Prospective and retrospective ECG gating for thoracic CT angiography: a comparative study

Area of Science:

• Radiology
• Cardiovascular Imaging
• Medical Physics

Background:

• Multidetector-row CT (MDCT) thoracic aortography is crucial for evaluating aortic diseases.
• Cardiac gating techniques, prospective and retrospective, are used to minimize motion artifacts in thoracic CT angiography.
• Optimizing radiation dose and contrast load while maintaining image quality is essential in CT imaging.

Purpose of the Study:

• To compare radiation dose, contrast load, thoracic aortic attenuation, and image quality between prospective and retrospective ECG-gated MDCT thoracic aortography.
• To determine the optimal gating strategy for thoracic CT angiography.

Main Methods:

• Eighty patients undergoing MDCT thoracic aortography were divided into two groups: prospective ECG gating (n=40) and retrospective ECG gating (n=40).
• Radiation dose (CTDIvol, DLP), contrast load, and aortic attenuation values were recorded.
• Image quality was assessed by evaluating motion and banding artifacts on MIP images.

Main Results:

• Prospective ECG gating resulted in significantly lower CTDIvol (28.8 mGy vs. 74.7 mGy) and DLP (833.8 mGy/cm vs. 2,547.3 mGy/cm) (p < 0.001).
• The prospective group had a slightly higher average contrast load (109.1 mL vs. 101.3 mL) (p < 0.05).
• Aortic attenuation values were higher in the prospective group across all measured segments.

Conclusions:

• Prospective ECG-gated thoracic CT angiography offers a significant reduction in radiation dose compared to retrospective gating.
• While contrast load was slightly higher with prospective gating, it yielded improved aortic attenuation values.
• Image quality, in terms of motion and banding artifacts, was equivalent between both gating techniques.