What is the best imaging study for evaluating a splenic artery aneurysm?

Best Imaging Study for Splenic Artery Aneurysm Evaluation

CT angiography (CTA) is the best imaging study for evaluating splenic artery aneurysm, providing optimal visualization of vascular anatomy, precise size measurements, differentiation between true aneurysms and pseudoaneurysms, and essential information for treatment planning. 1

Primary Imaging Modality

CTA with arterial-phase timing is the reference standard for splenic artery aneurysm evaluation because it:

• Accurately delineates the location, size, and extent of the aneurysm with submillimeter resolution 2
• Differentiates true aneurysms from pseudoaneurysms, which is critical since pseudoaneurysms have higher rupture risk and require different management 1
• Provides multiplanar reformations and 3D renderings essential for treatment planning, whether endovascular or surgical 2
• Assesses branch vessel involvement and relationship to surrounding structures 2
• Evaluates for thrombus within the aneurysm, which affects hemodynamic properties 2

Critical Technical Considerations

Arterial-phase timing is mandatory - this is a common pitfall that can lead to missed diagnoses:

• Portal venous-phase CT alone is insufficient and may miss splenic artery aneurysms, particularly when extensive portal venous collaterals are present 3
• Dedicated arterial-phase imaging distinguishes the aneurysm from adjacent venous structures like splenic varices, which can appear similar on venous-phase or Doppler ultrasound 3
• The distinction is especially critical in patients with portal hypertension or liver disease 3

Alternative Imaging Options

MR angiography (MRA) with contrast may be substituted when CTA is contraindicated (contrast allergy, significant renal dysfunction), though it is not the first choice 2, 4

Catheter angiography has very limited utility and is reserved only for:

• Patients with contraindications to both CTA and MRA 2, 4
• Immediate pre-procedural planning for endovascular intervention 5

Inadequate Imaging Modalities

Doppler ultrasound is insufficient as the primary diagnostic tool because:

• It cannot reliably differentiate splenic artery aneurysms from venous collaterals or varices 3
• It provides limited anatomic detail for treatment planning 6
• However, it may detect the lesion initially, prompting further evaluation with CTA 6

Non-contrast CT will miss or inadequately characterize splenic artery aneurysms, as contrast enhancement with arterial timing is essential for diagnosis 3

Clinical Context for Imaging

The urgency and approach depend on presentation:

• Ruptured aneurysms (5.5% of cases) require emergent CTA if the patient is stable enough, with 29% perioperative mortality 7
• Asymptomatic incidental findings should undergo CTA for complete characterization and size measurement 5, 7
• High-risk patients (pregnant women, women of childbearing age, liver transplant candidates, aneurysms >2 cm) require CTA for treatment planning since these warrant intervention 5, 6, 7

Common Pitfalls to Avoid

• Do not rely on portal venous-phase CT alone - always obtain dedicated arterial-phase imaging 3
• Do not use ultrasound as definitive imaging - it may suggest the diagnosis but cannot adequately characterize the aneurysm 3
• Do not delay CTA in symptomatic patients - symptoms suggest impending rupture requiring urgent evaluation 5, 6
• Ensure proper measurement technique using multiplanar reformations perpendicular to the vessel axis to avoid overestimation from tortuous anatomy 2