14 - Radiology of the Renal Tract Flashcards
What kinds of imaging are used in the renal tract?
plain film intravenous urogram (IVU) - less US CT MRI Nuclear medicine
Plain film?
Often the first imaging modality
cheap
Shows radio-opaque stones BUT there are non-radio-opaque stones
Little else you can see on plain film
Which renal calculi can you see on plain film?
Radio-opaque ones i.e. ones with CALCIUM salts. Means you can’t see renal calculi formed by accumulation/crystallisation of URIC ACID i.e. as occurs in GOUT
What is renal colic?
Abd pain commonly caused by kidney stones
Where do the ureters travel?
Parallel to the transverse processes of the lumbar vertebrae (so where you often will find a ureteric calculus)
IVU?
Intravenous urogram
Plain xray but with contrast injected. Now usually replaced with CT or MRI.
The minor calyces should look nice and sharp (where the medulla drains into)
If they are large and swollen/not well defined and can’t really see ureters then it suggests that the urine is blocked and can’t get out
Ultrasound?
- high frequency sound waves
- no radiation
- operator dependent
- patient body dependent (is a fixed frequency so a larger patient absorbs the US before it gets to the kidney
What is US useful for?
Renal stones, renal obstruction, renal mass, bladder lessions (good as is filled with WATER - air is bad on US)
What is US NOT useful for?
To assess the ureters
Describe the echogenicity of the kidney in US
- capsule is an echogenic line
- medulla darker?
- the central sinus complex has high echogenicity as contains fat, vessels and fibrous tissue
CT?
- more accurate, assesses soft tissues, fluid and calcification
- expensive
- significant radiation
- may need IV contrast (can have a reaction)
> need to think about age risk and benefits
What is CT useful for?
Stones/calculi, tumours, trauma, infection
How should the kidney look on ct?
- bright
- right kidney is DARKER suggesting it isn’t getting as much blood/perfusion (bf in or out problem)
- also see the dye in the aorta
- can see the renal vein draining into the ivc
What muscle are the kidney’s parallel to?
Psoas
MRI?
- EXCELLENT soft tissue evaluation and fluid
- expensive
- no rad
- longer scan time (someone with renal colic isn’t going to sit still this long)