Can a computed tomography (CT) scan with contrast agent show iliac stenosis?

CT with Contrast for Iliac Stenosis Detection

Yes, CT angiography (CTA) with contrast is highly accurate for detecting iliac artery stenosis, with sensitivity and specificity of 90-100% compared to catheter angiography, and can effectively visualize iliac vein stenosis when proper technique is used. 1

Iliac Artery Stenosis Detection

CTA demonstrates excellent diagnostic performance for arterial disease:

• Sensitivity and specificity for detecting stenoses >50% diameter range from 90% to 100% when compared with catheter angiography 1
• CTA provides volumetric imaging that enables extensive postprocessing including multiplanar reformatted and maximum-intensity projection images to create an arterial road map 1
• CTA can be used alone to plan treatment, including assessment of the length, severity, and number of stenoses 1
• The volumetric acquisition shows collaterals and arteries distal to occlusions that may not appear on catheter angiography 1

Important technical considerations for arterial imaging:

• Heavily calcified atheromatous disease can limit interpretation of CT images, though this is usually more pronounced in tibial arteries than iliac arteries 1
• Dual-energy CTA can reduce blooming and beam-hardening artifact created by heavily calcified disease and metallic stents 1
• CTA of the abdomen and pelvis should be obtained when aortoiliac disease is a concern 1

Iliac Vein Stenosis Detection

CTA can effectively identify iliac vein stenosis using caliber measurements:

• A two-segment caliber method using CTA (with arm vein contrast injection) demonstrates 97% sensitivity for detecting iliac vein stenosis when compared to intravascular ultrasound (IVUS) 2
• Caliber diameter <16 mm for common iliac vein or <14 mm for external iliac vein on CTA correlates with IVUS-confirmed stenosis 2
• The two-segment method (assessing both common and external iliac veins) provides superior accuracy (91%) compared to single-segment assessment 2
• CTV identifies stenosis, occlusion, venous atresia, collaterals, and edema 1

Comparison with other venous imaging modalities:

• MR venography can show webs, trabeculations, and vein wall thickening in addition to stenosis 1
• Duplex ultrasound has difficulty evaluating iliac vein involvement and may require additional imaging 1

Clinical Pitfalls and Caveats

Key limitations to recognize:

• Calcium artifact remains the primary limitation - heavily calcified vessels can lead to overestimation of stenosis severity, though this is less problematic in iliac vessels than in smaller tibial arteries 1
• For venous imaging, routine CT with standard protocols may not provide optimal visualization - dedicated CTV technique with appropriate contrast timing is preferred 2
• Iliac vein stenosis prevalence on imaging (up to 34% on left side) does not always correlate with clinical venous symptoms 3

Optimal imaging technique:

• Use arterial-phase bolus timing for arterial stenosis evaluation 1
• Consider dual-energy CT when significant calcification or stents are present 1
• For venous assessment, arm vein contrast injection with venous-phase timing optimizes iliac vein opacification 2

When CT May Not Be Ideal

• Patients over 80 years of age, diabetic patients, or those on dialysis may have heavily calcified tibial arteries that limit CT interpretation, though iliac vessels are typically less affected 1
• IVUS remains the gold standard for definitive iliac vein stenosis assessment when intervention is planned 2
• MRA may be superior for evaluating tantalum stents, though CT is better for steel, cobalt-based, and nitinol stents 4