Imaging the abdomen Flashcards
(34 cards)
List the imaging modalities for the abdomen
X-ray (plain film) / Fluoroscopy
Ultrasound (US)
Computed Tomography (CT)
Magnetic Resonance Imaging (MRI)
Which imaging modalities are cross sectional?
CT, MRI and ultrasound
What is the difference between spatial and contrast resolution?
Spatial- Number of megapixels
Contrast- differentiation of different soft tissue- Density, water or fat content
Which imaging modality is planar?
X-RAY
How do you differentiate between T1 and T2 weighted images?
T1 : fluid is black
T2 : fluid is white
What is contrast?
Agent used to increase contrast resolution (ie. highlight specific areas/organs)
Is given intravenously (IV), or enteral (oral/PR) before a scan
Is either more or less dense than surrounding tissues (for XR/CT), or paramagnetic (for MRI)
What is paramagnetic?
Affects the magnetic field
Give the pros and cons of X-ray
Pros: Cheap, Quick, Easy for patient, High spatial resolution (good for bone), Low radiation dose
Cons: Poor contrast resolution (poor for soft tissue) Planar imaging (superimposes structures)
Give the pros and cons of CT
Pros: Quick, widely available
Cross sectional images
High Contrast resolution (good for soft tissue)
Cons: Radiation dose, IV Contrast risks
Give the pros and cons of ultrasound
Pros: Cheap, Quick, No radiation, Cross sectional images, US guided interventions
Cons: Saved images are only a snapshot of examination (report operator dependant)
Give the pros and cons of MRI
Pros: Contrast resolution, Specific applications (e.g. Spine, MSK), No radiation
Cons: Limited availability, Patient experience (duration, claustrophobia), Expense, Magnet / Contrast risks
What are the risk of IV contrast?
Allergy
Kidney- renal dysfunction made worse - nephrotoxicity
What the difference between hollow and solid visceral imaging?
Hollow- tends to have gas
Solid- more tissue
What is the difference between intraperitoneal and retro-peritoneal?
Intraperitoneal- Inside the peritoneal and is coated all the way round
Retroperitoneal- behind the peritoneum on one said covered
What is the difference between the systemic and portal circulation?
Systemic- Blood around the body
Portal- blood from the gut to the liver
Give examples of solid abdominal viscera
Liver, spleen and pancreas
What are the liver segments divided by?
Divided by portal vein (horizontally) & hepatic (vertically) veins (portal triad)
What is a good first line test of the liver?
Ultrasound
What is it called where there is colour on the ultrasound?
Doppler
Colour gives a clue about velocity
What colour does fluid appear on an ultrasound?
Black
How does the liver appear on ultrasound?
Grainy with black vessels and bile ducts
Why should patients needing a gallbladder ultrasound be nil by mouth before?
Gall bladder contracts after you eat
Gain a better image
On CT what is white?
Bone
On CT what is black?
Air
