Will a computed tomography (CT) angiogram show ejection fraction?

CT Angiogram and Ejection Fraction Assessment

CT angiography does not directly show ejection fraction but can be used to calculate it through post-processing of the acquired images.

How CT Angiography Relates to Ejection Fraction

CT angiography primarily visualizes coronary artery anatomy and stenosis, but with appropriate ECG-gating and post-processing, it can provide quantitative measurements of left ventricular volumes and function, including ejection fraction.

Technical Requirements for EF Assessment via CT

• ECG-gating is essential for proper evaluation of cardiac function 1
• Contrast enhancement is required to visualize the cardiac chambers and calculate volumes 2
• Post-processing software is needed to segment the left ventricle and calculate end-systolic and end-diastolic volumes 3

Accuracy and Reliability

• Modern CT technology can provide quantitative measurements of left ventricular volumes, ejection fraction, and mass with results comparable to cardiac magnetic resonance (CMR) 1
• Low-dose CT protocols have demonstrated good correlation with radionuclide angiography for LVEF measurement (r = 0.863) while delivering lower radiation doses 4
• Software-based quantification of left ventricular function using 64-slice CT coronary angiography shows good reproducibility for EF measurements 3

Advantages of CT for EF Assessment

1. Comprehensive assessment: CT provides information about coronary anatomy and cardiac function in a single examination
2. Speed: CT LVEF imaging duration (mean 4:32 minutes) is significantly shorter than traditional radionuclide angiography (mean 9:05 minutes) 4
3. Reduced radiation: Modern low-dose CT protocols can deliver lower radiation doses than traditional radionuclide angiography (4.7 vs 9.5 mSv) 4

Limitations and Considerations

• Limited temporal resolution: Compared to echocardiography or CMR, CT has lower temporal resolution which may affect accuracy in patients with arrhythmias
• Radiation exposure: Despite advances in dose reduction, CT still involves ionizing radiation
• Contrast requirements: Iodinated contrast is necessary, which may be contraindicated in patients with renal impairment

Alternative Modalities for EF Assessment

• Echocardiography: Most commonly used imaging technique due to wide availability and lack of radiation 1
• Cardiac MRI: Provides excellent image resolution for accurate quantification of chamber volumes and ventricular function 1
• Radionuclide angiography: Allows accurate quantification of LVEF with gated acquisition 1

Clinical Application

When evaluating a patient who needs both coronary assessment and ejection fraction measurement, CT angiography with ECG-gating represents an efficient option that provides both pieces of information in a single examination, particularly when:

1. Echocardiographic windows are suboptimal
2. MRI is contraindicated or unavailable
3. Assessment of both coronary anatomy and ventricular function is needed

For patients who only need ejection fraction assessment without coronary evaluation, echocardiography remains the first-line modality due to its wide availability, lack of radiation, and established accuracy.