Imaging of the renal system Flashcards
How long is each kidney?
10-12cm
How much does each adult kidney weigh?
120-170g
Describe renal blood flow in cc/min
Renal blood flow 1200 cc/min
At what vertebral levels are the kidneys found?
They typically extend from T12 to L3, although the right kidney is often situated slightly lower due to the presence of the liver
How long are the ureters?
25-30 cm long
What is the diameter of the ureters?
3-8mm
Where are the 3 constrictions of the ureter?
o PUJ
o Pelvic brim
o VU junction
From what part of the bladder does the ureteric and urethral orifices found?
trigone
When is renal imaging indicated?
- Renal colic and renal stone disease
- Diagnosis and follow up
- Haematuria
- Suspected renal mass
- UTIs
- Hypertension
List some imaging techniques used for renal disease
Plain film – KUB x-ray Contrast studies o IVU o Pyelography: antegrade, retrograde, ileal conduit o Cystography Ultrasound +/- contrast CT and CTU (computed tomography urography) MR and MRU Isotope scans PET-CT
List the advantages and disadvantages of plain film xrays
Advantages
o Cheap and readily available
o Functional and anatomical information (intravenous urography, IVU)
Disadvantages
o Low sensitivity and specificity for urological diseases
o Radiation
List some contrast studies used in renal investigations
Pyelography
Intravenous urography, IVU
Micturating cystourethrography
List the advantages and disadvantages of ultrasound when investigating renal disease
Advantages o Cheap and readily available o No radiation o Contrast is not nephrotoxic o Real time imaging
Disadvantages o Limited by body habitus and gas o Poor visualisation of ureters o Operator dependant o No functional information
List the advantages and disadvantages of CT when investigating renal disease
Advantages
o Currently the imaging modality of choice for detection of renal stones, staging renal tumours, investigation of haematuria
o Good spatial resolution with capability of multi planar reformat
Disadvantages o Radiation dose o Cost o Contrast resolution less than MR o Contrast reaction and nephrotoxicity
Which imaging modality is the imaging of choice for detection of stones, staging of renal tumours and for investigating haematuria?
CT
List the advantages and disadvantages of MRI when investigating renal disease
Advantages
o Multiplanar imaging
o Excellent contrast resolution
o Imaging of urothelium without contrast injection (MRU)
Disadvantages
o Poor spatial resolution
o Poor detection of calcification and stones
o Cost
o Contraindications: pace maker, claustrophobia,etc
o Contrast reaction and other side effects
What is MRU?
Magnetic resonance urography - uses dye alongside MRI to see functionality of renal system
List 3 types of isotope scans used for renal disease
DMSA
o To look for renal scarring
MAG3
o Assess renal function and drainage
Bone scan
o Metastatic disease e.g. prostate cancer
What is a DMSA isotope scan used for?
Looks for renal scarring
What is a MAG3 isotope scan used for?
Assess renal function and drainage
What is a bone scan used for in renal disease?
Metastatic disease e.g. prostate cancer
What is PET-CT used for in renal disease?
- 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?
a) Plain films
b) US
c) CT
d) MR
e) Pyelography
c) CT
What imaging modality of choice in staging of renal tumours?
a) US
b) CT
c) MR
d) PET-CT
b) CT
What is the least helpful imaging modality in assessment of patient with suspected renal artery stenosis?
a) CTA
b) MRA
c) US
d) Conventional angiography
c) US
