1. What is ICA/CCA Ratio?

The ICA/CCA (Internal Carotid Artery/Common Carotid Artery) ratio is a Doppler ultrasound measurement used to assess carotid artery stenosis. It compares the peak systolic velocity in the internal carotid artery to that in the common carotid artery, providing a standardized method for evaluating stenosis severity.

2. How Does the Calculator Work?

The calculator uses the ICA/CCA ratio formula:

Where:

• \( PSV_{ICA} \) — Peak Systolic Velocity in Internal Carotid Artery (cm/s)
• \( PSV_{CCA} \) — Peak Systolic Velocity in Common Carotid Artery (cm/s)

Explanation: The ratio helps normalize velocity measurements, reducing variability between patients and improving the accuracy of stenosis assessment.

3. Importance of ICA/CCA Ratio

Details: The ICA/CCA ratio is particularly valuable in Australian clinical practice as it provides a reliable method for classifying carotid stenosis severity. Higher ratios typically indicate more severe stenosis, helping clinicians determine appropriate treatment strategies.

4. Using the Calculator

Tips: Enter PSV measurements in cm/s obtained from Doppler ultrasound. Both values must be positive numbers. The calculator will compute the ratio, which can then be compared to established thresholds for stenosis classification.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ICA/CCA ratio values for different stenosis levels?
A: Generally, ratios below 2.0 suggest mild stenosis (0-49%), ratios between 2.0-4.0 indicate moderate stenosis (50-69%), and ratios above 4.0 suggest severe stenosis (70-99%).

Q2: Why is this ratio specifically relevant in Australia?
A: Australian vascular ultrasound guidelines have adopted the ICA/CCA ratio as a standard measurement for carotid stenosis assessment, making it particularly relevant in the Australian clinical context.

Q3: Are there limitations to using the ICA/CCA ratio?
A: While valuable, the ratio should be interpreted alongside other Doppler parameters and clinical findings. Technical factors like angle correction and sample volume placement can affect accuracy.

Q4: How does contralateral disease affect the ratio?
A: Severe contralateral disease may elevate CCA velocities, potentially lowering the ratio and underestimating ipsilateral stenosis severity.

Q5: Should this ratio be used alone for treatment decisions?
A: No, the ratio should be part of a comprehensive assessment including other Doppler parameters, clinical symptoms, and possibly additional imaging before making treatment decisions.