Effects of combining multiple dose reduction techniques on coronary computed tomography angiography

Abstract

Background: Coronary computed tomography angiography (CCTA) is the preferred non-invasive examination method for coronary heart disease. However, the radiation from computed tomography has become a concern since public awareness of radiation hazards continue to increase.

Aim: To explore the value of multiple dose reduction techniques for CCTA.

Methods: Consecutive normal and overweight patients were prospectively divided into two groups: Group A₁, patients who received multiple dose reduction scans (n = 82); and group A₂, patients who received conventional scans (n = 39). The scan parameters for group A₁ were as follows: Isocentric scan, tube voltage = 80 kV, and tube current control using 80% smart milliampere. The scan parameters for group A₂ were as follows: Normal position, tube voltage = 100 kV, and smart milliampere.

Results: The average effective doses (EDs) for groups A₁ and A₂ were 1.13 ± 0.35 and 3.36 ± 1.30 mSv, respectively. There was a statistically significant difference in ED between the two groups (P < 0.01). Furthermore, noise was significantly lower, and both signal-to-noise ratio and contrast signal-to-noise ratio were higher in group A₂ when compared to group A₁ (P < 0.01). Moreover, the subjective image quality (IQ) scores were excellent in both groups, in which there was no significant difference in subjective IQ score between the two groups (P = 0.12).

Conclusion: Multiple dose reduction scan techniques can significantly decrease the ED of patients receiving CCTA examinations for clinical diagnosis.

Keywords: Coronary computed tomography angiography; Coronary heart disease; Dose reduction techniques; Isocentric scanning; Radiation.

Figure 1

For group A₁, the isocentric scan was performed with the patient in supine position and their body shifted to the right. A: Conventional position; B: Isocentric scanning.

Figure 2

Subjective imaging quality scores. A: Excellent imaging quality (IQ) (score = 5) with sharp, smooth contours of the vascular wall and no streaking or radiating artifacts; B: Good IQ (score = 4) with slight irregularities on the contour and few streaks or radiating artifacts; C: Fair IQ (score = 3) with blurred and irregular contours of the vascular wall and numerous streaks or radiating artifacts; D: Poor IQ (score = 2) with deformation of the vascular wall and various artifacts; E: Very poor IQ (score = 1) with obvious deformation of the vascular wall and extensive artifacts. Images with IQ scores within 3-5 satisfy the requirements for the diagnostic assessment.

Figure 3

A 69-year-old female patient in group A₁. For the multislice computed tomographic angiography, the image quality score was 5 (excellent) for left anterior descending artery segments 5-8. A and B: Volume rendering; C: Curved planar reformation. Body mass index: 26.40; Effective dose: 1.18 mSv; Noise: 18.80; Signal-to-noise ratio: 52.68; Contrast signal-to-noise ratio: 42.89.

Figure 4

A 64-year-old female patient in group A₁. For the multislice computed tomographic angiography, the image quality score was 5 (excellent) for left anterior descending artery segments 5-8. A and B: Volume rendering; C: Curved planar reformation. Body mass index: 26.40; Effective dose: 1.83 mSv; Noise: 22.50; Signal-to-noise ratio: 43.90; Contrast signal-to-noise ratio: 30.40.

Figure 5

A 68-year-old female patient in group A₂. For the multislice computed tomographic angiography, the image quality score was 5 (excellent) for left anterior descending artery segments 5-8. A and B: Volume rendering; C: Curved planar reformation. Body mass index: 22.38; Effective dose: 3.33 mSv; Noise: 13.10; Signal-to-noise ratio: 74.69; Contrast signal-to-noise ratio: 58.85.