Flashcards in Radiology of the Renal Tract Deck (24):
What are the indications of renal imaging?
Renal colic and renal stone disease
-Diagnosis and follow up
Suspected renal mass
- ?Renal artery stenosis
What imaging techniques can you use for the renal tract?
Ultrasound +/- contrast
CT and CTU
CR and MRU
What are the different types of pyelography?
What is CTU and MRU?
What are the advantages and disadvantages of plain film?
-Low sensitivity and specificity for urological diseases
-Cheap and readily available
-Functional and anatomical information (IVU)
What is IVU?
An IVU (Intravenous Urography) is an x-ray of your urinary tract (consisting of kidneys, ureters and bladder) following an injection of a clear dye called contrast into a vein in your arm.
The pictures produced are called intravenous urograms (IVU) or intravenous pyelograms (IVP).
A series of x-rays are taken of the abdomen at various time intervals. This usually takes up to an hour, but occasionally it may be necessary to take additional delayed images, which may continue for several hours.
What is a KUB x-ray?
KUB refers to a diagnostic medical imaging technique of the abdomen and stands for Kidneys, Ureters, and Bladder.
A KUB is a plain frontal supine radiograph of the abdomen. It is often supplemented by an upright PA view of the chest (to rule out air under the diaphragm or thoracic etiologies presenting as abdominal complaints) and a standing view of the abdomen (to differentiate obstruction from ileus by examining gastrointestinal air/water levels).
Doesnt actually really assess urological system
What is more commonly used IVU or CTU?
Historically IVU was used to view urinary system as KUB is rubbish for this.
Now CTU is used as it is so much better
What is a pyelography?
What are the different types?
-In which a contrast solution is introduced through a vein into the circulatory system.
-This is a form of anterograde pyelogram.
-IVU = IVP
-Any pyelogram in which contrast medium is introduced from the lower urinary tract and flows toward the kidney (i.e. in a "retrograde" direction, against the normal flow of urine).
-Any pyelogram where a contrast medium passes from the kidneys toward the bladder, mimicking the normal flow of urine.
-A pyelogram that uses a gaseous rather than liquid contrast medium.
What is micturating cystourethrography?
What is it used for?
A micturating cystourogram is used to investigate:
-Recurrent urinary tract infections in children, or
-A single urinary tract in a young child
-Disturbed bladder function in adults
Suspected vesico-ureteric reflux (and grading)
The patient is catheterised and the bladder filled with contrast. The patient is then screened whilst voiding.
What are the advantages of US?
-Cheap and readily available
-Contrast is not nephrotoxic
-Real time imaging
What are the disadvantages of US?
Limited by body habitus and gas
Poor visualisation of ureteres
No functional information
Why is US doppler handy?
Can show blood flow
-Peak diastolic and systolic flow can be measured
May show renal artery stenosis
CTA -CT angiography much better though
What are the advantages of CT?
-Imaging modality of choice in many circumstances
-Good spatial resolution with capability of multi planar reformat
What are the disadvantages of CT?
Contrast resolution less than MR
Contrast reaction and nephrotoxicity
What circumstances is CT the imaging of choice?
Detection of renal stones
Staging renal tumours
Investigation of haematuria
What should be done with all patients before contrast media is given?
eGFR because of contrast media nephrotoxicity
What are the advantages of MR?
Excellent contrast resolution
Imaging of urothelium without contrast injection (MRU)
What are the disadvantages of MR?
Poor spatial resolution
Poor detection of calcification and stones
Contraindications: pace maker, claustrophobia, etc
Contrast reaction and other side effects
Why can the use of saturation in MR be handy for tumours?
When using saturation can compare the tumour to surrounding tissues
If its the same as fat for lots of saturations its probably a lipoma
Describe the different isotope scans
- To look for renal scarring
-Asses renal function and drainage
-Metastatic disease e.g. prostate cancer
How is PET-CT used in urology?
Limited use in staging of urological malignancies due to high uptake in urine and variable uptake by tumours
May be useful for extra-urological metastatic disease if other imaging modalities are equivocal or in poor surgical candidates
What is the best imaging modality to diagnose renal tract stones?