of the tumour and staging
CT:
Useful for depiction of the tumour and for staging
PET/CT:
Much clearer depiction when CT is combined with PET
oesophagal pathology initial/referral pathway?
GP referral to specialist services,
e.g. for endoscopy, or possibly straight to oncology
What imaging can be done to diagnose pathologies of the oesophagus?
Endoscopy is used for initial diagnosis (biopsies can be taken)
Barium Swallow when endoscopy not a viable option
If abnormal, whole-body CT (WBCT) carried out for staging, +/- PET
If suitable for radical treatment,
PET-CT is useful for treatment planning (helps to detect metastatic disease)
Endoscopic ultrasound (EUS) can also be performed (biopsies can be taken)
What is the initial/referring pathway for stomach carcinoma?
GP referral to specialist services,
e.g. for gastroscopy, or possibly straight to oncology
What imaging is done for stomach carcinoma?
Very similar to oesophageal carcinoma imaging pathway
First line is endoscopy (gastroscopy) – readily available and biopsies can be taken
Radiological examinations usually for staging and/or treatment planning:
CT
PET
EUS
What is adenocarcinomas radiographic appearance?
CT image:
mass which has thickened walls
and central ulceration
EUS:
infiltration of serosa (membrane)
enlarged lymph nodes
Small bowel obstruction initial/referrring pathway?
Medical emergency – requires early diagnosis and intervention
Emergency referral to ED
What imaging is done for small bowel obstruction?
Radiographic appearance?
AXR
SBO:
- distended/dilated bowel
- central location
- Large bowel at the periphery is collapsed
- Valvulae conniventes can be identified across the full width of the dilated loops confirming it to be small (not large) bowel
CT (abdo/pelvis +C; no oral)
much more sensitive
aetiology
determine treatment pathway, e.g. immediate surgery when there is a risk of ischaemia, etc.
- Multiple dilated loops of small bowel
- large caecal mass
US can be used (“bedside test”)
- dilated small bowel loop
- considered dilated > 2.5cm
What is the imaging pathway for small bowel carcinoma?
Endoscopy first line
(No specific imaging pathway as rare in occurrence)
CT to assess spread small bowel tumours
CT findings are unclear:
CT or MR enterography or enteroclysis
PET-CT - metastatic disease
What are the advantages of a CT and MR Enterography for imaging small bowel carcinoma/IBD?
comparison of MRI and CT
- Minimally invasive
compared to small bowel enema/enteroclysis - evaluation of bowel wall thickness/demonstrate thickened bowel wall
-detect extra-intestinal
- assess small bowel lesions
- determine an aetiology for occult gastrointestinal bleeding
- evaluate known or suspected IBD, usually Crohn’s disease
MRI has no radiation dose
Takes longer than CT
MR generally has lower resolution than CT,
greater sensitivity/specificity for abnormalities,
esp. within the bowel walls
CT is a high dose examination
IBD affects younger people more, it’s preferable to use MRI as no ionising radiation
comparison of CT and MR enteroclysis to enterography:
Invasive – poor patient satisfaction
Conventional enteroclysis (SBE) still allows better bowel distention
Can be 3D reconstructed - superior images
Extrinsic structures are better visualised
quicker examination
What is Chrins disease?
Chronic IBD
Full thickness of intestinal wall is inflammed
What imaging is used to image Chrons disease?
Plain abdominal X-rays:
- identify small bowel or colonic dilatation, which may indicate obstruction
Colonoscopy +biopsy
children and young people:
Upper intestinal endoscopy
small bowel capsule endoscopy + US:
when endoscopy and conventional imaging have been non-diagnostic
Abdominal ultrasound:
- assess bowel thickness + dilatation (suggesting obstruction),
- abscesses, fistulas, and strictures
CT/MR enterography
- Stage Crohn’s disease
- look for extraluminal complications (such as abscesses and fistulas)
Pelvic MRI
- definition of the extent and location of abscesses and fistulas
What are the radiographic signs for chrons disease?
small bowel US:
- Thickened and stiff bowel wall
- Narrow lumen
- Proximal dilatation of more than 25mm
MR Enteroclysis:
- thickened wall of terminal ileum – Crohn’s disease
CT + C:
- Small bowel with wall thickening
- Prominence of the mesenteric vasculature - comb sign
Radiographic appearance of Hepatitis on US?
starry sky pattern
characterised by increased brightness portal venules and diminished parenchymal echogenicity
Transient Elastography (“sonoelastography”) how does it provide a use in diagnostic purposes?
Elastography techniques:
Takes advantage of changed soft tissue elasticity in various pathologies to yield qualitative and quantitative information that can be used for diagnostic purposes
Transient Elastography (“sonoelastography”) how is it used when imaging the liver?
