Imaging in Urology

This chapter covers common imaging techniques and indications in your day to day practice. It is not uncommon to sometimes wonder what modality would best serve to answer a clinical question.

General rules
Ensure that a urine pregnancy test has been completed before requesting ionising radiation for a woman of childbearing age.
ALARA - As Low As Reasonably Achievable - use the minimum amount of ionising radiation to achieve an adequate image to help with your diagnosis.

X Rays

1. For kidney/bladder/ureteric stones for follow-up (does not replace CTs for diagnosis)

2. Note ureteric stent position

3. For nephrostograms (flushing nephrostomies with dye and observing for patency) and to confirm the placement/position of a nephrostomy

4. When booking a patient in for a ureteroscopy and stent, always book fluoroscopy and contact the theatre radiographers to let them know, as a C-arm will be needed intraoperatively

5. Urethrogram (with dye)

6. Cystogram (with dye)
   
   

Ultrasound KUB

1. For kidney/bladder/ureteric stones in young patients

2. Upper tract imaging in non-visible haematuria

3. Upper tract imaging if deranged renal function, hydronephrosis and high-pressure chronic retention

4. Assessment of hydronephrosis
   
   

CT KUB (non-contrast CT scan)

1. Gold standard for renal tract calculi

2. Helps with diagnosing pyelonephritis (primarily a clinical diagnosis)

3. Can help follow up on conservatively managed ureteric stones / monitoring renal stones. In this case, a low dose or ultra-low dose protocol can be utilised.
   
   

CT urogram (CT KUB with contrast)

1. Upper tract imaging of choice in visible haematuria

2. Renal trauma

3. Confirming a PUJO
   
   

Nephrostogram

1. Assess the patency of a nephrostomy

2. Assess the patency of the ureter and if an obstruction is persisting

3. Pre-op for planning
   
   

MRI

1. Prostate imaging - can confirm if there is a target (described as PIRADS scores) or region of interest to biopsy. Bi-parametric MRIs do not use contrast while Multi-parametric MRIs rely on contrast for an additional series. The current standard of care is a pre-biopsy Multi-parametric MRI prostate

2. MR Urogram - useful in pregnancy to confirm if there is a filling defect compatible with a ureteric colic (useful in pregnancy)

3. MRI kidney - To characterise a renal mass especially if there is concern of IVC extension of the tumour thrombus
   
   

MAG 3

Uses furosemide

1. Assesses perfusion, filtration and drainage of the kidneys

2. Assessing split renal function

3. Assessment of hydronephrosis without an obviously identifiable radiological cause (PUJ obstruction)

4. Assessment of ectopic kidneys
   
   

DMSA

1. Useful in the assessment of renal scarring

2. Assessing split renal function