From the Guidelines
The best imaging modality to evaluate a carotid bruit in a patient with hypertension, stage 4 CKD, and a permanent pacemaker is carotid duplex ultrasonography. This non-invasive test should be the first-line approach as it provides detailed information about carotid stenosis without exposing the patient to radiation or nephrotoxic contrast agents. The ultrasound can effectively assess the degree of stenosis, plaque characteristics, and blood flow velocities in the carotid arteries. For this patient, carotid ultrasound is particularly advantageous because it avoids the risks associated with other imaging modalities:
- CT angiography would require iodinated contrast that could worsen kidney function in someone with stage 4 CKD;
- MRI/MRA is contraindicated due to the permanent pacemaker;
- and conventional angiography is too invasive as an initial test. According to the most recent guidelines, duplex carotid Doppler is a very accurate and useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in the asymptomatic patient with a carotid bruit, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis 1. The ultrasound should be performed by an experienced vascular technologist and interpreted by a specialist familiar with cerebrovascular disease. If the ultrasound results are inconclusive or if surgical intervention is being considered, further discussion with specialists would be needed to determine the safest additional imaging approach given the patient's complex comorbidities. It is also worth noting that carotid ultrasonography, CTA, and MRA can provide the information needed to guide the choice of medical, endovascular, or surgical treatment in most cases, but carotid duplex ultrasonography is the preferred initial test 1. In this case, given the patient's stage 4 CKD and permanent pacemaker, carotid duplex ultrasonography is the most appropriate initial imaging modality to evaluate the carotid bruit.
From the Research
Evaluation of Bruit in the Right Carotid Artery
To evaluate the bruit in the right carotid artery in a patient with primary hypertension, stage 4 Chronic Kidney Disease (CKD), and a permanent pacemaker, the following imaging modalities can be considered:
- Duplex ultrasonography of the carotid arteries: This is a non-invasive and widely used method for detecting and grading internal carotid artery (ICA) stenosis 2, 3, 4, 5.
- Magnetic Resonance Angiography (MRA): This modality can provide detailed images of the carotid arteries and is useful for detecting stenosis and occlusion 4, 6.
- Computed Tomography Angiography (CTA): This modality can also provide detailed images of the carotid arteries and is useful for detecting stenosis and occlusion 4, 6.
- Transcranial Doppler ultrasound: This modality is useful for evaluating blood flow in the cerebral vessels, but it may not provide direct imaging of the carotid arteries.
Recommended Imaging Modality
Based on the available evidence, duplex ultrasonography of the carotid arteries is the recommended initial imaging modality for evaluating the bruit in the right carotid artery 2, 3, 4, 5. This modality is non-invasive, widely available, and has been shown to be accurate in detecting and grading ICA stenosis. If the results of the duplex ultrasonography are inconclusive or if further evaluation is needed, MRA or CTA can be considered as additional imaging modalities 4, 6.
Key Findings
- Duplex ultrasonography has been shown to be accurate in detecting and grading ICA stenosis, with a sensitivity of 86.4% and a specificity of 90.1% for detecting 70% or more stenosis 3.
- The use of duplex ultrasonography as the single preoperative diagnostic method should be exercised with caution, and the limitations should be considered 4.
- MRA and CTA can provide detailed images of the carotid arteries and are useful for detecting stenosis and occlusion, but they may not be necessary as initial imaging modalities 4, 6.