[Can Echocardiography Adjust Corrected Contrast Injection Condition in Coronary CT Angiography?]

Area of Science:

• Cardiovascular Imaging
• Radiology
• Medical Physics

Background:

• Coronary computed tomography angiography (CCTA) requires optimal contrast enhancement for accurate diagnosis.
• Variability in patient cardiac function can lead to inconsistent contrast effects in CCTA.
• Achieving a target CT value (e.g., 350 HU) is crucial for diagnostic image quality.

Purpose of the Study:

• To identify echocardiographic factors correlating with CT values in CCTA.
• To refine contrast injection protocols using cardiac function to minimize inter-patient variability.
• To achieve a target CT value of 350 HU in CCTA examinations.

Main Methods:

• A conventional group (112 patients) received contrast at a fractional dose (FD) of 21 mgI/kg/s, with aortic CT values measured.
• A correction group (112 patients) had contrast injection adjusted based on the most correlated cardiac function factor and CT value.
• Stroke volume (SV) was identified as the primary correlating factor.

Main Results:

• The conventional group averaged 400.8±51.5 HU; the correction group averaged 360±46 HU.
• Stroke volume showed the strongest correlation (r=-0.555) with CT values.
• The proportion of scans meeting the target CT level improved from 46% to 74%.
• The corrected protocol reduced average FD to 18.5 mgI/kg/s and contrast material use in 95% of patients.

Conclusions:

• Stroke volume is the key cardiac function factor correlating with coronary artery CT values.
• Correcting contrast injection based on cardiac function and body weight allows precise control of CCTA CT values.
• This method enables consistent achievement of target CCTA CT values between 300-400 HU.