Image quality and radiation exposure using different low-dose scan protocols in dual-source CT coronary angiography:...

Area of Science:

• Radiology
• Cardiovascular Imaging
• Medical Imaging Technology

Background:

• Computed tomographic (CT) coronary angiography is crucial for diagnosing coronary artery disease.
• Image quality and radiation dose are key considerations in CT coronary angiography protocols.
• Patient heart rate significantly influences the success and safety of CT coronary angiography.

Purpose of the Study:

• To compare image quality, radiation dose, and their relationship with heart rate for different CT coronary angiographic scan protocols.
• To evaluate the efficacy of high-pitch spiral, sequential (narrow and wide-window), and retrospective spiral scanning techniques.
• To determine optimal CT coronary angiography protocols based on patient heart rate using a 128-section dual-source CT scanner.

Main Methods:

• A study involving 272 patients undergoing CT coronary angiography was conducted.
• Patients were categorized into two groups based on heart rate: <65 bpm (Group A) and ≥65 bpm (Group B).
• Group A patients were randomized to high-pitch spiral or narrow-window sequential scanning; Group B patients received wide-window sequential or retrospective spiral scanning.

Main Results:

• In Group A, high-pitch spiral scanning yielded significantly lower image quality compared to sequential scanning (P < .001), except in those with heart rates <55 bpm.
• Image quality was comparable between sequential and retrospective spiral scanning in Group B (P = .54).
• Mean radiation doses were significantly lower with high-pitch spiral scanning in Group A and sequential scanning in Group B compared to alternative protocols within each group (P < .001 and P = .02, respectively).

Conclusions:

• High-pitch spiral CT coronary angiography protocols are recommended for patients with regular, low heart rates (<55 bpm) due to reduced radiation exposure.
• Sequential CT coronary angiography protocols are preferred for patients with heart rates of 65 bpm or higher.
• Protocol selection should be tailored to patient heart rate to optimize the balance between image quality and radiation dose in CT coronary angiography.