Used to assess:
- tissue elasticity/stiffness in the assessment of liver fibrosis, as found in cirrhosis
Transient Elastography (“sonoelastography”)
benefits
and
limitations
US is widely available with equipment having elastography capabilities
Lack of ionising radiation,
non-invasive
low cost,
but operator dependent
Liver biopsy used to diagnose cirrhosis where elastography is not suitable
How does liver cirrhosis present on US?
free fluid surrounding
increased density
nodules??
Hepatocellular carcinoma radiographic appearances?
- Vast majority have liver cirrhosis
- hepato-cellular carcinoma (HCC) may be: - solitary
- multifocal
- diffusely infiltrating.
Larger HCC lesions typically have a mosaic appearance due to haemorrhage and fibrosis
Initial/referring pathway for Hepatocellular carcinoma?
GP referral to specialist services
or
possibly straight to oncology
What imaging is used for Hepatocellular carcinoma?
Initial CT assessment – highly sensitive and specific (possible to include chest if ?mets)
(2-3 phase liver CT)
late arterial phase - hypervascular tumor - 30 secs
MRI may be an additional tool in some cases (can assess primary and metastases, often with IV contrast – gadolinium)
US has a better sensitivity with larger lesions (3-5cm) - HCC can be hyper- OR hypo-echoic
NM – minimal input
What is Hepatic Haemangioma?
benign liver tumour
what imaging is used for a Hepatic Haemangioma?
Radiographic appearances?
CT or MRI are the most commonly used imaging modalities,
alongside US (often used as follow-up)
CT:
contrast - seen on arterial and post
MRI:
A: T1-W, lesion is hypointense
B: T2-W, lesion is hyperintense
Also enhances with Gadolinium
liver metastases appearance?
Normally multiple,
maybe more peripheral
varying sizes
what imaging modalities are used to image liver metastasis?
CT
NM - PET/CT
what imaging modalities are used to image polycystic liver?
US
CT
What are the radiographic appearances of a liver abscess?
May have similar appearances to cyst
Within liver tend to have thick walls and fluid centres
Wall also more irregular (different to simple cyst appearance)
what is the treatment for a polycystic liver?
Dialysis/transplant
What is the treatment for a liver cyst?
Aspiration and drainage is immediate treatment (under imaging guidance)
Liver trauma imaging and treatment?
Liver is the most commonly affected intra-abdominal organ in trauma (blunt and penetrating)
High risk of uncontrolled bleeding and delayed complications
Immediate assessment required – FAST and CT
Minor trauma self resolves (CT avoids surgery):
- as many as 86% of liver injuries have stopped bleeding by the time surgical exploration is performed
- 67% of operations performed for blunt abdominal trauma are nontherapeutic
imaging modalities and radiographic appearance of subcapsular haematoma?
US assessment may be possible – potential issues with direct contact of transducer and trauma site(s)
CT +C demonstrates:
small,
crescent-shaped subcapsular
parenchymal hematoma (less than 1 cm thick)
crescent-shaped hyperechoic collection
MRI:
- good at demonstrating fresh blood because of the difference in signal intensity,
however minimal role as initial imaging modality (useful for follow-up assessment)
What is the imaging pathway for cholecystitis?
people with suspected gallstone disease:
liver function tests
ultrasound
people with abdominal or gastrointestinal symptoms that have been unresponsive to previous management:
- magnetic resonance cholangiopancreatography (MRCP)
If ultrasound has not detected common bile duct stones but the:
bile duct is dilated and/or
liver function test results are abnormal:
- endoscopic ultrasound (EUS) if MRCP does not allow a diagnosis to be made
US radiographic appearances cholecystitis?
US (fast so full of bile) – usually detect
stones larger than 1 or 2mm
Wall thickening (>3mm)
Common hepatic or common bile duct should not be more than 7mm in size (unless have had cholecystectomy)
magnetic resonance cholangiopancreatography radiographic appearances cholecystitis?
A non-invasive alternative to ERCP:
- excellent images
- however, as no endoscope is used it is not therapeutic (and patient may need ERCP to e.g. remove any gallstones that are found!)
- Used to visualise biliary and pancreatic ducts
- fast for at least 6 hours before the procedure, as this allows better demonstration of gall stones
- may use IV Gadolinium
what is Intrahepatic Cholangiocarcinoma?
Carcinoma arising in any part of the:
- biliary tree
- from the small intrahepatic bile ducts to the Ampulla of Vater at the distal end of the common bile duct
What imaging is used for pancreatitis?
US - first line
- chronic and acute
Enlarged heterogeneous pancreas anterior bowing and surface irregularity surrounded by a rim of peri-pancreatic fluid
CT:
can differentiate acute and chronic
Chronic Main features:
Pancreatic duct dilatation
Parenchymal atrophy
Pancreatic calcification
Best visualised with water as contrast agent
What imaging is used for Pancreatic cancer?
- essential to assess and stage pancreatic tumours
- differentiate those who are suitable (or not) for surgery
- Can accurately stage pancreatic cancer
- Can identify cysts
- pseudocysts,
- necrosis
- abscesses
Use of tailored CT protocol is essential (using pre contrast, arterial and portal venous phases)
What is the treatment of pancreatic cancer?
