Imaging Flashcards
How long are the kidneys?
10-12 cm long
How does the size of kidneys vary in individuals?
- The kidneys are slightly larger in men than in women
- They increase in size up to the age of 20 years and become smaller again in later life
How much does each kidney weight?
120-170grams
What is the renal blood flow to the kidneys?
1200cc/min
How long are the ureters?
25-30cm
What is the diameter of the ureters?
3-8mm
What are the anatomical points of narrowing of the ureters?
- PUJ
- Pelvic brim
- VUJ
What separates the ureters from the tip of the transvers processes of the vertebrae?
Passes on the medial edge of psoas muscles which separate it from the tip of the transverse processes.
What is the structure of the bladder?
Pyramidal structure with its base posteriorly and apex behind the symphysis
How is the bladder peritonised?
Extra-peritoneal structure
What is the trigone of the bladder?
Trigone is a triangular area between the ureteric and urethral orifices
What indication are there for renal imaging?
Renal colic and renal stone disease (diagnosis and follow up)
- Haematuria
- Suspected renal mass
- UTIs
- Hypertension
What imaging techniques can be used in renal medicine?
- Plain film
- Contrast studies including IVU, pyelography: and cystography
- Ultrasound +/- contrast
- CT and CTU
- MR and MRU
- Isotope scans
- PET-CT
What are the advantages of plain film x-rays?
- Cheap and readily available
- Functional and anatomical information (IVU)
What are the disadvantages of plain film x-rays?
- Low sensitivity and specificity for urological diseases
- Radiation
What does pyelography involve?
Injection of contrast into the ureters
What does micturating cystourethrography assess?
Vesico-ureteric reflux and its grade
What are the advantages of ultrasound?
- Cheap and readily available
- No radiation
- Contrast is not nephrotoxic
- Real time imaging
What are the disadvantages of ultrasound?
- Limited by body habitus and gas
- Poor visualisation of ureters
- Operator dependant
- No functional information
What are the advantages of CT?
- Currently the imaging modality of choice for detection of renal stones, staging renal tumours, investigation of hematuria
- Good spatial resolution with capability of multi planar reformat
What are the disadvantages of CT?
- Radiation dose
- Cost
- Contrast resolution less than MR
- Contrast reaction and nephrotoxicity
What are the advantages of MR?
- Multiplanar imaging
- 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
- Cost
- Contraindications: pace maker, claustrophobia ,etc
- Contrast reaction and other side effects
Give examples of isotope scans.
- DMSA
- MAG3
- Bone scan
What is a DMSA used for?
To look for renal scarring
What is a MAG3 used for?
Assess renal function and drainage
What is a bone scan used for?
Metastatic disease e.g. prostate cancer
Why is there a limited use for PET-CT in urological malignancies?
Limited use in staging of urological malignancies due to high uptake in urine and variable uptake by tumours
What may PET-CT be useful for?
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?
CT
What imaging modality of choice in staging of renal tumours?
CT
What is the least helpful imaging modality in assessment of patient with suspected renal artery stenosis
US
