Imaging

Superior Vena Cava Syndrome

Preliminary Diagnosis: Superior vena cava syndrome

I. What imaging technique is first-line for this diagnosis

  • CT with IV contrast

II. Describe the advantages and disadvantages of this technique for diagnosis of superior vena cava syndrome.

Advantages

  • Will establish the level and extent of obstruction

  • Can guide therapeutic options by mapping collaterals and patent vasculature

  • Can determine if an obstructing lesion is intrinsic or extrinsic to the superior vena cava (SVC) and evaluate other critical structures

Disadvantages

  • Exposure to ionizing radiation

  • Risk of contrast-induced nephropathy

III. What are the contraindications for the first-line imaging technique?

  • Renal failure

  • Pregnancy

IV. What alternative imaging techniques are available?

  • MRI

  • Ultrasound

  • Angiography

  • Radionuclide imaging with Tc-99m pertechnetate

  • Plain-film radiography

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of superior vena cava syndrome.

MRI

Advantages

  • Demonstrates non-opacification of the SVC, similar to CT

  • MR venography can map out the extent and degree of venous obstruction and collateral circulation, which may aid in operative planning

  • Can evaluate causes of obstruction external to the SVC

  • May be performed without intravenous contrast

Disadvantages

  • Expensive

  • Long examination times require patient cooperation

  • Certain implanted metallic devices are non-compliant

  • Risk of nephrogenic systemic fibrosis in renal failure patients

Ultrasound

Advantages

  • Cost-effective noninvasive examination

  • May demonstrate dilated SVC and distended collateral vessels

  • Can show absent or sluggish blood flow

Disadvantages

  • Operator-dependent

  • Does not evaluate entire SVC

Angiography

Advantages

  • Conventional venography is the gold standard for diagnosing abnormalities of the SVC, demonstrating lack of contrast flow through the SVC

  • May be used in treatment planning for endovascular procedures

Disadvantages

  • Angiography may not reveal the primary pathology that results in extrinsic obstruction

  • It is an invasive procedure with risk of infection, bleeding, and vessel injury

  • Risk of contrast-induced nephropathy in patients with renal failure

Radionuclide imaging with Tc-99m pertechnetate

Advantages

  • The radionuclide injected in the brachial vein can demonstrate obstruction of flow to the right heart and enlarged collateral veins

Disadvantages

  • Limited evaluation of the underlying pathology

Plain-film radiography

Advantages

  • Simple examination to demonstrate widening of the superior mediastinum due to mediastinal mass or dilated SVC

  • Cost-effective screening modality with minimal radiation exposure

Disadvantages

  • Findings are nonspecific

  • Normal chest radiography does not exclude SVC obstruction

VI. What are the contraindications for the alternative imaging techniques?

MRI

  • Pacemakers, non-compatible metallic implants, and aneurysm clips

  • Renal failure if contrast is administered due to the risk of nephrogenic systemic fibrosis

  • Pregnancy during the first trimester may be a relative contraindication

Ultrasound

  • No significant contraindications

Angiography

  • Renal failure due to risk of contrast-induced nephropathy

  • Contrast allergy may be a relative contraindication

Radionuclide imaging with Tc-99m pertechnetate

  • Pregnancy and breast feeding

Plain-film radiography

  • No significant contraindications exist. Some institutions may require consent in pregnant patients.

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