(Whipple’s procedure:
- removal of the head of pancreas,
- the first part of the small intestine,
- the gallbladder
- the bile duct,
aka pancreaticoduodenectomy
what is the imaging pathway for pancreatic pathways (all the same) - NICE guidelines?
Depends on patient presentation, in relation to whether they have:
Obstructive jaundice
Pancreatic abnormalities on imaging
Pancreatic cysts
Inherited high risk of pancreatic cancer
Regardless, the imaging modalities of choice for all are:
CT scan (pancreatic protocol – likely to include water instead of oral contrast)
PET-CT and/or EUS (with US guided biopsy)
In addition:
For obstructive jaundice – ERCP (relieve biliary obstruction)
For pancreatic cysts – MRI/MRCP
What are Pancreatic Pseudocysts?
what are the appearances?
Small pancreatic cysts and pseudocysts are common features of both acute and chronic pancreatitis;
Pseudo-cysts greater than 6 cm in diameter seldom disappear spontaneously
Large pseudocysts:
can produce abdominal mass
may compress or erode surrounding structures.
What is the imaging pathway for Ulcerative colitis/colorectal cancer?
Colonoscopy first line imaging
CT and MRI
Benefits of CT colonography (CTC)?
CT colonography (CTC):
- offers a less-invasive alternative to conventional colonoscopy for imaging colon cancer
- This technique is sensitive for diagnosis of small polyps
limitations of CT colonography (CTC)?
- CT colonography (CTC)
- Some patients cannot tolerate the preparation for a CTC
what is the prep and procedure of a CT colonography (CTC)?
Full bowel cleansing is preferred (low residue diet and laxatives) but sometimes faecal tagging used
- Colon is insufflated with air or CO2 to fully distend colon
- Protocolled by radiologist for faecal tagging
- Patient will ingest a barium solution up to 24 hours prior to CT
- No laxatives, no low residue diet
Radiographic appearance of Ulcerative colitis?
CT and MRI:
might show a thickened,
ahaustral colon,
but are not sensitive or specific enough to be diagnostic tools hence the use of colonoscopy
Radiographic appearance of colorectal cancer?
irregular wall thickening with luminal narrowing
What are the advantages of CT virtual colonography?
- less invasive and safer with minimal perforation or sedation risks
- substantially lower cost than colonoscopy
offers complete colonic exam in patients with tortuosity or tumour that may prevent passage of a colonoscope - can assess colonic wall thickness and structures outside the colonic lumen
What are the limitations of CT virtual colonography?
- not entirely noninvasive - requires rectal tube and insufflation
- Radiation dose!
- inability to perform biopsy of suspicious findings at time of exam may require additional follow-up conventional colonoscopy
- less sensitivity for detection of very small polyps and superficial mucosal abnormalities than with colonoscopy
What are the advantages of MR virtual colonography?
- No ionising radiation
- Detailed images
What are the limitations of MR virtual colonography?
Less availability than CT
Longer scan time
More use in imaging of rectal pathologies
What imaging modalities are used for rectal carcinoma?
- MRI for staging of rectal tumour (better than CT for soft tissues)
- CT used to assess metastases
- Endorectal US compliments MRI as is better at looking at tumour extension within rectal wall
-Ultrasound good if local - Good for looking at sphincter muscles of the rectum and anus
- Fistulas
What is a CT Virtual Gastroscopy?
- CT with air-filled stomach
- Transparency-rendered image shows the mass
- The volume rendering technique can be applied to create transparency-rendered images.
What are the limitations of CT Virtual Gastroscopy?
cannot pick up flat lesions comparing to conventional gastroscopy
what is the dynamic contrast-enhanced magnetic resonance imaging (DCE MRI)?
- Functional imaging technique that can reflect tumour vascularity - largely used in the staging of rectal carcinomas
- The changes of signal intensity are plotted on a graph
what are the limitations of dynamic contrast-enhanced magnetic resonance imaging (DCE MRI)?
Downsides of DCE/MRI include:
- high cost,
- limited availability,
- longer exam time,
- as well as contraindication in patients with pacemakers or certain metal implants
The use of dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) in crohns disease?
- Increased bowel wall enhancement is an established finding indicative of active inflammation in patients with Crohn’s Disease
- Using standard post-contrast sequences, enhancement is evaluated as a snap shot in time
- Studies have shown that, compared with normal bowel, diseased bowel wall demonstrated early and intense uptake of contrast that increases over time until a plateau is reached
- The difference in enhancement pattern and dynamics was also observed between active disease and inactive disease.
What is 3D Ultrasound of the Bowel
- Data from the 2D scan is collected and by collecting known points and references can use the volume data to create a 3D image
- Adding the three-dimensional modality (3-D) increases the capabilities of this diagnostic tool in rectal cancer patients (particularly in staging)
