Module 4 - Abdomen Flashcards
imaging features of appendicitis
Inflamed: >6mm diameter, surrounded by inflamed hyperechoic fat, may have faecolith, may be hypervascular
Features of an amoebic abscess on CT
Amoebic abscess: hyperdense capsule, hypodense oedema beyond capsule
What is the characteristic finding of achalasia on a barium swallow?
bird-beak deformity
Outline the most common imaging techniques for assessing the oesophagus and stomach
XR
- barium swallow
- gastrograffin swallow
EUS: local staging of oesophageal cancer
CT: with oral contrast, useful for staging
FDG PET: for staging
Based on location, what are the likely diagnoses for oesophageal masses that are
- submucosal/intramural
- extrinsic
- mucosal
- Submucosal intramural: smooth filling defects
○ Smooth muscle tumor of oesophageal wall - Extrinsic lesions are often longer, obtuse angles not fixed to esophageal wall, epicentre outside oesophagus
○ Lymph node or cyst - Mucosal lesions show mucosal irregularity
Adenocarcinoma or SCC
Which is more sensitive for intra-abdominal bleeding, CTA or Angiography?
CTA
Where is it best to embolise the splenic artery to preserve collateral perfusion?
proximal to the short gastric
helps avoid infarction
Describe 6 different interventional radiological procedures that address liver cancers, in particular HCC
- TAE: transarterial embolisation, selective arterial embolisation to supply of tumour
- Ethanol ablation: injection of ethanol to induce chemical necrosis
- TACE: intra-arterial gel/substance or microspheres to deliver sustained release of drug while decreasing/obstructing the blood flow to the tumor(s)
- TARE: Selective intra-arterial infusion of radioactive microspheres into the arterial supply of a tumor
- Microwave ablation
- Cryotherapy
What is the expected appearance of post-treatment HCC?
What about recurrent or residual HCC?
CT/MR/CEUS no arterial contrast enhancement
Recurrent or residual tumor is commonly located along the periphery of an ablation zone and manifests as focal nodular arterial phase hyperenhancement (APHE)
Diagnostic features on U/S of cholecystitis vs choledocholithiasis
CHOLECYSTITIS
Sonographic Murphy’s sign
Pericholecystic fulid
Gallbladder thickening >4mm
CHOLEDOCHOLITHIASIS
Dilated CBD >6mm infers stones
Features of interstitial vs necrotising pancreatitis on CT
- Interstitial oedematous pancreatitis (80-90%)
○ Diffuse enlargement, stranding and lack of necrosis - Necrotising pancreatitis
○ Presence of tissue necrosis, commonly involving pancreatic parenchyma and peripancreatic tissue
○ Low signal intensity on CT
Imaging features of portal HTN/cirrhosis
- Steatosis ○ low hounsfield units on CT ○ MRI: out of phase image significant drop in signal indicating intra-voxular fat - Small, nodular liver - Varices - Splenomegaly - Ascites - Dilated portal vein >13mm
Who is in the population for HCCC screening and what does screening encompass?
- hep C
- asian
- cirrhosis
6 monthly U/S + AFP looking for nw hypoechoic lesions
If enlarging or >10mm for MRI, multiphase CT or contrast enhanced ultrasound
If definitive diagnosis not achieved with the above, for biopsy
CT and MRI appearance of FNH
CT
- central hypodense scar
- homogenous arterial hyperenhancement
- isoenhancing on PV
MRI
- T2 hyperintense scar
- retains primovist
Imaging appearance of hepatic adenoma
arterial enhancement
early washout
fat containing
NO retention of primovist
classic population: young woman on COCP, no risk factors
CT and MRI appearance of liver haemangioma
CT
- slow enhancement
- peripheral nodular and gradual “centripetal” filling in of contrast
MRI
- lightbulb bright on T2
CT and MRI appearance of HCC
CT
- arterial enhancement
- washout
- capsular retraction
MRI
- T2 fat-saturated hyperintense
- diffusion restriction
What are 2 common complications post liver transplant, time frame and their imaging characteristics ?
Hepatic arterial thrombosis
○ Post-op or years after
○ Increased likelihood if sepsis, graft ischaemia, rejection, hypercoagulable
○ Doppler: no detectable flow in hepatic artery with colour or spectral doppler
Hepatic Artery Stenosis
○ At anastomosis usually >3months post-transplant
○ Elevated peak systolic velocity >200cm/sec
○Parvus tardus waveform in intra-hepatic arteries
What is the appearance of RCC on CT?
What are some mimics? (4)
- Solid and Solid/cystic
- Enhancement: on MRI and CT
○ Often hypervascular compared to background parenchyma, hypovascular on late phase
- Renal cysts with internal complexity
- Angiomyolipoma: contains fat, echogenic on ultrasound, low attenuation on CT, fat suppression on MRI
- TCC: involvement of renal pelvis
- Renal oncocytoma : benign tumour, indistinguishable from RCC
What are some findings consistent with chronic renal impairment on imaging?
loss of corticomedullary differentiation, thinning cortex, increased echogenicity of renal parenchyma
Differentials for collections post-renal transplant and characteristic ultrasound appearance
- Haematoma: central black areas, fluid filled, thickened margins
- Lymphocele: thin wall, thin septations
- Urinoma: no septations, pure fluid
Imaging (U/S) features (6) and management of acute renal graft rejection
- diffusely enlarged graft with thickened cortex
- loss of corticomedullary differentiation
- prominent pyramids
- urothelial thickening
- Doppler: resistive index >0.8 but this is non-specific, if diastolic flow absent or reversed, more suggestive of acute rejection
- Renal artery thrombosis in rare severe cases
Treatment: high dose steroids and antibiotics
Imaging (U/S and nuc med) features of chronic graft rejection
U/S: enlargement of sinus fat and cortical thinning, dystrophic calcification, mild hydronephrosis
Doppler: Increased intrarenal RI
Nuclear med: reduced uptake of radiopharmaceuticlas but normal parenchymal transit or increased parenchymal retention
Complications of solid organ embolisation
- GB necrosis
- liver ischemia
- renal ischemia
- splenic infarct
- abscesses
