Three contrast injection protocols for electrocardiogram-gated 64-slice computed tomographic angiography: comparing...

Area of Science:

• Radiology
• Cardiovascular Imaging
• Medical Imaging

Background:

• Computed tomographic angiography (CTA) is crucial for diagnosing cardiovascular conditions.
• Optimizing contrast injection protocols is essential for maximizing image quality and diagnostic yield in CTA.

Purpose of the Study:

• To compare the effectiveness of three different contrast injection protocols (A, B, and C) for electrocardiogram-gated 64-detector row CTA.
• To evaluate aortic, pulmonary artery (PA), and coronary artery (CA) density and examination quality across these protocols.

Main Methods:

• A retrospective review of 90 CTA studies (30 per protocol) in patients with chest pain and low to moderate suspicion for coronary disease.
• Utilized a 20-mL timing bolus followed by 30 mL saline, with varying contrast volumes and flow rates for Protocols A, B, and C.
• Measured Hounsfield unit (HU) density at 20 points and graded study quality on a 4-point scale.

Main Results:

• Protocol A showed significantly lower main PA density (263 HU) compared to Protocols B (335 HU) and C (366 HU).
• Protocol A had 10 nondiagnostic PA studies, while Protocols B and C each had only 1 nondiagnostic study.
• Left main CA and aortic root densities were not significantly different across protocols, but Protocols B and C yielded more good/very good quality studies.

Conclusions:

• Protocols B and C provide consistently high attenuation in the aorta, PAs, and CAs.
• These optimized protocols lead to commensurate improvements in examination quality for CTA.
• Protocols B and C are recommended for enhanced diagnostic accuracy in CTA evaluations.