How Do You Calculate ICA/CCA Ratio

ICA/CCA Ratio Formula:

\[ ICA/CCA\ Ratio = \frac{PSV_{ICA}}{PSV_{CCA}} \]

ICA/CCA Ratio:

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1. What is ICA/CCA Ratio?

The ICA/CCA (Internal Carotid Artery/Common Carotid Artery) ratio is a measurement used in vascular ultrasound to assess carotid artery stenosis. It compares the peak systolic velocity (PSV) in the internal carotid artery to that in the common carotid artery.

2. How Does the Calculator Work?

The calculator uses the ICA/CCA ratio formula:

\[ ICA/CCA\ Ratio = \frac{PSV_{ICA}}{PSV_{CCA}} \]

Where:

\( PSV_{ICA} \) — Peak systolic velocity in the internal carotid artery (cm/s)
\( PSV_{CCA} \) — Peak systolic velocity in the common carotid artery (cm/s)

Explanation: This ratio helps normalize velocity measurements and provides a more accurate assessment of stenosis severity than PSV alone.

3. Importance of ICA/CCA Ratio Calculation

Details: The ICA/CCA ratio is crucial for diagnosing and grading carotid artery stenosis. Higher ratios typically indicate more severe stenosis, helping clinicians determine appropriate treatment strategies.

4. Using the Calculator

Tips: Enter PSV values in cm/s for both ICA and CCA. Ensure measurements are taken correctly with proper Doppler angle correction (typically 60 degrees or less).

5. Frequently Asked Questions (FAQ)

Q1: What is a normal ICA/CCA ratio?
A: A normal ICA/CCA ratio is typically less than 1.5. Ratios above 2.0 often indicate significant stenosis (>50%).

Q2: How does ICA/CCA ratio compare to PSV for stenosis assessment?
A: The ratio helps account for variations between patients and provides a more standardized measurement than PSV alone, especially in patients with low cardiac output.

Q3: When should ICA/CCA ratio be used?
A: It's particularly useful when PSV values are borderline or when there are technical limitations in obtaining absolute velocity measurements.

Q4: Are there limitations to using ICA/CCA ratio?
A: The ratio may be less reliable in cases with tandem lesions, contralateral high-grade stenosis, or when CCA velocities are abnormally high or low.

Q5: How does the ratio change with increasing stenosis?
A: The ratio generally increases with the severity of stenosis, with values above 4.0 typically indicating severe stenosis (>70%).