What is the significance of heart rate in a Cardiac Computed Tomography (CT) scan?

From the Guidelines

Heart rate plays a crucial role in Cardiac Computed Tomography (CT) scans, as it can significantly impact image quality by introducing motion artifacts.

Significance of Heart Rate

• A lower heart rate is desirable to minimize motion artifacts, with a target heart rate of 60 beats per minute or less for optimal image quality on lower temporal resolution MDCT scanners 1.
• For scanners with a temporal resolution of at least 167 ms, a heart rate of 75 beats per minute can result in acceptable image quality, while dual-source CT scanners can produce acceptable image quality at heart rates of up to 90 beats per minute 1.

Pharmacological Heart Rate Control

• Pharmacological heart-rate control may be necessary for patients with higher heart rates, using oral or intravenous beta-blockers to decrease heart rate, if there are no contraindications 1.
• The use of sublingual nitroglycerin immediately before the scan can also improve image quality by achieving vasodilatation, although this is based on a small study using 16-slice MDCT 1.

Technical Considerations

• Temporal resolution of the CT scanner is critical, with a desirable range of 19 to 75 ms for coronary CTA, depending on the patient's heart rate and the phase of the cardiac cycle 1.
• Electrocardiogram-gated imaging and retrospective reconstruction of images from projection data acquired during the phase of the cardiac cycle with the least cardiac motion can help minimize motion artifacts 1.

From the Research

Significance of Heart Rate in Cardiac Computed Tomography (CT) Scan

• Heart rate plays a crucial role in determining the image quality of Cardiac Computed Tomography (CT) scans 2, 3, 4, 5, 6
• A lower heart rate is generally associated with better image quality, as it reduces motion artifacts 4, 5, 6
• Studies have shown that heart rates above 70 beats per minute (bpm) can lead to decreased image quality and increased motion artifacts 2, 3, 4, 5, 6
• However, advancements in CT technology, such as whole-heart coverage in a single rotation and motion-correction algorithms, can improve image quality even at higher heart rates 2, 3
• The optimal heart rate for Cardiac CT scans varies depending on the specific CT scanner and technology used, but generally falls within the range of 60-70 bpm 4, 5

Factors Affecting Image Quality

• Heart rate: lower heart rates are associated with better image quality 4, 5, 6
• Body Mass Index (BMI): higher BMIs can lead to decreased image quality 6
• CT scanner technology: advancements in CT technology can improve image quality even at higher heart rates 2, 3
• Motion-correction algorithms: can improve image quality by reducing motion artifacts 3, 6

Optimal Reconstruction Phase

• The optimal reconstruction phase for Cardiac CT scans depends on the heart rate 4
• For heart rates below 70 bpm, reconstruction at the diastolic phase is generally preferred 4
• For heart rates above 70 bpm, larger studies are necessary to determine the optimal reconstruction phase 4