Genitourinary Tract

Ivu Radiograph

Currently ultrasound (US) and computed tomography (CT) are the most important imaging techniques in uro-radiology. Renal US is a very important and frequently performed investigation, hence you should be familiar with the fundamentals of this modality. Renal and adrenal tumors are mainly diagnosed by US, CT, and magnetic resonance imaging (MRI). Renal calculi can be demonstrated on US, renal and ureteric calculi on CT (Table 10.1). The intravenous urogram (IVU) or pyelogram (IVP), once the mainstay of imaging of the genito urinary (GU) tract has lost much of its importance. Obtaining an additional frontal scout image at the end of a contrast-enhanced CT examination provides a good overview of the ureters in analogy to the KUB (kidney-ureter-bladder) radiograph formerly obtained during an IVP.

Diseases of the lower urinary tract are mostly diagnosed by endoscopy. Specific investigations of the lower urinary tract and genitals are performed by radiologists, urologists, and gynecologists.

Table 10.1 Suggestions for radiographic work-up of genitourinary conditions1

Clinical problem

Investigation

Comment

Disorders of the kidneys

Hematuria, macroscopic and microscopic

US

To determine calcifications and tumors of kidneys, bladder, and prostate.

CT

Noncontrast CT demonstrates calculi down to the bladder level. Contrast CT reveals tumors of the kidneys, ureters, and bladder.

IVU

Demonstrates collecting system tumors, especially in ureters; less suitable for assessment of renal parenchymal abnormalities.

Hypertension: in the young adult or in patients unresponsive to medication

US

To determine renal size and assess renal parenchyma. Doppler US not sensitive enough for diagnosis.

Angiography (DSA/CTA/MRA)

To show stenosis if surgery or angioplasty is considered as a possible treatment; CTA and MRA allow noninvasive visualization of renal vasculature; may exclude significant stenosis or vascular disease such as fibromuscular dysplasia.

Renal failure

US and AXR

US first investigation to measure kidney size and parenchymal thickness and detect pelvicaliceal dilatation indicating possible obstruction. AXR or stone protocol CT to detect calculi not detectable by US.

CT/MRI

If US is nondiagnostic or does not show the cause of obstruction. MRI is the alternative, especially if nephrotoxic contrast medium must be avoided.

Suspected ureteric colic

CT/IVU

Stone protocol (unenhanced) CT is the method of choice for demonstration of renal and ureteric calculi. IVU is the alternative if CT is unavailable.

US/AXR

Used in combination where radiation or contrast medium is contraindicated.

1Modified after: RCR Working Party. Making the best use of a Department of Clinical Radiology. Guidelines For Doctors, 5th ed. London: The Royal College of Radiologists, 2003.

AXR, abdominal radiography; BUN, blood urea nitrogen; CT, computed tomography; CTA, CT angiography; DSA, digital subtraction angiography; IVU; intravenous urography; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; PSA, prostate specific antigen; US, ultrasound.

Table 10.1 Suggestions for radiographic work-up of genitourinary conditions (Continued)

Clinical problem

Investigation

Comment

Renal calculi in absence of acute colic

CT/AXR

CT best baseline assessment in renal stone disease. AXR is adequate for the majority of calculi.

US

Can detect urate calculi but is less sensitive than CT. Good hydration is essential.

Renal mass

US

Sensitive at detecting masses >2 cm; differentiation between cystic and solid mass.

CT

Sensitive at detecting renal masses of 1.0-1.5 cm or greater and accurately characterizes masses; staging.

MRI

If iodinated contrast medium is contraindicated.

Urinary tract obstruction

US

To assess the upper tract (after catheterization and relief of bladder distention), particularly if BUN/creatinine levels remain raised.

Disorders of the adrenal glands

Suspected adrenal mass

CT/MRI

To demonstrate and characterize an adrenal mass.

Disorders of the prostate

Benign prostatic hyperplasia

US

Renal and bladder US (with measurement of post-void residual volume and urine flow rate).

Rising PSA, suspected prostate cancer

Transrectal US

US-guided biopsies after clinical examination.

Disorders of the testicles

Scrotal mass or pain

For scrotal swelling and when presumed inflammatory scrotal pain does not respond to treatment. Allows differentiation of testicular from extratesticular suspected scrotal mass.

Suspected testicular torsion

Doppler US

Only if clinical findings are equivocal

AXR, abdominal radiography; BUN, blood urea nitrogen; CT, computed tomography; CTA, CTangiography; DSA, digital subtraction angiography; IVU; intravenous urography; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; PSA, prostate specific antigen; US, ultrasound.

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