What is the recommended initial imaging for a stable patient with a left upper quadrant (LUQ) bruit?

Initial Imaging for a Stable Patient with Left Upper Quadrant (LUQ) Bruit

Duplex carotid Doppler ultrasonography is the recommended initial imaging modality for a stable patient with a left upper quadrant bruit to evaluate for potential splenic artery stenosis or aneurysm. 1

Diagnostic Approach

• Duplex ultrasonography should be the first-line imaging test due to its non-invasive nature, lack of radiation exposure, and high sensitivity (90%) and specificity (94%) for detecting significant vascular stenosis 1
• Ultrasound is particularly valuable as an initial screening tool for vascular abnormalities in the abdominal region, providing both anatomical and hemodynamic information 2, 3
• The presence of a LUQ bruit correlates with potential splenic artery stenosis or aneurysm, similar to how carotid bruits correlate with systemic atherosclerosis 1, 4

Imaging Algorithm

Step 1: Initial Evaluation

• Begin with abdominal duplex ultrasonography focused on the left upper quadrant to evaluate the splenic artery and surrounding vasculature 2, 1
• Ultrasonography can identify potential causes of the bruit including stenosis, aneurysm, or arteriovenous malformations 2

Step 2: Follow-up Imaging (if indicated)

• If ultrasonography reveals significant vascular abnormalities or is technically limited:

  • CT angiography (CTA) with IV contrast is recommended as the next step to provide detailed anatomic assessment of stenosis and evaluation of other abdominal vessels 5
  • CTA offers superior spatial resolution approaching that of conventional angiography with modern multidetector scanners 5

• If CTA is contraindicated (renal impairment, contrast allergy):

  • MR angiography (MRA) with or without contrast is an acceptable alternative 5

Clinical Considerations

• A LUQ bruit may indicate splenic artery stenosis, similar to how carotid bruits indicate potential carotid stenosis 1, 6
• The positive predictive value of bruits for significant stenosis is relatively low (approximately 30%), which increases the importance of radiographic evaluation 2
• Abdominal bruits may have prognostic significance, as diastolic components can indicate more severe stenosis 4, 6

Common Pitfalls to Avoid

• Avoid proceeding directly to invasive angiography as an initial test, as non-invasive options provide sufficient diagnostic information in most cases 2, 1
• Do not order MRI or CT perfusion studies as initial tests in the evaluation of asymptomatic bruits 1
• Be aware that ultrasonography is operator-dependent, and its accuracy may be limited by patient body habitus or bowel gas 2, 3
• Remember that CTA may underestimate stenosis in the setting of tortuosity or dense calcifications, and may overestimate stenosis in cases of very severe near-occlusive stenosis 5